Development of a validated capillary electrophoresis method for enantiomeric purity testing of dexchlorpheniramine maleate

A capillary zone electrophoresis method has been developed for the detection of 0.1% of (R)-levochlorpheniramine maleate in samples of (S)-dexchlorpheniramine maleate. Using 1.5 mM carboxymethyl-beta-cyclodextrin in an acidic background electrolyte, resolution values of more than 10 were obtained. Under these conditions the R-enantiomer is migrating in front of the bulk S-enantiomer. The assay was validated for linearity (2-10 microg/ml; R2 = 0.9992), selectivity [(RS)-pheniramine maleate and (RS)-brompheniramine maleate], limit of detection (0.25 microg/ml), limit of quantification (0.75 microg/ml), analytical precision (intra- and inter-day variability), repeatability of the method (RSD = 5.0%) and accuracy. In samples of dexchlorpheniramine maleate from two different manufacturers, concentrations of, respectively, 0.15% and 1.95% (m/m) of levochlorpheniramine maleate were detected. The method was compared to the HPLC method described in the European Pharmacopoeia III monograph.     

Flow-injection chemiluminescence determination of enalapril maleate in pharmaceuticals and biological fluids using tris(2,2'-bipyridyl)ruthenium(II).

A chemiluminescence (CL) method using flow injection (FI) has been investigated for the rapid and sensitive determination of enalapril maleate. The method is based on the CL reaction of the drug with tris(2,2'-bipyridyl)ruthenium(II), Ru(bipy)3(2+) and acidic potassium permanganate. After selecting the best operating parameters, calibration graphs were obtained over concentration ranges of 0.005-0.2 microg/ml and 0.7-100 microg/ml with a detection limit (S/N=2) of 1.0 ng/ml. The average % found was 99.9 +/- 0.7 and 100.2 +/- 0.3 for the two concentration ranges respectively. %RSD (n=10) for 5.0 microg/ml was 0.44. The method was successfully applied to the determination of enalapril maleate in dosage forms and biological fluids without interferences.     

Spectrophotometric and atomic absorption determination of ramipril, enalapril maleate and fosinopril through ternary complex formation with molybdenum (V)-thiocyanate (Mo(V)-SCN)

Three different sensitive and accurate spectroscopic procedures were developed for the determination of three angiotensin-converting enzyme inhibitors, namely, ramipril, enalapril maleate and fosinopril. The first two spectrophotometric (extractive and non-extractive) procedures were based on ternary complex formation with molybdenum(V) thiocyanate. The formed complex can be determined by extraction with chloroform measured at lambdamax 517 nm Beer's law was obeyed in the concentration range from (10--90 microg ml(-1)) for ramipril and fosinopril and (4--36 microg ml(-1)) for enalapril maleate with molar absorptivity 1.2x10(4), 2x10(4) and 3.4x10(4) l mol(-1) cm(-1), respectively, or by direct measurement after addition of benzalkonium chloride as surfactant and measuring the formed ternary complex at lambdamax 545 nm with a linear relationship in the concentration range from (8-7-2 microg ml(-1)), (3--27 microg ml(-1)) and (8--72 microg ml(-1)) for ramipril, enalapril maleate and fosinopril with molar absorptivity 1.5x10(4), 5x10(4) and 2.1x10(4) l mol(-1) cm(-1), respectively. The third procedure is atomic absorption measurement through the quantitative determination of molybdenum content of the complex. These methods hold their accuracy and precision well when applied to the determination of ramipril, enalapril maleate and fosinopril in their dosage forms.     

High-performance liquid chromatographic method for the determination of eclanamine and its N-desmethyl and N,N-didesmethyl metabolites in urine

