Determination of diastereoisomeric alkaloids in urine by capillary electrophoresis with electrochemiluminescence detection

A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomenc alkaloids（ephedrine and pseudoephedrine）.The limits of detection（S/N = 3） were 4.5×10^-8 mol/L for ephedrine and 5.2×10^-8 mol/L for pseudoephedrine,respectively.The RSDs of migration time and peak area were less than 1.3 and 2.5%（n = 5）,respectively.The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine,ephedrine in nasal drops,and the monitoring of pharmacokinetics for pseudoephedrine.     

Development and validation of a novel stability indicating RP-HPLC method for the quantitative determination of marbofloxacin in its tablets

A fast, feasible, isocratic, stability indicating reverse phase-high performance liquid chromatography (RP-HPLC) method has been developed and validated for the quantitative determination of marbofloxacin in marbofloxacin tablets. The method was developed using Zorbax SB C18 (150?mm?×?4.6?mm), 5-µm column thermostated at 30°C, mobile phase A (1?mL of trifluoroacetic acid in 1000?mL of water), mobile phase B (acetonitrile) in the ratio of 83:17?v/v at flow rate of 1.0?mL/min, and an injection volume of 10?µL. The analyte was monitored at a wavelength of 298?nm. The method was validated in accordance with the Food and Drug Administration (FDA) Veterinary International Conference on Harmonization guidelines. To demonstrate stability indicating ability of method, drug product was subjected to the stress condition of acidic, basic, humidity, thermal, oxidative, and photolytic degradation.     

Solid contact PVC membrane electrodes based on neutral or charged carriers for the selective reading of anionic sulfamethoxazole and their application to the analysis of aquaculture water

Sulfamethoxazole (SMX) is among the antibiotics employed in aquaculture for prophylactic and therapeutic reasons. Environmental and food spread may be prevented by controlling its levels in several stages of fish farming. The present work proposes for this purpose new SMX selective electrodes for the potentiometric determination of this sulphonamide in water. The selective membranes were made of polyvinyl chloride (PVC) with tetraphenylporphyrin manganese (III) chloride or cyclodextrin-based acting as ionophores. 2-nitrophenyl octyl ether was employed as plasticizer and tetraoctylammonium, dimethyldioctadecylammonium bromide or potassium tetrakis (4-chlorophenyl) borate was used as anionic or cationic additive. The best analytical performance was reported for ISEs of tetraphenylporphyrin manganese (III) chloride with 50% mol of potassium tetrakis (4-chlorophenyl) borate compared to ionophore. Nersntian behaviour was observed from 4.0?×?10^?5 to 1.0?×?10^?2?mol/L (10.0 to 2500?µg/mL), and the limit of detection was 1.2?×?10^?5?mol/L (3.0?µg/mL). In general, the electrodes displayed steady potentials in the pH range of 6 to 9. Emf equilibrium was reached before 15?s in all concentration levels. The electrodes revealed good discriminating ability in environmental samples. The analytical application to contaminated waters showed recoveries from 96 to 106%.     

Determination of ephedrine and related compounds in pharmaceutical preparations by ion chromatography with direct conductivity detection

An ion chromatographic method with conductivity detection for the simultaneous determination of ephedrine, pseudoephedrine and norephedrine was developed. A mixture of 2.0 mmol/L HNO3 and 2% (v/v) acetonitrile was used as eluent. The three ephedrine-like compounds were separated and determined within 20 min. The linear ranges were 0.08-50 microg/mL for ephedrine, 0.08-40 microg/mL for pseudoephedrine and 0.06-40 microg/mL for norephedrine. The detection limits were 0.03 microg/mL for ephedrine and pseudoephedrine, and 0.02 microg/mL for norephedrine. The method has been applied successfully to the determination of these sympathomimetics in pharmaceutical preparations and in Ephedra herbs.     

An improved method of simultaneous determination of lutein and zeaxanthin in food

Based on an official standard method of lutein analysis, an improved high performance liquid chromatography (HPLC) method for simultaneously detecting lutein and zeaxanthin was developed as focusing on the sample preparation protocol. The optimal pretreatment conditions included a saponification in a water bath for 15?min at a constant temperature of 50?°C, using a 10?mL 60% (w/v) potassium hydroxide solution, followed by extraction using 100?mL mixture of n-hexane, ethyl ether and cyclohexane (40: 40: 20, v/v/v). A mixture of dichloromethane, acetonitrile and methanol (20: 30: 50, v/v/v) was validated to elute lutein and zeaxanthin on a C₃₀ column (4.6?×?250?mm, 5?µm). The resolution between lutein and zeaxanthin is ≥2.5. A millet sample was used for methodological verification and the results showed that the linear relations for lutein and zeaxanthin were good in ranges of 0.23–9.37?μg/mL and 0.30–12.02?μg/mL, respectively. The relative standard deviations of lutein and zeaxanthin were 1.40% and 5.09%, respectively, and their spiked recoveries were between 86.60% and 98.75%. The lutein and zeaxanthin results from this modified HPLC method are superior to those from the Chinese official method and ultrasonic extraction method.     

