A simple liquid chromatographic method was developed for the separation and simultaneous determination of cobalt and nickel as chelates with 1-(2-pyridylazo)-2-naphthol (PAN). The method, using a switching column technique for the on-line purification and separation, enables to reach the sub-microgram per litre concentration level excluding off-line sample treatment with the exception of the derivatization reaction. Two small-sized columns packed with CN- and C4-bonded stationary phases were selected and used considering their complementary behaviour with respect to chelated Co and Ni ions. The analysis was performed within 10 min using an optimised eluent (water–acetonitrile–methanol–tetrahydrofuran, 40:45:10:5, v/v/v/v) containing Tween 40 (10−3 M) and acetate buffer (5 × 10−3 M, pH 4.8). Detection was performed by UV-vis spectrophotometry (λ = 565 nm) permitting to reach quantification limits of 0.9 and 0.5 μg L−1 for Co and Ni, respectively.
相似文献Micellar electrokinetic capillary chromatography was used for the determination of picoxystrobin and pyraclostrobin. The background electrolyte consisted of borate buffer (40 mmol L−1 pH 8.5), SDS (30 mmol L−1) and acetonitrile (15% in volume). Runs were made at 25 °C with 25 kV applied potential. The developed method was applied to analyte fortified urine samples. On-line analyte concentration, combined with a capillary of a longer optical path length, allowed limits of quantification of 8.6 × 10−8 mol L−1 for picoxystrobin and 1.8 × 10−7 mol L−1 for pyraclostrobin.
相似文献A sensitive and simple HPLC method with fluorimetric detection has been developed for determination of droperidol in pharmaceutical tablets, human serum, and human milk. Chromatography was performed on a 100 mm × 3 mm i.d. C18 column with methanol–water, 30:70 (v/v), pH 3.5, as mobile phase at a flow-rate of 0.8 mL min−1. The injection volume was 5 μL and detection was by monitoring emission at 324 nm after excitation at 283 nm. Droperidol and p-hydroxybenzoic acid (internal standard) eluted after 5.3 and 6.1 min, respectively. The method was validated over the concentration range 1.14 × 10−7 to 9.12 × 10−6 M. Selectivity was good and the limits of detection and quantitation of the method were approximately 3.54 × 10−8 and 1.07 × 10−7 M, respectively, corresponding to 13 and 40 ng mL−1. The applicability of the method to determination of droperidol in pharmaceuticals, human serum, and human milk was demonstrated.
相似文献A capillary gas chromatography (GC) procedure has been developed for the determination of four pharmaceutical preparations (famotidine, ranitidine, cimetidine, and metformin) after precolumn derivatization with methylglyoxal (MGo). GC was carried out using an HP-5 column (30 m × 0.32 mm id) at an initial column temperature of 90 °C for 2 min, followed by heating rate of 25 °C min−1 up to 265 °C. Nitrogen flow rate was 2.5 mL min−1 with split ratio 10:1. A linear calibration curve was obtained within 50–1,000 ng mL−1 and the limit of detection (LOD) was within 17–25 ng mL−1. The derivatization, GC elution, and separation were repeatable in terms of retention time and peak height/peak area with relative standard deviation within ±4.6 %. The procedure was applied to the determination of the drugs in pharmaceutical preparations and the sera of volunteers who were given oral doses of the drugs. The results of the analysis agreed with the labeled values of the pharmaceutical preparations and were 147–4,903 ng mL−1 in serum with an RSD within 1.0–4.2 %, after ingestion of a single dose of 40–500 mg of active ingredient in a tablet.
相似文献Citalopram, a selective serotonin reuptake inhibitor, is used as an antidepressant agent. In this study an on-line solid phase extraction method with spectrofluorometric detection was developed. Solid phase extraction cartridges contain 200 mg C18 with a particle size of 45 μm. The best solvent system found was consistend of ethanol and 0.1 M acetic acid (40:60, v/v) for elution. The optimized values of injection volume and flow rate were 1 mL and 2.5 mL min−1. The excitation and emission wavelengths were 240 and 300 nm. The calibrations were linear in the concentration range of 1.0 × 10−7–1.5 × 10−6 M in aqueous solution and 2.5 × 10−7–1.2 × 10−6 M in serum. The limit of detection values were 1.6 × 10−8 M for citalopram in tablets and 1.7 × 10−8 M in serum samples. The limit of quantification values were 5.2 × 10−8 M for citalopram in tablets and 5.5 × 10−8 M in serum. The proposed method has been applied successfully for the determination of citalopram HBr in pharmaceutical tablets and also in spiked human serum. The recovery values of the method were 99.5–100.6% for tablets and 98.8–100.9% for serum.
