Direct chromatographic enantioresolution of fully constrained β-amino acids: exploring the use of high-molecular weight chiral selectors

To the best of our knowledge enantioselective chromatographic protocols on β-amino acids with polysaccharide-based chiral stationary phases (CSPs) have not yet appeared in the literature. Therefore, the primary objective of this work was the development of chromatographic methods based on the use of an amylose derivative CSP (Lux Amylose-2), enabling the direct normal-phase (NP) enantioresolution of four fully constrained β-amino acids. Also, the results obtained with the glycopeptide-type Chirobiotic T column employed in the usual polar-ionic (PI) mode of elution are compared with those achieved with the polysaccharide-based phase. The Lux Amylose-2 column, in combination with alkyl sulfonic acid containing NP eluent systems, prevailed over the Chirobiotic T one, when used under the PI mode of elution, and hence can be considered as the elective choice for the enantioseparation of this class of rigid β-amino acids. Moreover, the extraordinarily high α (up to 4.60) and R S (up to 10.60) values provided by the polysaccharidic polymer, especially when used with camphor sulfonic acid containing eluent systems, make it also suitable for preparative-scale enantioisolations.

Evaluation of liquid chromatographic behavior of lumazinic derivatives, from α-dicarbonyl compounds, in different C18 columns: application to wine samples using a fused-core column and fluorescence detection

Several C18 columns, packed with totally porous particles of different sizes and shell thicknesses, have been compared for simultaneous determination of α-dicarbonyl compounds, previous derivatization to lumazinic derivatives. Chromatographic conditions for the separation have been optimized for each column, and chromatographic parameters have been calculated and exhaustively compared. A core-shell C18 column provided the best results, and a HPLC method with fluorimetric detection has been proposed. The developed method has been validated in terms of linearity, precision, and sensitivity. Detection and quantification limits obtained were comprised between 0.02 and 0.30 and 0.07 and 1.0 ng mL(-1), respectively, while RSD values obtained were lower than 6% and 5% in intraday and interday repeatability studies, respectively. The method has been applied to analysis of the α-dicarbonyl compounds in different types of wines. The higher levels of the total α-dicarbonyl compounds were found in sweet wines and the lower levels in white wines.

A fully automated dual-online multifunctional ultrahigh pressure liquid chromatography system for high-throughput proteomics analysis

A fully automated dual-online multifunctional ultrahigh pressure liquid chromatography (DO-MULTI-UPLC) system has been developed for high throughput proteome analyses of complex peptide mixtures. The system employs two online solid phase extraction (SPE) columns (150μm inner diameter×3cm), two capillary reverse phase (RP) columns (75μm×100cm) and a strong cation exchange (SCX) column (150μm×15cm) on a single system utilizing one binary pump and one isocratic pump. With the automated operation of six switching valves, the selection of LC experiments between single-dimensional RPLC and online two-dimensional SCX/RPLC were achieved automatically, without manual intervention, while two RPLC columns were used independently and alternatively. By essentially removing the dead time for column equilibration between experiments, in either 1D mode or 2D experimental mode, the current system was demonstrated to increase the experimental throughput by about two folds, while keeping the inter-column reproducibility of peptide elution time in less than 1% of gradient time. The advantageous features of the proposed system were demonstrated by its application to proteome samples of varying complexities.

Application of ion chromatography in clinical studies and pharmaceutical industry

Ion chromatography is a well-established regulatory method for analyzing anions and cations in environmental, food and many other samples. It offers an enormous range of possibilities for selecting stationary and mobile phases. Additionally, it usually helps to solve various separation problems, particularly when it is combined with different detection techniques. Ion chromatography can also be used to determine many ions and substances in clinical and pharmaceutical samples. It provides: availability of high capacity stationary phases and sensitive detectors; simple sample preparation; avoidance of hazardous chemicals; decreased sample volumes; flexible reaction options on a changing sample matrix to be analyzed; or the option to operate a fully-automated system. This paper provides a short review of the ion chromatography applications for determining different inorganic and organic substances in clinical and pharmaceutical samples.

Global metabolic profiling using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry

Currently, liquid chromatography-mass spectrometry (LC-MS) is one of the most important analytical technologies for detecting hundreds of metabolites in the field of metabolomics. A recent advance in LC that has impacted metabolomics is the development of UPLC (ultra-performance liquid chromatography). In this chapter, we describe the analytical methodologies for the global metabolic profiling of serum, urine, and tissue samples using UPLC-Q-TOF (quadrupole-time-of-flight)-MS. Aqueous metabolites are extracted after adding methanol/acetonitrile/acetone and then analyzed by UPLC-MS under positive and/or negative ionization mode. With the aid of multivariate statistical analysis, separation between various groups can be observed in the score plots, and biomarkers are screened in the loading/weight/VIP (variable importance in the projection) scatterplots. Furthermore, putative markers can be identified through comparison with the authentic standards based on tandem mass spectrometry (MS/MS) fragmentation pattern and LC retention. We expect that our protocol, with modifications if necessary, can be useful in many metabolomics studies and a wide range of research areas related to small molecules and LC-MS.

Identification and quantification of soluble free, soluble conjugated, and insoluble bound phenolic acids in durum wheat (Triticum turgidum L. var. durum) and derived products by RP-HPLC on a semimicro separation scale

A straightforward semimicro separation scale RP-HPLC method was developed for the identification and quantification of phenolic acids (PAs) occurring as soluble free, soluble conjugated, and insoluble bound compounds, which were independently extracted from wholemeal of durum wheat and from its derived products coarse bran, semolina, and dried pasta. A narrow bore column and a semimicro photodiode array detector (PDA) cell, in conjunction with a single quadrupole mass spectrometer, equipped with an electrospray ionization source (ESI-MS), were employed. The method was validated in terms of linearity of calibration graphs, limits of detection, limits of quantification, repeatability, and accuracy, which was evaluated by a recovery study. In each sample (wholemeal, coarse bran, semolina, and dried pasta), the total amounts of the three different forms of PAs were in the order bound > conjugated > free, with bound PAs accounting for 61.0-83.6% of the total PAs. Ferulic acid was the most abundant PA in both soluble free and insoluble bound forms, whereas sinapic acid predominated in the conjugated ones. The highest PA content, calculated as the sum of total PAs quantified in the three forms, was found in coarse bran, followed by wholemeal, semolina, and dried pasta.

Electrogenerated chemiluminescence detector based on Ru(bpy)3(2+) immobilized in cation exchange resin for high-performance liquid chromatography: An approach to stable detection

In this work, an electrogenerated chemiluminescence (ECL) detector with improved stability was developed for high-performance liquid chromatography (HPLC) detection of hydrochlorothiazide (HCTZ). The detector was prepared by packing cation exchanged resin particles in a glass tube, followed by inserting Pt wires (working electrode) in this tube and sealing. The leakage of Ru(bpy)3(2+) from the resin was compensated by adding a small amount of Ru(bpy)3(2+) in the mobile phase. Factors affected the performance of the proposed ECL detector were investigated. Under the optimal conditions, the ECL intensity has a linear relationship with the concentration of HCTZ in the range of 5.0 × 10(-8) g mL(-1)-2.5 × 10(-5) g mL(-1) and the detection limit was 2.0 × 10(-8) g mL(-1) (S/N=3). Application of the detector to the analysis of HCTZ in human serum proved feasible.