A validated HPLC‐PDA method for identification and quantification of two bioactive alkaloids,ephedrine and cryptolepine,in different Sida species

A simple, rapid, accurate and reproducible reverse‐phase HPLC method has been developed for the identification and quantification of two alkaloids ephedrine and cryptolepine in different extracts of Sida species using photodiode array detection. Baseline separation of the two alkaloids was achieved on a Waters RP‐18 X‐terra column (250 × 4.6 mm, 5 µm) using a solvent system consisting of a mixture of water containing 0.1% Trifluoroacetic acid (TFA) and acetonitrile in a gradient elution mode with detection at 210 and 280 nm for ephedrine and cryptolepine, respectively. The calibration curves were linear in a concentration range of 10–250 µg/mL for both the alkaloids with correlation coefficient values >0.99. The limits of detection and quantification for ephedrine and cryptolepine were 5 and 10 µg/mL and 2.5 and 5 µg/mL, respectively. Relative standard deviation values for intra‐day and inter‐day precision were 1.22 and 1.04% for ephedrine and 1.71 and 2.06% for cryptolepine, respectively. Analytical recovery ranged from 92.46 to 103.95%. The developed HPLC method was applied to identify and quantify ephedrine and cryptolepine in different extracts of Sida species. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous determination of methotrexate and metoclopramide in physiological fluids using RP-HPLC with ultra-violet detection; application in evaluation of polymeric nanoparticles

Methotrexate (MTX) is an anticancer drug while metoclopramide (MCP) is an antiemetic agent. Both the drugs are commonly coprescribed to avoid the emesis caused by anticancer drug. In this study, a novel, rapid, sensitive, and cost-effective reverse-phase high-performance liquid chromatography method was developed and validated for simultaneous determination of the methotrexate and metoclopramide in biological and pharmaceutical samples using sparfloxacin as internal standard. The analytes were separated on a Kromasil 100-5C18 RP (250?×?4.6?mm, 5?µm) column, methanol, and 0.05% trifloroacetic acid (36:64?v/v) as mobile phase with a flow rate of 1?mL/min, detection wavelength of 290?nm, and column oven temperature at 40°C. Both the analytes were extracted from physiological fluids (bovine aqueous humor, vitreous humor, and human plasma) using mixture of methanol and 10% perchloric acid (50:50 v/v). The method was linear over the concentration range of 0.025–1.0?µg/mL for methotrexate and 0.030–1.0?µg/mL for metoclopramide. The % recovery from human plasma was 98.57 and 96.74% for MTX and MCP, respectively, while from aqueous humor and vitreous humor was 95.84 and 98.51% for MTX.

The developed method was applied for in vitro release of MTX from polymeric nanoparticles and can be applied for analysis of pharmaceutical and biological samples containing both the drugs.     

Determination of Albumin Using the Chemiluminescence of Tb3+/K2S2O8 System

A new chemiluminescence system of Tb³⁺/K₂S₂O₈ was developed for the determination of albumin. Some experimental conditions were examined and optimized. The linear ranges of the calibration curves are 5.0 × 10^?9–5.0 × 10^?6 mol/L for bovine serum albumin, 5.0 × 10^?8–1.0 × 10^?5 mol/L for human serum albumin and 2.5 × 10^?7–1.0 × 10^?5 mol/L for ovalbumin, and the corresponding detection limits are 1.9 × 10^?9 mol/L, 1.5 × 10^?8 mol/L, and 1.5 × 10^?7 mol/L, respectively. The method was applied to the determination of albumin in human serum samples, and the results were in agreement with those obtained by the bromcresol green method. The relative errors for the analytical results were from ?2.0% to 4.3%.     

Cloud-point extraction,preconcentration, and spectrophotometric determination of palladium in water samples

The possibility of using Thio-Michler's Ketone (TMK), 4,4′-bis(dimethylamino) thiobenzophenone, for palladium(II) concentrated by micellar extraction at the cloud-point temperature, and later spectrophotometric determination, was investigated. Under the optimum conditions, preconcentration of 50?mL of water samples in the presence of 0.1% (w/v) octylphenoxy polyethoxy ethanol (Triton X-114), 2?×?10^?6?mol?L^?1?TMK and 1?×?10^–3?mol?L^?1 buffer solution (pH?=?3.0) gave the limit of detection of 0.47?ng?mL^?1, and the calibration graph was linear in the range of 2–50?ng?mL^–1. The recovery under optimum working conditions was higher than 97%. The proposed method has been applied to the spectrophotometric determination of palladium(II) in natural water samples after cloud-point extraction with satisfactory results.     

Determination of Cryptotanshinone,Tanshinone I,and Tanshinone IIA in Salvia Miltiorrhiza by Micro HPLC with Amperometric Detection

A highly sensitive and simple method for determining cryptotanshinone (Cry), tanshinone I (Tan I), and tanshinone IIA (Tan IIA) in Salvia miltiorrhiza was developed using micro HPLC with electrochemical detection (µHPLC-ED). The tanshinones were extracted using an ultrasonic method, with methanol as the extractant. The separation was carried out on a C18 (150 mm × 1.0 mm i.d., 3 µm particle size) analytical column. The mobile phase was acetonitrile-water-formic acid mixture (52:48:0.6, v/v/v) solution. The flow rate and the temperature of the column were set at 30 µL/min and 35°C. The applied potential was set at ?0.4 V vs. Ag/AgCl. The peak heights for Cry, Tan I, and Tan IIA were found to be linearly related to the amounts injected, ranging from 0.145 µmol/L to 3.88 µmol/L, 0.226 µmol/L to 3.01 µmol/L, and 0.149 µmol/L to 3.98 µmol/L, respectively. The RSD values of intra-day precision and repeatability were not more than 3.0%, and the recovery of three analytes were ranged from 96.7% to 97.5%. The results of the method validation indicated that this method had good precision and accuracy. As such, the method was applied to analyze crude materials and decoction pieces of Salvia miltiorrhiza.     

基于中空纤维液相微萃取的麻黄碱和伪麻黄碱优势构象的确定及含量测定

利用中空纤维液相微萃取方法(HF-LPME)分析麻黄碱和伪麻黄碱在不同基质中的优势构象,阐明了麻黄碱和伪麻黄碱的萃取机理;结合高效液相色谱(HPLC)建立了微量麻黄碱和伪麻黄碱的分离测定方法。以聚偏氟乙烯中空纤维为有机溶剂载体,正己醇为萃取溶剂,麻黄碱和伪麻黄碱的NaOH(5 mol/L)溶液为样品相,0.01 mol/L H2SO4溶液为接收相,在1200 r/min转速下萃取35 min,收集萃取液直接进行HPLC分析。麻黄碱和伪麻黄碱在水溶液中的线性范围为5～100 μg/L,检出限分别为1.9 μg/L和1.2 μg/L,富集倍数分别为38和61倍,平均回收率分别为100.6%±1.2%和103.2%±3.5%;在鼠尿液中的线性范围为100～5×104 μg/L,检出限分别为30 μg/L和42 μg/L,富集倍数分别为20和17倍,平均回收率分别为108.4%±4.4%和106.1%±5.4%。研究表明该方法操作简单,选择性高,适用于微量麻黄碱的含量测定和分析。     

Simple HPLC method for detection of trace ephedrine and pseudoephedrine in high-purity methamphetamine

A simple and sensitive HPLC technique was developed for the qualitative determination of ephedrine and pseudoephedrine (ephedrines), used as precursors of clandestine d‐methamphetamine hydrochloride of high purity. Good separation of ephedrines from bulk d‐methamphetamine was achieved, without any extraction or derivatization procedure on a CAPCELLPACK C₁₈ MGII (250 × 4.6 mm) column. The mobile phase consisted of 50 mM KH₂PO₄–acetonitrile (94:6 v/v %) using an isocratic pump system within 20 min for detecting two analytes. One run took about 50 min as it was necessary to wash out overloaded methamphetamine for column conditioning. The analytes were detected by UV absorbance measurement at 210 nm. A sample (20 mg) was simply dissolved in 1 mL of water, and a 50 μL aliquot of the solution was injected into the HPLC. The detection limits for ephedrine and pseudoephedrine in bulk d‐methamphetamine were as low as 3 ppm each. This analytical separation technique made it possible to detect ephedrine and/or pseudoephedrine in seven samples of high‐purity d‐methamphetamine hydrochloride seized in Japan. The presence of trace ephedrines in illicit methamphetamine may strongly indicate a synthetic route via ephedrine in methamphetamine profiling. This method is simple and sensitive, requiring only commonly available equipment, and should be useful for high‐purity methamphetamine profiling. Copyright © 2011 John Wiley & Sons, Ltd.     

高效液相色谱法同时测定双酚伪麻干混悬剂中的盐酸伪麻黄碱和氢溴酸右美沙芬

建立了可同时测定双酚伪麻干混悬剂中盐酸伪麻黄碱和氢溴酸右美沙芬含量的反相高效液相色谱方法。样品先经甲醇溶解,过滤,然后以Lichrospher C6H6化学键合硅胶为固定相、乙腈-水-H3PO4（体积比为50∶50∶0.1,pH 2.5,内含1 g/L十二烷基硫酸钠)为流动相进行色谱分离,在220 nm处定量测定。结果表明,氢溴酸右美沙芬、盐酸伪麻黄碱的质量浓度分别为1.03~206 mg/L和5~200 mg/L时,其峰面积与质量浓度的线性关系良好;批内(n=7)测定的平均相对标准偏差（RSD）分别为1.8%和1.0%,批间(n=5)测定的RSD分别为2.2%和1.5%;对双酚伪麻干混悬剂中氢溴酸右美沙芬、盐酸伪麻黄碱测定回收率分别为100.0%~101.8%和95.7%~98.7%。该法适用于双酚伪麻干混悬剂中氢溴酸右美沙芬和盐酸伪麻黄碱的质量控制及含量测定,方法准确,操作简便。     

Development and validation of UPLC method for simultaneous quantification of carvedilol and ivabradine in the presence of degradation products using DoE concept

A methodical design-of-experiments were performed by applying quality-by-design concepts to establish a design-space for simultaneous and rapid quantification of Carvedilol and Ivabradine by UPLC in the presence of degradation products. Response-surface, central-composite design, and quadratic model were employed for statistical assessment of experimental data using the Design-Expert software. Response variables such as resolution and retention time were analyzed statistically for chromatographic screening. During DoE study, various plots such as perturbation, contour, 3D and design-space plots were considered for method optimization. The method was developed using C8 [100?×?2.1?mm, 1.8?µ] UPLC column, mobile phase comprising 0.5% triethylamine buffer [pH 6.4] and acetonitrile in the ratio of 50:50 v/v, the flow rate of 0.4?mL minute^?1 and UV detection at 285?nm for both Carvedilol and Ivabradine. The method was developed with a short run time of two minutes. The method was found to be linear in the range of 25.0–199.9?µg?mL^?1 and 8.9–21.3?µg?mL^?1 for Carvedilol and Ivabradine, respectively with a correlation coefficient of 0.9998 in each case. The recovery values were found in the range of 99.7–100.8% and 98.9–100.9% for Carvedilol and Ivabradine, respectively. The method was validated according to ICH Q2 (R1) guidelines.     

Determination of aromatic amines in environmental water samples using solid-phase extraction modified with sodium dodecyl sulphate and micellar liquid chromatography

Extraction and determination of seven aromatic amines in environmental water samples were performed with solid-phase extraction (SPE) and micellar liquid chromatography (MLC) using experimental design. Extraction of aromatic amines was carried out with a C₁₈ cartridge modified with sodium dodecyl sulphate (SDS). The washing solution and elution solvent for extraction of aromatic amines were aqueous solution containing 5% (v/v) acetonitrile and 5% (v/v) acetone and 3 mL methanol, respectively. The chemometrics approach was applied for the separation optimisation of these compounds using MLC. Different mobile phase compositions were used for modelling based on retention times to obtain the best separation using central composite design. The optimum mobile phase composition for separation and determination of analytes in water samples was 69 mM SDS, 9% v/v 1-propanol and pH = 6.4. Recoveries were between 84.8–93.5% with relative standard deviation (RSD) less than 5.8% (n = 5). Limits of detection and linear range were 1–4.5 and 3.1–125.0 µg/L, respectively. The proposed method was applied to determine the aromatic amines in real samples (river and well waters). Amount of 4-nitroaniline and 3-nitroaniline in river water sample were 2.15 and 1.91 µg/L, respectively.     

Analytical Quality by Design (AQbD)-oriented RP-UFLC method for quantification of lansoprazole with superior method robustness

A reversed-phase ultrafast liquid chromatography method was developed for quantification of lansoprazole in pharmaceutical dosage form using analytical quality by design approach. Systematic planning and experimentation using design of experiment approach were used for method development and optimization studies. A central composite design was used for optimizing the chromatography, by choosing organic phase proportion and flow rate as the critical method variables for evaluating their effect on critical analytical attributes like resolution, plate number, and tailing factor. The optimal chromatography was accomplished on a C-18 column (250?×?4.6?mm, 5?µm) using methanol:water (70:30, v/v) as mobile phase at a flow rate of 1.0?mL/min. Photo diode array (PDA) detection was performed at 284?nm. Caffeine was used as the internal standard. Method validation studies revealed that the calibration curve was linear over 1.0–300?µg/mL. The method was found accurate with average recovery between 98.99 and 102.87%. The percent relative standard deviation values obtained for precision were as per ICH guideline and within the acceptance limits (<2%). Results of system suitability indicated superior method robustness. In a nutshell, the method was found to be highly suitable for its applicability in the determination of lansoprazole in bulk and tablet dosage form.     

Applying green analytical chemistry for development and validation of RP-HPLC stability indicating assay method for estimation of fenoverine in bulk and dosage form using quality by design approach

A green and robust reverse-phase liquid chromatographic method has been developed for the determination of fenoverine (FEN), by applying combined principles of green analytical chemistry and quality by design approaches on a Spherisorb C18 column (150?×?4.6?mm, 3?µm) with UV detection at 262?nm. A two level fractional factorial design (2^^7-3) Res IV was used for screening of influential chromatographic factors. The critical method parameters actively affecting critical quality attributes (CQAs) were identified and further optimized using Box–Behnken design. The predicted optimum assay conditions comprised of methanol and ammonium acetate buffer 20?mM, in an extent of 81:19% v/v individually having a flow rate of 1.0?mL/min with a column oven temperature of 33°C. The drug was stressed in hydrolytic, oxidative, reductive, thermal, and photolytic conditions. The developed method was validated successfully. The detector response was linear in the concentration of 0.5–160?µg/mL with a limit of detection (LOD) and limit of quantitation (LOQ) as 0.1 and 0.3?µg/mL, respectively. The % recovery was found to be 99.7%. The analytical method volume intensity value for developed method was 45?mL and the environment assessment tool (EAT) score was 41.07. The method is simple, environmentally benign, rapid, and robust for the determination of FEN in bulk and in its dosage form.     

Salen impregnated silica gel as a new sorbent for on-line preconcentration of cadmium(II)

A new sorbent – salen impregnated silica gel – was prepared and characterised for application as a minicolumn packing for flow-injection on-line preconcentration of cadmium(II). The system was coupled with flame atomic absorption spectrometer (FI-FAAS). The optimal pH for Cd(II) sorption was in the range of 7.4–8.8 and nitric acid (1%, v/v) was efficient as eluent. Sorption was most effective within the sample flow rate up to 7?mL?min^?1. Sorption capacity of the sorbent found in a batch procedure was 26.3?µmol?g^?1 (2.95?mg?g^?1). Enrichment factor (EF) and limit of detection (LOD) obtained for 120-second loading time were 113 and 0.26?µg?L^?1, respectively. The sorbent stability in the working conditions was proved for at least 100 preconcentration cycles. The evaluated method was applied to Cd(II) determination in various water samples.     

Determination of Antimony(III) by Differential Pulse Voltammetry Using a Gold Nanoparticle–Ionic Liquid–Graphene-Modified Selenium-Doped Carbon Paste Electrode

A simple and sensitive differential pulse stripping voltammetric method was developed for the determination of antimony(III) using a selenium-doped carbon paste electrode modified with an ionic liquid, graphene, and gold nanoparticles. The conditions, including the mass of graphene, concentration of hydrochloric acid, deposition potential, and deposition time were optimized by single-factor experiments. Under the optimal conditions, a linear equation of I_Sb(III) (µA)?=??16.9882???11.0929 c (µmol/L) (R?=?0.9965) and a detection limit of 2.7?×?10^?8?mol/L were obtained for 8.0?×?10^?8 to 4.8?×?10^?6?mol/L antimony(III). The response shows that the sensor enhances the sensitivity of antimony due to the high conductivity and large surface areas of the ionic liquid, graphene, and gold nanoparticles. This electrode may provide a new sensing platform for the determination of antimony.     

高效毛细管电泳分离/电导检测麻黄碱和伪麻黄碱

采用高效毛细管电泳电导检测法分离麻黄碱和伪麻黄碱，初步探讨了分离机理，建立了检测方法。以柠檬酸－柠檬酸钠为缓冲体系，铜盐为络合剂，在pH值为4．5、电压13.5kV的条件下，盐酸麻黄碱和伪麻黄碱得到了较好的分离，加入适量乙醇可改善峰形和分离效果。用该法以水杨酰胺为内标，对含盐酸麻黄碱和伪麻黄碱的实际样品进行检测，回收率为97.3%-101.1%，结果令人满意。