Determination of bisphenol A in canned food by microwave assisted extraction, molecularly imprinted polymer-solid phase extraction and liquid chromatography-mass spectrometry

Bisphenol A (BPA), a known potential endocrine disrupting compound (EDC) is expected to be present in low quantities in canned food due to its migration from the inner surface coating of cans made of epoxy resins. A selective and confirmatory analytical method, based on microwave assisted extraction (MAE), molecularly imprinted solid phase extraction (MISPE) using a polymer prepared by a non-covalent molecular imprinting technique and liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI/MS) was developed for the determination of BPA in canned pineapple, tuna and mushrooms. First, the effect of the loading medium of hydro- organic solutions on the binding of BPA and its deuterated analogue on the MISPE sorbent was investigated. Subsequently, the effects of the experimental conditions of the microwave assisted extraction (solvent, sample mass/solvent volume, time and temperature) on the obtained recovery of BPA from canned food were assessed and the parameters were optimized to provide maximum recovery and selectivity. It was demonstrated that the combination of MAE with MISPE permits the use of a selective extraction solvent (methanol/water, 4/6, v/v), simplifying the sample preparation steps and enhancing sample clean-up of complex food matrices. The method was validated in different food matrices, using BPA-d16 as internal standard and quantitative relative recoveries were determined. The precision (RSD %) of the method ranged from 7% to 10% and the limit of detection was at low ng/g level for all food matrices. The determined concentration of BPA in commercial canned samples ranged between 7.3 and 42.3 ng/g.

HILIC-MS/MS Multi-Targeted Method for Metabolomics Applications

Metabolomics aims at the identification and quantification of key-end point metabolites, basically polar, in order to study changes in biochemical activities in response to pathophysiological stimuli or genetic modifications. Targeted profiling assays have enjoyed a growing popularity during the last years with LC-MS/MS as a powerful tool for development of such (semi-) quantitative methods for a large number of metabolites. Here we describe a method for absolute quantification of ca. 100 metabolites belonging to key metabolite classes such as sugars, amino acids, nucleotides, organic acids, and amines with a hydrophilic interaction liquid chromatography (HILIC) system comprised of ultra (high) performance liquid chromatography (UHPLC) with detection on a triple-quadrupole mass spectrometer operating in both positive and negative electrospray ionization modes.

Metabolic Profiling: Status, Challenges, and Perspective

Metabolic profiling has advanced greatly in the past decade and evolved from the status of a research topic of a small number of highly specialized laboratories to the status of a major field applied by several hundreds of laboratories, numerous national centers, and core facilities. The present chapter provides our view on the status of the remaining challenges and a perspective of this fascinating research area.

Quality Control and Validation Issues in LC-MS Metabolomics

Global metabolic profiling (untargeted metabolomics) of different and complex biological matrices aims to implement an holistic, hypothesis-free analysis of (potentially) all the metabolites present in the analyzed sample. However, such an approach, although it has been the focus of great interest over the past few years, still faces many limitations and challenges, particularly with regard to the validation and the quality of the obtained results. The present protocol describes a quality control (QC) procedure for monitoring the precision of the analytical process involving untargeted metabolic phenotyping of urine and plasma/serum. The described/suggested methodology can be applied to different biological matrices, such as biological biofluids, cell, and tissue extracts.

Effects of Different Exercise Modes on the Urinary Metabolic Fingerprint of Men with and without Metabolic Syndrome

Exercise is important in the prevention and treatment of the metabolic syndrome (MetS), a cluster of risk factors that raises morbidity. Metabolomics can facilitate the optimization of exercise prescription. This study aimed to investigate whether the response of the human urinary metabolic fingerprint to exercise depends on the presence of MetS or exercise mode. Twenty-three sedentary men (MetS, n = 9, and Healthy, n = 14) completed four trials: resting, high-intensity interval exercise (HIIE), continuous moderate-intensity exercise (CME), and resistance exercise (RE). Urine samples were collected pre-exercise and at 2, 4, and 24 h for targeted analysis by liquid chromatography-mass spectrometry. Time exerted the strongest differentiating effect, followed by exercise mode and health status. The greatest changes were observed in the first post-exercise samples, with a gradual return to baseline at 24 h. RE caused the greatest responses overall, followed by HIIE, while CME had minimal effect. The metabolic fingerprints of the two groups were separated at 2 h, after HIIE and RE; and at 4 h, after HIIE, with evidence of blunted response to exercise in MetS. Our findings show diverse responses of the urinary metabolic fingerprint to different exercise modes in men with and without metabolic syndrome.

