Poly(dimethylsiloxane) microchip capillary electrophoresis with electrochemical detection for rapid measurement of acetaminophen and its hydrolysate

Poly(dimethylsiloxane) microchip capillary electrophoresis with amperometric detection has been used for rapid separation and determination of acetaminophen and its hydrolysate, i.e. p-aminophenol. A Pt ultramicroelectrode with a diameter of 10 m positioned at the outlet of the separation channel was used as a working electrode for amperometric detection. Factors influencing separation and detection were investigated and optimized. Results show that acetaminophen and p-aminophenol can be well separated within 35 s with RSD<1% for migration time and <7% for detection current for both analytes. Detection limits for both analytes are estimated to be 5.0 mol L^–1 (approximately 0.1 fmol) at S/N=3. This method has been successfully applied to the detection of traces of p-aminophenol in paracetamol tablets.     

Indirect Determination of Sulfadiazine by Cloud Point Extraction/Flow Injection‐Flame Atomic Absorption (CPE/FI‐FAAS) Spectrometry

An indirect simple and rapid cloud point extraction is proposed for separation and preconcentration of sulfadiazine and its determination by flow injection‐flame atomic absorption spectroscopy (FI‐FAAS). The sulfadiazine from 35 mL of solution was readily converted to silver sulfadiazine upon addition of silver nitrate (9.7 × 10^‐5 mol/L). Then, Triton X‐114 a non ionic surfactant was added and the solution was heated to 60 °C. At this stage, two separate phases was formed and silver sulfadiazine enters the surfactant rich phase of non‐ionic micelles of Triton X‐114. The surfactant‐rich phase (～50 μL) was then separated and diluted to 300 μL with acidic methanol. The concentration of silver in the surfactant‐rich phase which is proportional to the concentration of sulfadiazine in sample solution was determined by FI‐FAAS. The parameters affecting extraction and separation were optimized. Under the optimum conditions (i.e. pH 2‐10, silver concentration (9.7 × 10 ^‐5 mol/L), Triton X‐114 (0.075% v/v) and temperature 60 °C) a preconcentration factor of 117 and a relative standard deviation of 4.9% at 37 μg L^‐1 of sulfadiazine was obtained. The method was successfully applied to analysis of milk, urine and tablet samples and accuracy was determined by recovery experiments.     

硫辛酸片含量与降解物的高效液相色谱测定研究

建立了硫辛酸片中硫辛酸及其降解物快速测定的高效液相色谱方法。采用Waters XBridge色谱柱(5μm,150 mm×4.6 mm),流动相为0.05 mol/L磷酸二氢钾溶液(磷酸调至pH 2.5)-乙腈-甲醇(50∶45∶5),流速为1.0 mL/min,进样量为20μL,二极管阵列检测器,检测波长为220 nm,全波长扫描范围为200～400 nm,柱温为室温。结果表明,在上述色谱条件下,硫辛酸浓度在0.4～20.0 mg/L范围内线性关系良好(r=0.999 9);其检出限为0.2 mg/L;定量下限为0.6 mg/L;精密度RSD(n=12)为3.4%;加标回收率为100.9%,RSD为2.0%。该法简便、快速、准确、选择性好、灵敏度高,可用于硫辛酸片含量与降解物的测定。     

高效液相色谱法测定葛根芩连片中的葛根素

建立高效液相色谱测定葛根芩连片中葛根素含量的方法。以体积分数50%的甲醇为提取液对样品超声提取20 min,采用DiamonsilTMC18(250 mm×4.6 mm,5μm)色谱柱,以甲醇–乙腈–水(体积比8∶12∶80)为流动相,流速为1.0 mL/min,检测波长为250 nm,柱温为30.0℃,进样量体积10μL。在最佳实验条件下,葛根素与其它物质能完全分离,葛根素的质量浓度在5.43~543.2μg/mL范围内与色谱峰面积呈良好的线性,线性相关系数r=0.999 9,方法检出限为3.50μg/mL(S/N=3)。方法加标回收率为100.0%,测定结果的相对标准偏差为1.6%(n=6)。该方法简单、快速、重现性好,适用于葛根芩连片中葛根素的测定。     

