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Photodiode Array Detector (photodiode + array_detector)
Selected AbstractsOxidative Degradation of Bisphenol A by Fruit HomogenatesJOURNAL OF FOOD SCIENCE, Issue 9 2005Masaaki Imanaka ABSTRACT: The oxidative degradation of bisphenol A (BPA) by several fruit homogenates was investigated. Their homogenates were incubated with BPA at 25 °C for 0 to 120 min, and the acetone extracts were analyzed by high-performance liquid chromatography (HPLC) with a photodiode array detector (200 to 650 nm). The 2 degradation products (UK-1 and UK-2) from BPA were detected on HPLC chromatograms (280 nm). UK-1 and UK-2 were identified to be 2-(3,4-dihydroxyphenyl)-2-(4-ydroxyphenyl) propane, (3-OH-BPA) and 4-[1-(3,4-dihydroxyphenyl)-isopropyl]benzene-1,2-diol, (3,3,-diOH-BPA), respectively, by HPLC-MassPectrometry (LC-MS). In the process of incubation, the peak of 3-OH-BPA attained the maximum value in the 1st 20 min, and that of 3,3,-diOH-BPA increased more slowly, attaining the maximum in 50 min. On the other hand, incubation of 3-OH-BPA (instead of BPA) with grape homogenates gave the maximum peak of 3,3,-diOH-BPA in only 10 min. 3, 3,-diOH-BPA was a polyphenol compound that contained 4 hydroxyl groups. These results suggested that BPA would be degraded (converted) to brown pigments through the compounds of 3-OH-BPA and 3, 3,-diOH-BPA in some fruit homogenates. [source] Inhibitory effects of urinary metabolites on platelet aggregation after orally administering Shimotsu-To, a traditional Chinese medicine, to ratsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2003Takaaki Yasuda ABSTRACT Shimotsu-To, which consists of four herbal extracts, has been used clinically for improving abnormal blood coagulation, fibrinolysis, atherosclerosis and chronic inflammation in Japan and China. We have investigated the pharmacological relationship between the effects and chemical components of Shimotsu-To after oral administration to rats. The urinary constituents were separated and identified by three dimensional (3D-) HPLC equipped with a photodiode array detector as a new tool and the chemical structures were determined by spectroscopic methods to be trans -ferulic acid-3- O -sulfate (1), vanillic acid (2), m -hydroxyphenylpropionic acid (3), trans -ferulic acid (4) and cis -ferulic acid (5). Of these compounds, 2,5 strongly inhibited platelet aggregation induced by ADP and arachidonic acid. Compound 1, the sulfate conjugate of 4, did not show any inhibitory effect, which suggested that the inhibitory effect on platelet aggregation was inactivated by sulfate conjugation. These results indicated that compounds 2,5 partly contributed to the anti-Oketsu effect of Shimotsu-To through the inhibition of platelet aggregation. [source] Quantitative analysis and chromatographic fingerprinting for the quality evaluation of Forsythia suspensa extract by HPLC coupled with photodiode array detectorJOURNAL OF SEPARATION SCIENCE, JSS, Issue 23-24 2009Yonggang Xia Abstract A simple and reproducible HPLC-photodiode array detector method has been described for evaluating and controlling quality of Forsythia suspensa extract (FSE). First, by analysis of chromatographic fingerprints, the similarities of chromatograms of FSE samples from the same pharmaceutical company exceeded 0.999, 0.997 and 0.960, respectively, although they were much lower from different pharmaceutical companies. Second, by further comparing many batches of extract chromatograph charts with the corresponding reference herb materials, the "common peaks" 3, 5, 7 and 10 were defined as "marker peaks", which were identified as (+)-pinoresinol-,- D -glucoside, forsythiaside, phillyrin and phillygenin, respectively. Third, four "marker peaks" were simultaneously determined based on fingerprint chromatogram for further controlling the quality of FSE quantitatively. Namely, the newly developed method was successfully applied to analyze 38 batches of FSE samples supplied by three pharmaceutical factories, which showed acceptable linearity, intra-day precision (RSD<2.76%), inter-day precision (RSD<3.43%) and the average recovery rates in the range of (95.38±2.96)% to (101.60±3.08)%. At last, hierarchical clustering analysis and Bayes discriminant analysis statistical methods were used to classify and