Polymeric monolith column composited with multiwalled carbon nanotubes‐β‐cyclodextrin for the selective extraction of psoralen and isopsoralen

A polymeric column that contains multiwalled carbon nanotubes‐β‐cyclodextrin composite was developed. The composite was wrapped into the poly(butyl methacrylate‐ethylene dimethacrylate) monolith column (0.76 mm id and 10 cm in length). The column was then applied for the online solid‐phase microextraction of psoralen and isopsoralen from Fructus Psoraleae. Following microextraction, the coumarins were quantified by high‐performance liquid chromatography with C₁₈ separation column and UV detection. The effects of sample flow rate, sample volume, and pH value were optimized. The method showed low limits of detection (20 pg/mL, S/N = 3) for both psoralen and isopsoralen. Finally the method was successfully applied to the determination of psoralen and isopsoralen in spiked herb extracts and rat plasma where it gave recoveries that ranged between 93.2 and 102.1%. The empty hydrophobic cavities of β‐cyclodextrin and the hydrophobicity of multiwalled carbon nanotubes provided specific extraction capability for psoralen and isopsoralen.     

Simultaneous quantification of chlorogenic acid and caffeic acid in rat plasma after an intravenous administration of mailuoning injection using liquid chromatography/mass spectrometry

A simple, rapid and sensitive method was developed for the simultaneous quantification of chlorogenic acid (CGA) and caffeic acid (CA) in rat plasma using a high-performance liquid chromatography system coupled to a negative ion electrospray mass spectrometric analysis. The plasma sample preparation was a simple deproteinization by the addition of two volumes of acetonitrile followed by centrifugation. The analytes and internal standard ferulic acid were separated on an Intersil C8-3 column (5 mm; 250 x 2.1 mm) with acetonitrile/0.05% triethylamine solution (70:30, v/v) as mobile phase at a flow rate of 0.2 mL/min with an operating temperature of 30 degrees C. Detection was performed on a quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source operated in selected ion monitoring (SIM) mode. Negative ion ESI was used to form deprotonated molecules at m/z 353 for chlorogenic acid, m/z 179 for caffeic acid, and m/z 193 for the internal standard ferulic acid. Linear detection responses were obtained for CGA concentrations ranging from 0.005 to 2.0 microg/mL and for CA concentrations ranging from 0.010 to 2.0 microg/mL and the lower limits of quantitation (LLOQs) for CGA and CA were 0.005 and 0.01 microg/mL, respectively. The intra- and inter-day precisions (RSD%) were within 9.0% for both analytes. Deviation of the assay accuracies was within +/-10.0% for both analytes. Their average recoveries were greater than 88.0%. Both analytes were proved to be stable during all sample storage, preparation and analytic procedures. The method was successfully applied to the pharmacokinetic study of CGA and CA following an intravenous dose of 5 mL/kg mailuoning injection to rats.     

Simultaneous determination of vitexin-2"-O-glucoside, vitexin-2"-O-rhamnoside, rutin, and hyperoside in the extract of hawthorn (Crataegus pinnatifida Bge.) leaves by RP-HPLC with ultraviolet photodiode array detection

RP-HPLC with UV photodiode array detection (UV-DAD) was developed and validated for the simultaneous determination of vitexin-2"-O-glucoside, vitexin-2"-O-rhamnoside, rutin, and hyperoside in the extract of hawthorn (Crataegus pinnatifida Bge.) leaves. The analytes of interest were separated on a Diamonsil C18 column (250 x 4.6 mm id, 5 microm) with the mobile phase consisting of THF/ACN/methanol/ 0.05% phosphoric acid solution (pH 5.0) (18:1:1:80 v/vl/v). The flow rate was set at 1.0 mL/min and the eluent was detected at 340 nm for the four flavonoids. The method was linear over the studied range of 1.00-100 microg/mL for the four analytes of interest with the correlation coefficient for each analyte greater than 0.999. The LOD and LOQwere 0.03 and 0.10 microg/mL, 0.03 and 0.10 microg/mL, 0.05 and 0.15 pg/mL, 0.10 and 0.30 microg/mL for vitexin-2"-O-glucoside, vitexin-2"-0-rhamnoside, rutin, and hyperoside, respectively. The optimized method was successfully applied to the analysis of four important flavonoids in the extract of hawthorn leaves. The total amounts of the four flavonoids were 22.2, 62.3, 4.27, and 8.24 mg/g dry weight for vitexin-2"-O-glucoside, vitexin-2"-O-rhamnoside, rutin, and hyperoside in the extract of hawthorn leaves, respectively.     

