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ODS Column (ods + column)
Selected AbstractsQuantification of fudosteine in human plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry employing precolumn derivatization with 9-fluorenylmethyl chloroformateJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2006Fengguo Xu Abstract This paper describes a novel method for the sensitive and selective determination of fudosteine in human plasma. The method involves a derivatization step with 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer and detection based on high-performance liquid chromatography-electrospray ionization mass spectrometry (LC/ESI/MS). After acetonitrile-induced protein precipitation of plasma samples, fudosteine was derivatized with FMOC-Cl, then extracted by ethyl acetate, evaporated, reconstituted and injected using an LC/ESI/MS instrument. Separation was achieved using an ODS column and isocratic elution. Excellent linearity was obtained for the entire calibration range from 0.05 to 20 µg/ml. Validation assays of the lower limit of quantification (LLOQ) as well as for the intra- and inter-batch precision and accuracy met the international acceptance criteria for bioanalytical method validation. Using the developed analytical method, fudosteine could be detected for the first time in human plasma with a low limit of detection (LLOD) of 0.03 µg/ml. The proposed method has been successfully applied to study the pharmacokinetics of fudosteine in healthy Chinese volunteers after single and multiple oral administration. Copyright © 2006 John Wiley & Sons, Ltd. [source] Highly sensitive and accurate profiling of carotenoids by supercritical fluid chromatography coupled with mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2009Atsuki Matsubara Abstract We attempted to establish a high-speed and high-resolution profiling method for a carotenoid mixture as a highly selective and highly sensitive detection method; the analysis was carried out by supercritical fluid chromatography (SFC) coupled with mass spectrometry (MS). When an octadecyl-bonded silica (ODS) particle-packed column was used for separation, seven carotenoids including structural isomers were successfully separated within 15 min. This result indicated not only improved separation but also improved throughput compared to the separation and throughput in RP-HPLC. The use of a monolithic ODS column resulted in additional improvement in both the resolution and the throughput; the analysis time was reduced to 4 min by increasing the flow rate. Furthermore, carotenoids in biological samples containing the complex matrices were separated effectively by using several monolithic columns whose back pressure was very low. The mass spectrometer allowed us to perform a more sensitive analysis than UV detection; the detection limit of each carotenoid was 50 pg or below. This is the first report of carotenoid analysis carried out by SFC-MS. The profiling method developed in this study will be a powerful tool for carrying out accurate profiling of biological samples. [source] High-performance liquid chromatographic resolution of 1-(1,4-benzodioxane-2-formyl)- piperazine enantiomers after chiral derivatizationJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2005Zhiqiong Chen Abstract Chiral separation of racemic mixtures is of the greatest importance to the pharmaceutical industry, as the isomers of a given racemate may exhibit substantially different pharmacological effects, not to mention possibly differing toxicity behaviour. A novel chiral separation method is developed for the determination of 1-(1,4-benzodioxane-2-formyl)piperazine (BFP) enantiomers. The indirect resolution is performed by applying precolumn derivatization with the chiral reagent 2,3,4,6-tetra- O -acetyl-,-D-glucopyranosyl isothiocyanate (GITC). The resulting diastereoisomers are separated on a reversed-phase ODS column with methanol-potassium dihydrogen phosphate (0.02mol/L, 50:50) as mobile phase. UV detection is at 250 nm. The effect of mobile phase composition upon resolution and analysis time is investigated. Two