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Mean Recoveries (mean + recovery)
Selected AbstractsDevelopment and validation of an HPLC confirmatory method for the determination of seven tetracycline antibiotics residues in milk according to the European Union Decision 2002/657/ECJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2007Victoria F. Samanidou Abstract An HPLC method with diode-array detection, at 355 nm, was developed and validated for the determination of seven tetracyclines (TCs) in milk: minocycline (MNC), TC, oxytetracycline (OTC), methacycline (MTC), demeclocycline (DMC), chlortetracycline (CTC), and doxycycline (DC). Oxalate buffer (pH 4) was used with 20% TCA as a deproteinization agent for the extraction of analytes from milk followed by SPE. The separation was achieved on an Inertsil ODS-3, 5 ,m, 250×4 mm2 analytical column at ambient temperature. The mobile phase, a mixture of A: 0.01 M oxalic acid and B: CH3CN, was delivered using a gradient program. The procedure was validated according to the European Union decision 2002/657/EC determining selectivity, stability, decision limit, detection capability, accuracy, and precision. Mean recoveries of TCs from spiked milk samples (50, 100, and 200 ng/g) were 93.8,100.9% for MNC, 96.8,103.7% for OTC, 96.3,101.8% for TC, 99.4,107.2% for DMC, 99.4,102.9% for CTC, 96.3,102.7% for MTC, and 94.6,102.1% for DC. All RSD values were lower than 8.5%. The decision limits CCa calculated by spiking 20 blank milk samples at MRL (100 ,g/kg) ranged from 101.25 to 105.84 ,g/kg, while detection capability CCbfrom 103.94 to 108.88 ,g/kg. [source] Quantification of arecoline (areca nut alkaloid) in neonatal biological matrices by high-performance liquid chromatography/electrospray quadrupole mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2003Simona Pichini A high-performance liquid chromatography (HPLC) method with mass spectrometric detection is described for determination of arecoline in newborn meconium, urine and cord serum, using pilocarpine as internal standard. The analytes were extracted from neonatal biological matrices with chloroform/isopropanol (95:5, v/v) at alkaline pH. Extracts were analyzed by HPLC coupled to an electrospray (ESI) interface and a quadrupole mass spectrometer. Chromatography was performed on a C8 reversed-phase column using 10 mM ammonium acetate (pH 4.3)/acetonitrile (90:10, v/v) as mobile phase. The mass spectrometer was operated in selected ion monitoring mode. The method was validated over the concentration range 0.005,1.00,,g/g meconium, 0.004,1.00,,g/mL cord serum and 0.001,1.00,,g/mL urine. Mean recoveries ranged between 86.5 and 90.7% for arecoline in the different biological matrices, with precision always better than 10%. The quantification limits of arecoline were 0.005,,g/g meconium, 0.004,,g/mL cord serum, and 0.001,,g/mL urine. The method was applied to the analysis of neonatal biological matrices to assess eventual fetal exposition to arecoline. Two newborns from Asian mothers who declared areca nut consumption presented arecoline in meconium with concentrations in the range 0.006,0.008,,g/g; also the urine from one neonate tested positive for the drug. Copyright © 2003 John Wiley & Sons, Ltd. [source] Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass SpectrometryCHINESE JOURNAL OF CHEMISTRY, Issue 9 2007Yan Liu Abstract A determination method has been optimized and validated for the simultaneous analysis of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DC) in honey. Tetracyclines (TCs) were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction (SPE), while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile, and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 µg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% (n=18). Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey(2,50 ng/g) was realized by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r>0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey. [source] Advantages of deuterium-labelled mixed triacylglycerol in studies of intraluminal fat digestionRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2006Christine Slater The 13C-mixed triacylglcerol (MTG, 1,3-distearyl, 2-[1- 13C]octanoyl glycerol) breath test is a non-invasive measure of intraluminal fat digestion. Recovery of 13C in breath CO2 is incomplete (<50%) owing to sequestration of 13C into organic molecules via the tricarboxylic acid (TCA) cycle. In addition lack of knowledge of CO2 production rate (VCO2) during the test leads to errors in the calculated percentage dose recovered (PDR). 