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Detector Set (detector + set)
Selected AbstractsORGANIC ACIDS PROFILE IN TOMATO JUICE BY HPLC WITH UV DETECTIONJOURNAL OF FOOD QUALITY, Issue 1 2007OMBRETTA MARCONI ABSTRACT A simple method was developed to determine 10 organic acids simultaneously in tomato products using reverse-phase high performance liquid chromatography (HPLC) column with the diode array detector set at 210 nm. After centrifugation and filtration, the samples were passed through to an anion exchange resin and the organic acids were released using 0.1 N HCl. The chromatographic separation was achieved with isocratic analysis in a 20-min run. The method was reliable and sensitive. The coefficient of determination of the standard calibration curve is 0.9925 , r2 , 0.9999 and the limit of detection ranged from 0.08 to 6.00 mg/kg for trans -aconitic acid and acetic acid, respectively. The limit of quantification ranged from 0.19 to 15.18 mg/kg for trans-aconitic and acetic acid, respectively. To establish the efficiency of the anion resin the procedure was applied to a standard solution of a mixture of organic acids. The organic acids recovery ranged from 87.0% ± 1.9 for citramalic acid to 109.9% ± 5.2 for fumaric acid. [source] Analysis of aromatic and terpenic constituents of pepper extracts by capillary electrochromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2007Alessandro Musenga Abstract An original method based on CEC has been developed for the determination of aromatic and terpenic compounds in extracts of spices obtained from Piper nigrum. The method is based on the use of a fused silica capillary (effective length: 23.5 cm, internal diameter: 100 ,m) packed with a C18 sorbent (packing length: 23 cm, particle size: 5 ,m). The mobile phase is a 50 mM, pH 6.0 ammonium acetate/ACN (10:90 v/v) mixture. Applying a 30 kV voltage, the following 11 compounds were separated and analysed: terpinen-4-ol, caryophyllene oxide, limonene, ,-pinene, 3-carene, ,-pinene, ,-humulene, ,-caryophyllene, ,-phellandrene, eugenol and piperine. Compound determination is carried out using a diode-array detector set at 265 and 338 nm for ,-phellandrene and piperine, respectively, and at 210 nm (reference subtraction at 282 nm) for all the other analytes. The optimised method has been validated with good results in terms of linearity, limits of quantitation, detection and precision. The CEC method was successfully applied to the analysis of essential oils and methanolic extracts of ,black', ,white' and ,green' pepper. [source] Identification of New Zealand bats (Chalinolobus tuberculatus and Mystacina tuberculata) in flight from analysis of echolocation calls by artificial neural networksJOURNAL OF ZOOLOGY, Issue 4 2001Stuart Parsons Abstract Time-expanded and heterodyned echolocation calls of the New Zealand long-tailed Chalinolobus tuberculatus and lesser short-tailed bat Mystacina tuberculata were recorded and digitally analysed. Temporal and spectral parameters were measured from time-expanded calls and power spectra generated for both time-expanded and heterodyned calls. Artificial neural networks were trained to classify the calls of both species using temporal and spectral parameters and power spectra as input data. Networks were then tested using data not previously seen. Calls could be unambiguously identified using parameters and power spectra from time-expanded calls. A neural network, trained and tested using power spectra of calls from both species recorded using a heterodyne detector set to 40 kHz (the frequency with the most energy of the fundamental of C. tuberculatus call), could identify 99% and 84% of calls of C. tuberculatus and M. tuberculata, respectively. A second network, trained and tested using power spectra of calls from both species recorded using a heterodyne detector set to 27 kHz (the frequency with the most energy of the fundamental of M. tuberculata call), could identify 34% and 100% of calls of C. tuberculatus and M. tuberculata, respectively. This study represents the first use of neural networks for the identification of bats from their echolocation calls. It is also the first study to use power spectra of time-expanded and heterodyned calls for identification of chiropteran species. The ability of neural networks to identify bats from their echolocation calls is