Connecting microfluidic chips using a chemically inert, reversible, multichannel chip-to-world-interface

In this paper we present a reusable, chemically inert, multichannel Chip-to-World-Interface (CWI). The concept of this interface is based on a force fit connection similar to the hollow screw connectors known from high-performance liquid chromatography (HPLC) instruments. It allows contamination free connection of up to 100 thermoplastic tubes to microfluidic chips made from various materials e.g., epoxy polymers, glass and polydimethylsiloxane (PDMS). The spacing of the tubes is fixed whereas the outer dimensions of the CWI can be adapted to the microfluidic chip it should be used with. We demonstrate that such a CWI with 100 tubes is pressure-tight up to (at least) 630 kPa (6.3 bar) pressure and the connection easily sustains flow rates above 4 ml min(-1). The presented CWI is designed such that the fluid probed in the microfluidic chip is in direct contact only with the tube material and the material from which the microfluidic chip is made. This not only enables fluid transport without dead volume, it also ensures that CWI itself will not be contaminated or contaminate the samples being probed. Using polytetrafluoroethylene (PTFE, Teflon®) tubing we demonstrate that the CWI can even be used with harsh organic solvents such as dichloromethane or dimethylformamide during continuous solvent probing over several hours without damage to the CWI or leakage. This CWI therefore effectively allows using almost all types of organic solvents in microfluidic applications.

Development of a rapid LC-DAD/FLD method for the simultaneous determination of auxins and abscisic acid in plant extracts

Plant hormones play a crucial role in controlling plant growth and development. These groups of naturally occurring substances trigger physiological processes at very low concentrations, which mandate sensitive techniques for their quantitation. This paper describes a method to quantify endogenous (±)-2-cis-4-trans-abscisic acid, indole-3-acetic acid, indole-3-propionic acid, and indole-3-butyric acid. The method combines high-performance liquid chromatography (HPLC) with diode array and fluorescence detection in a single run. Hybrid tea rose 'Monferrato' matrices (leaves, petals, roots, seeds, androecium, gynoecium, and pollen) were used as references. Rose samples were separated and suspended in extracting methanol, after which (±)-2-cis-4-trans-abscisic acid and auxins were extracted by solvent extraction. Sample solutions were added first to cation solid phase extraction (SPE) cartridges and the eluates to anion SPE cartridges. The acidic hormones were bound to the last column and eluted with 5% phosphoric acid in methanol. Experimental results showed that this approach can be successfully applied to real samples and that sample preparation and total time for routine analysis can be greatly reduced.

Profiling polyphenols in five Brassica species microgreens by UHPLC-PDA-ESI/HRMS(n.)

Brassica vegetables are known to contain relatively high concentrations of bioactive compounds associated with human health. A comprehensive profiling of polyphenols from five Brassica species microgreens was conducted using ultrahigh-performance liquid chromatography photodiode array high-resolution multistage mass spectrometry (UHPLC-PDA-ESI/HRMS(n)). A total of 164 polyphenols including 30 anthocyanins, 105 flavonol glycosides, and 29 hydroxycinnamic acid and hydroxybenzoic acid derivatives were putatively identified.The putative identifications were based on UHPLC-HRMS(n) analysis using retention times, elution orders, UV-vis and high-resolution mass spectra, and an in-house polyphenol database as well as literature comparisons. This study showed that these five Brassica species microgreens could be considered as good sources of food polyphenols.

Evaluation between ultrahigh pressure liquid chromatography and high-performance liquid chromatography analytical methods for characterizing natural dyestuffs

An evaluation was undertaken of ultrahigh pressure liquid chromatography (UHPLC) in comparison to high-performance liquid chromatography (HPLC) for characterizing natural dyes in cultural heritage objects. A new UHPLC method was optimized by testing several analytical parameters adapted from prior UHPLC studies developed in diverse fields of research. Different gradient elution programs were tested on seven UHPLC columns with different dimensions and stationary phase compositions by applying several mobile phases, flow rates, temperatures, and runtimes. The UHPLC method successfully provided more improved data than that achieved by the HPLC method. Indeed, even though carminic acid has shown circa 146% higher resolution with HPLC, UHPLC resulted in an increase of 41-61% resolution and a decrease of 91-422% limit of detection, depending on the dye compound. The optimized method was subsequently assigned to analyse 59 natural reference materials, in which 85 different components were ascribed with different physicochemical properties, in order to create a spectral database for future characterization of dyes in cultural heritage objects. The majority of these reference samples could be successfully distinguished with one single method through the examination of these compounds' retention times and their spectra acquired with a photodiode array detector. These results demonstrate that UHPLC analyses are extremely valuable for the acquisition of more precise chromatographic information concerning natural dyes with complex mixtures of different and/or closely related physicochemical properties, essential for distinguishing similar species of plants and animals used to colour cultural heritage objects.

Analysis of N-nitrosamines and other nitro(so) compounds in water by high-performance liquid chromatography with post-column UV photolysis/Griess reaction

Despite their potential carcinogenicity and probable formation during water disinfection processes, little is known about the occurrence of other nitro(so) compounds than a few specific N-nitroso compounds such as N-nitrosodimethylamine (NDMA). An analytical method was developed to monitor various nitro(so) compounds including N-nitrosamines based on the Griess colorimetric determination of nitrite generated by UV-254 nm photolysis of nitro(so) compounds after separation by HPLC (HPLC-Post Column UV photolysis/Griess reaction (HPLC-PCUV)). To differentiate N-nitro(so) compounds (i.e. UV-labile) from other nitro(so) and N-containing compounds (i.e. UV-resistant), a pre-treatment was established by photolyzing solid-phase extracted samples at 254 nm (1000 mJ/cm(2)) and thus removing N-nitro(so) compounds selectively. Considering a 1000-fold concentration factor and extraction efficiencies (57-83%) during solid phase extraction, the method detection limits ranged from 4 to 28 ng/L for dimethylnitramine and eight N-nitrosamines (EPA 8270 nine nitrosamines mixture except for N-nitrosodiphenylamine). For four pool waters, the UV-resistant groups accounted for more than 78% of the estimated total concentration of nitro(so) and other N-containing compounds (6.1-48.6 nM). Only one unknown UV-labile compound was detected in one pool water (2.0-7.9 nM). NDMA was most frequently detected and N-nitrosodipropylamine (NDPA) and N-nitrosodibutylamine (NDBA) were additionally detected in one pool water. Chloramination of a secondary wastewater effluent with NDMA (0.2 nM) and UV-resistant compounds (7.9 nM) from a pilot-scale municipal wastewater treatment plant led to a significant formation of not only unidentified UV-resistant compounds (67.8 nM) and UV-labile compounds (14.6 nM), but also identified nitrosamines such as NDMA (4.3 nM), N-nitrosopiperidine (1.8 nM), NDPA (0.5 nM), and NDBA (0.5 nM). Overall, the novel HPLC-PCUV system is a powerful screening tool for the detection of (un)known N-nitro(so) as well as other nitro(so) and UV-induced nitrite-producing compounds.

[Determination of eight ginsenosides in renshenshouwu capsules by HPLC-DAD]

OBJECTIVE

To establish an HPLC-DAD method for simultaneous determination of eight ginsenosides in Renshenshouwu capsules.

METHOD

Ultimate C18 column (4.6 mm x 250 mm, 5 microm) was adopted for gradient elution, with acetonitrile and water as the mobile phase. The flow rate was 1 mL x min(-1), the column temperature was set at 30 degrees C, and the detection wavelength was 203 nm.

