Development and validation of a liquid chromatographic method for the determination of hydroxymethylfurfural and alpha-ketoglutaric acid in human plasma

Determination of genotoxic impurities of aromatic aldehydes in pharmaceutical preparations by high performance liquid chromatography after derivatization with N-Cyclohexyl-4-hydrazino-1,8-naphthalenediimide

The detection of aromatic aldehydes, considered potential genotoxic impurities, holds significant importance during drug development and production. Current analytical methods necessitate complex pre-treatment processes and exhibit insufficient specificity and sensitivity. This study presents the utilization of naphthalenediimide as a pre-column derivatisation reagent to detect aromatic aldehyde impurities in pharmaceuticals via high-performance liquid chromatography (HPLC). We screened a series of derivatisation reagents through density functional theory (DFT) and investigated the phenomenon of photoinduced electron transfer (PET) for both the derivatisation reagents and the resulting products. Optimal experimental conditions for derivatisation were achieved at 40 °C for 60 min. This approach has been successfully applied to detect residual aromatic aldehyde genotoxic impurities in various pharmaceutical preparations, including 4-Nitrobenzaldehyde, 2-Nitrobenzaldehyde, 1,4-Benzodioxane-6-aldehyde, and 5-Hydroxymethylfurfural. The pre-column derivatisation method significantly enhanced detection sensitivity and reduced the limit of detection (LOD), which ranged from 0.002 to 0.008 μg/ml for the analytes, with relative standard deviations < 3 %. The correlation coefficient (R2) >0.998 demonstrated high quality. In chloramphenicol eye drops, the concentration of 4-Nitrobenzaldehyde was measured to be 8.6 µg/mL below the specified concentration, with recoveries ranging from 90.0 % to 119.2 %. In comparison to existing methods, our work simplifies the pretreatment process, enhances the sensitivity and specificity of the analysis, and offers comprehensive insights into impurity detection in pharmaceutical preparations.

Highly Sensitive Amperometric α-Ketoglutarate Biosensor Based on Reduced Graphene Oxide-Gold Nanocomposites

Herein, a rapid and highly sensitive amperometric biosensor for the detection of α-ketoglutarate (α-KG) was constructed via an electrochemical approach, in which the glutamate dehydrogenase (GLUD) was modified on the surface of reduced graphene oxide-gold nanoparticle composite (rGO-Aunano composite). The rGO-Aunano composite was one-step electrodeposited onto glassy carbon electrode (GCE) surface and was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electrochemical techniques. In addition, the rGO-Aunano/GCE was also found to electrocatalyze the oxidation of β-nicotinamide adenine dinucleotide (NADH) at the peak potential of 0.3 V, which was negatively shifted compared with that at bare GCE or Aunano/GCE, illustrating better catalytic performance of rGO-Aunano. After the modification of GLUD, the GLUD/rGO-Aunano/GCE led to effective amperometric detection of α-KG through monitoring the NADH consumption and displayed a linear response in the range of 66.7 and 494.5 μM, with the detection limit of 9.2 μM. Moreover, the prepared GLUD/rGO-Aunano/GCE was further evaluated to be highly selective and used to test α-KG in human serum samples. The recovery and the RSD values were calculated in the range of 97.9-102.4% and 3.8-4.5%, respectively, showing a great prospect for its real application.

Determination of α-ketoglutaric and pyruvic acids in urine as potential biomarkers for diabetic II and liver cancer

Background: A simple and sensitive hollow fiber-liquid phase microextraction with in situ derivatization method was developed for the determination of α-ketoglutaric (α-KG) and pyruvic acids (PA) in small-volume urine samples. 2,4,6-trichloro phenyl hydrazine was used as derivatization agent. Results: Under the optimum extraction conditions, enrichment factors of 742 and 400 for α-KG and PA, respectively, were achieved. Calibration curves were linear over the range 1 to 1000 ng/ml (r2 ≥ 0.998). Detection and quantitation limits were 0.03 and 0.02, and 0.10 and 0.05 ng/ml for α-KG and PA, respectively. Conclusion: The concentrations in diabetic II and liver cancer samples were significantly lower than those from healthy people, showing their potential as biomarkers for these diseases.

