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Cleanup Procedure (cleanup + procedure)
Selected AbstractsImproved workup for glycosaminoglycan disaccharide analysis using CE with LIF detectionELECTROPHORESIS, Issue 22 2008Alicia M. Hitchcock Abstract This work describes improved workup and instrumental conditions to enable robust, sensitive glycosaminoglycan (GAG) disaccharide analysis from complex biological samples. In the process of applying CE with LIF to GAG disaccharide analysis in biological samples, we have made improvements to existing methods. These include (i) optimization of reductive amination conditions, (ii) improvement in sensitivity through the use of a cellulose cleanup procedure for the derivatization, and (iii) optimization of separation conditions for robustness and reproducibility. The improved method enables analysis of disaccharide quantities as low as 1,pmol prior to derivatization. Biological GAG samples were exhaustively digested using lyase enzymes, the disaccharide products and standards were derivatized with the fluorophore 2-aminoacridone and subjected to reversed polarity CE-LIF detection. These conditions resolved all known chondroitin sulfate (CS) disaccharides or 11 of 12 standard heparin/heparan sulfate disaccharides, using 50,mM phosphate buffer, pH 3.5, and reversed polarity at 30,kV with 0.3,psi pressure. Relative standard deviation in migration times of CS ranged from 0.1 to 2.0% over 60 days, and the relative standard deviations of peak areas were less than 3.2%, suggesting that the method is reproducible and precise. The CS disaccharide compositions are similar to those obtained by our group using tandem MS. The reversed polarity CE-LIF disaccharide analysis protocol yields baseline resolution and quantification of heparin/heparan sulfate and CS/dermatan sulfate disaccharides from both standard preparations and biologically relevant proteoglycan samples. The improved CE-LIF method enables disaccharide quantification of biologically relevant proteoglycans from small samples of intact tissue. [source] Enrichment and low-level determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water after cleanup by cation exchange resinJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2010Markus Küsters Abstract For the determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water, different procedures of enrichment and cleanup were examined using anion exchange or SPE. In many cases interactions of, e.g. alkaline earth metal ions especially calcium could be observed during enrichment and cleanup resulting in loss of analytes. For that reason, a novel cleanup and enrichment procedure for the determination of these phosphonic acid herbicides has been developed in drinking water using cation-exchange resin. In summary, the cleanup procedure with cation-exchange resin developed in this study avoids interactions as described above and is applicable to calcium-rich drinking water samples. After derivatization with 9-fluorenylmethylchloroformate followed by LC with fluorescence detection, LOD of 12, 14 and 12,ng/L and mean recoveries from real-world drinking water samples of 98±9, 100±16 and 101±11% were obtained for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. The low LODs and the high precision permit the analysis of these phosphonic acid herbicides according to the guidelines of the European Commission. [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] Determination of S -phenylmercapturic acid in human urine using an automated sample extraction and fast liquid chromatography-tandem mass spectrometric methodBIOMEDICAL CHROMATOGRAPHY, Issue 6-7 2006Yinghe Li Abstract S -phenylmercapturic acid is widely accepted as a specific biomarker for the evaluation of benzene exposure. Here, we describe a fast, specific and sensitive high-performance liquid achromatography coupled with tandem mass spectrometry (LC-MS/MS) method that has been developed and validated for the determination of S- phenylmercapturic acid in human urine. Isotope-labeled S- phenylmercapturic acid- d5 was used as internal standard to improve the method ruggedness. The fully automated solid-phase extraction method on a 96-well Oasis MAX (mix-mode anion exchange) plate was employed to clean up the urine samples before analysis. The rapid LC-MS/MS analysis of extracted samples was achieved on a Genesis C18 column with a run time of only 3 min. Negative electrospray ionization with multiple reaction monitoring (ESI-MRM) mode was used to detect S- phenylmercapturic acid (m/z 238 , 109) and S- phenylmercapturic acid - d5 (m/z 243 , 114). The method fulfils all the standard requirements of method validation. The calibration curve was linear within the concentration range 0.400,200 ng/mL. The method performed accurately and precisely in validation with <7.5% relative error and <6.5% relative standard deviation of quality control samples. The method efficacy was also verified by the analysis of urine samples from 12 smokers and 12 non-smokers. With the fully automated sample cleanup procedure and the fast LC-MS/MS analysis, a sample analysis throughput of 384 samples per day could be achieved. Copyright © 2006 John Wiley & Sons, Ltd. [source] Development of HPLC and NACE methods for the simultaneous determination of benzoic and sorbic acids in sour snap beans containing oilELECTROPHORESIS, Issue 22 2007Po Han Abstract The practical methods were developed for the simultaneous determination of benzoic acid (BA) and sorbic acid (SA) in sour snap bean samples containing oil. BA and SA in the samples were extracted by ultrasonication with water, followed by cleanup procedures with precipitation for removing the potential proteins and with petroleum ether liquid,liquid extraction for removing the edible oil contained in the samples. The HPLC method was developed using Supelco C18 (250,mm×4.6,mm id, 5,,m) as column, MeOH,20,mM NH4Ac (25:75 v/v) at 1.0,mL/min as the mobile phase and 230,nm as the detection wavelength. The optimal NACE method was established with a running buffer of 20.0,mM NH4Ac in 95% MeOH (pH*,10.6), and an applied voltage of ,30,kV over a capillary of 50,,m id×48.5,cm (40,cm to the detector window), which gave a baseline separation of BA and SA, and as well as of the blank matrix within ca. 10,min. Both HPLC and NACE methods gave the relatively lower limits of quantification at about 0.01,0.02 and 0.04,0.05,mg/kg, respectively, whereas the overall recoveries were larger than 85.0%. The proposed methods have been successfully applied to measure 15 real sour bean samples and the content profile of BA and SA in sour bean samples was obtained and evaluated. [source] Application of pressurized liquid extraction in the analysis of aflatoxins B1, B2, G1 and G2 in nutsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009Luca Campone Abstract Aflatoxins (AFs) B1, B2, G1 and G2 were extracted from nuts by using pressurized liquid extraction (PLE) and the PLE extracts were analyzed using HPLC with fluorescence detection using photochemical post-column derivatization without further cleanup procedures. Several extraction parameters such as temperature (25, 40, 60 and 80°C), pressure (500, 1000, 1500 and 2000,psi), solvent extraction mixture (acetone, acetonitrile, ethyl acetate and methanol), number of cycles (1 and 2), use of dispersing agents and cell size (5 and 11,mL) were investigated for their effects on the extraction performance. The results showed 60°C, 1500,psi, acetonitrile, one cycle and a cell size of 5,mL as most favorable PLE operating conditions. The proposed analytical method provides LODs below the maximum levels established by European Union regulations and the recoveries of the four AFs were between 77 and 93% at spiking levels of 4, 2 and 0.5,,g/kg for AFB1 and AFG1 and 1, 0.5 and 0.13,,g/kg for AFB2 and AFG2. Validation was carried out using certified reference materials. PLE has been applied for the first time to the analysis of AFs in nuts and offers the possibility for fast simple and accurate quantitative determination of studied mycotoxins. [source] | ||||||||||