diastereoisomers show nearly base-line separation under optimal chromatographic conditions. The presented study provides a simple and accurate method for the enantiomeric quality control and the optical purity assay of BFP. [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] Sensitive determination of MDMA and its metabolite MDA in rat blood and brain microdialysates by HPLC with fluorescence detectionBIOMEDICAL CHROMATOGRAPHY, Issue 10 2007Mamoru Tomita Abstract Simultaneous determination of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) in rat blood and brain microdialysates by high-performance liquid chromatography with fluorescence detection (HPLC-FL) was developed. Microdialysates were directly subjected to derivatization with 4-(4,5-diphenyl-1H -imidazol-2-yl)benzoyl chloride (DIB-Cl). The DIB-derivatives of MDMA, MDA and the internal standard, 1-methyl-3-phenylpropylamine (MPPA), were isocratically separated on an ODS column using a mixture of 50 mm phosphate buffer (pH 7.0),acetonitrile,methanol,2-propanol (50:45:5:2, v/v/v/v %) as an eluent at a flow rate of 1.5 mL/min. The calibration curves of MDA and MDMA spiked to blood and brain microdialysates were linear over the ranges 2.5,500 and 5.0,1000 ng/mL, respectively. The detection limits of MDA and MDMA were 1.2 and 4.2 for blood and 1.3 and 4.8 ng/mL for brain, respectively. Additionally, the intra- and the inter-assay precisions were lower than 5.6% for the blood and brain microdialysates (n = 4). The proposed method was successfully applied for the monitoring of MDMA and its metabolite MDA in rat blood and brain microdialysates, and the pharmacokinetic parameters of MDMA and MDA in the microdialysates after administration of MDMA (5 mg/kg, i.p.) with or without caffeine (20 mg/kg, i.p.) were evaluated. Copyright © 2007 John Wiley & Sons, Ltd. [source] Determination of paclitaxel in human and rat blood samples after administration of low dose paclitaxel by HPLC-UV detectionBIOMEDICAL CHROMATOGRAPHY, Issue 3 2007Haruo Yonemoto Abstract A simple and sensitive HPLC-UV method was developed for the determination of paclitaxel (TXL) in human and rat blood samples. 4-Hydroxybenzoic acid n -hexyl ester was used as an internal standard. TXL was extracted by a liquid,liquid extraction with tert -butylmethyl ether. The disturbing peaks in the case of serum sample were removed by pre-extraction with hexane. The separation of TXL was achieved within 25 min using an ODS column with 50% acetonitrile aqueous solution as a mobile phase at a flow rate of 1.0 mL/min. The eluent was monitored at 230 nm, and the resulted retention times of TXL and IS were 11.2 and 20.4 min. The detection limits of TXL for human plasma, serum and rat plasma samples at a signal-to-noise ratio of 3 were 10, 9.5 and 7.5 ng/mL, respectively. The proposed methods were applicable to the determination of TXL in human patients' plasma ranging from 15 to 27 ng/mL. Furthermore, monitoring of the time course of TXL after its single administration to rat could be demonstrated. Copyright © 2007 John Wiley & Sons, Ltd. [source] A simple and sensitive HPLC-fluorescence method for quantification of MDMA and MDA in blood with 4-(4,5-diphenyl-1H -imidazol-2-yl)benzoyl chloride (DIB-Cl) as a labelBIOMEDICAL CHROMATOGRAPHY, Issue 12 2006Mamoru Tomita Abstract A sensitive high-performance liquid chromatographic method with fluorescence detection to determine 3,4-methylenedioxymethamphethamine (MDMA) and 3,4-methylenedioxyamphethamine (MDA) in human and rat whole blood or plasma samples was developed by using 4-(4,5-diphenyl-1H -imidazol-2-yl)benzoyl chloride (DIB-Cl) as a label. MDMA and MDA in a small amount of blood sample (ca 100 µL) were extracted by liquid,liquid extraction with ethyl acetate, and were derivatized with DIB-Cl under mild conditions (10 min at room temperature). A good separation of DIB-derivatives could be achieved within 45 min using a commercially available ODS column with an isocratic eluent of 10 mm citric acid,20 mm Na2HPO4 aqueous buffer (pH 4.0),CH3CN,CH3OH (50:45:5, v/v/v %). The calibration curves prepared with 