RESULT

A good linearity was observed in the range of 0.242-12.1, 0.222-11.1, 0.251-25.1, 0. 245-24.5, 0.232-23.2, 0.232-23.2, 0.264-26.4, 0.244-24.4 microg for ginsenoside Rg1, Re, Rb1, Rc, Rb2, Rb3, Rd and 20(S)-ginsenoside Rg3, respectively, with the average recoveries of 102.7%, 103.2%, 101.6%, 101.2%, 102.0%, 100.7%, 101.9%, 102.0%, respectively.

CONCLUSION

The method was so simple, accurate and effective that it could be used for quality control of the above eight components in Renshenshouwu capsules.

Highly sensitive and selective high-performance liquid chromatography method for bioequivalence study of cefpodoxime proxetil in rabbit plasma via fluorescence labeling of its active metabolite

Cefpodoxime proxetil (CFP), a broad-spectrum third-generation cephalosporin, has been used most widely in the treatment of respiratory and urinary tract infections. For bioequivalence study of CFP in rabbit plasma, it was necessary to develop a highly sensitive and selective high-performance liquid chromatographic (HPLC) method with fluorescence (FL) detection. The pre-column labeling of cefpodoxime acid (CFA) (active metabolite) with an efficient benzofurazan type fluorogenic reagent, 4-N,N-dimethyl aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) was carried out in the present study in 100mM borate buffer (pH=8.5) at 50°C for 15min. The obtained fluorescent products were separated on C18 column with an isocratic elution of the mobile phase, which consists of 10mM phosphate buffer (pH=3.5)/CH3CN (70:30, v/v). The fluorescent product (DBD-CFA) was detected fluorimetrically at 556nm with an excitation wavelength of 430nm. Cefotaxime sodium was used as internal standard. The method was validated according to the requirements of US-FDA guidelines. The correlation coefficient of 0.999 was obtained in the concentration ranges of 10-1000ngmL(-1). The limits of detection and quantification (S/N=3) were 3 and 10ngmL(-1), respectively. Plasma CFA levels were successfully determined in rabbit with satisfactory precision and accuracy. The proposed HPLC-FL method was successfully applied to study bioequivalence in rabbits for two formulations of different brands contained CFP (prodrug) in a randomized, two-way, single-dose, crossover study and all pharmacokinetic parameters for the two formulations were assessed.

Use of diffusion-ordered NMR spectroscopy and HPLC-UV-SPE-NMR to identify undeclared synthetic drugs in medicines illegally sold as phytotherapies

The informal (and/or illegal) e-commerce of pharmaceutical formulations causes problems that governmental health agencies find hard to control, one of which concerns formulas sold as natural products. The purpose of this work was to explore the advantages and limitations of DOSY and HPLC-UV-SPE-NMR. These techniques were used to identify the components of a formula illegally marketed in Brazil as an herbal medicine possessing anti-inflammatory and analgesic properties. DOSY was able to detect the major components present at higher concentrations. Complete characterization was achieved using HPLC-UV-SPE-NMR, and 1D and 2D NMR analyses enabled the identification of known synthetic drugs. These were ranitidine and a mixture of orphenadrine citrate, piroxicam, and dexamethasone, which are co-formulated in a remedy called Rheumazim that is used to relieve severe pain, but it is prohibited in Brazil because of a lack of sufficient pharmacokinetic and pharmacodynamic information.

Development of an offline bidimensional high-performance liquid chromatography method for analysis of stereospecific triacylglycerols in cocoa butter equivalents

Acyl migration is a serious problem in enzymatic modification of fats and oils, particularly in production of cocoa butter equivalent (CBE) through enzymatic acidolysis reaction, which leads to the formation of non-symmetrical triacylglycerols (TAGs) from symmetrical TAGs. Non-symmetrical TAGs may affect the physical properties of final products and are therefore often undesired. Consequently, an accurate method is needed to determine positional isomer TAGs during the production of CBE. A bidimentional high-performance liquid chromatography (HPLC) method with combination of non-aqueous reversed-phase HPLC and silver ion HPLC joining with an evaporative light scattering detector was successfully developed for the analysis of stereospecific TAGs. The best separation of positional isomer standards was obtained with a heptane/acetone mobile-phase gradient at 25 °C and 1 mL/min. The developed method was then used in multidimensional determination of the TAG positional isomers in fat and oil blends and successfully identified the TAGs and possible isomers in enzymatically acidolyzed CBE.

Genotoxicity-related chemistry of human metabolites of benzo[ghi]perylene (B[ghi]P) investigated using electro-optical arrays and DNA/microsome biocolloid reactors with LC-MS/MS

There is limited and sometimes contradictory information about the genotoxicity of the polycyclic aromatic hydrocarbon benzo[ghi]perylene (B[ghi]P). Using recently developed metabolic toxicity screening arrays and a biocolloid reactor-LC-MS/MS approach, both featuring films of DNA and human metabolic enzymes, we demonstrated the relatively low reactivity of metabolically activated B[ghi]P toward DNA. Electro-optical toxicity screening arrays showed that B[ghi]P metabolites damage DNA at a 3-fold lower rate than benzo[a]pyrene (B[a]P), whose metabolites have a strong and well-understood propensity for DNA damage. Metabolic studies using magnetic bead biocolloid reactors coated with microsomal enzymes in 96-well plates showed that cyt P450s 1A1 and 1B1 provide high activity for B[ghi]P and B[a]P conversion. Consistent with published results, the major metabolism of B[ghi]P involved oxidations at 3,4 and 11,12 positions, leading to the formation of B[ghi]P 3,4-oxide and B[ghi]P 3,4,11,12-bisoxide. B[ghi]P 3,4-oxide was synthesized and reacted with deoxyadenosine at N6 and N7 positions and with deoxyguanosine at the N2 position. B[ghi]P 3,4-oxide is hydrolytically unstable and transforms into the 3,4-diol or converts to 3- or 4-hydroxy B[ghi]P. LC-MS/MS of reaction products from the magnetic biocolloid reactor particles coated with DNA and human enzymes revealed for the first time that a major DNA adduct results from the reaction between B[ghi]P 3,4,11,12-bisoxide and deoxyguanosine. Results also demonstrated 5-fold lower formation rates of the major DNA adduct for B[ghi]P metabolites compared to B[a]P. Overall, results from both the electro-optical array and biocolloid reactor-LC-MS/MS consistently suggest a lower human genotoxicity profile of B[ghi]P than B[a]P.

Simultaneous analysis of circulating 25-hydroxy-vitamin D3, 25-hydroxy-vitamin D2, retinol, tocopherols, carotenoids, and oxidized and reduced coenzyme Q10 by high performance liquid chromatography with photo diode-array detection using C18 and C30 columns alone or in combination

Circulating lipid-phase micronutrients (LPM) such as 25-hydroxylated D vitamers, retinol, tocopherols, carotenoids including their isomers, and coenzyme Q10 play important roles in health maintenance and disease prevention and can serve as useful biomarkers. We developed fast, affordable, and accurate HPLC assays that simultaneously measured all above LPM in a single run using UV/VIS detection at 265nm, 295nm, and 480nm with (1) a C18 column alone; (2) a C30 column alone; or (3) each of these columns connected in series. The C18 column alone could separate all major LPM of interest in less than 17min but insufficiently resolved the lycopene isomers, the 25-hydroxylated D vitamers, lutein from zeaxanthin and β- from γ-tocopherol. The C30 column alone separated all LPM of interest including many isomeric analytes but failed to resolve the Q10 compounds, which co-eluted with carotenoids. Connecting the C18 and C30 columns in series with a detector after the C30 column and a pressure resistant detector between the columns resulted in ideal resolution and accurate quantitation of all LPM of interest but required software capable of processing the acquired data from both detectors. Connecting the C18 and C30 columns in series with exclusively one detector after the C30 column resulted in carotenoid-Q10 interferences, however, this was remedied by heart-cutting 2D-LC with a 6-port valve between the columns, which resolved all analytes in 42min. Faster run times led to some analytes not being resolved. Many variations of these methods are possible to meet the needs of individual requirements while minimizing sample material and turn-around-times.