A high-performance liquid chromatographic method has been defined for the determination of eclanamine (free base of eclanamine maleate) and two of its metabolites, N-desmethyleclanamine and N,N-didesmethyleclanamine in urine. The method employs 10-ml urine samples, has a linear range from 5 to 500 ng/ml for the three compounds, and has a detection limit of 0.5 ng/ml for each compound. Sample preparation uses a cyanopropylsilane extraction column with washes of water, acetonitrile-water (30:70, v/v), and acetonitrile, and elution with 2% trifluoroacetic acid in acetonitrile. The eluate is evaporated to dryness, the residue dissolved in 1.0 ml acetonitrile-water (10:90, v/v) and 100 microliter are injected onto a Supelcosil LC-CN column. Eclanamine and its metabolites are eluted with an acetonitrile-water (35:65, v/v) eluent containing 0.01 M triethylamine and adjusted to pH 7.0 with phosphoric acid. The method has been validated by preparing and analyzing a series of fortified urines (range 2-500 ng/ml for each compound) on four separate days. Good linearity, precision, reproducibility, and specificity were obtained. Certification of the analytical method was accomplished by analyzing urine specimens collected from one volunteer administered a single oral dose of 45 mg eclanamine maleate. The data suggest that the metabolites of eclanamine have long elimination half-lives with levels still quantifiable in the 72-96 h collection interval.     

大体积进样-乙腈盐堆积-胶束扫集毛细管电动色谱法对马来酸氯苯那敏的测定

建立了大体积进样-乙腈盐堆积-胶束扫集毛细管电动色谱法测定马来酸氯苯那敏片中马来酸氯苯那敏的新方法,并考察了样品中乙腈和NaCl浓度对分离效果的影响.结果表明,以12 mmol/L四硼酸钠-50 mmol/L硼酸- 50 mmol/L十二烷基硫酸钠(SDS)为缓冲液(含10%甲醇,pH9.1),以70%乙腈- 200m...     

Simultaneous determination of chlorpheniramine maleate and dexamethasone in a tablet dosage form by liquid chromatography

An accurate, simple, reproducible, and sensible liquid chromatographic method was developed and validated for the determination of chlorpheniramine maleate and dexamethasone in a tablet formulation. The analysis was performed at room temperature on a reversed-phase C18 column with UV detection at 254 nm. The mobile phase consisted of 7.5 mM monobasic potassium phosphate in methanol-water (62.5 + 37.5) at a constant flow rate of 1 mL/min. The method was validated in terms of linearity, precision, accuracy, and specificity by forced decomposition of chlorpheniramine maleate and dexamethasone initiated by using acid, base, water, hydrogen peroxide, heat, and light. The response was linear in the ranges of 0.04-0.12 and 0.006-0.016 mg/mL for chlorpheniramine maleate (r2 = 0.9999) and dexamethasone (r2 = 0.9994), respectively. The relative standard deviation values for intra- and interday precision studies were 2.39 and 2.02, respectively, for chlorpheniramine maleate and 2.39 and 1.25, respectively, for dexamethasone. Recoveries ranged from 95.07 to 101.95% for chlorpheniramine maleate and from 97.75 to 102.10% for dexamethasone.     

Determination of chlorpheniramine maleate and tincture ipecac in dosage form by liquid chromatography with ultraviolet detection

A procedure was developed and validated for measuring chlorpheniramine maleate and tincture ipecac (as emetine hydrochloride) by reversed-phase liquid chromatography with methanol-10 mM sodium heptanesulfonate (20 + 30) as the mobile phase; the pH was adjusted to 4 with acetic acid, and the flow rate was at 1.5 mL/min, with ultraviolet detection at 254 nm. Propyl paraben was used as the internal standard. The standard curves were linear (r = 0.998 and 0.9998) for both chlorpheniramine maleate and emetine hydrochloride over the ranges of 5-100 and 0.1-40 microg/mL, respectively. The mean recoveries +/- standard deviation were 101.37 +/- 2.77% for chlorpheniramine maleate and 98.8 +/- 1.47% for emetine hydrochloride. The proposed method was applied to the determination of chlorpheniramine maleate alone in tablet and syrup dosage forms. The method also was applied to the determination of the emetine content of ipecac liquid extract and tincture ipecac; the results were compared with those of the method of the British Pharmacopoeia. The proposed method was applied successfully to the simultaneous determination of chlorpheniramine maleate and tincture ipecac, as emetine hydrochloride, in syrup dosage form. Both drugs and the internal standard were separated from all interfering components in < 5 min. The proposed method is simple, specific, and economical, when compared with other published methods that determine each component alone.     