Simultaneous quantitation of alpha-ketoglutaric acid and 5-hydroxymethylfurfural in plasma by HPLC with UV and fluorescence detection

Alpha-ketoglutaric acid (KG) and hydroxymethylfurfural (HMF) are currently being investigated in clinical trials as an approach in targeted cancer therapy. Hence, a method for the simultaneous determination of KG and HMF in plasma has been developed. Due to the strongly discriminative chemical properties of KG and HMF, SPE purification is performed using an ion-exchange cartridge to separate KG, and a hydrophobic polymeric cartridge to separate HMF. The cartridges are connected together for several steps, thus resulting in a quicker approach for the purification of plasma samples. The derivatization step is based on the reaction of the carbonyl groups of KG and HMF with dansylhydrazine (DNSH) catalyzed by trifluoroacetic acid. The formed derivatives could be separated by reversed-phase LC on a C8-column, and analyzed by UV and fluorescence detection in a single run using a gradient program. The obtained results show good reproducibility, specificity, and detection limits down to the low picomole range.

Determination of metabolites of 5-hydroxymethylfurfural in human urine after oral application

5-Hydroxymethylfurfural (5-HMF) is a natural occurring substance taken up by everyday food. In former studies it was shown that 5-HMF is completely decomposed in the body after oral or intravenous application resulting in three main metabolites named 5-hydroxymethylfuroic acid, 2,5-furandicarboxylic acid, and N-(hydroxymethyl)furoyl glycine, and possibly a forth metabolic substance, termed 5-sulphoxymethylfurfural, is formed. Determination is possible via HPLC using a hydrophilic interaction chromatography (HILIC) column with an appropriate gradient system (ACN/ammonium formate 100 mM, pH 2.35). Urine samples were purified by use of an SPE method beforehand working with ScreenA cartridges. This cleaning procedure was validated based on ICH guidelines in terms of linearity, quantification, and detection limit, as well as precision, repeatability, and accuracy. Analysis of real-life samples coming from two healthy probands and one cancer patient, who all received 240 mg 5-hydroxymethylfurfural orally once a day, showed dicarboxylic acid and the glycine conjugate in their urine samples. Recovery of the initial compound in form of transformed metabolites was up to 90% within 48 h. Potentially toxic 5-sulphoxymethylfurfural could not be found.

A liquid chromatography and tandem mass spectrometry method for the determination of potential biomarkers of cardiovascular disease

A simple, accurate and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of α-ketoglutaric acid (α-KG), L-carnitine (L-CAR) and acetyl-L-carnitine (acetyl-L-CAR) in human urine as potential biomarkers of cardiovascular disease. The separation was performed using an isocratic elution of 0.1% formic acid in water and acetonitrile (97:3, v/v) on an Acclaim 120 C8 column (150 mm × 4.6 mm, 3.0 μm). The flow rate of the mobile phase was 1.2 mL/min and the total assay run time was 3 min. Detection was performed on a triple-quadrupole mass spectrometer in selected reaction monitoring (SRM) mode via an electrospray ionization (ESI) source in positive and negative ion modes. This method covered a linearity range of 0.1-500 ng/mL for L-CAR and acetyl-L-CAR and 1-1000 ng/mL for α-KG with lower limits of quantification (LLOQ) of 0.08 ng/mL for L-CAR, 0.04 ng/mL for acetyl-L-CAR and 0.8 ng/mL for α-KG. The intra-day and inter-day precision and accuracy of the quality control samples exhibited relative standard deviations of less than 5.54% and relative error values from -5.95% to 3.11%. Analyte stability was evaluated under various sample preparation, analysis and storage conditions and varied from -9.89% to -0.47%. A two-step solid-phase extraction (SPE) procedure using silica gel and quaternary amine cartridges was used for urine sample cleanup. The average recoveries for all analyzed compounds were better than 86.64% at three concentrations. The method was successfully applied for the quantitation of α-KG, L-CAR and acetyl-L-CAR in human urine samples.