2H sequestration into organic molecules is low (,4%) and is not influenced by factors that affect VCO2 such as food intake or physical activity. After oxidation of 2H-labelled macromolecules, the label appears in body water, which can be sampled non-invasively in urine or saliva. After an overnight fast, two healthy adults consumed [2H]MTG (1,3-distearyl, 2-[2H15]octanoyl glycerol) and [13C]MTG (1,3 distearyl, 2-[1- 13C]octanoyl glycerol) simultaneously. Total body water (TBW) was measured by 18O dilution and also estimated from height and weight. Urine and saliva were sampled at baseline and for 10,h after consumption of the test meal. The abundance of 2HOH and H218O in urine and saliva was measured by continuous-flow isotope-ratio mass spectrometry. Cumulative PDR of 2H and 18O was calculated from the plateau enrichment, which was reached by 6,h in both saliva and urine. Recovery of 2H calculated using measured TBW was compared with that using an estimated value of TBW. Mean recovery of 2H in saliva was 99.3% and in urine was 96.4%. Errors introduced by estimating TBW were <5%. [2H]MTG could provide a simpler, more robust, indirect test of intraluminal fat digestion compared with the 13C-breath test. Further studies are required in pancreatic insufficient patients. Copyright © 2005 John Wiley & Sons, Ltd. [source] Arbutin determination in medicinal plants and creamsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2009W. Thongchai Synopsis A simple flow injection (FI) manifold with spectrophotometric detection was fabricated and tested for arbutin determination. It is based on the measurement of a red-coloured product at 514 nm formed by the complexation reaction between arbutin and 4-aminoantipyrine (4-AP) in the presence of hexacyanoferrate (III) in an alkaline medium. On injecting 300 ,L standard solutions at various concentrations of arbutin into the FI system under optimum conditions, a linear calibration graph over the range of 1.0,30.0 ,g mL,1 arbutin was established. It is expressed by the regression equation y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). The detection limit (3,) and the limit of quantitation (10,) were 0.04 ,g mL,1 and 0.13 ,g mL,1, respectively. The RSD of intraday and interday precisions were found to be 1.2,1.4% and 1.7,2.7%, respectively. The method was successfully applied in the determination of arbutin in four selected fruits and three commercial whitening cream extracts with the mean recoveries of the added arbutin over the range of 96.2,99.0%. No interference effects from some common excipients used in commercial whitening creams were observed. The method is simple, rapid, selective, accurate, reproducible and relatively inexpensive. Résumé Un collecteur simple pour injection en flux (FI) avec détection spectrométrique a été fabriqué et testé pour le dosage de l'arbutine. Son principe repose sur la mesure à 514 nm du produit rouge formé par la réaction de complexation entre l'arbutine et le 4-aminoantipyrine (4-AP) en présence d'hexacyanoferrate (III) en milieu alcalin. On procède à une injection de 300 ,L des solutions standards à diverses concentrations d'arbutine dans le système FI aux conditions optimales, puis on réalise un graphe de calibration linéaire dans l'intervalle de 1,0 à 30,0 ,g mL,1 d'arbutine. Le graphe correspond à l'équation de régression y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). La limite de détection (3,) et la limite de quantification (10,) sont respectivement de 0.04 ,g mL,1 et 0.13 ,g mL,1. La RSD des précisions intra et inter jours sont respectivement de 1.2,1.4% et 1.7,2.7%. La méthode a été appliquée avec succès à la mesure de l'arbutine dans 4 fruits sélectionnés et 3 extraits de crèmes de blanchiment commercialisées avec une recouvrance moyenne de l'arbutine ajoutée de 96.2 à 99%. Aucune interférence avec les