1-methyl-3-phenylpropylamine (MPPA) as an internal standard showed good linearity (r = 0.999) with 0.36,0.83 ng/mL detection limit at a signal-to-noise ratio of 3. MDMA and MDA in rat whole blood could be monitored for 6 h after a single administration of MDMA (2.2 mg/kg, i.p.). The pharmacokinetic parameters for MDMA and MDA obtained by triplicate measurements were 426 ± 23 and 39 ± 6 ng/mL (Cmax), 20 ± 5 and 100 ± 10 min (Tmax), respectively. Copyright © 2006 John Wiley & Sons, Ltd. [source] A sensitive and selective determination method of histamine by HPLC with intramolecular excimer-forming derivatization and ,uorescence detectionBIOMEDICAL CHROMATOGRAPHY, Issue 8 2003Takashi Yoshitake Abstract A highly sensitive, selective and simple method is described for the determination of histamine by high-performance liquid chromatography (HPLC) with ,uorescence detection. The method is based on an intramolecular excimer-forming ,uorescence derivatization of histamine with 4-(1-pyrene)butyric acid N -hydroxysuccinimide ester (PSE), followed by reversed-phase HPLC. Histamine, having two amino moieties in a molecule, was converted to the dipyrene-labeled derivative by reaction with PSE. The derivative afforded intramolecular excimer ,uorescence (450,540 nm), which can clearly be discriminated from the monomer ,uorescence (370,420 nm) emitted from PSE. Typically, a 10 µL sample solution was mixed with 100 µL of derivatization reagent solution, which was a mixture of 0.5 mm PSE in acetonitrile and 0.5 mm potassium carbonate in water (8:2, v/v). The derivatization was carried out at 100°C for 90 min. The PSE derivative of histamine could be separated by reversed-phase ODS column with isocratic elution using acetonitrile:water (82:18, v/v) containing 0.03% triethylamine. The detection limit (singnal-to-noise ratio = 3) of histamine was 0.5 fmol for a 30 µL injection. The method was successfully applied to the determination of histamine in human urine, and had enough selectivity and sensitivity for urinary histamine quanti,cation. Copyright © 2003 John Wiley & Sons, Ltd. [source] Determination of lipophilic descriptors of antihelmintic 6,7-diaryl-pteridine derivatives useful for bioactivity predictionsBIOMEDICAL CHROMATOGRAPHY, Issue 6 2003Mario Reta Abstract The liquid chromatographic retention factors extrapolated to pure water, k,w, for several 6,7-diaryl-pteridine derivatives in both an octadecylsilane (ODS) and an immobilized arti,cial membrane column (IAM.PC.DD2), using acetonitrile,aqueous buffer pH = 7.45 as mobile phase, were obtained. The logarithms of the k,w values in the IAM.PC.DD2 column, log k,wIAM, show good correlation with the calculated values of the octanol,water partition coef,cients, log Po/w, showing that the chromatographic parameter can be used as lipophilicity descriptor for the studied pteridines. However, interactions other than the lipophilic ones seem to be involved in the ODS column. Previous studies have shown that pteridines have antihelmintic properties. In spite of the complexity of the studied biological system as compared with the chromatographic one, good correlation between the descriptors obtained in the IAM column and biological activity (expressed as the log of the inhibitory concentration required to obtain up to 50% in the reduction of population growth of nematodes, log IC50) was observed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Elevated temperature,extended column length conventional liquid chromatography to increase peak capacity for the analysis of tryptic digestsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2007Pat Sandra Abstract High efficiency separations (200 000 plates) were obtained on conventional LC equipment by coupling 8×25 cm×2.1 (or 4.6) mm id×5 ,m dp ODS columns (total length 2 m) and operation at 60°C using a dedicated LC oven. The peak capacity in this 1-D set-up was 900 for the separation of human serum tryptic peptides analyzed after depletion of six highly abundant proteins. The chromatographic performance of an elevated temperature,extended column length conventional LC is highlighted. [source] | ||||||||||