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Scattering Detection (scattering + detection)
Kinds of Scattering Detection Selected AbstractsSelective extraction of polyunsaturated triacylglycerols using a novel ionic liquid precursor immobilized on a mesoporous complexing adsorbentBIOTECHNOLOGY PROGRESS, Issue 5 2009Patrisha J. Pham Abstract Mesoporous silica (SBA-15) synthesized by using Pluronic123 as the structure-directing template was functionalized by imidazolium-based ionic liquid precursors. Silver salts were then immobilized onto the supported ionic liquids using the incipient wetness impregnation technique. The separation of unsaturated species was achieved through the reversible and specific interaction between silver ions and carbon,carbon double bonds. This adsorbent was examined for the selective separation of polyunsaturated triacylglycerols (PUTAG) using High Pressure Liquid Chromatography (HPLC) with Evaporative Light Scattering Detection (ELSD) as the quantification methodology. AgBF4/SBA15·HPSiOEtIM·PF6 showed an adsorption capacity for linolenin of about 217 mg adsorbed/gram of sorbent. This adsorbent had good selectivity and a high capacity for the most highly unsaturated triacylglycerol when applied to a mixture of triacylglycerols with varying degrees of unsaturation. Consequently, a stepwise methodology was also developed to increase the recovery of the adsorbed components. This adsorbent retained its selectivity and capacity when recycled up to five times. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Controlled radical polymerization of a trialkylsilyl methacrylate by reversible addition,fragmentation chain transfer polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005M. N. Nguyen Abstract The reversible addition,fragmentation chain transfer (RAFT) polymerization of a hydrolyzable monomer (tert -butyldimethylsilyl methacrylate) with cumyl dithiobenzoate and 2-cyanoprop-2-yl dithiobenzoate as chain-transfer agents was studied in toluene solutions at 70 °C. The resulting homopolymers had low polydispersity (polydispersity index < 1.3) up to 96% monomer conversion with molecular weights at high conversions close to the theoretical prediction. The profiles of the number-average molecular weight versus the conversion revealed controlled polymerization features with chain-transfer constants expected between 1.0 and 10. A series of poly(tert -butyldimethylsilyl methacrylate)s were synthesized over the molecular weight range of 1.0 × 104 to 3.0 × 104, as determined by size exclusion chromatography. As strong differences of hydrodynamic volumes in tetrahydrofuran between poly(methyl methacrylate), polystyrene standards, and poly(tert -butyldimethylsilyl methacrylate) were observed, true molecular weights were obtained from a light scattering detector equipped in a triple-detector size exclusion chromatograph. The Mark,Houwink,Sakurada parameters for poly(tert -butyldimethylsilyl methacrylate) were assessed to obtain directly true molecular weight values from size exclusion chromatography with universal calibration. In addition, a RAFT agent efficiency above 94% was confirmed at high conversions by both light scattering detection and 1H NMR spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5680,5689, 2005 [source] Pulsed laser polymerization study of the propagation kinetics of acrylamide in waterJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2005Shane A. Seabrook Abstract Pulsed laser polymerization was used in conjunction with aqueous-phase size exclusion chromatography with multi-angle laser light scattering detection to determine the propagation rate coefficient (kp) for the water-soluble monomer acrylamide. The influence of the monomer concentration was investigated from 0.3 to 2.8 M, and kp decreased with increasing monomer concentration. These data and data for acrylic acid in water were consistent with this decrease being caused by the depletion of the monomer concentration by dimer formation in water. Two photoinitiators, uranyl nitrate and 2,2,-azobis(2-amidinopropane) (V-50), were used; kp was dependent on their concentrations. The concentration dependence of kp was ascribed to a combination of solvent effects arising from association (thermodynamic effects) and changes in the free energy of activation (effects of the solvent on the structure of the reactant and transition state). Arrhenius parameters for kp (M,1 s,1) = 107.2 exp(,13.4 kJ mol,1/RT) and kp (M,1 s,1) = 107.1 exp(,12.9 kJ mol,1/RT) were obtained for 0.002 M uranyl nitrate and V-50, respectively, with a monomer concentration of 0.32 M. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1357,1368, 2005 [source] Determination of multicomponent contents in Calculus bovis by ultra-performance liquid chromatography,evaporative light scattering detection and its application for quality controlJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2010Weijun Kong Abstract A fast ultra-performance liquid chromatography,evaporative light scattering detection (UPLC-ELSD) method was established for simultaneous quantification of seven components in natural Calculus bovis (C. bovis) and its substitutes or spurious breeds. On a Waters Acquity UPLC® BEH C18 column, seven analytes were efficiently separated using 0.2% aqueous formic acid,acetonitrile as the mobile phase in a gradient program. The evaporator tube temperature of ELSD was set at 100°C with the nebulizing gas flow-rate of 1.9,L/min. The results showed that this established UPLC-ELSD method was validated to be sensitive, precise and accurate with the LODs of seven analytes at 2,11,ng, and the overall intra-day and inter-day variations less than 3.0%. The recovery of the method was in the range of 97.8,101.6%, with RSD less than 3.0%. Further results of PCA on the contents of seven investigated analytes suggested that compounds of cholic acid, deoxycholic acid and chenodeoxycholic acid or cholesterol should be added as chemical markers to UPLC analysis of C. bovis samples for quality control and to discriminate natural C. bovis sample and its substitutes or some spurious breeds, then normalize the use of natural C. bovis and ensure its clinical efficacy. [source] Simple method for determination of five terpenoids from different parts of Tripterygium wilfordii and its preparations by HPLC coupled with evaporative light scattering detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2007Xiao-Ling Luo Abstract By optimizing the extraction, separation, and analytical conditions, a reliable and accurate high-performance liquid chromatography method coupled with evaporative light scattering detection (ELSD) was developed for simultaneous determination of five terpenoids, i. e., triptolide, tripchlorolide, demethylzelastral, wilforlide B, and wilforlide A, in root, stem, leaves, root bark, twig, and root without bark of Tripterygium wilfordii Hook. f and six of its herbal preparations. This approach would thus provide a more accurate and general method for evaluating the quality of the herb and its preparations. Separation of these five terpenoids was achieved on a ZORBAX Eclipse XDB-C8 column with gradient elution using water and acetonitrile as solvents, both containing 0.05% formic acid, at a temperature of 30°C and a flow rate of 0.8 mL/min. The drift tube temperature of ELSD was set at 100°C, and the nitrogen flow rate at 1.5 L/min. Good linear relationships were obtained with correlation coefficients for the analytes exceeding 0.992, and the LOD and LOQ were less than 0.149 ,g and 0.297 ,g on column, respectively. Intra-day and inter-day precision of the analytes were less than 1.25% and 5.97%, respectively, and the average recovery rates obtained were in the range of 95.9 ± 3.7% to 100.4 ± 5.0% for all terpenoids with RSDs below 4.99%. Quantitative analysis of the five terpenoids in different parts of Tripterygium wilfordii and its six preparations showed that the contents of the terpenoids varied significantly. The tender root contained higher concentrations of triptolide, tripchlorolide, demethylzelastral, and wilforlide B than any other part of the herb. Correspondingly, the root bark contained the greatest concentration of wilforlide A, and the stem and twig came in second and third. This suggested that we could infer whether the medicinal materials were absolute roots without bark or not from the comparative contents of these terpenoids in the tablets in view of the fact that only the roots without bark are the valid officinal part of the plant. This method and the quantitation results obtained can provide a scientific and general as well as simple and convenient approach for the product manufacturers to set up quality control standards and for informing the public about the quality and safety of the preparations. [source] Simultaneous qualification and quantification of eight triterpenoids in Radix Achyranthis Bidentatae by high-performance liquid chromatography with evaporative light scattering detection and mass spectrometric detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2007Juan Li Abstract An HPLC with evaporative light scattering detection (ELSD) and ESI-MS was established for the simultaneous determination of eight triterpenoids in Radix Achyranthis Bidentatae. The optimal chromatographic conditions were achieved on a Zorbax C18 column by linear gradient elution with 0.08% v/v aqueous formic acid and ACN as the mobile phase at the flow rate of 0.8 mL/min. Temperature for the detector drift tube was set at 101°C and the nitrogen flow rate was 2.8 L/min. The identities of the analytes were accomplished by comparing retention times and mass data with those of reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, recovery, and stability. All the calibration curves of the eight triterpenoids showed good linear regression (R2 >0.997) within the test ranges. The method provides desirable repeatability with overall intra- and interday variations of less than 4.9%. The obtained recoveries varied between 93.6 and 98.1% while the RSDs were below 3.9% (n = 3). The analysis results indicate that the content of investigated triterpenoids in Radix Achyranthis Bidentatae from different locations was greatly diverse, and the triterpenoids could be used as chemical markers for the