Separation and characterization of sucrose esters from Oriental tobacco leaves using accelerated solvent extraction followed by SPE coupled to HPLC with ion-trap MS detection

Sucrose esters (SEs) were successfully extracted from Oriental tobacco leaves using a new methodology based on accelerated solvent extraction followed by hydrophilic-lipophilic balanced cartridge cleanup step. The SEs were detected by HPLC with ion-trap MS detection using an electrospray interface operated in the positive ion mode. This methodology combines the high efficiency of extraction provided by a pressurized fluid and the highly sensitive characterization offered by ion-trap MS. Under the optimized conditions, 14 SEs were first identified among a total of 23 SEs found in Oriental tobacco leaves. Under the same conditions, only four new SEs were extracted by using traditional ultrasound-assisted extraction and liquid-solid extraction methods. The present method might be potentially useful in high-efficiency extraction and sensitive characterization of SEs from complex matrices such as tobacco leaves.

Simultaneous analysis of trace polymer additives in plastic beverage packaging by solvent sublation followed by high-performance liquid chromatography

Using solvent sublation (SS), a novel pretreatment method for separating and concentrating antioxidants and ultraviolet absorbers from plastic beverage packaging was developed, and these target compounds were quantitatively analyzed by high-performance liquid chromatography (HPLC). In the pretreatment section, the effects of the sublation solvent, solution pH, NaCl concentration, nitrogen flow rate, sublation time, and light condition on the sublation efficiency were investigated in detail and the optimal conditions of the solvent sublation process were selected. The analytical method of SS-HPLC showed good linearity in the range from 0.33 to 667 ng/mL with good presenting regression coefficients (0.9995 ≥ R(2) ≥ 0.9972). Low limits of detection (LODs) of 0.34-1.25 ng/mL and limits of quantification (LOQs) of 1.13-4.15 ng/mL were achieved. The mean recoveries were in the range from 88.73 to 107.65% at 20, 30, and 40 ng/mL spiked levels, and the relative standard deviations (RSDs) were in the range from 2.16 to 10.55%.

A novel approach of periodate oxidation coupled with HPLC-FLD for the quantitative determination of 3-chloro-1,2-propanediol in water and vegetable oil

A novel approach of periodate oxidation coupled with high-performance liquid chromatography (HPLC)-fluorescence detection (FLD) for the quantitative determination of 3-chloro-1,2-propanediol (3-MCPD) has been established. The essence of this approach lies in the production of chloroacetaldehyde by the oxidization cleavage of 3-MCPD with sodium periodate and the HPLC analysis of chloroacetaldehyde monitored by an FLD detector after fluorescence derivatization with adenine. The experimental parameters relating to the efficiency of the derivative reaction such as concentration of adenine, chloroacetaldehyde reaction temperature, and time were studied. Under the optimized conditions, the proposed method can provide high sensitivity, good linearity (r(2) = 0.999), and repeatability (percent relative standard deviations between 2.57% and 3.44%), the limits of detection and quantification were 0.36 and 1.20 ng/mL, respectively, and the recoveries obtained for water samples were in the range 93.39-97.39%. This method has been successfully applied to the analysis of real water samples. Also this method has been successfully used for the analysis of vegetable oil samples after pretreatment with liquid-liquid extraction; the recoveries obtained by a spiking experiment with soybean oil ranged from 96.27% to 102.42%. In comparison with gas chromatography or gas chromatography-mass spectrometry, the proposed method can provide the advantages of simple instrumental requirement, easy operation, low cost, and high efficiency, thus making this approach another good choice for the sensitive determination of 3-MCPD.

Interval multivariate curve resolution in the dereplication of HPLC-DAD data from Jatropha gossypifolia

INTRODUCTION

Jatropha gossypifolia has been used quite extensively by traditional medicine for the treatment of several diseases in South America and Africa. This medicinal plant has therapeutic potential as a phytomedicine and therefore the establishment of innovative analytical methods to characterise their active components is crucial to the future development of a quality product.

OBJECTIVE

To enhance the chromatographic resolution of HPLC-UV-diode-array detector (DAD) experiments applying chemometric tools.

METHODS

Crude leave extracts from J. gossypifolia were analysed by HPLC-DAD. A chromatographic band deconvolution method was designed and applied using interval multivariate curve resolution by alternating least squares (MCR-ALS).

RESULTS

The MCR-ALS method allowed the deconvolution from up to 117% more bands, compared with the original HPLC-DAD experiments, even in regions where the UV spectra showed high similarity. The method assisted in the dereplication of three C-glycosylflavones isomers: vitexin/isovitexin, orientin/homorientin and schaftoside/isoschaftoside.

CONCLUSION

The MCR-ALS method is shown to be a powerful tool to solve problems of chromatographic band overlapping from complex mixtures such as natural crude samples.

Comparison of high-performance liquid chromatography/tandem mass spectrometry and high-performance liquid chromatography/photo-diode array detection for the quantitation of carotenoids, retinyl esters, α-tocopherol and phylloquinone in chylomicron-rich fractions of human plasma

RATIONALE

Bioavailability of essential lipophilic micronutrients and carotenoids is of utmost interest for human health, as the consumption of these compounds may help alleviate major nutritional deficiencies, cardiovascular disease, and cancer. High-performance liquid chromatography/photo-diode array detection (HPLC-PDA) and high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) were compared for the quantitative analysis of α- and β-carotene, β-cryptoxanthin, lutein, lycopene, α-tocopherol, phylloquinone, and several retinyl esters from chylomicron-containing triglyceride rich lipoprotein (TRL) fractions of human plasma obtained from two clinical trials.

METHODS

After selecting an efficient extraction method for the analytes, both the HPLC/PDA and the HPLC/MS/MS methods were developed and several parameters validated using an HP 1200 series HPLC system interfaced with a HP 1200 series diode-array detector (Agilent Technologies, Santa Clara, CA, USA) and a QTRAP 5500 (AB Sciex, Foster City, CA, USA) via an atmospheric pressure chemical ionization (APCI) probe operated in positive ion mode.

RESULTS

For lycopene, α- and β-carotene, HPLC/MS/MS was up to 37 times more sensitive than HPLC-PDA. PDA detection was shown to be up to 8 times more sensitive for lutein. MS/MS signals were enhanced by matrix components for lutein and β-cryptoxanthin, as determined by referencing to the matrix-independent PDA signal. In contrast, matrix suppression was observed for retinyl palmitate, α-carotene, and β-carotene. Both detectors showed similar suitability for α-tocopherol, lycopene and retinyl palmitate (representing ~73% of total retinyl esters). MS/MS exclusively allowed the quantitation of minor retinyl esters, phylloquinone, and (Z)-lycopene isomers.