discussed, as is the ecology of both species in relation to the design of their echolocation calls. [source] A new fault detection method based on artificial immune systemsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008Cunjie Wang Abstract A new fault detection method with a continuous learning feature for a complicated process is proposed based on the concept of artificial immune systems (AIS). Both the negative and the clonal selections are adopted in the method. The real-valued negative selection algorithm (RNSA) is utilized to generate fault detectors. When the detector set is used to perform the fault detection, a clonal selection is employed to update the fault detector set. The proposed method is applied to the Tennessee Eastman (TE) process. The simulation results show that the performance of the proposed method is superior to those of both classical principal component analysis (PCA) and negative selection algorithm. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] HPLC determination of irbesartan in human plasma: its application to pharmacokinetic studiesBIOMEDICAL CHROMATOGRAPHY, Issue 6 2009Soo Kyung Bae Abstract A simple and rapid HPLC method using fluorescence detection was developed for determination of irbesartan in human plasma. Sample preparation was accomplished through a simple deproteinization procedure with 0.4 mL of acetonitrile containing 800 ng/mL of losartan (internal standard), and to a 0.1 mL plasma sample. Chromatographic separation was performed on a Zorbax Xclipse XDB C18 column (150 × 4.6 mm, i.d., 5 µm) at 40°C. An isocratic mobile phase, acetonitrile:0.1% formic acid (37:63, v/v), was run at a flow-rate of 1.0 mL/min, and the column eluent was monitored using a fluorescence detector set at excitation and emission wavelengths of 250 and 370 nm, respectively. The retention times of irbesartan and losartan were 4.4 and 5.9 min, respectively. This assay was linear over a concentration range of 10,5000 ng/mL with a lower limit of quantification of 10 ng/mL. The coefficient of variation for this assay precision was less than 8.48%, and the accuracy exceeded 94.4%. The mean relative recoveries of irbesartan and losartan were 98.4 and 99.1%, respectively. This method was successfully applied for pharmacokinetic study after oral administration of irbesartan (300 mg) to 23 Korean healthy male volunteers. Copyright © 2009 John Wiley & Sons, Ltd. [source] HPLC method for determination of DRF-4367 in rat plasma: validation and its application to pharmacokinetics in Wistar rats,BIOMEDICAL CHROMATOGRAPHY, Issue 8 2004Ramesh Mullangi Abstract A speci,c, accurate, precise and reproducible high-performance liquid chromatography (HPLC) method was developed for the estimation of DRF-4367, a novel cyclooxygenase-2 inhibitor in rat plasma. The assay procedure involved simple liquid/liquid extraction of DRF-4367 and internal standard (IS, celecoxib) from plasma into dichloromethane. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40°C. The residue was reconstituted in the mobile phase and injected onto a Kromasil KR 100-5C18 column (4.6 × 250 mm, 5 µm). The mobile phase consisting of 0.01 m potassium dihydrogen ortho -phosphate (pH 3.2) and acetonitrile (40:60, v/v) was used at a ,ow rate of 1.0 mL/min. The eluate was monitored using an UV detector set at 247 nm. The ratio of peak area of analyte to IS was used for quanti,cation of plasma samples. Nominal retention times of DRF-4367 and IS were 6.6 and 11.2 min, respectively. The standard curve for DRF-4367 was linear (r2 > 0.999) in the concentration range 0.1,20 µg/mL. Absolute recovery was >86% from rat plasma for both analyte and IS. The lower limit of quanti,cation of DRF-4367 was 0.1 µg/mL. The inter- and intra-day precisions in the measurement of quality control samples, 0.1, 0.3, 8.0 and 15.0 µg/mL, were in the range 6.93,9.34% relative standard deviation (RSD) and 0.48,6.59% RSD, respectively. Accuracy in the measurement of QC samples was in the range 91.24,109.36% of the nominal values. Analyte and IS were stable in the battery of stability studies, viz. benchtop, autosampler and freeze,thaw cycles. Stability of DRF-4367 was established for 1 month at ,80°C. The application of the assay to a pharmacokinetic study in rats is described. Copyright © 2004 John Wiley & Sons, Ltd. 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