Amniotic Fluid and Maternal Serum Metabolic Signatures in the Second Trimester Associated with Preterm Delivery

Preterm delivery (PTD) represents a major health problem that occurs in 1 in 10 births. The hypothesis of the present study was that the metabolic profile of different biological fluids, obtained from pregnant women during the second trimester of gestation, could allow useful correlations with pregnancy outcome. Holistic and targeted metabolomics approaches were applied for the complementary assessment of the metabolic content of prospectively collected amniotic fluid (AF) and paired maternal blood serum samples from 35 women who delivered preterm (between 29 weeks + 0 days and 36 weeks +5 days gestation) and 35 women delivered at term. The results revealed trends relating the metabolic content of the analyzed samples with preterm delivery. Untargeted and targeted profiling showed differentiations in certain key metabolites in the biological fluids of the two study groups. In AF, intermediate metabolites involved in energy metabolism (pyruvic acid, glutamic acid, and glutamine) were found to contribute to the classification of the two groups. In maternal serum, increased levels of lipids and alterations of key end-point metabolites were observed in cases of preterm delivery. Overall, the metabolic content of second-trimester AF and maternal blood serum shows potential for the identification of biomarkers related to fetal growth and preterm delivery.

Targeted Metabolic Profiling of the Tg197 Mouse Model Reveals Itaconic Acid as a Marker of Rheumatoid Arthritis

Rheumatoid arthritis is a progressive, highly debilitating disease where early diagnosis, enabling rapid clinical intervention, would provide obvious benefits to patients, healthcare systems, and society. Novel biomarkers that enable noninvasive early diagnosis of the onset and progression of the disease provide one route to achieving this goal. Here a metabolic profiling method has been applied to investigate disease development in the Tg197 arthritis mouse model. Hind limb extract profiling demonstrated clear differences in metabolic phenotypes between control (wild type) and Tg197 transgenic mice and highlighted raised concentrations of itaconic acid as a potential marker of the disease. These changes in itaconic acid concentrations were moderated or indeed reversed when the Tg197 mice were treated with the anti-hTNF biologic infliximab (10 mg/kg twice weekly for 6 weeks). Further in vitro studies on synovial fibroblasts obtained from healthy wild-type, arthritic Tg197, and infliximab-treated Tg197 transgenic mice confirmed the association of itaconic acid with rheumatoid arthritis and disease-moderating drug effects. Preliminary indications of the potential value of itaconic acid as a translational biomarker were obtained when studies on K4IM human fibroblasts treated with hTNF showed an increase in the concentrations of this metabolite.

Monitoring the Response of the Human Urinary Metabolome to Brief Maximal Exercise by a Combination of RP-UPLC-MS and (1)H NMR Spectroscopy

The delineation of exercise biochemistry by utilizing metabolic fingerprinting has become an established strategy. We present a combined RP-UPLC-MS and (1)H NMR strategy, supplemented by photometric assays, to monitor the response of the human urinary metabolome to short maximal exercise. Seventeen male volunteers performed two identical sprint sessions on separate days, consisting of three 80 m maximal runs. Using univariate and multivariate analyses, we followed the fluctuation of 37 metabolites at 1, 1.5, and 2 h postexercise. 2-Hydroxyisovalerate, 2-hydroxybutyrate, 2-oxoisocaproate, 3-methyl-2-oxovalerate, 3-hydroxyisobutyrate, 2-oxoisovalerate, 3-hydroxybutyrate, 2-hydroxyisobutyrate, alanine, pyruvate, and fumarate increased 1 h postexercise and then returned toward baseline. Lactate and acetate were higher than baseline at 1 and 1.5 h. Hypoxanthine and inosine remained above baseline throughout the postexercise period. Urate decreased at 1 h and increased at 1.5 h before returning to baseline. Valine, isoleucine, succinate, citrate, trimethylamine, trimethylamine N-oxide, tyrosine, and formate decreased at 1 h and/or 1.5 h postexercise and then returned to baseline. Creatinine gradually decreased over the sampling period. Glycine, 4-aminohippurate, and hippurate remained below baseline throughout the postexercise period. Our findings show that even one-half minute of maximal exercise elicited major perturbations in human metabolism, several of which persisted for at least 2 h.