differentiate the 38 FSE samples to provide the basis for guiding reasonable use of FSE and controlling its quality better. [source] HPLC method for simultaneous determination of retinoids and tocopherols in human serum for monitoring of anticancer therapyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Lenka Kr, mová Abstract A simple and rapid HPLC method requiring small volumes (250 ,L) of human serum after C18 SPE sample preparation was developed using monolithic technology for simultaneous determination of all- trans- retinoic acid, 13- cis -retinoic acid, retinol, gamma- and alpha-tocopherol. The monolithic column, Chromolith Performance RP-18e (100×4.6 mm), was operated at ambient temperature. The mobile phase consisted of a mixture of acetonitrile (ACN) and 1% ammonium acetate in water (AMC) at pH 7.0. The mobile phase started at 98:2 (v/v) ACN/AMC (column pre-treatment) at a flow rate of 2 mL/min, then changed to 95:5 (v/v) ACN/AMC for 4 min at a flow rate of 1.5 mL/min and a further 3 min at a flow rate of 3.2 mL/min. Detection and identification were performed using a photodiode array detector. Retinol, 13- cis - and all- trans- retinoic acid were monitored at 325 nm. Both alpha- and gamma-tocopherol were detected at 295 nm. The total analysis time was 7.2 min. Tocol (synthesized tocopherol, not occurring in humans) was used as internal standard. The method was linear in the range of 0.125,10.00 ,mol/L for all- trans- retinoic acid, 0.125,5.00 ,mol/L for 13- cis -retinoic acid, 0.25,10.00 ,mol/L for retinol, 0.5,50.00 ,mol/L for gamma-tocopherol, and 0.5,50.00 ,mol/L for alpha-tocopherol. The present method may be useful for monitoring of retinoids and tocopherols in clinical studies. [source] Enantioselective HPLC resolution of synthetic intermediates of armodafinil and related substancesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6-7 2008Ramisetti Nageswara Rao Abstract Armodafinil is a unique psychostimulant recently approved by the US Food and Drug Administration for the treatment of narcolepsy. The chromatographic resolution of its chiral intermediates including related substances in the total synthesis of armodafinil was studied on polysaccharide-based stationary phases, viz. cellulose tris-(3,5-dimethylphenylcarbamate) (Chiralcel OD-H) and amylose tris-(3,5-dimethylphenylcarbamate) (Chiralpak AD-H) by HPLC. The effects of 1-propanol, 2-propanol, ethanol, and trifluoroacetic acid added to the mobile phase and of column temperature on resolution were studied. A good separation was achieved on cellulose-based Chiralcel OD-H column compared to amylose-based Chiralpak AD-H. The effects of structural features of the solutes and solvents on discrimination between the enantiomers were examined. Baseline separation with Rs >1.38 was obtained using a mobile phase containing n -hexane,ethanol,TFA (75:25:0.15 v/v/v). Detection was carried out at 225 nm with photodiode array detector while identification of enantiomers was accomplished by a polarimetric detector connected in series. The method was found to be suitable not only for process development of armodafinil but also for determination of the enantiomeric purity of bulk drugs and pharmaceuticals. [source] Multiresidue HPLC analysis of ten quinolones in milk after solid phase extraction: Validation according to the European Union Decision 2002/657/ECJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2007Eleni A. Christodoulou Abstract A rapid and sensitive analytical method was developed for the residue analysis of ten quinolones (enoxacin (ENO), ofloxacin (OFL), norfloxacin (NOR), ciprofloxacin (CIP), danofloxacin (DAN), enrofloxacin (ENR), sarafloxacin (SAR), oxolinic acid (OXO), nalidixic acid (NAL), and flumequine (FLU)) in cow's milk. The analytes were extracted from milk by a deproteinization step followed by a simple SPE cleanup procedure using LiChrolut RP-18 Merck cartridges. Recoveries varied between 75 and 92%. HPLC separation was performed at 25°C using an ODS-3 PerfectSil® Target (250×4 mm2) 5 ,m analytical column (MZ-Analysentechnik, Germany). The mobile phase consisted of a mixture of TFA 0.1%,CH3CN,CH3OH, delivered by a gradient program at the flow rate of 1.2 mL/min. Elution of the ten analytes and the internal standard (caffeine, 7.5 ng/,L) was completed within 27 min. Column effluent