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Chromatographic Determination (chromatographic + determination)
Kinds of Chromatographic Determination Selected AbstractsChromatographic determination of herbicide residues in various matricesBIOMEDICAL CHROMATOGRAPHY, Issue 6 2004Tibor Cserháti Abstract The newest results in the use of various extraction techniques and chromatographic methods such as gas,liquid and high-performance liquid chromatography used for the assessment of herbicide residues in various matrices have been compiled and critically evaluated. Practical employments in water and soil research, environmental protection, clinical and food chemistry are presented. Copyright © 2004 John Wiley & Sons, Ltd. [source] High-performance liquid chromatographic determination and pharmacokinetic study of cefepime in goat plasma and milk after pre-column derivatization with Hg(I)JOURNAL OF SEPARATION SCIENCE, JSS, Issue 17-18 2010Nawal A. El-Rabbat Abstract A highly sensitive and selective HPLC method with UV detection was developed for the determination of cefepime in goat plasma and milk. The proposed method was based on the complexation of cefepime with Hg(I) ions that imparts the high selectivity of the proposed method with enhancement of the sensitivity which enabled the analysis of cefepime in complex matrices such as plasma and milk. Detection was performed at 263,nm, using cefuroxime sodium as an internal standard. Chromatographic separation of cefepime and the internal standard was achieved with Aqua RP-C18 column using methanol/triethylamine-acetate buffer, pH 3.5 (18:82, v/v) as mobile phase at a flow rate of 1,mL/min. Linear detector responses were observed spanning the range of 1.3,20,,g/mL. The LOD for standard cefepime was 0.43,,g/mL, whereas the LOD for cefepime in goat plasma was 0.84,,g/mL and the corresponding value in goat milk was 1.1,,g/mL. No interference from endogenous substances in plasma and milk was observed. The developed HPLC method has been successfully applied for the pharmacokinetic study of cefepime in goat plasma and milk, for the first time, after a single intramuscular injection of 50,mg cefepime/kg body weight. [source] Determination of pKa values of nonsteroidal antiinflammatory drug-oxicams by RP,HPLC and their analysis in pharmaceutical dosage formsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2009Ebru Cubuk Demiralay Abstract In this study, pKa values were determined by using the dependence of the capacity factor on the pH of the mobile phase for four ionizable substances, namely, tenoxicam, piroxicam, meloxicam, and naproxen (I.S.). The effect of the mobile phase composition on the ionization constant was studied by measuring the pKa at different ACN concentrations, ranging from 30 to 40%. The adequate condition for the chromatographic determination of these compounds in pharmaceutical dosage forms was established based on the different retention behaviors of the species. An octadecylsilica Nucleosil C18 column (150×4.6 mm, 5 ,m) was used for all the determinations. The chromatographic separation of oxicams was carried out using acetonitrile (ACN)/water at 35% v/v, containing 65 mM phosphoric acid and UV detection at a wavelength of 355 nm. The method developed was successfully applied to the simultaneous determination of these drug compounds in laboratory-prepared mixtures and their commercial pharmaceutical dosage forms. Each analysis requires no longer than 12 min. [source] Solid phase microextraction-high performance liquid chromatographic determination of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in the presence of sodium dodecyl sulfate surfactantJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2008Gaurav Abstract A simple and sensitive method has been developed using preconcentration technique solid phase microextraction (SPME) and analytical technique HPLC-UV for the determination of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from the environmental samples. Aqueous solution of anionic surfactant SDS was used for the extraction of both nitramine high explosives, viz., HMX and RDX from soil samples which were subsequently sorbed on SPME fiber. The static desorption was carried out in the desorption chamber of the SPME-HPLC interface in the presence of mobile phase ACN/methanol/water (30:35:35) and the subsequent chromatographic analysis at a flow rate of 0.5 mL/min and detection at 230 nm. For this purpose, a C18, 5 ,m RP analytical column was used as a separation medium in this method. Several parameters relating to SPME, e.g., adsorption/desorption time, concentration of salt, stirring rate, etc., were optimized. The method was linear over the range of 20,400 ng/mL for HMX and RDX standards in the presence of surfactant in aqueous phase, respectively. The correlation coefficient (R2) for HMX and RDX are 0.9998 and 0.9982, respectively. With SPME, the detection limits (S/N = 3) in ng/mL are 0.05 and 0.1 for HMX and RDX, respectively in the presence of the SDS surfactant. The developed method has been applied successfully to the analysis of real environmental samples like bore well water, river water, and ground alluvial soil. [source] Fast miniaturised sample preparation for the screening and comprehensive two-dimensional gas chromatographic determination of polychlorinated biphenyls in sludgeJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2005E. Maria Kristenson Abstract Polychlorinated biphenyls (PCBs) in sludge are usually extracted by a technique such as Soxhlet with subsequent fractionation prior to long GC runs using GC,ECD or GC,HRMS. In this study, the extraction of selected chlorinated biphenyls (CBs) from a spiked sludge sample by three rapid techniques, i.e. ultrasonic (USE), pressurised-liquid (PLE), and microwave-assisted (MAE) extraction using a domestic microwave, was studied, with subsequent direct GC,ECD, GC,MS, or GC×GC,,ECD analysis of the extracts. The main goal was to select an appropriate, and