Preparative isolation and purification of psoralen and isopsoralen from Psoralea corylifolia by high-speed counter-current chromatography

Psoralen and isopsoralen were separated from Psoralea corylifolia by high-speed counter-current chromatography (HSCCC). A two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (5:5:4.5:5.5, v/v) was used for HSCCC separation, and yielded, from 100 mg of crude extract, 39.6 mg of psoralen and 50.8 mg of isopsoralen each at over 99% purity as determined by high performance liquid chromatography (HPLC). The identification of psoralen and isopsoralen were performed with 1H NMR and 13C NMR.     

Simultaneous determination of phenytoin and dextromethorphan in urine by solid-phase extraction and HPLC-DAD

A rapid and simple high-performance liquid chromatographic method with photodiode array detection was developed for the separation and the simultaneous determination of phenytoin and dextromethorphan in human urine. Analysis was performed in less than 4.5 min in isocratic mode on a reversed-phase C18 column (5 microm; 150 x 4.6 mm) using a mobile phase composed of acetonitrile-buffer phosphate 0.01 M (60:40, v/v) adjusted to pH 6.0, at 1 mL/min flow rate and UV absorbance at 210 nm. The elution order of analytes was dextromethorphan (DXM), Internal Standard (IS), and phenytoin (PHT). Calibration curves were linear in the 7.5-25 microg/mL range for PHT and in the 10-30 microg/mL range for DXM. Spike recoveries for urine samples prepared at three spiking levels ranged from 97.8 to 102.3% for PHT and from 94.8 to 100.4% for DXM. The detection limit (LOD) values ranged from 0.08 microg/mL for PHT to 0.5 microg/mL for DXM. The quantitation limit (LOQ) values ranged from 0.3 microg/mL for PHT to 1.6 microg/mL for DXM. The sample preparation method involves a rapid and simple procedure based on solid-phase extraction using a C18 reversed-phase column. Validation of the optimised method was carried out according to the ICH guidelines. The method developed in this study allows the reliable simultaneous analysis of PHT and DXM, drugs that were never quantified together in previously reported analytical methods. The described method has the advantage of being rapid and easy and it could be applied in therapeutic monitoring of these drugs in human urine of epileptic patients.     

A rapid and simple high-performance liquid chromatography method for the determination of human plasma levofloxacin concentration and its application to bioequivalence studies

A high-performance liquid chromatography method with fluorescence detection (HPLC-FLD) for the determination of levofloxacin in human plasma is described. Neutralized with phosphate buffer (pH 7.0), the sample (0.1 mL) was extracted with dichlormethane (1 mL). After voltex-mixing and centrifuged at 3000g for 6 min at 4 degrees C, the upper aqueous layer was aspirated using a micro vacuum pump and the organic layer was directly transferred to a clean test tube without pipetting. The organic solvent was evaporated and the residues were reconstituted with the mobile phase. Levofloxacin and terazosin (internal standard, IS) were chromatographically separated on a C(18) column with a mobile phase containing phosphate buffer (pH 3.0, 10 mm), acetonitrile and triethylamine (76:24:0.076, v/v/v) at a flow rate of 1 mL/min. The analytes were detected using fluorescence detection at an excitation and emission wavelength of 295 and 440 nm, respectively. The linear range of the calibration curves was 0.0521-5.213 microg/mL for levofloxacin with a lower limit of quantitation (0.0521 microg/mL). The retention times of levofloxacin and terazosin were 2.5 and 3.1 min, respectively. Within- and between-run precision was less than 12 and 11%, respectively. Accuracy ranged from -6.3 to 4.5%. The recovery ranged from 86 to 89% at the concentrations of 0.0521, 0.5213 and 5.213 microg/mL. The present HPLC-FLD method is sensitive, efficient and reliable. The method described herein has been successfully used for the pharmacokinetic and bioequivalence studies of a levofloxacin formulation product after oral administration to healthy Chinese volunteers.     

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.     