Development and validation of a HILIC-MS/MS multitargeted method for metabolomics applications

The paper reports the development of a multianalyte method and its application in metabolic profiling of biological fluids. The initial aim of the method was the quantification of metabolites existing in cell culture medium used in in-vitro fertilization (IVF) and in other biological fluids related to embryo growth. Since most of these analytes are polar primary metabolites a hydrophilic interaction liquid chromatography system was selected. The analytical system comprised Ultra-HPLC with detection on a triple quadrupole mass spectrometer operating in both positive and negative modes. Mobile phase and gradient elution conditions were studied with the aim to achieve the highest coverage of metabolic space in a single injection namely the largest number of analytes that could be detected and quantified. The developed method provides absolute quantitation of ca. 100 metabolites belonging to key metabolite classes such as sugars, aminoacids, nucleotides, organic acids, and amines. Following validation, the method was applied for the metabolic profiling of hundreds of samples of spent culture medium originating from human IVF procedures and several hundreds of biological samples such as amniotic fluid, human urine and blood serum from pregnant women. The bioanalytical end-point was to provide assistance in the process of embryo transfer and improving IVF success rates but also to provide insight in complications related to the subsequent embryo growth during pregnancy.

Liquid Chromatographic Techniques in Metabolomics

In the past decade, LC‐MS‐based metabolomic/metabonomic profiling has become a major analytical focus for biomarker research. Chromatographic resolution is continually improving with the development of more advanced separation platforms based on smaller particle sizes, new types of stationary phase and miniaturized systems allowing the profiling of biological samples for metabolites in ways that were simply not possible before. Chromatographic advances, combined with increased mass resolution instruments that provide sub‐2 ppm mass accuracy and high sensitivity, have greatly facilitated the detection and identification of potential biomarkers. In this chapter, the most common LC(‐MS) methods utilized in metabolic analyses are presented, with emphasis on novel high‐efficiency and high‐throughput analyses and their suitability for metabolic analyses. Guidelines for the selection of the appropriate method for different applications are given, with emphasis on the use of LC‐MS.

Investigation of chronic alcohol consumption in rodents via ultra-high-performance liquid chromatography-mass spectrometry based metabolite profiling

Alcohol consumption in man, when seen in its extreme form of alcoholism, is a complex and socially disruptive disorder that can result in significant levels of liver injury. Here the rodent "intragastric feeding model" was used together with UHPLC-TOFMS analysis to determine changes in global metabolite profiles for plasma and urine from alcohol treated rats and mice compared to control animals. Multivariate statistical analysis (using principal components analysis, PCA) revealed robust differences between profiles from control and alcohol-treated animals from both species. A large number of metabolites were seen to differ between control and alcohol-treated animals, for both biofluids.

Liquid chromatography-mass spectrometry based global metabolite profiling: a review

Untargeted, global metabolite profiling (often described as metabonomics or metabolomics) represents an expanding research topic and is, potentially, a major pillar for systems biology studies. To obtain holistic metabolic profiles from complex samples, such as biological fluids or tissue extracts, requires powerful, high resolution and information-rich analytical methods and for this spectroscopic technologies are generally used. Mass spectrometry, coupled to liquid chromatography (LC-MS), is increasingly being used for such investigations as a result of the significant advances in both technologies over the past decade. Here we try to critically review the topic of LC-MS-based global metabolic profiling and describe and compare the results offered by different analytical strategies and technologies. This review highlights the current challenges, limitations and opportunities of the current methodology.

Determination of anabolic steroids in bovine serum by liquid chromatography-tandem mass spectrometry

In the present paper we report the LC-MS/MS determination of residues of 12 anabolic steroids in bovine serum, as an expansion of our work protocols for steroids determination in biological matrices. Steroids analyzed included α-zearalanol, β-zearalanol, α-trenbolone, β-trenbolone, methyltestosterone, α-estradiol, β-estradiol, ethynylestradiol, α-boldenone, β-boldenone, α-nortestosterone and β-nortestosterone. Following protein precipitation, serum samples were cleaned up by solid-phase extraction using Oasis HLB and Amino cartridges. Atmospheric pressure chemical ionization (APCI) in both positive and negative ionization modes was used and mass spectrometry detection was carried out in multiple reaction monitoring mode following two or (in most cases) three product ions per precursor ion. The method was validated in accordance with the Commission Decision 2002/657/EC. The decision limit (CCα) values obtained, ranged from 0.01 to 0.07 ng/ml and the detection capability (CCβ) values obtained ranged from 0.02 to 0.12 ng/ml. The recoveries ranged from 70.2% to 118.2%. The developed method is suitable for routine and confirmatory purposes such as control of illegal use in livestock production.