was monitored using a photodiode array detector, set at 275 and 255 nm. The developed method was validated according to the criteria of Commission Decision 2002/657/EC. The LODs of the specific method of quinolones' determination in milk varied between 1.5 and 6.8 ng/,L. [source] Chemical fingerprinting of Andrographis paniculata using HPLC, HPTLC and densitometryPHYTOCHEMICAL ANALYSIS, Issue 5 2004Alpana Srivastava Abstract An attempt has been made to develop a method by which to determine the chemical ,ngerprint of Andrographis paniculata (Acanthaceae). High-performance thin layer chromatography (HPTLC) was used to analyse hexane, chloroform, methanol and water extracts of leaves of A. paniculata. A computerised densitometer was applied to the two-dimensional spectrographic image analysis of the HPTLC plates. An HPLC equipped with a photodiode array detector was used for the analyses of these different extracts. The analyses showed that andrographolide and neoandrographolide are absent in the hexane extract but are present in greater amounts in the methanol extract as compared with the other extracts. These chromatograms may serve as a chemical ,ngerprint of the drug A. paniculata for quality control purposes and in the preparation of formulations based on the drug. Copyright © 2004 John Wiley & Sons, Ltd. [source] Development and validation of a high-performance liquid chromatography method for the simultaneous determination of aspirin and folic acid from nano-particulate systemsBIOMEDICAL CHROMATOGRAPHY, Issue 9 2010Abhishek Chaudhary Abstract Attention has shifted from the treatment of colorectal cancer (CRC) to chemoprevention using aspirin and folic acid as agents capable of preventing the onset of colon cancer. However, no sensitive analytical method exists to simultaneously quantify the two drugs when released from polymer-based nanoparticles. Thus, a rapid, highly sensitive method of high-performance liquid chromatography analysis to simultaneously detect low quantities of aspirin (hydrolyzed to salicylic acid, the active moiety) and folic acid released from biodegradable polylactide-co-glycolide (PLGA) copolymer nanoparticles was developed. Analysis was done on a reversed-phase C18 column using a photodiode array detector at wavelengths of 233,nm (salicylic acid) and 277,nm (folic acid). The mobile phase consisted of acetonitrile,0.1% trifluoroacetic acid mixture programmed for a 30,min gradient elution analysis. In the range of 0.1,100,,g/mL, the assay showed good linearity for salicylic acid (R2 = 0.9996) and folic acid (R2 = 0.9998). The method demonstrated good reproducibility, intra- and inter-day precision and accuracy (99.67, 100.1%) and low values of detection (0.03, 0.01,,g/mL) and quantitation (0.1 and 0.05,,g/mL) for salicylic acid and folic acid, respectively. The suitability of the method was demonstrated by simultaneously determining salicylic acid and folic acid released from PLGA nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd. [source] Transport behavior of ellagic acid of pomegranate leaf tannins and its correlation with total cholesterol alteration in HepG2 cellsBIOMEDICAL CHROMATOGRAPHY, Issue 5 2009Jiaqi Lan Abstract The aim of this study was to investigate whether ellagic acid in pomegranate leaf tannins could be transported into HepG2 cells and its transport behavior. High-performance liquid chromatography coupled with a 996 photodiode array detector at 254 nm was applied. The mobile phase was an acetonitrile,water solution (containing 0.1% triethylamine, pH 3.0; 16:64, v/v, for determining ellagic acid in cells). The flow rate was 0.8 mL/min. Cells were incubated with pomegranate leaf tannins with 100 and 50 µg/mL (containing 1.71 and 0.85 µg/mL of ellagic acid, respectively) for a specific time, then lysed and sonicated in methanol to extract intracellular ellagic acid. A 10 µL aliquot of sample was injected into the HPLC system to determine ellagic acid concentration. The results showed that ellagic acid in pomegranate leaf tannins could be transported into the cells, which was in correlation with total cholesterol alteration in the cells. This is the first time that the transport behavior of ellagic acid through HepG2 cells in vitro has been comprehensively demonstrated. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||