Simultaneous separation of eight beta-adrenergic drugs using titanium dioxide nanoparticles as additive in capillary electrophoresis

The analysis is described for separating seven beta-adrenergic blocking agents (atenolol, celiprolol, clorprenaline, fenoterol, metoprolol, propranolol, terbutaline) and clenbuterol (sympathomimetic beta-2 receptor stimulating agonist, decongestant and bronchodilator, illicit anabolic used in athletics) by CE with UV detection. In order to simultaneously separate all analytes, Tris-H3PO4 solution was applied containing titanium dioxide nanoparticles (TiO2 NPs) as BGEs. The effects of important factors, such as concentration of TiO2 NPs, optimum pH, run buffer concentration, and separation voltage, were investigated so as to achieve best CE separation. The eight analytes could be well separated applying a separation voltage of 15 kV in 75 mM Tris-H3PO4 buffer at a pH of 2.40, containing 6.0 x 10(-6) g/mL TiO2 NPs. Under these optimal conditions, the RSDs for peak areas and for migration times were less than 2.7 and 2.3%, respectively. The detection limits were 0.1 microg/mL for celiprolol, 0.1 microg/mL for propranolol, 0.2 microg/mL for fenoterol, 1.0 microg/mL for atenolol, 1.0 microg/mL for clenbuterol, 1.0 microg/mL for clorprenaline, 1.0 microg/mL for metoprolol, and 1.0 microg/mL for terbutaline. The proposed method was successfully applied for the rapid CE determination of the frequently applied antihypertensive beta-blocking compounds atenolol, metoprolol, terbutaline, and propranolol in pharmaceutical tablets.     

Quantification of the plant-derived hallucinogen Salvinorin A in conventional and non-conventional biological fluids by gas chromatography/mass spectrometry after Salvia divinorum smoking

A gas chromatography method with mass spectrometric detection is described for the determination of Salvinorin A, the main active ingredient of the hallucinogenic mint Salvia divinorum. The method was validated in plasma, urine, saliva and sweat using 17-alpha-methyltestosterone as internal standard. The analytes were extracted from biological matrices with chloroform/isopropanol (9:1, v/v). Chromatography was performed on a 5% phenyl methyl silicone capillary column and analytes were determined in the selected ion monitoring mode. The method was validated over the concentration range 0.015-5 microg/mL plasma, urine and saliva and 0.01-5 microg/patch in the case of sweat. Mean recoveries ranged between 77.1 and 92.7% for Salvinorin A in different biological matrices, with precision and accuracy always better than 15%. The method was applied to the analysis of urine, saliva and sweat from two consumers after smoking 75 mg plant leaves to verify the presence of the active ingredient of S. divinorum in human biological fluids as a biomarker of plant consumption. Salvinorin A was detected in urine (2.4 and 10.9 ng/mL) and saliva (11.1 and 25.0 ng/mL), but not in sweat patches from consumers.     

Quantification of myrislignan in rat plasma by solid-phase extraction and reversed-phase high-performance liquid chromatography

A rapid and simple reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for determination of myrislignan in rat plasma after intravenous administration. The analytes extracted from plasma samples by solid-phase extraction were successfully carried out on a Diamonsiltrade mark ODS C(18) column (250 x 4.6 mm i.d., 5 microm) with an RP(18) guard column (8 x 4.6 mm i.d., 5 microm) and a mobile phase of MeOH-H(2)O (4:1, v/v). The UV detector was set at a single wavelength of 270 nm. The linear ranges of the standard curves were 0.5-30.0 microg/mL with the correlation coefficients greater than 0.9992. The lower limits of detection and quantification were 0.1 and 0.3 microg/mL for myrislignan. Intra- and inter-day precisions were 2.4-7.5 and 1.3-5.7%, respectively. The extraction recovery from plasma was more than 90%. This assay method has been successfully used to study the pharmacokinetics of myrislignan in rats.     

Validated HPLC determination of the two fixed dose combinations (chlordiazepoxide hydrochloride and mebeverine hydrochloride; carvedilol and hydrochlorothiazide) in their tablets

Simple, rapid, and selective RP-HPLC methods with UV detection were developed for simultaneous determination of chlordiazepoxide hydrochloride and mebeverine hydrochloride (Mixture I) and carvedilol and hydrochlorothiazide (Mixture II). The chromatographic separation in both mixtures was achieved by using an RP-C8 (octylsilyl) analytical column. For Mixture I, a mobile phase composed of acetonitrile-0.05 M disodium hydrogen phosphate-triethylamine (50 + 50 + 0.2, v/v/v), pH 2.5, was used; the detector wavelength was 247 nm. For Mixture II, the mobile phase consisted of acetonitrile-0.05 M disodium hydrogen phosphate (50 + 50, v/v), pH 4.0, and the detector was set at 220 nm. Quantification of the analytes was based on measuring their peak areas. Both mixtures were resolved in less than 6 min. The reliability and analytical performance of the proposed HPLC procedures were statistically validated with respect to linearity, range, precision, accuracy, selectivity, robustness, LOD, and LOQ. The linear dynamic ranges were 2.5-150 and 2.5-500 microg/mL for chlordiazepoxide HCI and mebeverine HCI, respectively, and 0.25-200 and 0.25-150 microg/mL for carvedilol and hydrochlorothiazide, respectively. The validated HPLC methods were successfully applied to the analysis of their commercial tablet dosage forms, for which no interfering peaks were encountered from common pharmaceutical adjuvants.     