(1)H NMR-based metabonomic investigation of the effect of two different exercise sessions on the metabolic fingerprint of human urine

Physical exercise modifies animal metabolism profoundly. Until recently, biochemical investigations related to exercise focused on a small number of biomolecules. In the present study, we used a holistic analytical approach to investigate changes in the human urine metabolome elicited by two exercise sessions differing in the duration of the rest interval between repeated efforts. Twelve men performed three sets of two 80 m maximal runs separated by either 10 s or 1 min of rest. Analysis of pre- and postexercise urine samples by (1)H NMR spectroscopy and subsequent multivariate statistical analysis revealed alterations in the levels of 22 metabolites. Urine samples were safely classified according to exercise protocol even when applying unsupervised methods of statistical analysis. Separation of pre- from postexercise samples was mainly due to lactate, pyruvate, hypoxanthine, compounds of the Krebs cycle, amino acids, and products of branched-chain amino acid (BCAA) catabolism. Separation of the two rest intervals was mainly due to lactate, pyruvate, alanine, compounds of the Krebs cycle, and 2-oxoacids of BCAA, all of which increased more with the shorter interval. Metabonomics provides a powerful methodology to gain insight in metabolic changes induced by specific training protocols and may thus advance our knowledge of exercise biochemistry.

Does the mass spectrometer define the marker? A comparison of global metabolite profiling data generated simultaneously via UPLC-MS on two different mass spectrometers

By coupling a single UPLC separation to two different types of mass spectrometer an unbiased comparison of the metabolite profiles produced by each instrument for a set of rat urine samples was obtained. The flow from the UPLC column was split equally and both streams of eluent were simultaneously directed to the inlets of the two mass spectrometers. Mass spectrometry on the eluent was undertaken using a triple quadrupole linear ion trap and a hybrid quadrupole time-of-flight mass spectrometer using both positive and negative ESI. Data from both mass spectrometers were subjected to multivariate statistical analysis, after applying the same data extraction software, and showed the same general pattern of correlation between the samples using both unsupervised and supervised methods of statistical analysis. Based on orthogonal partial least-squares discriminant analysis models a number of ions were recognized as "responsible" for the separation of the animal groups. From the peaks detected, and denoted as significant by the statistical analysis a number of ions were found to be unique to one data set or the other, a result which may have consequences for biomarker discovery and interlaboratory comparisons. The software package used for data analysis also had an effect on the outcome of the statistical analysis.

Daptomycin determination by liquid chromatography-mass spectrometry in peritoneal fluid, blood plasma, and urine of clinical patients receiving peritoneal dialysis treatment

A 13-min LC-MS method was developed for the determination of daptomycin, a new potent antibiotic, in peritoneal fluid, blood plasma, and urine of patients receiving renal replacement therapy. Chromatography was performed on a C(18) column and detection was performed by a single-quadrupole mass spectrometer coupled to LC via an electrospray interface (ESI). The column effluent was also monitored at 370 nm using a photodiode-array detector. The developed method provided a linear dynamic range for concentrations from 0.5 microg mL(-1) to 100 microg mL(-1). Method precision and accuracy were found to be satisfactory for clinical application, thus the method was successfully used for the analysis of daptomycin in pharmacokinetic studies. The drug was preventively administered against Gram-positive infections to 19 clinical patients undergoing peritoneal dialysis. Peritoneal fluid, blood plasma, and urine samples were collected at 13 time points over a period of 48 h. Clinical samples were analysed following simple sample-preparation procedures and daptomycin was unambiguously detected and quantified.