excipients communément utilisés dans les crèmes de blanchiment commerciales n'a été observée. La méthode est simple, rapide, sélective, précise, reproductible et relativement bon marché. [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] Development and validation of an HPLC method for the determination of seven penicillin antibiotics in veterinary drugs and bovine blood plasmaJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2009Victoria F. Samanidou Abstract Herein a quantitative method for the determination of seven penicillins in bovine plasma and veterinary drugs has been developed. Amoxicillin (AMO), ampicillin (AMP), penicillin G (PENG), penicillin V (PENV), oxacillin (OXA), cloxacillin (CLO) and dicloxacillin (DICLO) were separated on a Perfectsil ODS-2 (250×4 mm, 5 ,m) column, using gradient elution, with a mobile phase of 0.1% v/v TFA and ACN,methanol (90:10 v/v). PDA detection was used at 240 nm. Penicillins were isolated from bovine plasma by SPE on Lichrolut RP-18 cartridges with mean recoveries from 85.7 to 113.5%. Colchicine (3 ng/,L) was used as an internal standard. The developed method was validated in terms of selectivity, linearity, accuracy, precision, stability and sensitivity. Repeatability (n = 5) and between-day precision (n = 5) revealed RSD < 12%. The detection limits in the bovine plasma were estimated as 18 ng for AMO and AMP, 25 for PENG, PENV and OXA, 3 ng for CLO and 12 ng for DICLO. Spiked plasma samples were stable for 1 wk, except for AMP and CLO, which were stable for 3 wk and OXA for 4 wk. AMO, PENG and PENV were stable for two freeze,thaw cycles, OXA, CLO and DICLO for four, while AMP only for one. [source] Determination of cylindrospermopsin in freshwaters and fish tissue by liquid chromatography coupled to electrospray ion trap mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2009Pasquale Gallo Cylindrospermopsin (CYN) is a toxic alkaloid-like compound produced by some strains of cyanobacteria, procariotic organisms occurring in water blooms, observed worldwide in eutrophic lakes and drinking water reservoirs. Methods for determination of CYN in freshwater and fish muscle by liquid chromatography coupled to electrospray ion trap mass spectrometry are herein described. The performances of both methods are reported; ion trap LC/ESI-MS/MS resulted highly selective and reliable in unambiguous identification of CYN, based on monitoring the precursor ion and three product ions. The methods developed showed satisfactory mean recoveries (higher than 63.6%) and relative standard deviations, ranging from 5.8 to 9.8%. The limits of quantification at 0.10,ng/mL in freshwaters and 1.0,ng/g in fish muscle, respectively, allow for determination of CYN also in early contamination stages. Ion trap LC/ESI-MS/MS was successfully applied to the identification and quantification of CYN in water and cyanobacteria extracts from Lake Averno, near Naples, representing the first case of contamination described in southern Italy. Copyright © 2009 John Wiley & Sons, Ltd. [source] Liquid chromatography coupled to quadruple time-of-flight tandem mass spectrometry for microcystin analysis in freshwaters: method performances and characterisation of a novel variant of microcystin-RRRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2009Pasquale Ferranti Cyanobacteria, also called blue-green algae, occur worldwide within water blooms in eutrophic lakes and drinking water reservoirs, producing several biotoxins (cyanotoxins). Among these, microcystins (MCs) are a group of cyclic heptapeptides showing potent hepatotoxicity and activity as tumour promoters. So far, at least 89 MCs from different cyanobacteria genera have been characterised. Herein, ion trap, matrix-assisted laser desorption/ionisation time-of-flight (MALDI-ToF) and quadruple time-of-flight (Q-ToF) mass spectrometry (MS)-based methods were tested and compared for analysing MCs in freshwaters. Method performances in terms of limit of detection, limit of quantification, mean recoveries, repeatability, and specificity were evaluated. In particular, a liquid chromatography/electrospray ionisation (LC/ESI)-Q-ToF-MS/MS method was firstly described to analyse MCs in freshwaters; this technique is highly