CONCLUSIONS

HPLC/MS/MS was more sensitive than HPLC-PDA for six of the eight analytes and represents a powerful tool for the analysis of chylomicron samples and potentially other biological samples of limited sample size. When internal standards are available for the target carotenoid, employing MS/MS detection may reduce the necessary blood sample volume, which is particularly advantageous for minimizing risk and discomfort to human subjects during clinical studies.

Continuous-flow liquid microjunction surface sampling probe connected on-line with high-performance liquid chromatography/mass spectrometry for spatially resolved analysis of small molecules and proteins

RATIONALE

A continuous-flow liquid microjunction surface sampling probe extracts soluble material from surfaces for direct ionization and detection by mass spectrometry. Demonstrated here is the on-line coupling of such a probe with high-performance liquid chromatography/mass spectrometry (HPLC/MS) enabling extraction, separation and detection of small molecules and proteins from surfaces in a spatially resolved (~0.5 mm diameter spots) manner.

METHODS

A continuous-flow liquid microjunction surface sampling probe was connected to a six-port, two-position valve for extract collection and injection to an HPLC column. A QTRAP® 5500 hybrid triple quadrupole linear ion trap equipped with a Turbo V™ ion source operated in positive electrospray ionization (ESI) mode was used for all experiments. The system operation was tested with the extraction, separation and detection of propranolol and associated metabolites from drug dosed tissues, caffeine from a coffee bean, cocaine from paper currency, and proteins from dried sheep blood spots on paper.

RESULTS

Confirmed in the tissue were the parent drug and two different hydroxypropranolol glucuronides. The mass spectrometric response for these compounds from different locations in the liver showed an increase with increasing extraction time (5, 20 and 40 s). For on-line separation and detection/identification of extracted proteins from dried sheep blood spots, two major protein peaks dominated the chromatogram and could be correlated with the expected masses for the hemoglobin α and β chains.

CONCLUSIONS

Spatially resolved sampling, separation, and detection of small molecules and proteins from surfaces can be accomplished using a continuous-flow liquid microjunction surface sampling probe coupled on-line with HPLC/MS detection.

Investigation of an on-line detection method combining near infrared spectroscopy with local partial least squares regression for the elution process of sodium aescinate

An on-line detection method combining near infrared (NIR) spectroscopy with local partial least squares regression (PLSR) was investigated for the elution process of sodium aescinate. A 2 mm pathlength flow cell which transmitted NIR radiation through two fiber optic probes was placed in bypass of the macroporous resin column to collect real-time spectra of the sodium aescinate eluate. To compare the predictive accuracy, both local and global PLSR were employed to build mathematical models between NIR spectra and reference values. Meanwhile, Mahalanobis distance was introduced to select the appropriate local model for the prediction of unknown samples. Experimental results demonstrated that local PLSR was superior to global PLSR in both calibration performance and predictive accuracy. Moreover, the on-line detection method was proven to be feasible in real application and thereby would be of great value for monitoring the elution process of sodium aescinate in real time as well as determining the start and end points of eluate collection.

HPLC-ESI-QTOF-MS as a powerful analytical tool for characterising phenolic compounds in olive-leaf extracts

INTRODUCTION

Olea europaea L. leaves may be considered a cheap, easily available natural source of phenolic compounds. In a previous study we evaluated the possibility of obtaining bioactive phenolic compounds from olive leaves by pressurised liquid extraction (PLE) for their use as natural anti-oxidants. The alimentary use of these kinds of extract makes comprehensive knowledge of their composition essential.

OBJECTIVE

To undertake a comprehensive characterisation of two olive-leaf extracts obtained by PLE using high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS).

METHOD

Olive leaves were extracted by PLE using ethanol and water as extraction solvents at 150°C and 200°C respectively. Separation was carried out in a HPLC system equipped with a C₁₈-column working in a gradient elution programme coupled to ESI-QTOF-MS operating in negative ion mode.

RESULTS

This analytical platform was able to detect 48 compounds and tentatively identify 31 different phenolic compounds in these extracts, including secoiridoids, simple phenols, flavonoids, cinnamic-acid derivatives and benzoic acids. Lucidumoside C was also identified for the first time in olive leaves.

CONCLUSION

The coupling of HPLC-ESI-QTOF-MS led to the in-depth characterisation of the olive-leaf extracts on the basis of mass accuracy, true isotopic pattern and tandem mass spectrometry (MS/MS) spectra. We may conclude therefore that this analytical tool is very valuable in the study of phenolic compounds in plant matrices.

Fast and direct quantification of underivatized muscone by ultra performance liquid chromatography coupled with evaporative light scattering detection

A new reversed phase ultra performance liquid chromatography coupled with evaporative light scattering detection is developed for the fast and direct quantification of underivatized muscone in precious herbal medicine musk. Separation of muscone was achieved on a Waters Acquity BEH C18 (50 × 2.1 mm id, 1.7 μm) column. The runtime was as short as 5 min. The mode of evaporative light scattering detection was set at Impact On. The influence of evaporative light scattering detection condition on sensitivity was investigated. The optimized condition was: drift tube temperature at 30°C, gas flow rate 4.2 L/min. The method was validated with respect to the precision, sensitivity, accuracy, linearity, stability, and robustness were measured in this paper. The calibration curves showed good linear regression (r = 0.9914) within the test range. The recovery rate was 98.6%. The limit of detection for muscone was 2.0 ng. The validated method was rapid, simple, reproducible, and convenient for the quantification of muscone in musk and the related products.

Radio-UHPLC: a tool for rapidly determining the radiochemical purity of technetium-99m radiopharmaceuticals?

Determining the radiochemical purity (RCP) of technetium-99m ((99m)Tc) radiopharmaceuticals using the method described in the package insert is a time-consuming process, requiring particular attention in order to achieve accurate RCP results. The purpose of this study was to evaluate whether radio-ultra high performance liquid chromatography (radio-UHPLC) may be an alternative method for RCP testing of (99m)Tc-tetrofosmin, (99m)Tc-MAG3 and (99m)Tc-sestamibi. Results obtained using radio-UHPLC were in excellent agreement with the standard method, with total analysis time being reduced to less than 3 min.

[Comparison of content of total alkaloids and aconitine in Aconitum szechenyianum from different producing areas on basis of macroporous adsorption resin purification technology]

OBJECTIVE

To optimize the conditions of purifying the total alkaloids in Aconitum szechenyianum with macroporous adsorption resin, and compare the content of total alkaloids and aconitine in A. szechenyianum from different producing areas, in order to provide basis for further studies.

METHOD

The orthogonal experiment method was adopted for optimizing the conditions of purifying the total alkaloids in A. szechenyianum with macroporous adsorption resin. The content of total alkaloids and aconitine were determined by using the titration method. The total alkaloids in A. szechenyianum from different producing areas were purified under optimum processing conditions. Aconitine was determined by HPLC.

RESULT

Different processing conditions showed different influences on the purification of total alkaloids. The optimum conditions were resin type HPD-722, ethanol concentration of 80% , and ethanol elution volume of 80 mL x min(-1). The contents of aconitine in A. szechenyianum from different producing areas--Qinghai, Maxianshan, Ningxia and Yongdeng were 0.493 5, 0.883 5, 1.527 8, 1.664 4 mg x g(-1), respectively.