Quantitation of oxcarbazepine and its metabolites in human plasma by micellar electrokinetic chromatography

A reliable micellar electrokinetic chromatographic method for the determination of oxcarbazepine and its two main metabolites, 10-hydroxycarbamazepine and 10,11-trans-dihydroxy-10,11-dihydroxycarbamazepine, in human plasma was developed. The separation and determination of the analytes was achieved using a system consisting of 60 mM SDS in phosphate buffer (30 mM, pH 8.0), to which 20% (v/v) methanol was added. Separation was carried out in an uncoated fused-silica capillary with a separation voltage of 25 kV and currents typically less than 40 microA. Spectrophotometric detection was at 205 nm. Isolation of oxcarbazepine and its metabolites from plasma was accomplished by a solid-phase extraction procedure. The mean extraction yield of the analytes from plasma was higher than 94%. The linear correlation coefficients were better than 0.994 for all analytes. The limit of detection was 0.05 microg/mL, the limit of quantitation 0.15 microg/mL. The repeatability for the spiked blank plasma samples was lower than 1.9% and the intermediate precision lower than 2.1%, both expressed as RSD%. The results obtained analysing real plasma samples from epileptic patients under therapy with Tolep were satisfactory in terms of precision, accuracy and detectability.     

Separation and determination of two sesquiterpene lactones in Radix inulae and Liuwei Anxian San by microemulsion electrokinetic chromatography

A novel microemulsion electrokinetic chromatography (MEEKC) method for separating and determining two sesquoterpene lactones, alantolactone (AL) and isoalantolactone (IAL), in Radix inulae and Liuwei Anxian San has been developed. The effects of several important factors such as internal organic phases, concentration of microemulsion, concentration of acetonitrile, injection time and running voltage were systematically investigated to determine the optimum conditions. The optimum microemulsion system was composed of n-hexane (0.32% w/w), SDS (1.24% w/w), 1-butanol (2.64% w/w), acetonitrile (10% w/w) and 10 mm sodium tetraborate buffer (85.80% w/w, pH 9.2). The applied voltage was 20 kV. The analytes were detected at 214 nm. Regression equations revealed linear relationships (correlation coefficients 0.9950 for AL and 0.9946 for IAL) between the peak area of each analyte and the concentration. The limits of detection (defined as a signal-to-noise ratio of about 3) were approximately 0.45 microg/mL for AL and 0.56 microg/mL for IAL. The levels of the analytes were successfully determined with recoveries ranging from 98.2 to 104.3%. Furthermore, a simple and effective extraction method, with methanol in an ultrasonic water bath for 60 min, was used for sample preparing. Also, MEEKC was compared with micellar electrokinetic chromatography (MEKC) and shown better separation results.     

Simultaneous separation and determination of Tarabine PFS and Adriblastine using micellar electrokinetic chromatography and high performance liquid chromatography. Application to some biological fluids

The simultaneous determination of Tarabine PFS and Adriblastine by two independent techniques, viz. micellar electrokinetic chromatography (MEKC) and high performance liquid chromatography (HPLC), has been studied. For MEKC analysis, separations and identifications were accomplished using uncoated fused-silica capillaries and injections were performed in the hydrodynamic mode. The running buffer consisted of 0.05 M borate/phosphate pH 8.70, with 0.10 M SDS at an operating voltage of 15.0 kV and the temperature held at 25.0 degrees C. Under these conditions, the migration times of Tarabine PFS and Adriblastine were 2.70 and 6.40 min, respectively. Calibration curves were established for 0.010-0.300 microg/mL (r = 0.99) Tarabine PFS and 8.000-120.0 microg/mL (r = 0.99) Adriblastine. The limit of detection (LOD) was estimated and found to be 0.003 and 3.000 microg/mL of Tarabine PFS and Adriblastine, respectively. The limit of quantitation (LOQ) was found to be 0.009 and 8.000 microg/mL of Tarabine PFS and Adriblastine, respectively. For HPLC analysis, separations and determinations were performed on teicoplanin stationary phase with reversed mobile phase containing methanol:buffer pH 4.05 (20.0:80.0%, v/v) at 285 nm. Calibration curves were established for 3.000-90.00 microg/mL (r = 0.99) Tarabine PFS and for 10.00-120.0 microg/mL (r = 0.99) Adriblastine. LOD and LOQ were estimated and found to be 0.950 and 2.050 microg/mL of Tarabine PFS and 3.130 and 9.250 microg/mL of Adriblastine, respectively. Both MEKC and HPLC methods were applied for the simultaneous determination of analytes in urine samples. It was found that 8.00-10.0% (Tarabine PFS) and 13.0-15.0% (Adriblastine) of the injected dose was recovered in urine samples with 99.5-102% recovery.     