selective and sensitive, and allowed us to characterise the molecular structure of an unknown compound. Indeed, the full structural characterisation of a novel microcystin variant from a bloom of Planktothrixrubescens in the Lake Averno, near Naples, was attained by the study of the fragmentation pattern. The new cyanotoxin was identified as the 9-acetyl-Adda variant of microcystin-RR. Copyright © 2009 John Wiley & Sons, Ltd. [source] Liquid chromatography/electrospray ionization tandem mass spectrometry validated method for the simultaneous quantification of sibutramine and its primary and secondary amine metabolites in human plasma and its application to a bioequivalence studyRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2006Deepak S. Jain A high-throughput and sensitive bioanalytical method using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) has been developed for the estimation of sibutramine and its two metabolites (M1 and M2). The extraction of sibutramine, its metabolites and imipramine (internal standard (IS)) from the plasma involved treatment with phosphoric acid followed by solid-phase extraction (SPE) using a hydrophilic-lipophilic balanced HLB cartridge. The SPE eluate without drying and reconstitution was analyzed by LC/MS/MS, equipped with a with turbo ion spray (TIS) source, operating in the positive and multiple reaction monitoring (MRM) acquisition mode. Sample preparation by this method yielded extremely clean extracts with quantitative and consistent mean recoveries; 95.12% for sibutramine, 92.74% for M1, 95.97% for M2 and 96.60% for the IS. The total chromatographic run time was 3.0,min with retention times of 2.51, 2.13, 2.09,min for sibutramine, M1, M2 and imipramine, respectively. The developed method was validated in human plasma matrix, with a sensitivity of 0.1,ng/mL (coefficient of variance (CV), 2.07%) for sibutramine, 0.1,ng/mL (CV, 3.59%) for M1 and 0.2,ng/mL (CV, 4.93%) for M2. Validation of the method for its accuracy, precision, recovery, matrix effect and stability was carried out especially with regard to real subject sample analysis. The response was linear over the dynamic range 0.1 to 8.0,ng/mL for sibutramine and M1, and 0.2 to 16.0,ng/mL for M2 with correlation coefficients of r,,,0.9959 (sibutramine), 0.9935 (M1) and 0.9943 (M2). The method was successfully applied for bioequivalence studies in 40 human subjects with 15,mg capsule formulations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Monitoring of fluoroquinolone residual levels in chicken eggs by microbiological assay and confirmation by liquid chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 1 2008Hee-Jung Cho Abstract The primary objective of this study was to develop a simple, rapid, and efficient method for the simultaneous determination of four fluoroquinolone residues, ciprofloxacin (CFX), danofloxacin (DFX), enrofloxacin (EFX) and norfloxacin (NFX), in chicken eggs. The samples were first monitored by microbiological assay using Escherichia coli as the reference organism, and were then quantified using HPLC with a fluorescence detector. Egg samples were extracted by the liquid-phase extraction process, and the analytes were analyzed via an ODS column using a mixture of acetonitrile and 0.4% phosphoric acid,0.4% triethylamine (15: 85, v/v) as a mobile phase (pH = 2) without purification. The calibration curves were linear (r2 , 0.999) over a concentration range of 0.1,1.0 µg/mL. The majority of the mean recoveries at four different fortification levels, 0.1, 0.2, 0.5 and 1.0 ppm, ranged from 73.7 ± 7.2% to 87.1 ± 12.7%, and the repeatability (as the relative standard deviation) from three repetitive determinations of recovery was between 1.03 and 18.83%. The calculated limit of quantitation (LOQ) was 9 ppb for CFX, EFX and NFX and 0.6 ppb for DFX. Both the bioassay and HPLC methods were applied to 120 total egg samples collected from the six major cities in the Republic of Korea. The bioassay, showed that two samples were positive (i.e contained inhibiting substances). On the other hand, the results of HPLC only identified and quantified the residues of enrofloxacin (from 0.43 to 1.02 ppm) in three samples out of 120. We concluded that the bioassay