Hydrophilic interaction and reversed-phase ultra-performance liquid chromatography TOF-MS for metabonomic analysis of Zucker rat urine

Hydrophilic interaction chromatography (HILIC) provides a complementary technique to RP methods for the retention of polar analytes for LC-MS-based metabonomic studies. Combining the advantages of both RP and HILIC separations with the efficient and rapid separations obtained using sub-2 mum particles via the recently introduced ultra-performance LC (UPLC) enables increased coverage of the metabolites present in biological samples to be achieved. Here an HILIC-UPLC-MS method was developed to provide metabolite profiles for urine samples obtained from male Zucker rats. The resulting data were compared with results obtained for the same samples by RP-UPLC-MS and demonstrated the complementary nature of the two separations with both methods enabling discrimination between the different sample types. Interestingly sample type differentiation was based on different markers.

Liquid chromatography and ultra-performance liquid chromatography-mass spectrometry fingerprinting of human urine: sample stability under different handling and storage conditions for metabonomics studies

Typically following collection biological samples are kept in a freezer for periods ranging from a few days to several months before analysis. Experience has shown that in LC-MS-based metabonomics research the best analytical practice is to store samples as these are collected, complete the sample set and analyse it in a single run. However, this approach is prudent only if the samples stored in the refrigerator or in the freezer are stable. Another important issue is the stability of the samples following the freeze-thaw process. To investigate these matters urine samples were collected from 6 male volunteers and analysed by LC-MS and ultra-performance liquid chromatography (UPLC)-MS [in both positive and negative electrospray ionization (ESI)] on the day of collection or at intervals of up to 6 months storage at -20 degrees C and -80 degrees C. Other sets of these samples underwent a series of up to nine freeze-thaw cycles. The stability of samples kept at 4 degrees C in an autosampler for up to 6 days was also assessed, with clear differences appearing after 48h. Data was analysed using multivariate statistical analysis (principal component analysis). The results show that sample storage at both -20 and -80 degrees C appeared to ensure sample stability. Similarly up to nine freeze thaw cycles were without any apparent effect on the profile.

Within-day reproducibility of an HPLC-MS-based method for metabonomic analysis: application to human urine

Self-evidently, research in areas supporting "systems biology" such as genomics, proteomics, and metabonomics are critically dependent on the generation of sound analytical data. Metabolic phenotyping using LC-MS-based methods is currently at a relatively early stage of development, and approaches to ensure data quality are still developing. As part of studies on the application of LC-MS in metabonomics, the within-day reproducibility of LC-MS, with both positive and negative electrospray ionization (ESI), has been investigated using a standard "quality control" (QC) sample. The results showed that the first few injections on the system were not representative, and should be discarded, and that reproducibility was critically dependent on signal intensity. On the basis of these findings, an analytical protocol for the metabonomic analysis of human urine has been developed with proposed acceptance criteria based on a step-by-step assessment of the data. Short-term sample stability for human urine was also assessed. Samples were stable for at least 20 h at 4 degrees C in the autosampler while queuing for analysis. Samples stored at either -20 or -80 degrees C for up to 1 month were indistinguishable on subsequent LC-MS analysis. Overall, by careful monitoring of the QC data, it is possible to demonstrate that the "within-day" reproducibility of LC-MS is sufficient to ensure data quality in global metabolic profiling applications.

Coupling of sequential injection analysis and capillary electrophoresis - Laser-induced fluorescence via a valve interface for on-line derivatization and analysis of amino acids and peptides

The on-line coupling of sequential injection analysis (SIA) and capillary electrophoresis (CE) via an in-line injection valve is presented. The SIA system is used for automated derivatization of amino acids and peptides. Dichlorotriazinylaminofluorescein serves as the derivatization agent, thus enabling sensitive laser-induced fluorescence detection of the derivatized analytes. The SIA procedure includes the following steps: (a) introduction of reagent and sample zones in a holding coil, (b) sample and reagent mixing in a reaction coil, (c) stop-flow step for increase of the reaction time, and (d) delivery of derivatized sample into the loop of the micro-valve interface. A small portion of the analyte zone is introduced electrokinetically in the separation capillary via the valve interface and CE analysis is performed. Factors affecting the CE separation, such as pH, the borate and sodium dodecyl sulphate concentration of the background electrolyte have been optimized. The derivatization conditions have been studied to obtain a high reaction yield in a relative short time. The transfer of a part of the reaction plug into the loop of the valve interface has been optimized. Using des-Tyr(1)-[Met]-enkephalinamide as test compound, it is demonstrated that after automated derivatization, on-line electrophoretic analysis could be achieved. Glycine has been selected as the internal standard in order to correct for variations in reaction time and filling of the injection loop. For the enkephalin, good reproducibility (RSD<4.5% calculated by the ratio of the peak areas) and linearity (0.5-5 microg mL(-1), R(2)>or=0.994) are obtained with a detection limit of 30 ng mL(-1) (S/N=3).