CONCLUSION

The optimum processing conditions used in this essay could be used for purifying the total alkaloids and aconitine. A. szechenyianum from Yongdeng and Gansu contains the highest content of aconitine.

Detection of type A trichothecene di-glucosides produced in corn by high-resolution liquid chromatography-Orbitrap mass spectrometry

The existence of di-glucosylated derivative of T-2 toxin in plant (corn powder) was confirmed for the first time in addition to that of HT-2 toxin. These masked mycotoxins (mycotoxin glucosides) were identified as T-2 toxin-di-glucoside (T2GlcGlc) and HT-2 toxin-di-glucoside (HT2GlcGlc) based on accurate mass measurements of characteristic ions and fragmentation patterns using high-resolution liquid chromatography-Orbitrap mass spectrometric (LC-Orbitrap MS) analysis. Although the absolute structure of T2GlcGlc was not clarified, two glucose molecules were suggested to be conjugated at 3-OH position in tandem when considering the structure of T-2 toxin. On the other hand, the specification of the structure seems to be more complicated in the case of HT2GlcGlc, since HT-2 toxin has two possible positions (at 3-OH and 4-OH) to be glusocylated. In addition, 15-monoacetoxyscirpenol-glucoside (MASGlc) was also detected in the identical sample.

Determination of captopril by high-performance liquid chromatography with direct electrogenerated chemiluminescence

Captopril exhibit electrogenerated chemiluminescence (ECL) in NaNO(3) solution when constant current is exerted. Based on this observation, a direct ECL method coupled with high-performance liquid chromatography (HPLC) separation is developed for determination of captopril in human serum. Factors affected the ECL emission are investigated. Under the optimal conditions, the ECL intensity has a linear relationship with the concentration of captopril in the range of 4.0×10(-6)-2.0×10(-3) g mL(-1) and the detection limit is 2×10(-6) g mL(-1) (S/N=3). Compared with the common electrogenerated chemiluminescence experiments, the developed method need no any other fluorescence additives.

Differentiation of tannin-containing herbal drugs by HPLC fingerprints

A new HPLC system coupled with multiple detectors - Diode array detector (DAD), fluorescence detector (FLD), electrochemical amperometric detector (ADC) and mass spectrometry detector (MSD) was developed for the characterization and differentiation of tannin-containing herbal drugs included in The European Pharmacopoeia. The HPLC separation system consisted of an Agilent ZORBAX Eclipse XDB C18 column and a gradient water and methanol as the mobile phase which was kept at a flow rate of 0.3 mL x min(-1). Four kinds of detectors were connected by a micro-splitter valve and simultaneously recorded the response of each analytical sample. Thirty-one samples from eight kinds of tannin-containing drugs were measured using this HPLC system and their signals from all detectors were comprehensively processed via principal component analysis (PCA). The statistic result demonstrates that thirty-one batches from different herbal drugs can be reasonably identified and systematically classified by their chemical fingerprints. The proposed multi-detector HPLC method aided by chemometrics not only offers a new pattern for the study of tannin-containing herbs, but also provides a useful foundation for quality control of herbal medicines.

Determination of light-medium-heavy polycyclic aromatic hydrocarbons in vegetable oils by solid-phase extraction and high-performance liquid chromatography with diode array and fluorescence detection

A new method for determination of 16 polycyclic aromatic hydrocarbons (PAHs)-naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene-in vegetable oils was developed. Solid-phase extraction (SPE) prior to high-performance liquid chromatography with fluorescence detection could be used for all those PAHs except acenaphthylene. Acenaphthylene could be detected using a diode array detector at 228 nm. The parameters and variables that affect the extraction were investigated. Under optimum conditions: the extract reagent was centrifuged at 4 °C and evaporated. After that a SPE procedure was used for further cleanup. The limits of detection and limits of quantification were in the range of 0.01-2.35 and 0.04-7.00 μg kg(-1) in vegetable oil, respectively. The relative standard deviations were under 5%.

HPLC-PDA-MS and NMR characterization of a hydroalcoholic extract of Citrus aurantium L. var. amara peel with antiedematogenic activity

The phytochemical profile of a hydroalcoholic extract of Citrus aurantium var. amara L. peel, used as herbal medicine, was characterized by HPLC-PDA-MS. Two di-C-glycosyl flavones (vincenin II and diosmetin 6,8-di-C-glucoside), a series of flavones (luteolin 7-O-neohesperidoside, rhoifolin, and neodiosmin), and flavanone (neoeriocitrin, naringin, and neohesperidin) 7-O-neohesperidosides and two methoxyflavones (nobiletin and tangeretin), commonly present in Citrus, were identified. Furthermore, brutieridin and melitidin, two 3-hydroxy-3-methylglutaryl flavanone glycosides, were also characterized along with rhoifolin 4'-glucoside and three coumarins (8,3'-β-D-glucopyranosyloxy-2'-hydroxy-3'-methylbutyl-7-methoxycoumarin, merazin hydrate, and isomerazin). A preparative isolation procedure followed by NMR spectroscopy confirmed the proposed structures of the major flavonoids and identified the coumarins. The phenolic content was found to be 14.8 mg mL(-1), and naringin and neohesperidin were the compounds present in the highest concentration (3.6 and 2.6 mg mL(-1)). The extract of C. aurantium peel inhibited significantly (p < 0.05) both histamine- and dextran-induced edema in rats in a concentration-dependent manner (IC(50) = 119.6 and 118.3 mg kg(-1), respectively), providing evidence for the therapeutic use of C. aurantium var. amara peel.

Quantitative evaluation of auraptene and umbelliferone, chemopreventive coumarins in citrus fruits, by HPLC-UV-FL-MS

An analytical strategy, based on the development of two HPLC methods with spectrophotometric (UV), spectrofluorometric (FL), and mass spectrometric (MS) detection, has been developed to investigate the presence of and to quantitate two important chemopreventive coumarins, auraptene and umbelliferone, in foodstuffs. The analytes were determined in fruits, and fruit parts, of plants belonging to the Citrus , Poncirus , and Fortunella genera, to test their nutraceutical potential. The method validation has been carried out according to international guidelines, with good results in terms of precision (RSD < 6.9%) and extraction yields (>91%). Application to the quantitative analysis of auraptene and umbelliferone in several kinds of citrus fruits was successful, providing reliable and consistent data. Exploiting three different kinds of detection, the analytical methodology proposed herein has been demonstrated to be sound but versatile, as well as reliable. Performances and results were compared and always found in good agreement among themselves. Thus, this approach is suitable for the identification and simultaneous quantitation of auraptene and umbelliferone in citrus fruits, with the aim of evaluating their nutraceutical potential.

Determination of ochratoxin A in wine by means of immunoaffinity and aminopropyl solid-phase column cleanup and fluorometric detection

A new analytical method for the determination of ochratoxin A (OTA) in red wine has been developed by using a double-extract cleanup and a fluorometric measurement after spectral deconvolution. Wine samples were diluted with a solution containing 1% polyethylene glycol and 5% sodium hydrogencarbonate, filtered, and purified by immunoaffinity and aminopropyl solid-phase column. OTA contents in the purified extract were determined by a spectrofluorometer (excitation wavelength, 330 nm; emission wavelength, 470 nm) after deconvolution of fluorescence spectra. Average recoveries from wine samples spiked with OTA at levels ranging from 0.5 to 3.0 ng/mL were 94.5-105.4% with relative standard deviations (RSD) of <15% (n = 4). The limit of detection (LOD) was 0.2 ng/mL, and the total time of analysis was 30 min. The developed method was tested on 18 red wine samples (naturally contaminated and spiked with OTA at levels ranging from 0.4 to 3.0 ng/mL) and compared with AOAC Official Method 2001.01, based on immunoaffinity column cleanup and HPLC with fluorescence detector. A good correlation (r(2) = 0.9765) was observed between OTA levels obtained with the two methods, highlighting the reliability of the proposed method, the main advantage of which is the simple OTA determination by a benchtop fluorometer with evident reductions of cost and time of analysis.

