By employing an electrical micro-titration system, in which a capacitively coupled contactless conductivity detector(C4D) was used to monitor the reaction process in real time, herein a novel method for determining ciprofloxacin hydrochloride(CIPHCl) was developed for the first time. Mode 1: Standard CIPHCl solutions at different concentrations were loaded into reaction cells, respectively, and were titrated with standard Ag+. Upon the titration, the formation of a precipitate alters the number of ions in the solution, raising the change of conductivity, which was monitored by a special C~4 D to construct a titration curve. The endpoint of the titration was located from the peak of the curve. Between the elapsed time and the initial concentration of titrand, a linear relationship was established over the range of2.0–8.0 mmol/L. Mode 2: Standard Fe~(3+) took the place of Ag~+, and was used as titrant to recognize ciprofloxacin contributed to the formation of complexation, which also resulting a change of solution conductivity. Under optimized conditions, a working range of 1.0–5.0 mmol/L CIPHCl was found. Because the reaction solutions were isolated from the working electrodes, this pioneer work shows significant simplicity and cost-effectiveness, by eliminating the requirements for detector exchange/renewal between different measurements, and by involving no auxiliary chemicals. Both of the two approaches were applied successfully to determine CIPHCl in tablet samples. And the results were in good agreement with those obtained by reference method. 相似文献
By employing a developed automatic eight-channel electrical titrator, ciprofloxacin, clomipramine and fexofenadine hydrochlorides are determined in batch, respectively, with satisfactory accuracy and precision. It shows a higher efficiency superior to traditional titration method, and maximally 30 measurements per minute can be completed. 相似文献
Enrofloxacin (ENR) and its metabolite ciprofloxacin (CIP) were determined by capillary zone electrophoresis (CZE) with end-column amperometric detection. The effect of several factors, such as pH and concentration of running buffer solution, separation voltage, injection time, and working potential, on CZE were investigated to establish the optimal conditions of separation and detection. Under a given set of conditions (pH 8.00 phosphate buffer solution (20 mmol/L); +0.95 V for the working potential; 18 kV for the separation voltage; sample injection at 18 kV for 10 s), the compounds investigated can be well separated and detected within 8 min. Excellent linearity was observed between peak currents and concentration of analytes in the range from 0.034 to 70.0 mg/kg for these two compounds. The detection limits (S/N= 3) for enrofloxacin and ciprofloxacin were 13.68 mg/kg and 14.35 mg/kg, respectively, which were about 7-fold lower than the maximum residue limits (MRLs) established by the European Union. A simple sample pretreatment method was developed and proved to be effective in obtaining good recoveries and short analysis time. The developed CE-AD method was simpler, faster, and less cost intensive than other reported methods, and allows the determination of ENR and its metabolite CIP in contaminated eel liver samples and other animal tissue samples at the required maximum residue limits. 相似文献
The aim of this work was to develop and validate a simple and sensitive analytical method for determining enrofloxacin (EFX) and ciprofloxacin (CFX) in equine plasma and endometrial tissue samples, as a precursor to conducting pharmacokinetic/pharmacodynamic studies on equine endometritis This was achieved in the form of a liquid chromatographic procedure, with fluorometric detection, which also gave good separation of other fluoroquinolones including marbofloxacin (MFX), danofloxacin (DFX) and ofloxacin (OFX). Analytes were separated on a C18 reversed phase column using an acidified mobile phase. The exact composition of the mobile phase differed for plasma (16% acetonitrile:methanol [13:1,v/v] 84% water containing 0.4% triethylamine and 0.4% phosphoric acid [35%]) and endometrial tissue (14% acetonitrile, 86% water, without methanol) samples. EFX and CFX were both detected at excitation and emission wavelengths of 294 and 500 nm, respectively. Prior to chromatography, EFX and CFX were purified by solid phase extraction from plasma, and a combination of solvent/solid phase extraction from endometrial tissue.
Mean absolute recoveries for EFX and CFX from plasma were 94.1 and 78.0%, respectively, and from endometrial tissue, 78.0 and 57.8%, respectively, with a percentage residual standard deviation (%R.S.D.) <10% in each case. Mean relative recoveries for EFX and CFX from plasma were 91.3 and 119.4%, respectively, and from endometrial tissue, 80.2 and 108.0%, respectively, with a %R.S.D. <20% in each case.
Standard curves constructed using blank plasma and endometrial tissue samples, spiked with authentic EFX and CFX in the ranges 0.005–10.0 μg mL−1 and 0.05–10.0 μg g−1, respectively, all showed acceptable linearity with correlation coefficients, r2 ≥ 0.977. Mean intra- and inter-day precision (expressed as %R.S.D.) was <6 and <13%, respectively, with an associated accuracy (expressed as percentage relative error, %R.E.) of <20% for both analytes in both matrices. Acceptable precision and accuracy was also demonstrated at the pre-assigned LOQs of 0.005 μg mL−1 for both EFX and CFX in plasma, and 0.05 μg g−1 for both drugs in endometrial tissue. EFX and CFX were stable in both plasma and endometrial tissue for at least 60 days at −20 °C. 相似文献
A simple and sensitive reversed-phase liquid chromatography method was developed and validated for the determination of nicardipine hydrochloride (NC) in rabbit plasma. Nicardipine hydrochloride and nimodipine, used as internal standard, were initially extracted from plasma by a rapid solid-phase extraction using C(18) cartridges. After extraction, nicardipine hydrochloride was separated by HPLC on a C(18) column and quantified by ultraviolet detection at 254 nm. A mixture of acetonitrile-0.02 M sodium phosphate buffer-methanol (45:40:15) with 0.2% of triethylamine of pH of 6.1 was used as mobile phase. The mean (+/-SD) extraction efficiency of NC was 77.56 +/- 5.4, 84.23 +/- 4.32 and 83.94 +/- 3.87% for drug concentrations of 5, 25 and 100 ng/mL, respectively. The method proved to be linear in the range of 5-100 ng/mL with a regression coefficient of 0.9993. The relative standard deviations of intra- and inter-day analysis for NC in plasma were 3.26-6.52% (n = 5) and 4.71-9.38% (n = 5), respectively. The differences of the mean value measured from the concentration prepared, expressed in percentages (bias percentage), were only - 5.2, 0.4 and 0.8% at NC 5, 25 and 50 ng/mL, which confirmed the accuracy of the method. The analytical technique was used to determine NC plasma concentration after drug oral administration to rabbits. The results inferred that NC is rapidly absorbed in rabbits and has a short half-life (t(1/2) = 1.34 h). 相似文献