HPLC method development and validation of chromafenozide in paddy

A simple and efficient HPLC-UV method was developed and validated for determination of chromafenozide in paddy as there was no previous report on record in this regard. The residue analysis method of chromafenozide, its dissipation and final residue in paddy along with soil were also studied after field treatment. Residues of chromafenozide were extracted and purified from paddy and soil followed by liquid/liquid partitioning, chromatographic column and determination by HPLC equipped with PDA detector. The separation was performed on a Phenomenex Luna RP C(18) (250 × 4.6 mm i.d, 5 μm particle size) column at room temperature. The mean accuracy of analytical method were 94.92 %, 95.38 %, 94.67 % and 96.90 % in straw, grain, soil and field water respectively. The precision (repeatability) was found in the range of 1.30 %-9.25 % for straw/grain, 1.27 %-11.19 % in soil; 1.0 %-9.25 % in field water. The precision (reproducibility) in straw/grain was ranging from 2.2 % to 12.1 %, in soil it from 2.0 % to 11.7 %. The minimum detectable concentration was 0.01 mg kg(-1). The degradation of chromafenozide formulation in rice, soil and water was determined and results showed that chromafenozide as wettable powder formulation degraded with the half-lives of about 4.4 and 2.9 days in paddy plant and soil respectively for double recommended dose. The results indicated that the developed method is easier and faster then could meet the requirements for determination of chromafenozide in paddy.

Simultaneous quantitative determination of alpha-ketoglutaric acid and 5-hydroxymethylfurfural in human plasma by gas chromatography-mass spectrometry

Alpha-ketoglutaric acid (alpha-KG) and 5-hydroxymethylfurfural (5-HMF) are currently under investigation as promising cancer cell damaging agents. A method for the simultaneous quantitative determination of alpha-KG and 5-HMF in human plasma was established for screening these compounds in human plasma. Plasma samples were directly treated with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride to form the corresponding oximes, thus facilitating subsequent liquid-liquid extraction. After formation of the trimethylsilyl ethers, samples were analyzed by gas chromatography with electron ionization mass spectrometry. Stable isotope labeled standards were used, the preparation of (13)C(6)-5-HMF is described. Limits of quantitation were set to 0.938 microg/mL for alpha-KG and 0.156 microg/mL for 5-HMF. Inter-day accuracy was < or = 93.7% (alpha-KG) and < or = 92.8% (5-HMF). Inter-day precision was < or = 6.0% (alpha-KG) and < or = 4.6% (5-HMF). The method has been successfully applied to pharmacokinetic profiling of the compounds after intravenous application.

Determination of 5-hydroxymethylfurfural using derivatization combined with polymer monolith microextraction by high-performance liquid chromatography

A simple and sensitive method for the determination of 5-hydroxymethylfurfural (HMF) in coffee, honey, beer, Coke, and urine by high-performance liquid chromatography (HPLC) is presented. This method is based on the formation of the 2,4-dinitrophenylhydrazone of HMF and subsequent polymer monolith microextraction (PMME) of this derivative. A poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EGDMA) monolithic capillary column was selected as the extraction medium. Several parameters affecting the derivatization of HMF with 2,4-dinitrophenylhydrazine (DNPH) followed by extraction of the derivative were optimized. The procedure is simple and offers high sensitivity and specificity since the derivative of HMF is well preconcentrated by PMME with poly(MAA-co-EGDMA) monolith and well separated from the other components of the samples under examination. The recoveries in coffee, honey, beer, Coke, and urine samples were in the range of 83.9-110.8% spiked at different levels with HMF. The inter- and intraday precisions were less than 10%. The LOD (S/N = 3) and LOQ (S/N = 10) for HMF were 1.0 ng/mL and 3.4 ng/mL, respectively.