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Chromatography Determination (chromatography + determination)
Selected AbstractsVoltammetric Determination of ,-Tocopheryl Acetate in Pharmaceutical Dosage FormsELECTROANALYSIS, Issue 11 2004Slawomir Michalkiewicz Abstract A simple and rapid voltammetric method has been developed for the quantitative determination of ,-tocopheryl acetate (,-TOAc) in pharmaceutical preparations. Studies with linear scan (LSV), square-wave (SQWV) and differential pulse voltammetry (DPV) were carried out using platinum microelectrodes. A well-defined, irreversible oxidation wave/peak was obtained at 1.30,V (vs. Ag/AgCl reference electrode.) The use of SQWV or DPV technique provides a precise determination of ,-tocopheryl acetate using the multiple standard addition method. The statistical parameters and the recovery study data clearly indicate good reproducibility and accuracy of the method. Accuracy of the results assessed by recovery trials was found within the 99.3% to 103.5%, and 99.1% to 101.4%, for SQWV and DPV, respectively. The quantification limits for the both voltammetric techniques were found to be 6×10,5,M (SQWV) and 7×10,5,M (DPV). Analysis of the authentic samples containing ,-TOAc showed no interference with common additives and excipients, such as unsaturated fatty acids (co-formulated as glycerine esters) and vitamin A (as retinol or ,-carotene). The method proposed does not require any pretreatment of the pharmaceutical dosage forms. A gas chromatography determination of ,-TOAc in real samples was also performed for comparison. [source] Thermally oxidized palm olein exposure increases triglyceride polymer levels in rat small intestineEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 9 2010Raul Olivero David Abstract The origin and presence of triglyceride polymers in small intestine have been poorly studied. The present study combined a short in vivo absorption experiment and high-performance size-exclusion chromatography determination. Groups of six male Wistar rats were administered by esophageal probe 1,g/100,g body weight unused palm olein and palm oleins used in 40 and 90 potato frying operations. Small intestines were dissected, cleaned of luminal fat, and analyzed for the presence of triglyceride polymers (oligomers and/or dimers) after 4,h oil administration. The intestinal fat content did not change but the polymers content was positively and significantly correlated (r,=,0.5983; p<0.01) with the amount of polymers present in the oil tested. The small intestine contained 5.05,mg [median and percentile 25 (1.57,mg),percentile 75 (10.40,mg)] of polymers after 4-h exposure to palm olein used for frying 90 times. The results suggested that 2.7,4.9% of the triglyceride polymers administered were present in the small intestine 4,h after ingestion. TBARS levels (p<0.05) and the redox index (oxidized glutathione/total glutathione) (p<0.01) in the small intestine increased significantly after exposure to the palm olein used in 90 frying operations. In conclusion, administration of altered oil increased the presence of resynthesized polymers in the small intestine, thus contributing to small intestine oxidative stress. [source] High-performance liquid chromatography determination of hydrastine and berberine in dietary supplements containing goldensealJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2001Ehab A. Abourashed Abstract Goldenseal (Hydrastis canadensis L., Ranunculaceae) is an ingredient of various dietary supplements intended for enhancing general body immunity. Many goldenseal products are currently available in the United States, either alone or in combination with echinacea. In most products, the content of the main active alkaloids of goldenseal, hydrastine and berberine, is not indicated on the label. A high-performance liquid chromatography (HPLC) method has been developed for the detection and quantification of hydrastine and berberine in a number of products obtained from the United States market. The method uses a Phenomenex® Luna C18 column, a mobile phase consisting of solvent A (100 mM sodium acetate/acetic acid, pH 4.0) and solvent B (acetonitrile/methanol; 90/10, v/v). Elution was run at a flow rate of 1.0 mL/min, with a linear gradient of 80, 40% A in B over 20 min and ultraviolet detection at 290 nm. A wide range of content variation was observed for both alkaloids in the tested samples. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:817,822, 2001 [source] Micellar electrokinetic capillary chromatography determination of zinc bacitracin and nystatin in animal feedJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2006Rade Injac Abstract An MEKC procedure was developed for the separation of zinc bacitracin (Zn-BC) and nystatin (NYS) in mixtures and in animal feedstuff. The running buffer was 15 mM borate/19 mM phosphate, pH 8.2, containing 20 mM SDS and 10% v/v methanol. Samples were run at 25°C, the applied voltage was 25 kV, and an additional pressure of 5 mbar was applied. Both analytes were detected by UV simultaneously at 215 nm, Zn-BC alone at 192 and 254 nm, and NYS alone at 305 nm. The method was shown to be specific, accurate (recoveries were 100.0 ± 0.6% and 100.1 ± 0.6% for Zn-BC and NYS, respectively), linear over the tested range (correlation coefficients 0.9991 and 0.9994), and precise (RSD below 1.3% for both analytes). The method was applied to determine Zn-BC and NYS as additives in animal feed. [source] Near-critical carbon dioxide extraction and liquid chromatography determination of UV filters in solid cosmetic samples: A green analytical procedureJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005Amparo Salvador Abstract Near-critical carbon dioxide extraction of four UV filters used as sunscreens in lipsticks and makeup formulations is reported. Extraction parameters were optimized. Efficient recoveries were obtained after 15 min of dynamic extraction with a 80:20 CO2/ethanol mixture at 300 atm and 54°C, using a 1.8 mL/min flow rate. Extracts were collected in ethanol, and appropriately diluted with ethanol and 1% acetic acid to obtain a 70:30 v/v ethanol/1% acetic acid solution. The four UV filters were determined by LC with gradient elution using ethanol/1% acetic acid as mobile phase. The accuracy of the analytical procedure was estimated by comparing the results with those obtained by methods based on classical extraction. The proposed method only requires the use of CO2, ethanol and acetic acid avoiding the use of more toxic organic solvents, thus it could be considered as both operator and environment friendly. [source] High-performance liquid chromatography determination of nitrated polycyclic aromatic hydrocarbons by indirect fluorescence detectionBIOMEDICAL CHROMATOGRAPHY, Issue 2 2009Salma M. Al-Kindy Abstract A high-performance liquid chromatography (HPLC) method for the analysis of nitrated polcyclic aromatic hydrocarbons (NPAHs) is reported. NPAH mixtures were pre-concentrated using solid-phase extraction and well resolved on a C18 column. They were detected using an indirect method involving the quenching of the emission from the fluorophores 5,6,7,8-tetrahydronaphthol (5,6,7,8-THN-1-OH), 7-amino-4-methyl coumarin (Coumarin 120, COU-120) and 3-hydroxy-4-(2-hydroxy-4-sulfo-1-naphthylazo)2-naphthalene carboxylic acid (Calcon carboxylic acid, CCA). Linear calibration curves were obtained in the range 1.1 × 10,9 to 1.1 × 10,8 mol/L. Using COU 120 as the fluorophore, the detection limit was 2.9 × 10,10 mol/L for 1-nitronaphthalene and 2.1 × 10,11 mol/L for 2-nitrofluorene. Recoveries of NPAHs from spiked tap water samples were between 88 and 100%. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||