相似文献A newly-developed method of complete separation and sensitive determination of o-, m-, and p-aminobenzoic acid isomers was achieved by combining open-tubular columns for capillary electrochromatography (OT-CEC) and online sample stacking. In this study, spherical gold nanoparticles were modified by a covalent attachment of mono-6-thio-β-cyclodextrin, and OT-CEC was formed by immobilizing cyclodextrin-modified gold nanoparticles (CD-AuNP) on prederivatized 3-mercaptopropyl-trimethoxysilane fused-silica capillaries. Based on the theory of moving chemical reaction boundary, effects of several important factors such as the pH and concentration of running buffer and the conditions of stacking analytes were optimized. The optimized separations were carried out in 58 mmol/L HAc buffer at pH 3.0 using a capillary coated with CD-AuNP, while the optimized concentration was carried out in 50 mmol/L disodium hydrogen phosphate (pH 9.5). The linear ranges for m-, p-, and o-aminobenzoic acid were from 5.0 × 10−4–0.1, 5.0 × 10−4–0.1 and 1.0 × 10−4–0.1 mmol/L, respectively. And the detection limits (S/N = 3) were as low as 8.22 × 10−5, 8.21 × 10−5, and 3.76 × 10−5 mmol/L for m-, p-, and o-aminobenzoic acid, respectively. The run-to-run, day-to-day, and column-to-column reproducibilities of migration time were satisfactory with relative standard deviation values of less than 4.5 % in all cases. This method was successfully used in determining procaine hydrochloride injection sample with recoveries in the range of 96.1–106.6 % and relative standard deviations less than 5.0 %.
相似文献Proteinuria, i.e. increased excretion of proteins in urine, is a common sign indicating renal or urinary tract diseases. In this study, a fast and simple procedure for urine sample preparation and capillary micellar electrokinetic chromatographic analysis is presented, without any sample pretreatment prior to the analysis. The developed MEKC method was employed for simultaneous determination of albumin (ALB), haemoglobin (HGB), and myoglobin (MYO) in human urine samples obtained from patients with diagnosed proteinuria. Optimum conditions for detection and separation of ALB, HGB, and MYO are 50 mmol L−1 borate buffer containing 20 mmol L−1 SDS (pH 9.3), injection 40 mbar × 20 s, voltage 25 kV, temperature 30 °C, and detection wavelength 200 nm. The method was shown to be specific, accurate, linear (correlation coefficients r 2 > 0.99), and precise (RSD below 3.75 and 7.23% for migration time and peak area, respectively). Multi-variable-at-a-time (MVAT) approach for robustness testing shows no significant variations in accuracy, specificity, and precision as RSD values were lower than 5 and 10% for migration time and peak area, respectively. The presented method is applicable for routine analyses of urine samples as a screening method for patients with excess ALB, HGB, and MYO.
相似文献A precise and sensitive LC method for determination of enantiomeric purity of trelagliptin has been developed and validated. Pre-column derivatization was performed before separation. Baseline separation with a resolution factor >2.5 was accomplished within 10 min by use of a Chiralpak AD column (250 × 4.6 mm; particle size 5 µm) and n-hexane–2-propanol (90:10 v/v) as mobile phase at a flow rate of 1 mL min−1. Eluted analytes were monitored by UV detection at 260 nm. The effects of mobile phase composition and temperature on enantiomeric selectivity and on resolution of enantiomers were thoroughly investigated. Calibration curves were plotted within the concentration range 0.005–2 mg mL−1 (n = 12), and recoveries between 98.23 and 101.34 % were obtained, with relative standard deviation (RSD) <1.39 %. LOD and LOQ for the trelagliptin derivative were 1.51 and 5.03 µg mL−1; those for its enantiomer were 1.49 and 4.94 µg mL−1, respectively. The method was evaluated and validated by analysis of bulk samples of trelagliptin of different enantiomeric purity. It was demonstrated that the method was accurate, robust, and sensitive, and enabled practical analysis of real samples.