discrimination of genuine and ungenuine crude drugs. [source] Simultaneous determination of 11 saponins in Panax notoginseng using HPLC-ELSD and pressurized liquid extractionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2006Jian-Bo Wan Abstract A new HPLC coupled with evaporative light scattering detection (ELSD) method was developed for simultaneous determination of 11 major triterpene saponins, namely notoginsenoside R1 (1), ginsenosides Rg1 (2), Re (3), Rf (4), Rb1 (5), Rg2 (6), Rc (7), Rb2 (8), Rb3 (9), Rd (10), and Rg3 (11) in Panax notoginseng, a commonly used traditional Chinese medicine (TCM). Pressurized liquid extraction (PLE) was employed for sample preparation, and the analysis was achieved using a Zorbax ODS C18 column eluted with gradient water-ACN in 60 min. The drift tube temperature of ELSD was set at 60°C, and nitrogen flowrate was at 1.4 L/min. The method provided good repeatability and sensitivity for quantification of 11 saponins with overall precision (including intra- and interday) and LOD of less than 2.9% (RSD) and 98 ng, respectively. The validated method was successfully applied to quantify 11 saponins in 28 samples of P. notoginseng collected in different places, which is helpful to control the quality of P. notoginseng and its related products. [source] Determination of propafenone hydrochloride by flow-injection analysis coupled with resonance light scattering detectionLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2009Xiaoli Hu Abstract A simple, sensitive and rapid flow injection analysis (FIA) method with resonance light scattering (RLS) was described for the determination of propafenone (PPF). The method was based on the ion-association reaction of 12-tungstophosphoric acid (TP) with propafenone. In pH 1.0 acidic medium, TP reacted with PPF to form an ion-associate complex, which resulted in a significant enhancement of RLS intensity. The maximum scattering peak was located at 340 nm, the RLS intensity was proportional to the concentration of PPF in the range 0.003,9.0 µg/mL, and the detection limit (3,) of 1.0 ng/mL was obtained at a sampling rate of 60 samples/h. The feasible reaction conditions and FIA parameters for the system were optimized. The method proposed in this paper shows satisfactory reproducibility with a relative standard deviation (RSD) of 2.1% for 10 successive determinations of 2.0 µg/mL PPF. The present method had been successfully applied to the determination of PPF in serum samples and pharmaceutical samples. The results obtained were in agreement with the method used in the Chinese Pharmacopoeia. Copyright © 2008 John Wiley & Sons, Ltd. [source] Quality control of Pulsatilla koreana based on the simultaneous determination of triterpenoidal saponins by HPLC-ELSD and principal component analysisPHYTOCHEMICAL ANALYSIS, Issue 4 2010Ki Yong Lee Abstract Introduction , Pulsatilla koreana Nakai, with triterpenoidal saponins as its main pharmacological effective compounds, is known to have several biological activities, including hypoglycaemic, antitumour, cognition-enhancing, neuroprotective, cytotoxic and antiangiogenic activities. However, few analytical methods have been reported on the quality assessment of P. koreana roots. Obejective , To establish a high-performance liquid chromatography coupled with evaporative light scattering detection for the simultaneous determination of five triterpenoidal saponins, including pulsatilloside E (1), pulsatilla saponin H (2), anemoside B4 (3), hederacolchiside E (4) and cussosaponin C (5) in P. koreana. Methodology , The chromatographic separation was performed on a Shiseido CapCell PAK C18 analytical column efficiently using gradient elution with acetonitrile and water. Results , All calibration curves showed excellent linear regressions (R2 > 0.9996) within the range of tested concentrations. The intra- and inter-day variations were below 4.78% in terms of RSD. The recoveries were 94.82,102.97% with RSD of 0.27,3.92% for spiked P. koreana samples. Conclusion , The validated method was successfully used for the analysis of five saponins in P. koreana from different locations. Moreover, the different samples were clustered in accordance with contents of triterpenoidal saponins based on aglycon type by a principal component analysis. Copyright © 2010 John Wiley & Sons, Ltd. [source] Simultaneous quantification of three major triterpenoids in radix asteris by high-performance liquid chromatography with evaporative light scattering detectionPHYTOCHEMICAL ANALYSIS, Issue 3 2009Yaping Tian Abstract Introduction Radix asteris, with triterpenoids as its main pharmacological effective compounds, has been widely used for moistening the lung, dispersing phlegm and relieving cough. Quantification of the triterpenoids is important for the quality control of Radix asteris. Objective To establish a high-performance liquid chromatography method with evaporative light scattering detection for simultaneous determination of three major triterpenoids, shionone, friedelin and epi-friedelinol, in Radix asteris. Methodology The optimal chromatographic conditions were achieved on an RP18 column with