Incorporation of a monolithic column into sequential injection system for drug-protein binding studies

A sequential injection analysis (SIA) manifold was incorporated with a monolithic strong anion-exchanger disk for on-line drug-protein interaction studies. The antibiotic ciprofloxacin (CF) was selected as a model drug compound. The separation principle was based on the strong retention of bovine serum albumin (BSA) on the monolithic strong anion-exchanger and the liberation/release of the free form of the drug. Elution of the retained BSA was easily achieved by delivering a different mobile phase via the SIA manifold. The type of functional group of the monolithic support, the breakthrough volume and the injected volumes of CF and BSA were studied and optimized. The influence of the variation of incubation time was studied in on-line binding assays. Scatchard plot was employed to obtain the number of binding sites and the equilibrium binding constants. For the off-line study of the CF-BSA binding, two binding classes were determined with constants of (3.16+/-0.21)x10(6)M(-1) and (1.27+/-0.48)x10(4)M(-1) and 6.1+/-1.3 and 17.8+/-3.9 binding sites per class, respectively. In non-equilibrium binding experiments the binding rate constant was k(1)=785 M(-1)min(-1). All measurements were monitored with fluorescence (lambda(ext)=300 nm, lambda(em)=460 nm) and spectrophotometric detection (lambda=280 nm). To evaluate the accuracy of the developed method the obtained results were compared versus ultrafiltration experiments and were found in good agreement.

On-line coupling of sequential injection with liquid chromatography for the automated derivatization and determination of ?-aminobutyric acid in human biological fluids

The principle of sequential injection analysis (SIA) was exploited to develop a rapid fully automated and efficient pre-column derivatization procedure coupled on-line to liquid chromatography (HPLC). Using the SIA-HPLC derivatization protocol gamma-aminobutyric acid (GABA) was determined fluorimetrically in human biological fluids with o-phthaldialdehyde (OPA) as derivatization reagent and minimum sample pretreatment. A lab-built SIA system was used to handle samples, standard solutions and OPA reagent. Appropriate volumes of the reagents were introduced in the holding coil of the SIA system and were mixed on propulsion to the HPLC loop through a suitable reaction coil. The chemical (pH, c(OPA), c(mercaptoethanol)) and instrumental variables (volumes of sample and reagent, reaction time) of the reaction were studied and optimized in terms of maximum sensitivity. The chromatographic variables (gradient composition of the eluent and flow rate) were studied for optimum selectivity and peak characteristics. The developed experimental configuration facilitated fully-automated operation thus minimizing errors in handling. Additionally the method as a whole provided very satisfactory sensitivity, precision and accuracy. Direct determination of GABA in human urine and cerebrospinal fluid (CSF) at microg L(-1) (ppb) levels was accomplished, with minimum sample pretreatment.

Rapid spectrofluorimetric determination of lisinopril in pharmaceutical tablets using sequential injection analysis

The present work reports for the first time a simple and rapid method for the spectrofluorimetric determination of lisinopril (LSP) in pharmaceutical formulations using sequential injection analysis (SIA). The method is based on reaction of LSP with o-phthalaldehyde (OPA) in the presence of 2-mercaptoethanol (borate buffer medium, pH=10.6). The emission of the derivative is monitored at 455 nm upon excitation at 346 nm. The various chemical and physical conditions that affected the reaction were studied. The calibration curve was linear in the range 0.3-10.0 mg L(-1) LSP, at a sampling rate of 60 injections h(-1). Consumption of OPA reagent was significantly reduced compared with conventional flow injection (FI) systems, because only 50 microL of OPA was consumed per run. The method was found to be adequately precise ( s(r)=2% at 5 mg L(-1) LSP, n=10) and the 3 sigma detection limit was 0.1 mg L(-1). The method was successfully applied to the analysis of two pharmaceutical formulations containing LSP. The results obtained were in good agreement with those obtained by use of high-performance liquid chromatography (HPLC), because the mean relative error, e(r), was <1.8%.