食品中碘的光谱电化学法测定

本文研究了用光谱电化学法测定食品中的碘，探讨了最佳的测定条件，用于海带，海带表层盐及模拟碘盐中碘的测定，结果满意，回收率高，抗干扰力强，操作快捷，方法简单易行。     

Gas-Liquid Chromatographic Determination of Pipemidic Acid

A gas chromatographic method was established for the quantitative analysis of pipemidic acid. The method is based on alkylation of pipemidic acid with diazomethane catalyzed by boron trifluoride. The sample was chromatographed on a stainless steel column packed with 5% OV-101 on Chromosorb G-HP and n-octacosane was used as an internal standard. Quantitation is achieved by measuring peak-height ratio. The method was satisfactorily applied to the analysis of pipemidic acid in tablet.     

Total monitoring of the constituents of Danshen tablet using micellar electrokinetic chromatography fingerprinting for antioxidant activity profiling

A micellar electrokinetic chromatography fingerprint coupled with quantification was developed for assessing the quality consistency of Danshen tablets, a traditional Chinese medicine, with pharmacological activities of activating blood to remove blood stasis and regulating the flow of vital energy to alleviate pain. Square optimization method was proposed to select the suitable background electrolyte. Subsequently, the index of chromatographic fingerprints F was simultaneously employed as an objective function to evaluate capillary electrophoresis conditions. After that, the method was proved to meet the fingerprint analysis criteria by evaluating stability, linearity, limit of detection, limit of quantification, precision, accuracy, and repeatability. Moreover, systematic quantified fingerprint method was used to evaluate chromatographic fingerprints of 30 batches of samples in terms of both quality and quantitation. The result indicated that the chemical compositions of samples were basically similar while their contents showed marked variation. In addition, the fingerprint–efficacy relationship was established using partial least squares model, which can serve as anti‐oxidant activity evaluation of Danshen tablets as well as a reference for the selection of active constituents. The proposed method can be applied for the holistic quality control of Danshen tablets.     

微流控芯片非接触电导法快速测定盐酸美金刚片中盐酸美金刚的含量

建立了微流控芯片非接触电导法快速测定盐酸美金刚片中盐酸美金刚含量的方法。探讨了缓冲溶液的种类、浓度、pH值、进样时间及分离电压等因素对分离检测的影响。优化得到缓冲体系为含2%(体积分数)二甲基亚砜(DMSO)的3.0 mmol/L三乙胺-2.0 mmol/L磷酸缓冲溶液(pH 3.3),进样时间为10 s,分离电压为2.0 kV。优化条件下,盐酸美金刚的线性范围为10～2 000μg/mL(r~2=0.999 1);检出限为7μg/mL,定量下限为10μg/mL;精密度、稳定性、重复性实验的相对标准偏差(RSD)均小于2.0%;平均加标回收率为96.5%～99.2%;盐酸美金刚的检测时间小于18 s。该方法快速简便,适用于盐酸美金刚片中盐酸美金刚含量的测定。     

Determination of Candesartan Cilexetil in Tablet Dosage Forms and Dissolution Testing Samples by First Derivative UV Spectrophotometric Method

Abstract

This article describes the development and validation of a first derivative UV quantitative analytical method for determination of candesartan cilexetil in tablet dosage forms. A signal at 270.1 nm of the first derivative spectrum (ID_270.1) was found adequate for quantification. The limit of quantification was 3.06 µg/ml. The linearity between ID_270.1 nm and concentration of candesartan cilexetil in the range of 6.00–32.00 µg/ml presented a correlation coefficient of (r²) = 0.9990. The mean recovery percentage was 100.97 and 99.23% for candesartan cilexetil standard solution and candesartan standard cilexetil solution with excipients, respectively. The intraday and interday accuracy of the assay was 98.60% and 99.10% respectively. The intraday and interday variability was below 2.0%.

The proposed method is accurate, precise, sensitive, and selective and can be used in quality control laboratories for its intended purpose.