相似文献A validated capillary zone electrophoretic method for analysis of sotalol is described. Analysis was performed in a fused-silica capillary with 20 mM phosphate buffer (pH 4.20) containing 10% (v/v) acetonitrile as background electrolyte. The applied potential was +20 kV, the injection time 0.08 min, signal detection was at 200 nm, and 3,4-dihydoxybenzylamine was used as internal standard. The method was validated over the concentration range 1.98 × 10−5 to 9.90 × 10−5 M; repeatability was good and there was no interference. Highly satisfactory results were obtained from analysis of tablets and serum, indicating the method is specific, accurate, and precise, and suitable for routine analysis of sotalol in pharmaceutical tablets and in pharmacokinetic studies.
相似文献A simple and mild method for the determination of fatty acids (C1 – C10) based on a condensation reaction using 7-aminonaphthalene-1,3-disulfonic acid (ANDSA) as labeling reagent with capillary zone electrophoresis has been developed. The detection was performed with a diode array detector at 254 nm. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 30 mmol L−1 borate buffer (pH 9.5), 15 mmol L−1 β-CD, temperature at 20 °C, pressure 50 mbar and injection time 8 s. Under the established conditions, 10 fatty acid derivatives could be well-separated within 17 min. The linearity was in the range of 0.07–5.0 μmol L−1. Detection limits (at a signal-to-noise ratio of 3) were in the range of 0.027–0.042 μmol L−1. The fatty acids from the extracted Funaria Hedw. and Selaginella samples were determined with satisfactory results.
相似文献The purpose of the present work is to develop a simple, rapid, sensitive and accurate method for the derivatization and subsequently preconcentration of Hg(II) and the determination of its derivative, diphenylmercury, in natural water samples using gas chromatography-flame ionization detection. The method is based on the diphenylation using phenyl boronic acid, subsequent extraction of phenylmercury into a single drop of an organic solvent (toluene), followed by gas chromatography-flame ionization detection GC-FID analysis of the extract. The pH of the feed solution was kept in pH 5 with acetate buffer solution. Thus, the optimized conditions are: organic solvent, toluene; derivatization time, 10 min; extraction time, 15 min; microdrop volume, 1.6 μL; stirring rate, 600 rpm; sample volume, 5 mL. The limit of detection (LOD), calculated on the basis of five replicates was 0.02 μg mL−1. The relative standard deviation of the method (RSD%, n = 5) was 3.0. Linear range was between 0.05 and 5 μg mL−1 and preconcentration factor obtained for phenyl-mercury was 105.
相似文献A reversed-phase liquid chromatography (RP-LC) method was validated for the determination of rupatadine in pharmaceutical dosage forms. The LC method was carried out on a Gemini C18 column (150 mm × 4.6 mm I.D.), maintained at 30 °C. The mobile phase consisted of ammonium acetate buffer (pH 3.0; 0.01 M) with 0.05% of 1-heptanesulfonic acid–acetonitrile (71.5:28.5, v/v), run at a flow rate of 1.0 mL min−1 and using photodiode array (PDA) detection at 242 nm. The chromatographic separation was obtained with retention time of 5.15 min, and was linear in the range of 0.5–400 μg mL−1 (r 2 = 0.9999). The specificity and stability-indicating capability of the method was proven through the degradation studies and showing also, that there was no interference of the excipients. The accuracy was 100.39% with bias lower than 0.58%. The limits of detection and quantitation were 0.01 and 0.5 μg mL−1, respectively. Moreover, method validation demonstrated acceptable results for precision, sensitivity and robustness. The proposed method was applied for the analysis of pharmaceutical dosage forms assuring the therapeutic efficacy.
相似文献A simple, stability-indicating, reversed-phase liquid chromatographic method was developed for the determination of lacidipine in the presence of its degradation products. The analysis was carried out using a 150 mm × 4.6 mm i.d., 5 μm particle size Nucleodur MN-C18 column. Mobile phase containing a mixture of acetonitrile and 0.02 M phosphate buffer (70:30) at pH = 5.0 was pumped at a flow rate of 1 mL min−1 with UV-detection at 254 nm. The method showed good linearity in the range of 0.06–15 μg mL−1 with a limit of detection (S/N = 3) of 0.016 μg mL−1 (3.5 × 10−8 M). The suggested method was successfully applied for the analysis of lacidipine in bulk and in commercial tablets with average recoveries of 100.19 ± 0.81% and 100.05 ± 0.69%, respectively. The results were favorably compared to those obtained by a reference method. The suggested method was utilized to investigate the kinetics of alkaline, acidic, peroxide and photo-induced degradation of the drug. The apparent first-order rate constant, half-life times and activation energies of the degradation process were calculated. The pH profile curve was derived. The proposed method was successfully applied to the content uniformity testing of tablets.
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