miniaturised, extraction method after only a brief optimisation and demonstrate the power of GC×GC analysis of dirty extracts. For PLE similar CB recoveries were found when extracting with either n -hexane or n -hexane/acetone (1/1). For USE and MAE, n- hexane/acetone (1/1) was the preferred extraction solvent. USE gave the best recoveries (80,95%; except 130% for CB 105). The only clean-up needed prior to GC,MS or GC×GC,,ECD analysis was the removal of sulphur-containing compounds. GC,ECD was not suitable for these dirty extracts. The lowest LODs for the CBs (20 fg or 0.1 ng/g sludge) were found when combining USE and GC×GC,,ECD, because of the powerful extraction, high separation power and excellent detectability provided by this technique. [source] High-performance liquid chromatographic determination of creatine kinase activity influenced by methylglyoxalBIOMEDICAL CHROMATOGRAPHY, Issue 2 2009Xiaofang Peng Abstract Protein glycation has been implicated in the development of diabetic complications and other health disorders, which mainly arise from accumulation of advanced glycation endproducts (AGEs) in vivo. Methylglyoxal (MGO), a typical reactive intermediate carbonyl formed in early glycation process, can react non-enzymatically with N -terminal amino groups on proteins, leading to their inactivation and generation of detrimental AGEs. Recently, it was reported that activity of creatine kinase (CK, EC 2.7.3.2) could be reduced or even eliminated completely after incubation with MGO in vitro. CK activity is usually determined by conventional colorimetric assays. However, these methods are not appropriate for monitoring the influence of MGO on CK activity since MGO can also directly react with creatine, a substrate of CK. In this study, an efficient and much more accurate HPLC approach was established to investigate the effect of MGO on CK activity. Aminoguanidine was utilized to eliminate interference from the undesirable reaction between residual MGO and creatine. It was found that higher concentrations of MGO and longer incubation time for CK and MGO caused more pronounced reduction in CK activity. This HPLC method greatly facilitates acquisition of kinetic data about CK reaction and through further improvement it may be adopted to rapidly screen potential inhibitors of MGO-induced glycation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Liquid chromatographic fluorescence determination of amino acids in plasma and urine after derivatization with phanquinoneBIOMEDICAL CHROMATOGRAPHY, Issue 2 2008Rita Gatti Abstract Phanquinone (4,7-phenanthroline-5,6-dione) has been investigated as a pre-column derivatization fluorogenic reagent for liquid chromatographic determination of primary amino acids in biological samples. The derivatization reaction was carried out at 68°C both in the presence of aqueous phosphate buffer (pH 8) for 30 min and without buffer for 60 min to allow the determination of basic amino acids (Orn, Lys, Arg). The resulting derivatives were separated under reversed-phase HPLC and detected at ,em = 460 nm with ,ex = 400 nm. The proposed method was validated and applied to the determination of a variety of amino acids directly in urine and after deproteinization with 5-sulfosalicylic acid in plasma samples. The detection and quantitation limits were found in the range 10,450 and 35,1400 fmol, respectively. Copyright © 2007 John Wiley & Sons, Ltd. [source] A solid-phase extraction method for high-performance liquid chromatographic determination of salvianolic acid B in rabbit plasma: application to pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 2 2007Yueming Ma Abstract A sensitive solid-phase extraction/high-performance liquid chromatographic method with ultraviolet detection was established for the analysis of salvianolic acid B in rabbit plasma. The analyte was separated on a reversed-phase column with trifluoroacetic acid,methanol,acetonitrile (70:10:20, v/v/v) as mobile phase at a flow rate of 1 mL/min, and ultraviolet detection at 315 nm. The calibration curve for salvianolic acid B was linear over the range 35,1400 µg/L with coefficients of correlation >0.999. The inter-day and intra-day precisions of analysis were <15%, and assay accuracy ranged from 95.3 to 109.1%. This method is suitable for determining salvianolic acid B in plasma and thus investigating the pharmacokinetics of salvianolic acid B. Copyright © 2007 John Wiley & Sons, Ltd. [source] Photostability studies for micellar liquid chromatographic determination of nifedipine in serum and urine samplesBIOMEDICAL CHROMATOGRAPHY, Issue 2 2006M. T. Gil-Agustí Abstract Nifedipine is a photosensitive compound that is converted into its 4-(2-nitrophenyl) pyridine and 4-(2-nitrosophenyl) pyridine homologue. In order to obtain the most adequate conditions for handling nifedipine solutions in the analytical laboratory, a number of studies on the decomposition of this compound were performed. A simple micellar liquid chromatographic procedure was described to determine nifedipine in different biological matrices such as serum and urine, and to control its decomposition. To perform the analysis, nifedipine was dissolved in 0.1 m SDS at pH 3 and chromatographed using a mobile phase containing 0.125 m SDS,3% pentanol, pH 3 on a C18 column and UV detection at 235 nm. The chromatographic analysis time was 8 min. The response of the drug for both biological matrices was linear in the 1,100 µg/mL range, with r2 > 0.997 at all times. Repeatability, intermediate precision (CV, %) and limits of quantification and detection (ng/mL) were 0.19, 4.3, 104 and 31 in serum and 0.81, 2.1, 136 and 41 in urine. The method developed here does not show interferences or matrix effects produced by endogenous compounds. Micellar media and mobile phases have the advantage of stabilising the compounds, thus preventing photodegradation and allowing the direct injection of biological samples. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||