Foodomics platform for the assay of thiols in wines with fluorescence derivatization and ultra performance liquid chromatography mass spectrometry using multivariate statistical analysis

The presence of specific volatile and aminothiols in wine is associated with quality, worth, price, and taste. The identification of specific thiol-containing compounds in various wines has been reported in many valuable and interesting works. In this study, a novel foodomics assay of thiol-containing compounds, such as free aminothiols and related conjugates, was developed using ultra performance liquid chromatography (UPLC) with fluorescence (FL) and electrospray (ESI) time-of-flight mass spectrometric (TOF/MS) detections. FL specific derivatization was applied along with multivariate statistical analysis. First, the optimal experimental conditions were studied using representative thiols, such as l-cysteine, N-acetyl-l-cysteine, cysteamine, and l-glutathione, and then the UPLC-FL derivatization and separation steps were fixed for the subsequent screening of unknown thiol-containing compounds. The screening assay consisted of monitoring the UPLC-TOF/MS peaks of unknown thiols, which decreased due to the derivatization as compared to the nonderivatized thiols. The principal component analysis of the UPLC-TOF/MS data could be well-differentiated and categorized into two groups. The orthogonal signal correction partial least-squares discriminant analysis, the so-called S-plot, showed that the quality differentiation is directly related to the decrease of native thiols and increase of derivatized thiols. With this strategy, the mass difference from the derivatization reagent (+m/z 198) could be utilized for the identification of these thiols using the FL peaks retention time and metabolomics-databases. The presence of l-glutathione in rice wine was for the first time reported on the basis of the available metabolomics-databases and standard matching. This novel concept based on foodomics could be applied in food analysis for the ready screening of specific functional compounds by exploiting the various derivatization modes available.

Common screening approaches for efficient analytical method development in LC and SFC on columns packed with immobilized polysaccharide-derived chiral stationary phases

Owing to their remarkable enantioselectivity, versatility, and stability, immobilized polysaccharide-based chiral stationary phases (CSPs) have been successfully integrated into the tool box of many research and industry groups for the separation of enantiomers or stereoisomers by liquid and supercritical fluid chromatography. Due to the structurally diverse range of compounds available, efficient method development for chiral separations utilizing such CSPs is a challenging subject. In this chapter, we will discuss simplified screening protocols and straightforward approaches to achieve chiral separations in HPLC and SFC using the column series CHIRALPAK™ IA, IB, IC, and ID in reasonable time frame and with limited experimental work and a high success rate.

High-resolution time-of-flight mass spectrometry for suspect screening and target quantification of pharmaceuticals in river water

The growing interest in screening and quantification of potential harmful pharmaceuticals in the environment requests multi-residue analytical techniques. Large-volume injection ultra performance liquid chromatography (LVI-UPLC) in combination with full-spectrum high-resolution mass spectrometry (HRMS) is a promising alternative for the state-of-the-art MS/MS instruments, because of its ability to analyse a virtually unlimited number of analytes thereby avoiding the time-consuming sample enrichment steps. We developed and fully validated an innovative analytical method for suspect screening and target quantification of a set of 69 pharmaceutical compounds in surface water based on LVI-UPLC coupled to a quadrupole time-of-flight (QTOF) MS. In a systematic research, we showed that optimal mass accuracy was obtained after centroiding the spectra. A novel suspect screening strategy was developed, assuring the detection of 95% of the pharmaceuticals spiked in surface water by modelling the variability of the signal intensity-dependent accurate mass error. A first screening of five Belgian river water samples revealed the occurrence of 30 pharmaceuticals (antibiotics, analgesics, antidepressants, alkylating agents, antiinflammatories, etc.). Concentrations between 17 ng/L up to 3.3 microg/L were subsequently measured by the validated target quantification.

Detection of Ca2+-binding S100 proteins in human saliva by HPLC-ESI-MS

High-performance liquid chromatography (HPLC) coupled with electrospray ionization (ESI) mass -spectrometry (MS) is a relevant technique for the detection and relative quantitation of naturally occurring peptides and proteins. The peptide/protein mass is determined by deconvolution of the ESI-MS spectrum, and the resolution can be better than 1:10,000 with the instruments currently available. Accurate mass measurement, coupled with sufficient resolution, makes it possible to greatly restrict the enormous number of possible molecular formulas that might be represented by a specific molecular mass. As soon as the protein mass has been unequivocally attributed to a specific structure by means of different enzymatic and chemical treatments, the m/z values detected in the ESI spectrum can be utilized to reveal the protein and to perform its relative quantitation, by the extracted ion current (XIC) procedure, in an unlimited number of samples. This chapter describes the HPLC-ESI-MS experimental conditions which allow detecting and quantifying-in human saliva-different S100 proteins and their isoforms.

Enantioseparations by high-performance liquid chromatography based on chiral ligand-exchange

Chiral ligand-exchange chromatography (CLEC) first described in the late 1960s to early 1970s by Davankov and Rogozhin can be still considered as an elective choice for the direct enantioseparation of compounds endowed with chelating moieties. Among the numerous chelating species that have been evaluated as chiral selectors in ligand-exchange (LE) chromatography, a special role is played by a group of amino acids including proline, hydroxyproline, cysteine, phenylalanine, and penicillamine. More to the point, relevant chromatographic performances are also provided by amino alcohol-based chiral selectors, among which, those carrying a leucinol residue as the basic scaffold are worth to be mentioned. Among the various enantiomer chromatographic separation techniques, CLEC has been exploited in all the main techniques including a chiral mobile phase (CMP), a covalently bound chiral stationary phase (B-CSP), and a coated chiral stationary phase (C-CSP). It is the objective of this chapter to describe selected CLEC applications dealing with the above three distinct approaches.

Simple and reliable methods for the determination of three steroidal glycosides in the eight species of Solanum by reversed-phase HPLC coupled with diode array detection

INTRODUCTION

Solanum species are important ingredients of many traditional Indian medicines and thus the quality control of their herbal formulations is of paramount concern.

OBJECTIVE

To establish a simple and effective high-performance liquid chromatographic (HPLC) method to evaluate the quality of Solanum species and their herbal formulations.

METHODOLOGY

A rapid, simple, sensitive, robust and reproducible HPLC method was developed for the determination of three steroidal glycosides (SG); indioside D, solamargine and α-solanine in eight species of the genus Solanum. The analytes were separated on a monolithic performance RP-18e column (100 mm × 4.6 mm i.d.) using a gradient elution of acetonitile-water containing 0.1% trifluoroacetic acid (TFA) as the mobile phase with a flow rate 0.4 mL/min and UV detection at λ 210 nm.

RESULTS

The method was linear over the range 3-15 µg/mL (r > 9994). Accuracy, precision and repeatability were all within the required limits. The mean recoveries measured at the three concentrations were higher than 98.8% with RSD < 2% for the targets.

