Development of HPLC method for estimation of glyoxylic acid after pre-column fluorescence derivatization approach based on thiazine derivative formation: A new application in healthy and cardiovascular patients’ sera

Glyoxylic acid (GA) is the intermediate metabolite in various mammalian metabolic pathways. GA showed high reactivity towards formation of advanced glycation end-products (AGEs); the main cause of pathogenesis and complications of many diseases. The presented study aimed to detect GA in healthy and cardiovascular patients’ (CV) sera; however analysis of GA in biological fluid is a challenge and requires chemical derivatization. Hence, a new, highly sensitive, time saving and reproducible pre-column fluorescence derivatization procedure coupled with high performance liquid chromatography (HPLC) method was developed. The derivatization method was based on reaction of 2-aminobenzenthiol (2-ABT), a fluorogenic reagent, with GA in acidic medium to form highly fluorescent thiazine derivative (290 and 390 nm for excitation and emission wavelengths respectively). The fluorescent derivative was separated within 6 min on a reversed-phase ODS column using an isocratic elution with a mixture of methanol–water (70:30, v/v%). The proposed method parameters were optimized and the method was validated. A good linearity in the concentration range (0.05–5.0 µM) was obtained with detection limit (LOD) of 10 nM (200 fmol/injection), which is more sensitive than several previous methods. Moreover, the recovery results were within the range of 85.0–95.5 % and the intra- and inter-day precision results were ≤3.5%. It should be emphasized that this method is the first one for monitoring of GA in CV patients; to investigate its role for diagnosis and monitoring the severity and complications of this disease in clinical laboratory

A selective and highly sensitive high performance liquid chromatography with fluorescence derivatization approach based on Sonogashira coupling reaction for determination of ethinyl estradiol in river water samples

A selective and highly sensitive high performance liquid chromatography (HPLC) with fluorescence derivatization method was developed for determination of ethinyl estradiol (EE); one of endocrine-disrupting compounds (EDCs). The fluorescence derivatization procedure was based on Sonogashira coupling reaction using 4-(4, 5-diphenyl-1H-imidazole-2-yl) iodobenzene (DIB-I), a fluorescence labeling reagent, to derivatize EE in presence of copper and palladium ions. The formed fluorescent product was separated on Cosmosil 5C18 MS-II by an isocratic elution with a mobile phase composed of acetonitrile: 5.0 mM Tris-HNO3 buffer, pH 7.4 (60:40, v/v %). The detection wavelengths were set at 310 and 400 nm as excitation and emission wavelengths, respectively. Various parameters affecting derivatization reaction were optimized. Further, the proposed method was validated and a good linearity with low detection limit (S/N=3) 7.4 ng L?1 was obtained in water sample after a simple solid-phase disk extraction (C18 SPE disk) method. The proposed method was successfully applied for detection of EE in river water samples in order to monitor EE concentration and to distinguish its effect on the ecosystem and human health