gradient elution by acetonitrile and 0.05% acetic acid in 22 min with ELSD set at an evaporating temperature of 40°C. Validation of the method included tests of linearity, sensitivity, precision, repeatability, stability and accuracy. Results All calibration curves showed good linear regression (r2 > 0.9991) within test ranges. The established method showed good precision and accuracy with overall intra-day and inter-day variations of 1.61,2.97 and 1.74,2.42%, respectively, and overall recoveries of 97.35,101.13% for the three compounds analysed. Conclusion The method developed was successfully applied to quantify the main triterpenoids in 14 Radix asteris samples. Copyright © 2009 John Wiley & Sons, Ltd. [source] The extraction of imperialine and imperialine-3,-glucoside from Fritillaria pallidiflora Schrenk and quantitative determination by HPLC-evaporative light scattering detectionPHYTOCHEMICAL ANALYSIS, Issue 3 2002Ping Li Abstract The extraction procedure and quantitative determination by HPLC-evaporative light scattering detection (ELSD) of the main bioactive components, namely, imperialine (1) and imperialine-3,-glucoside (2), of bulbs of Fritillaria pallidiflora Schrenk have been investigated. The most efficient method for the simultaneous extraction of 1 and 2 involved pre-treatment of the bulb powder with ammonia, followed by reflux with dichloromethane:methanol at 90°C for 4,h. Simultaneous determination of non-chromophoric 1 and 2 by HPLC-ELSD employed a KromasilÔ C18 column eluted with acetonitrile:water:diethylamine. The assay was accurate and reproducible with an overall variation lower than 4% and a sample recovery higher than 98%. The methods described have been successfully used to evaluate the quality of three batches of the crude traditional Chinese medicinal herb derived from the bulbs of F. pallidiflora. Copyright © 2002 John Wiley & Sons, Ltd. [source] Simultaneous determination of eight major steroids from Polyporus umbellatus by high-performance liquid chromatography coupled with mass spectrometry detectionsBIOMEDICAL CHROMATOGRAPHY, Issue 2 2010Ying-yong Zhao Abstract Polyporus umbellatus is a widely used diuretic herbal medicine. In this study, a high-performance liquid chromatography coupled with atmospheric pressure chemical ionization,mass spectrometric detection (HPLC-APCI-MS) method was developed for qualitative and quantitative analysis of steroids, as well as for the quality control of Polyporus umbellatus. The selectivity, reproducibility and sensitivity were compared with HPLC with photodiode array detection and evaporative light scattering detection (ELSD). Selective ion monitoring in positive mode was used for qualitative and quantitative analysis of eight major components and ,-ecdysterone was used as the internal standard. Limits of detection and quantification fell in the ranges 7,21 and 18,63 ng/mL for the eight analytes with an injection of 10 µL samples, and all calibration curves showed good linear regression (r2 > 0.9919) within the test range. The quantitative results demonstrated that samples from different localities showed different qualities. Advantages, in comparison with conventional HPLC,diode array detection and HPLC-ELSD, are that reliable identification of target compounds could be achieved by accurate mass measurements along with characteristic retention time, and the great enhancement in selectivity and sensitivity allows identification and quantification of low levels of constituents in complex Polyporus umbellatus matrixes. Copyright © 2009 John Wiley & Sons, Ltd. [source] Simultaneous quantitation of three major triterpenoid glycosides in Centella asiatica extracts by high performance liquid chromatography with evaporative light scattering detectionBIOMEDICAL CHROMATOGRAPHY, Issue 2 2008Feng-Lun Zhang Abstract A high-performance liquid chromatography method with evaporative light scattering detection was established for simultaneous determination of three major triterpenoid glycosides, i.e. asiaticoside, madecassoside and asiaticoside-B, in Centella asiatica extracts. The optimal chromatographic conditions were achieved on a COSMOSIL 5C18 -MS-II column by constant elution with water (0.01% trifluoroacetic acid, v/v) and acetonitrile (1.0% methyl tert-butyl ether, 0.01% trifluoroacetic acid, v/v) (78:22) as mobile phase at a flow rate of 1.0 mL/min; the column temperature was 30°C. The evaporative light scattering detector was set at an evaporating temperature of 40°C and nitrogen gas pressure of 3.5 bar. The validation of the method included tests of linearity, sensitivity, precision, repeatability, stability and accuracy. All calibration curves showed good linear regression (r2 > 0.9993) within test ranges. The established method showed good precision and accuracy with overall intra-day and inter-day variations of 1.73,3.06 and 3.89%,4.92%, respectively, and overall recoveries of 97.63,99.39% for the three compounds analyzed. The method developed was successfully applied to quantify the main triterpenoid glycosides in Centella asiatica extracts from different companies. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||