Evaluation of the influence of salt processing on pharmacokinetics of psoralen and isopsoralen in Psoralea corylifolia L.

A sensitive, specific and rapid ultra‐high‐pressure liquid chromatography tandem mass spectrometry (UHPLC‐MS/MS) method has been developed to investigate pharmacokinetic properties of psoralen and isopsoralen, two compounds isolated from raw/salt‐processed fruit of Psoralea corylifolia L. UHPLC‐MS/MS was used with positive ion electrospray. The mobile phase was composed of acetonitrile and 0.1% formic acid aqueous solution and a gradient elution program at flow rate of 0.3 mL/min was applied. Multiple reaction monitoring mode was used for the quantification of psoralen, isopsoralen ([M + H]⁺ m/z 187.0 → m/z 131.0) and scoparone (m/z 207.0 → m/z 151.1). Scoparone served as an internal standard. The method was fully validated for its sensitivity, selectivity, stability, matrix effect and extraction recovery. The obtained results showed that salt‐processed Buguzhi significantly promoted the absorption of psoralen and isopsoralen, and increased the bioavailability of these compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Determination of iguratimod in rat plasma by high performance liquid chromatography: method and application

A high-performance liquid chromatographic method with UV detection has been developed for the determination of iguratimod (T-614) in rat plasma. Plasma was precipitated with acetonitrile after the addition of the internal standard (IS), N-[4-(2-formylaminoacetyl)-5-methoxy-2-phenoxyphenyl]-methanesulfonamide. The chromatographic separation was achieved on a reversed-phase C(18) column with the mobile phase acetonitrile-acetic acid aqueous solution, pH 4.5 (40:60, v/v), at a flow rate of 1 mL/min, and the UV detection wavelength was set at 257 nm. The calibration curve was linear over the range 0.10-50.0 microg/mL, and the lower limit of quantification was 0.10 microg/mL. The intra- and inter-day relative standard deviations were all less than 11.5%. The method has been successfully applied to study the pharmacokinetics of iguratimod in rats. A single 10 mg/kg dose of iguratimod was given to the rats by intragastric administration. The mean maximum plasma concentration of iguratimod for the six rats was 14.5 microg/mL, and the mean elimination half-life of iguratimod was 4.0 h.     

Separation and determination of flavonoids using microemulsion EKC with electrochemical detection

A selective and sensitive method of microemulsion EKC (MEEKC) with electrochemical detection (ED) was developed for separation and determination of 14 flavonoids. In order to obtain the better stability for the studied flavonoids, oil (ethyl acetate) with low interfacial surface tension was employed as organic solvent. A running buffer composed of 0.9% (w/v, 30 mM) SDS, 0.9% (w/v, 21 mM) sodium cholate (SC), 0.9% (w/v, 121 mM) butan-1-ol, 0.6% (w/v, 68 mM) ethyl acetate, and 98.2% v/v 10 mM Na(2)B(4)O(7)-20 mM H(3)BO(3) buffer (pH 7.5) was applied for the separation of flavonoids. Under the optimum conditions, the relationship between peak currents and analyte concentrations was linear over about 1.3 and 1.7 orders of magnitude with detection limits (defined as S/N = 3) ranging from 0.02 to 0.5 microg/mL for all analytes. This method was applied for the determination of flavonoids in real samples with simple extraction procedures, and the assay results were satisfactory.     

A high-performance liquid chromatographic method for determination of scopolin in rat plasma: application to pharmacokinetic studies

An analytical method based on high-performance liquid chromatographic (HPLC) with ultraviolet (UV) detection was developed for determination of scopolin in rat plasma using aesculin as internal standard (IS). After protein precipitation of plasma sample with methanol, the supernatant was directly injected and analyzed. Chromatographic separation was achieved on a C18 column using methanol and distilled water (22:78, v/v) containing 0.2% (v/v) glacial acetic acid as mobile phase with a column temperature of 30 degrees C. The UV detector was set at 338 nm. The calibration curve was linear over the range of 0.105-13.125 microg/mL with a correlation coefficient of 0.9998. The retention times of aesculin and scopolin were 10.4 and 12.8 min, respectively. The recoveries for plasma samples of 0.105, 4.725 and 13.125 microg/mL were 91.08, 95.30 and 96.10%, respectively. The RSD of intra- and inter-day assay variations was less than 7.35%. The lower limit of detection was 0.03 microg/mL .This HPLC assay is a simple, sensitive and accurate and was successfully applied to the pharmacokinetic study of scopolin in rats.     

Simultaneous determination of seven triterpenoids and triterpenoid saponins in Folium llicis Purpureae by high performance liquid chromatography coupled with evaporative light scattering detection

A new HPLC coupled with evaporative light scattering detection method was established for the simultaneous determination of seven triterpenoids and triterpenoid saponins in Folium Ilicis Purpureae traditional Chinese medicinal herb derived from the leaf of Ilex purpurea, namely, 3-omicron-beta-D-glucopyranosyl (1-->2)-beta-D-[6-omicron-methyl-glucuronopyranosyl]-28-omicron-beta-D-glucopyranosyl oleanolic acid (SQ-1), pedunculoside (SQ-2), 23-hydroxytormentic acid 28-omicron-beta-D-glucopyranoside (SQ-3), 23-hydroxytormentic acid (SQ-4), rutundic acid (SQ-5), ilexoside B (SQ-6), and ursolic acid (SQ-7). The optimal chromatographic conditions were achieved on a C18 column with a linear gradient elution of mobile phase A: deionized water-isopropyl alcohol-THF-acetic acid (90:10:6:1, v/v) and B: methanol-isopropyl alcohol-THF-acetic acid (90:10:6:1, v/v) at the flow rate of 1.0 mL/min; temperature for drift tube was set at 98degreesC and nitrogen flow rate was 2.8 L/min. All calibration curves of the seven compounds showed good linear regression (r2 > 0.995) within test ranges. The developed method has good repeatability for quantitation of all analytes interested with overall intraday and interday variation of less than 4.1%. The LOD (S/N = 3) and LOQ (S/N = 10) were less than 0.13 and 0.26 microg/mL, respectively, for all analytes. The established method was successfully used to evaluate the quality of Folium Ilicis Purpureae samples of different collections.     

Stability-indicating methods for determination of tiapride in pure form, pharmaceutical preparation, and human plasma

Four different stability-indicating procedures are described for determination of tiapride in pure form, dosage form, and human plasma. Second derivative (D2), first derivative of ratio spectra (1DD), spectrofluorimetric, and high-performance column liquid chromatographic (LC) methods are proposed for determination of tiapride in presence of its acid-induced degradation products, namely 2-methoxy-5-(methylsulfonyl) benzoic acid and 2-diethylaminoethylamine. These approaches were successfully applied to quantify tiapride using the information included in the absorption, excitation, and emission spectra of the appropriate solutions. In the D2 method, Beer's law was obeyed in the concentration range of 1.5-9 microg/mL with a mean recovery of 99.94 +/- 1.38% at 253.4 nm using absolute ethanol as a solvent. In 1DD, which is based on the simultaneous use of the first derivative of ratio spectra and measurement at 245 nm in absolute ethanolic solution, Beer's law was obeyed over a concentration range of 1.5-9 microg/mL with mean recovery 99.64 +/- 1.08%. The spectrofluorimetric method is based on the determination of tiapride native fluorescence at 339 nm emission wavelength and 230 nm excitation wavelength using water-methanol (8 + 2, v/v). The calibration curve was linear over the range of 0.2-3 microg/mL with mean recovery of 99.66 +/- 1.46%. This method was also applied for determination of tiapride in human plasma. A reversed-phase LC method performed at ambient temperature was validated for determination of tiapride using methanol-deionized water-triethylamine (107 + 93 + 0.16, v/v/v) as the mobile phase. Sulpiride was used as an internal standard at a flow rate of 1 mL/min with ultraviolet detection at 214 nm. A linear relation was obtained over a concentration range of 2-30 microg/mL with mean recovery of 99.66 +/- 0.9%. Results were statistically analyzed and compared with those obtained by applying the reference method. They proved both accuracy and precision.