can be used as a routine screening method for the presence of fluoroquinolones in chicken eggs, which can be confirmed and quantified using LC. Copyright © 2007 John Wiley & Sons, Ltd. [source] Simultaneous determination of four antiepileptic drugs in serum by high-performance liquid chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 1 2002H. Levert A high-performance liquid chromatographic method has been developed for the simultaneous determination of oxcarbazepine, 10-hydroxycarbamazepine, epoxycarbamazepine, carbamazepine, phenobarbital and phenytoin. After protein precipitation by acetonitrile, the supernatant was analysed on a C18 reversed-phase HPLC column. Antiepileptic drugs and oxazepam (internal standard) were detected by ultraviolet absorbance at 240,nm. Linearity was established for the whole concentration range for each compound. Quantitation limits of oxcarbazepine, 10-hydroxycarbamazepine, epoxycarbamazepine, carbamazepine, phenobarbital and phenytoin were 0.58, 3.5, 2.35, 0.66, 1.02 and 3.13,µg/mL, respectively, and mean recoveries added to serum were 105.15, 84.76, 94,45, 96.52, 98.62 and 95.08%, respectively. This method has been used for the simultaneous determination of steady-state serum concentration of antiepileptic drugs in patients treated by one or more anticonvulsive treatment. Copyright © 2001 John Wiley & Sons, Ltd. [source] Clinical trial: a randomized, study comparing meperidine (pethidine) and fentanyl in adult gastrointestinal endoscopyALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009D. J. ROBERTSON Summary Background, There is little evidence to guide choice between meperidine (pethidine) and fentanyl for sedation for gastrointestinal endoscopy. Aim, To compare meperidine with fentanyl in terms of procedure time and analgesia. Methods, Single centre randomized controlled trial. Patients received narcotic doses and midazolam at the discretion of the attending endoscopist who was unaware of narcotic assignment. Endoscopy and recovery times were then recorded. The main outcome was total procedure time, defined as endoscopy time plus recovery time. Patient discomfort was assessed prior to discharge via visual analogue scale (VAS). Results, In total, 55 patients were randomized to meperidine [44 colonoscopy and 11 esophagogastroduodenoscopy (EGD)] and 56 to fentanyl (45 colonoscopy and 11 EGD). Total procedure time was shorter for those receiving fentanyl (mean = 87.7 min) than for those receiving meperidine (mean = 102.9 min) (P = 0.05). The difference between the groups was explained by a shorter mean recovery time in the fentanyl group (63.0 min) than in the meperidine group (76.2 min) (P = 0.07). Based on post procedure pain scores, examinations with meperidine (mean = 1.99) were less painful when compared with those receiving fentanyl (mean = 2.86, P = 0.03). Conclusions, Fentanyl shortened total procedure time by reducing recovery time. A simple change in narcotic choice could increase endoscopy unit efficiency. [source] Analysis of glycopeptide antibiotics using micellar electrokinetic chromatography and borate complexationBIOMEDICAL CHROMATOGRAPHY, Issue 2-3 2003Carmelle Lucas Abstract Micellar electrokinetic chromatography (MEKC) was investigated as a technique for the separation and analysis of the following related glycopeptide antibiotics: ,-avoparcin, ,-avoparcin, ristocetin A, ristocetin B and vancomycin. Sodium dodecyl sulfate (SDS) micelles were employed as the pseudostationary phase in conjunction with borate or CHES buffers at pH 9.2. A complete separation of the glycopeptides was achieved only when two separation mechanisms were employed simultaneously: (i) differential partitioning of the glycopeptides into SDS micelles; and (ii) differential complexation of the glycopeptides with the borate anion from the borate buffer. Quantitatively, linearity was confirmed for each antibiotic from 0.5 to 40,ppm, with correlation coefficients (r2) ranging from 0.9996 (vancomycin and ,-avoparcin) to 0.9986 (,-avoparcin). Detection limits ranging from 0.01,ppm (vancomycin) to 0.2,ppm (avoparcin) were achieved, and the mean recovery of avoparcin at the 10,ppm level was 99.2%. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||