CONCLUSION

The established method is simple and can be used as a tool for quality control of plant material or herbal formulation containing SG.

Optimization of human serum albumin monoliths for chiral separations and high-performance affinity chromatography

Various organic-based monoliths were prepared and optimized for immobilization of the protein human serum albumin (HSA) as a binding agent for chiral separations and high-performance affinity chromatography. These monoliths contained co-polymers based on glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) or GMA and trimethylolpropane trimethacrylate (TRIM). A mixture of cyclohexanol and 1-dodecanol was used as the porogen, with the ratio of these solvents being varied along with the polymerization temperature to generate a library of monoliths. These monoliths were used with both the Schiff base and epoxy immobilization methods and measured for their final content of HSA. Monoliths showing the highest protein content were further evaluated in chromatographic studies using R/S-warfarin and d/l-tryptophan as model chiral solutes. A 2.6-2.7-fold increase in HSA content was obtained in the final monoliths when compared to similar HSA monoliths prepared according to the literature. The increased protein content made it possible for the new monoliths to provide higher retention and/or two-fold faster separations for the tested solutes when using 4.6mm i.d.× 50 mm columns. These monoliths were also used to create 4.6mm i.d.× 10 mm HSA microcolumns that could separate the same chiral solutes in only 1.5-6.0 min. The approaches used in this study could be extended to the separation of other chiral solutes and to the optimization of organic monoliths for use with additional proteins as binding agents.

Fast HPLC-DAD quantification of nine polyphenols in honey by using second-order calibration method based on trilinear decomposition algorithm

This paper describes the use of second-order calibration for development of HPLC-DAD method to quantify nine polyphenols in five kinds of honey samples. The sample treatment procedure was simplified effectively relative to the traditional ways. Baselines drift was also overcome by means of regarding the drift as additional factor(s) as well as the analytes of interest in the mathematical model. The contents of polyphenols obtained by the alternating trilinear decomposition (ATLD) method have been successfully used to distinguish different types of honey. This method shows good linearity (r>0.99), rapidity (t<7.60 min) and accuracy, which may be extremely promising as an excellent routine strategy for identification and quantification of polyphenols in the complex matrices.

Quantitation of α-galactosides in Rehmannia glutinosa by hydrophilic interaction chromatography-evaporative light scattering detector

INTRODUCTION

The use of raffinose family oligosaccharides (RFOs) to control several diseases and stimulate immune systems has been studied. Rehmannia glutinosa is reported to contain RFOs; however, there are no reports on their content level in R. glutinosa. Furthermore, it is difficult to analyse RFOs using common reverse-phase chromatographic techniques due to their high polarity.

OBJECTIVE

To develop a rapid and reliable chromatographic method for the simultaneous quantitation of multiple RFOs in R. glutinosa.

METHODOLOGY

Chromatographic separation was performed by using hydrophilic interaction liquid chromatography coupled with an evaporative light scattering detector. For efficient ultrasound-assisted extraction of oligosaccharides, a central composite design was used.

RESULTS

Response surface analysis estimated the highest-obtained yields of raffinose, stachyose and verbascose to be 58.31, 408.75 and 26.59 mg, respectively, from 1 g of R. glutinosa, while under optimal conditions, experimental yields per gram were 56.79, 391.42 and 27.69 mg, respectively.

CONCLUSION

A rapid and reliable chromatographic method to simultaneously quantitate multiple RFOs in R. glutinosa was developed. Three RFOs in R. glutinosa were separated within 10 min using isocratic conditions. Quantitative analysis of RFOs showed that R. glutinosa may be a rich source of α-galacto-oligosaccharides, especially stachyose.

Structural characterisation and identification of phenylethanoid glycosides from Cistanches deserticola Y.C. Ma by UHPLC/ESI-QTOF-MS/MS

INTRODUCTION

Phenylethanoid glycosides (PhGs) are the major active constituents of Cistanches deserticola Y.C. Ma. However, the isolation, purification and identification procedures of PhGs are difficult and time-consuming.

OBJECTIVE

To establish a rapid and sensitive ultrahigh-pressure liquid chromatography (UHPLC)/ESI (electrospray ion source)-quadrupole time of flight (QTOF)-MS/MS method that could be applied to rapidly profile and identify PhGs.

METHODOLOGY

Seven standard compounds were used for the investigation of the fragmentation pattern. Based on the UHPLC/ESI-QTOF-MS/MS method, the important structural information on the types of aglycone and saccharide sequences present should be obtained.

RESULTS

According to the HPLC retention behaviour, the proposed fragmentation pathways provided by high-resolution MS and MS/MS spectra and literature sources, a total of 13 PhGs in the crude extract of C. deserticola were identified or tentatively identified.

CONCLUSION

A rapid and accurate UHPLC/ESI-QTOF-MS/MS method was established for the identification of PhGs in the crude extract of C. deserticola. This method therefore can be used for rapid prediction of the chemical constituents and qualities of this plant.

[Determination of morphine and codeine in forensic chemical studies with the use of a single quadrupole mass-selective detector coupled to the HPLC system]

It was shown that a single quadrupole mass-selective detector coupled to the HPLC system can be used in forensic chemical practice for the detection and quantitative measurement of morphine and codeine in forensic in various biological objects. An algorithm for the reliable identification of opiates in a concentration range starting from 0.002 mg% with a relative error below 20% (mean ca 9.5%) is proposed.

Tandem solid phase extraction followed by online trapping-hydrophilic interaction chromatography-tandem mass spectrometry for sensitive detection of endogenous cytokinins in plant tissues

INTRODUCTION

Cytokinins (CKs) are a group of plant hormones that play pivotal roles at low concentration in plant growth, development and regulatory pathways. In order to study the function, metabolism and signal transduction of CKs, high performance analytical techniques are required for determination of their endogenous levels.

OBJECTIVE

To develop a highly sensitive, selective and reliable method for identification and quantification of CKs by employing a tandem solid phase extraction (SPE)-online trapping-hydrophilic interaction chromatography (HILIC)-MS/MS method.

MATERIAL AND METHODS

The extraction was performed firstly with tandem SPE containing a C(18) cartridge and a silica@C(8) /SO(3) H cartridge. After CKs were eluted from the silica@C(8)/SO(3) H cartridge, the desorption solvent was concentrated and redissolved in H(2)O and then injected into the online trapping-HILIC-MS/MS system with (Poly(MAA-co-EGDMA)) monolith as the trapping column. Subsequently, trapping, washing, desorption, separation and detection were accomplished automatically on the system.

RESULTS

Good linearities were obtained for eight cytokinins with correlation coefficients (R(2)) > 0.9964. The limits of detection (LOD; S:N = 3) for the targets ranged from 0.042 to 1.6 pg/mL. Reproducibility of the method was evaluated with intraday and interday relative standard deviations (RSDs) less than 13.4% and the recoveries ranged from 77.3% to 116.3%. The results showed that the LOD of the analytical method were at least one order of magnitude lower compared with other previously reported methods. Furthermore, only 20 mg of plant tissues were required for the quantitative analysis of the major CKs, which is, to the best of our knowledge, the smallest amount reported so far for the determination of endogenous CKs in plant tissues.

CONCLUSION

The tandem SPE-online trapping-HILIC-MS/MS method developed in current study provides a powerful tool for the convenient and highly sensitive quantification of the major CKs in plant tissue.

Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection

An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 μm) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples.