A new method for the determination of arecoline in Semen Arecae decoction pieces by microchip capillary electrophoresis with contactless conductivity detection (MCE-CCD) was proposed. The effects of various electrophoretic operating parameters on the analysis of arecoline were studied. Under the optimal conditions, arecoline was rapidly separated and detected in 1min with good linearity over the concentration range of 20–1500μM (r2=0.9991) and the detection limit of 5μM (S/N=3). The method was used for the analysis of arecoline satisfactorily with a recovery of 96.8–104%.
In this paper, the feasibility and advantages of employing high performance liquid chromatographic (HPLC) fingerprints combined with pattern recognition techniques for quality control of Shenmai injection were investigated and demonstrated. The Similarity Evaluation System was employed to evaluate the similarities of samples of Shenmai injection, and the HPLC generated chromatographic data were analyzed using hierarchical clustering analysis (HCA) and soft independent modeling of class analogy (SIMCA). Consistent results were obtained to show that the authentic samples and the blended samples were successfully classified by SIMCA, which could be applied to accurate discrimination and quality control of Shenmai injection. Furthermore, samples could also be grouped in accordance with manufacturers. Our results revealed that the developed method has potential perspective for the original discrimination and quality control of Shenmai injection.
This paper describes a new approach for the determination of amitriptyline in wastewater by ionic liquid based immersed droplet microextraction (IL-IDME) prior to high-performance liquid chromatography with ultraviolet detection. 1-Hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) was used as an ionic liquid. Various factors that affect extraction, such as volume of ionic liquid, stirring rate, extraction time, pH of the aqueous solution and salting effect, were optimized. The optimal conditions were as follows: microextraction time, 10min; stirring rate, 720rpm; pH, 11; ionic drop volume, 100μL; and no sodium chloride addition. In quantitative experiments the method showed linearity in a range from 0.01 to 10μg/mL, a limit of detection of 0.004μg/mL and an excellent pre-concentration factor (PF) of 1100. Finally, the method was successfully applied to the determination of amitriptyline in the hospital wastewater samples.
Vidangadi churna is a popular Ayurvedic formulation described in the chapter Krimicikitsa of the Ayurvedic literature Cakradatta for the treatment of Krimiroga. The preparation is a composite mixture of the fine powder of fruits of Vidang (Embelia ribs), glandular trichomes of the fruits of Kamala (Mallotus philippensis), mature fruits of Harde (Terminalia chebula), Saindhava and Yavakshara. The use of reversed phase C18 column eluted with gradient mobile phase of acetonitrile and water enabled the efficient separation of the chemical markers in 22min. Validation of the method was performed in order to demonstrate its selectivity, accuracy, precision, repeatability and recovery. All calibration curves showed good linear correlation coefficients (r2>0.995) within the tested ranges. Three markers in Vidangadi churna were quantified with respect to Embelin (0.647%, w/w), Rottlerin (4.419%, w/w), and Ellagic acid (0.459%, w/w). Intra-and inter-day RSDs of retention times and peak areas were less than 3.12%. The recoveries were between 99.66% and 102.33%. In conclusion, a method has been developed for the simultaneous quantification of three markers in Vidangadi churna. The RP-HPLC method was simple, precise and accurate and can be used for the quality control of the raw materials as well as formulations.
The most suitable bio-analytical method based on liquid-liquid extraction has been developed and validated for quantification of Rasagiline in human plasma. Rasagiline-13C3 mesylate was used as an internal standard for Rasagiline. Zorbax Eclipse Plus C18 (2.1 mm×50 mm, 3.5 μm) column provided chromatographic separation of analyte followed by detection with mass spectrometry. The method involved simple isocratic chromatographic condition and mass spectrometric detection in the positive ionization mode using an API-4000 system. The total run time was 3.0 min. The proposed method has been validated with the linear range of 5-12000 pg/mL for Rasagiline. The intra-run and inter-run precision values were within 1.3%-2.9% and 1.6%-2.2% respectively for Rasagiline. The overall recovery for Rasagiline and Rasagiline-13C3 mesylate analog was 96.9% and 96.7% respectively. This validated method was successfully applied to the bioequivalence and pharmacokinetic study of human volunteers under fasting condition.
Simple and sensitive normal and reverse flow injection methods for spectrophotometric determination of thiamine hydrochloride (THC) at the microgram level were proposed and optimized. Both methods are based on the reaction between THC and diazotized metoclopramide in alkaline medium. Beer’s law was obeyed over the range of 10–300 and 2–90μg/mL, the limits of detection were 2.118 and 0.839μg/mL and the sampling rates were 80 and 95 injections per hour for normal and reverse flow injection methods respectively. The application of both methods to commercially available pharmaceuticals produced acceptable results. The flow system is suitable for application in quality control processes.
A simple and sensitive kinetic spectrophotometric method has been developed and validated for determination of amlodipine besylate (AML). The method was based on the condensation reaction of AML with 7-chloro-4-nitro-2,1,3-benzoxadiazole in an alkaline buffer (pH 8.6) producing a highly colored product. The color development was monitored spectrophometrically at the maximum absorption λmax 470nm. The factors affecting the reaction were studied and the conditions were optimized. The stoichiometry of the reaction was determined, and the reaction pathway was postulated. Moreover, both the activation energy and the specific rate constant (at 70°C) of the reaction were found to be 6.74kcalmole−1 and 3.58s−1, respectively. The initial rate and fixed time methods were utilized for constructing the calibration graphs for the determination of AML concentration. Under the optimum reaction conditions, the limits of detection and quantification were 0.35 and 1.05μg/mL, respectively. The precision of the method was satisfactory; the relative standard deviations were 0.85–1.76%. The proposed method was successfully applied to the analysis of AML in its pure form and tablets with good accuracy; the recovery percentages ranged from 99.55±1.69% to 100.65±1.48%. The results were compared with that of the reported method.
A simple, sensitive and accurate method based on high performance liquid chromatography (HPLC) with diode array detector (DAD) was developed and validated for systematic quality evaluation of one type of traditional Chinese medicine preparations named Xinkeshu (XKS) tablet. In this study, the chromatographic fingerprints of XKS tablet were developed first, 23 peaks were selected as the common peaks to evaluate the similarities among different batches of XKS samples, which were manufactured in a long time span of three years. Additionally, simultaneous quantification of six markers in XKS tablet, including Danshensu, Protocatechuic aldehyde, Puerarin, Daidzin, Salvianolic acid B and Daidzein, was performed. The validation results showed that the developed method was specific, accurate, precise and robust. The preliminary explanation on why a close similarity between fingerprints did not exactly mean similar contents of chemical components in samples was given. The contribution of each chromatographic peak to similarity was also evaluated. The developed method offers an efficient, reliable and practical approach for systematic quality evaluation of XKS tablet.
In the eradication therapy of Helicobacter pylori changes of antibiotics as these concentrations or amount in the stomach after oral administration were not clear. A simple and accurate method for determining the concentration of metronidazole (MTZ) in homogenate of rat stomach was developed in order to obtain basic data to design a pharmaceutical preparation having targeting ability to the surface of gastric-mucosa. This method included a deproteinization process by methanol, separation with reversed-phase high-performance liquid chromatography, and detection with an ultraviolet wavelength of 370nm. Regression analysis showed that the method was linear over a standard curve range from 5μg/mL to 2000μg/mL. The inter-day precision and accuracy values between the ranges were 5.0% or better and −7.5 to 5.2%, respectively. The newly developed method was applied to an analysis of gastric samples after oral administration of MTZ at a dose of 5mg/kg. It was found that the residual MTZ in the stomach was determined within 5h after dosing. This method is useful for monitoring MTZ in stomach after its oral administration to rats.
In order to prepare a high capacity packing material for solid-phase extraction with specific recognition ability of trace ractopamine in biological samples, uniformly-sized, molecularly imprinted polymers (MIPs) were prepared by a multi-step swelling and polymerization method using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and toluene as a porogen respectively. Scanning electron microscope and specific surface area were employed to identify the characteristics of MIPs. Ultraviolet spectroscopy, Fourier transform infrared spectroscopy, Scatchard analysis and kinetic study were performed to interpret the specific recognition ability and the binding process of MIPs. The results showed that, compared with other reports, MIPs synthetized in this study showed high adsorption capacity besides specific recognition ability. The adsorption capacity of MIPs was 0.063 mmol/g at 1 mmol/L ractopamine concentration with the distribution coefficient 1.70. The resulting MIPs could be used as solid-phase extraction materials for separation and enrichment of trace ractopamine in biological samples.
Simvastatin (SIM) is a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor widely used in hyperlipidemia therapy. SIM has recently been studied for its anticancer activity at doses higher than those used for the hyperlipidemia therapy. This prompted us to study the pharmacokinetics of high-dose SIM in cancer patients. For this purpose, an LC–MS/MS method was developed to measure SIM and its acid form (SIMA) in plasma and peripheral blood mononuclear cells (PBMCs) obtained from patients. Chromatographic analyte separation was carried out on a reverse-phase column using 75:25 (% v/v) acetonitrile:ammonium acetate (0.1M, pH 5.0) mobile phase. Detection was performed on a triple quadrupole mass spectrometer, equipped with a turbo ion spray source and operated in positive ionization mode. The assay was linear over a range 2.5–500ng/mL for SIM and 5–500ng/mL for SIMA in plasma and 2.5–250ng/mL for SIM and 5–250ng/mL for SIMA in cell lysate. Recovery was >58% for SIM and >75% for SIMA in both plasma and cell lysate. SIM and SIMA were stable in plasma, cell lysate and the reconstitution solution. This method was successfully applied for the determination of SIM and SIMA in plasma and PBMCs samples collected in the pharmacokinetic study of high-dose SIM in cancer patients.
A simple, specific, precise, sensitive and rapid reverse phase-HPLC method was developed for determination of ketorolac enantiomers, a potent nonnarcotic analgesic in pharmaceutical formulations. The method was developed on a chiral AGP column. Mobile phase was 0.1M sodium phosphate buffer (pH 4.5): Isopropanol (98:2, v/v), at a flow rate of 1mL/min with run time of 15min. Ultraviolet detection was made at 322nm. The linearity range was 0.02–10μg/mL for each of the enantiomers. The mobile phase composition was systematically studied to find the optimum chromatographic conditions. Validation of the method under the conditions selected showed that it was selective and precise and that the detector response was linear function of ketorolac.
A rapid and simple high performance liquid chromatography(HPLC) method with a UV detection(241 nm) was developed and validated for estimation of eplerenone from spiked human plasma.The analyte and the internal standard(valdecoxib) were extracted with a mixture of dichloromethane and diethyl ether.The chromatographic separation was performed on a HiQSil C-18HS column(250 mm 4.6 mm,5 μm) with a mobile phase consisting of acetonitrile:water(50:50,v/v) at flow rate of 1 mL/min.The calibration curve was linear in the range 100-3200 ng/mL and the heteroscedasticity was minimized by using weighted least squares regression with weighting factor 1/X.
The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effects and affect the determination of dissolution rate assaying. In this study, the technique of differential spectra was employed, which made it possible to monitor the dissolution testing in situ. The results showed that the hydrolyzation of aspirin made the percentage of salicylic acid exceed the limit of free salicylic acid (4.0), and the hydrolyzation may affect the quality detection of aspirin delayed-release tablets.
An isocratic stability indicating RP-HPLC–UV method is presented for the determination of metaxalone (MET) in the presence of its degradation products. The method uses Dr. Maisch C18 column (250mm×4.6mm, 5μm) with mobile phase consisting of acetonitrile–potassium dihydrogen orthophosphate buffer with 4mL of 0.4% triethyl amine (pH 3.0; 10mM) (58:42, v/v) at a flow rate of 1.0mL/min. pH of the buffer was adjusted with o-phosphoric acid. UV detection was performed at 225nm. The method was validated for specificity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness. The calibration plot was linear over the concentration range of 1–100μg/mL having a correlation coefficient (r2) of 0.999. Limits of detection and quantification were 0.3 and 1μg/mL, respectively. Intra-day and inter-day precision (% RSD) was 0.65 and 0.79 respectively. The proposed method was used to investigate the degradation kinetics of MET under different stress conditions employed. Degradation of MET followed a pseudo-first-order kinetics, and rate constant (K), time left for 50% potency (t1/2), and time left for 90% potency (t90) were calculated.
A new simple spectrophotometric method was developed for the simultaneous determination of drugs with interfering spectra in binary mixtures without previous separation. The new method is based on a simple modification for the ratio subtraction method. This modification enabled wider range of application. The proposed ratio difference method was applied for the determination of brimonidine and timolol in laboratory prepared mixtures with mean percentage recoveries 100.40±2.29 and 101.23±1.30 respectively, and in their pharmaceutical formulation with mean percentage recoveries 101.08±0.44 and 100.66±0.52 respectively. The suggested ratio difference method was validated according to USP guidelines and can be applied for routine quality control testing.
Liquid chromatography (LC) is considered by many as a mature technique. Nonetheless, LC technology continues to evolve driven by the need for high-throughput and high-resolution analyses. Over the past several years, small particle size packing materials have been introduced by several column manufacturers to enable fast and efficient LC separations. Several examples of pharmaceutical analyses, including impurity profiling of taxanes and atracurium besylate, in-process testing of peptides in injectable dosage form, using sub-2μm column technology are presented in this paper, demonstrating some of the capabilities and limitations of the technology.
Granisetron showed one well-defined reduction peak at Hanging Mercury Drop Electrode (HMDE) in the potential range from -1.3 to -1.5 V due to reduction of C=N bond. Solid-phase extraction technique was employed for extraction of Granisetron from spiked human plasma. Granisetron showed peak current enhancement of 4.45% at square-wave voltammetry and 5.33% at cyclic voltammetry as compared with the non stripping techniques. The proposed voltammetric method allowed quantification of Granisetron in pharmaceutical formulation over the target concentration range of 50-200 ng/mL with detection limit 13.63 ng/mL, whereas in human plasma 50-225 ng/mL with detection limit 11.75 ng/mL.
A novel method for the simultaneous high-performance liquid chromatographic determination of nortriptyline hydrochloride and fluphenazine hydrochloride was developed and validated. Fluvastatin sodium was used as internal standard. The determination was performed on a Hypersil Gold C8 column (250 mm × 4.6 mm i.d., 5μm particle size) at 25°C; the mobile phase, consisting of a mixture of formic acid (0.1M, pH 2.16)-methanol (33:67, v/v), was delivered at a flow rate of 1.1mL/min and detector wavelength at 251nm. The retention time of nortriptyline, fluphenazine and fluvastatin was found to be 5.11, 8.05 and 11.38min, respectively. Linearity ranges were 5.0–1350.0 and 10.0–1350.0μg/mL with limit of detection values of 0.72 and 0.31μg/mL, for nortriptyline and fluphenazine, respectively. Results of assay and recovery studies were statistically evaluated for its accuracy and precision. Correlation coefficients (r2) of the regression equations were greater than 0.999 in all cases. According to the validation results, the proposed method was found to be specific, accurate, precise and could be applied to the simultaneous quantitative analysis of nortriptyline and fluphenazine.
A rapid, specific and economic UV spectrophotometric method has been developed using a solvent composed of water:methanol:acetonitrile （9:0.5:0.5） to determine the levofloxacin content in bulk and pharmaceutical dosage formulations. At a pre-determined λmax of 292 nm, it was proved linear in the range of 1.0-12.0 μg/mL, and exhibited good correlation coefficient （R2 0.9998） and excellent mean recovery （99.00-100.07%）. This method was successfully applied to the determination of levofloxacin content in five marketed brands from Bangladesh and the results were in good agreement with the label claims. The method was validated statistically and by recovery studies for linearity, precision, repeatability, and reproducibility. The obtained results proved that the method can be employed for the routine analysis of levofloxacin in bulks as well as in the commercial formulations.