Quantitation of flupirtine and its active acetylated metabolite by reversed-phase high-performance liquid chromatography using fluorometric detection

A simple, selective and sensitive procedure is described for the quantitation of flupirtine maleate (FLU) and its active acetylated metabolite (Met. 1) in plasma and urine. Using a 0.5-ml sample, a sensitivity of 10 ng/ml is easily achieved with a reversed-phase octadecylsilane (C18) column, and a high-performance liquid chromatographic system with fluorescence detection. Quantitation from plasma involves addition of an internal standard, protein precipitation with acetonitrile and a sample concentrating step, while for urinalysis the samples are taken through a single extraction with methylene chloride. Analytical recoveries of FLU and Met. 1 from plasma averaged greater than or equal to 95%, while from urine only 60 and 50%, respectively, could be recovered. The overall, inter- and intra-day variability for both FLU and Met. 1 averaged 6, 5 and 3%, in plasma, respectively. Standard calibration plots in plasma were linear (r greater than or equal to 0.99) for FLU (range: 0.01-10.0 micrograms/ml) and Met. 1 (range: 0.5-25 micrograms/ml) over the extended range. A slightly modified elution system was employed for quantitation of FLU and Met. 1 in urine.     

Spectrophotometric determination of some dibenzazepines with picryl chloride

A simple and sensitive spectrophotometric method has been developed for the determination of some dibenzazepines, based on reaction with picryl chloride in chloroform medium and measurement at 395 nm. Beer's law is obeyed in concentration ranges 0.1-1.0 microg/ml for imipramine hydrochloride, trimipramine maleate and opipramol dihydrochloride, 0.16-1.6 microg/ml for desipramine hydrochloride and 0.4-2.4 microg/ml for clomipramine hydrochloride. The method was applied successfully to the determination of dibenzazepines in tablets and the results were comparable to those obtained by official procedures.     

Synthesis of colorimetric sensors for isomeric dicarboxylate anions: selective discrimination between maleate and fumarate

Four new colorimetric receptors (1-4) were synthesized and characterized. Upon addition of maleate to receptor in DMSO, the appearance of the solution of receptor 1 showed a color change from dark-blue to dark-red, which can be detected by the naked eye at parts per million. Similar experiments were repeated using receptors 2-4; the solution showed a distinct color change from blue to violet for receptor 2 and from blue-green to purple for both receptors 3 and 4, when they are formed as complexes with maleate. The striking color changes are thought to be due to the deprotonation of the thiourea moiety of the 4-nitronaphthyl chromophore. Whereas, in the addition of fumarate to receptors 1-4, the color of the solution changed from dark-blue to bright yellow for receptor and did not induce any color change for receptors 2-4. Thus, for a distinct color change, receptors 1-4 can act as optical chemosensors for recognition of maleate versus fumarate. Especially, only receptor 1 has a unique color change for the recognition of fumarate, accordingly it can be used for detection of the fumarate anion. In this research it was also found that the performance of the receptor is highly dependent on the substituent group on the phenyl ring; a stronger electron-withdrawing group resulted in a receptor with a higher binding constant with the maleate anion.     

Simultaneous determination of perhexiline and its monohydroxy metabolites in biological fluids by gas chromatography-electron-capture detection

A rapid and sensitive method for the simultaneous determination of perhexiline and its cis-4-axial and trans-4-equatorial monohydroxy metabolites (M1 and M3, respectively) in human plasma, urine and bile is described. The assay utilises a single diethyl ether extraction, heptafluorobutyric acid anhydride derivatisation and separation and detection by gas chromatography-electron-capture detection. The limits of detection are 0.1 microgram/ml for perhexiline and 0.025 microgram/ml for the M1 and M3 metabolites. This method has been used in a five-day kinetic study of three healthy adult males who ingested a single 300-mg dose of perhexiline maleate. One of these volunteer subjects exhibited elevated plasma perhexiline and markedly reduced plasma and urinary M1 concentrations together with profoundly prolonged plasma and urinary M1 elimination times when compared with the other two subjects. These differences are thought to be of genetic origin. There were also obvious differences in urinary M3 concentrations which were discussed.     

Simultaneous determination of codeine and chlorpheniramine in human plasma by capillary column gas chromatography

A specific and highly sensitive capillary column gas chromatographic method was developed for the simultaneous determination of codeine and chlorpheniramine in human plasma. The method involves a solvent extraction and analysis by capillary column gas chromatography on a cross-linked 50% phenylmethyl silicone fused-silica capillary column with flame thermionic detection. A 10% solution of n-butanol in toluene was used as extraction medium and pyrilamine was used as internal standard. Reproducibility, linearity of calibration curves and specificity were all satisfactory with both drugs. The plasma concentration of codeine and chlorpheniramine could be measured at levels down to 0.9 ng/ml as codeine phosphate and 0.4 ng/ml as chlorpheniramine maleate, respectively. The method was applied to plasma samples from normal volunteers, and was confirmed to be adequate for biopharmaceutical and pharmacokinetic studies.     

Gas-liquid chromatographic method for the measurement of plasma levels of d-7,8-dimethoxy-3-methyl-phenyl-2,3,4,5-tetrahydro-1h-3-benzazepine acid maleate (SCH-12679) and its major metabolites in aggressive mental retardites

A sensitive gas-liquid chromatographic technique for the quantitative analysis of SCH-12679 (d-7,8-dimethoxy-3-methyl-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine acid maleate) and its major metabolites in plasma of aggressive mental retardates receiving therapeutic doses of the medicament has been developed. The lower limits of detection are 20 ng/ml for SCH-12679, 0.5 ng/ml for 3-desmethyl SCH-12679 and 0.4 ng/ml for 7-desmethyl plus 8-desmethyl SCH-12679. SCH-12679 is estimated with a flame ionization detector. Its metabolites are quantitated using an electron-capture detector after conversion of the compounds to their heptafluorobutyryl derivatives by reaction with the appropriate anhydride. Data on plasma levels of unchanged SCH-12679, 3-desmethyl SCH-12679 and a combination of 7-desmethyl and 8-desmethyl SCH-12679 in fifteen patients treated with the medicament are presented.     

Spectrophotometric and fluorimetric determination of nomifensine maleate

Three methods have been developed for the determination of nomifensine maleate alone and in capsules: a spectrophotometric, an iodine charge-transfer, and a spectrofluorimetric method. All three give linear calibration graphs, over the ranges 20-100, 1-5 and 0.1-0.5 microg/ml, respectively, with coefficients of variation of 0.8, 1.3 and 1.3%, respectively.     

Ion-Pair RP-LC of Tegaserod Maleate and its Impurities in Pharmaceutical Formulations and in Dissolution Studies

A simple ion-pair reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for determination of tegaserod maleate and related impurities in tablet dosage forms. The mobile phase was 60:40 (v/v) acetonitrile-25 mmol L^?1 sodium dodecyl sulfate, adjusted to pH 2.6 with glacial acetic acid. A C18 column was used as stationary phase and UV detection was at 314 nm. The method was optimized and validated. Response was linearly dependent on concentration between 0.1 and 100 µg mL^?1 with a limit of quantification (LOQ) of 0.1 µg mL^?1 for tegaserod maleate (S/N = 10). Under optimum conditions, tegaserod maleate was successfully separated from related substances, including 5-methoxyindole-3-carboxaldehyde remaining after synthesis and other impurities possibly resulting from oxidization and decomposition. The excipients did not interfere with assay of tegaserod maleate in tablet dosage forms. It is suggested that the proposed method can be used for routine quality control and dosage-form assay of tegaserod maleate.     

在线扫集-胶束毛细管电动色谱法测定复方氨酚烷胺胶囊中的3种有效成分

以在线扫集-胶束毛细管电动色谱法(Sweeping-MEKC)测定了复方氨酚烷胺胶囊中的马来酸氯苯那敏、咖啡因和对乙酰氨基酚3种有效成分。考察了缓冲溶液pH值、SDS浓度、分离电压及进样时间等对分离效果的影响。优化条件:以未涂层熔融石英毛细管(55 cm×50μm,有效柱长35 cm)为分离柱;环境温度25℃;80 mmol/L十二烷基磺酸钠+20 mmol/L NaH2PO4(pH 2.2)+15%乙腈为缓冲体系,分离电压-20kV,进样时间60 s(H=20.0 cm),测量波长210 nm。在该条件下氯苯那敏、咖啡因和对乙酰氨基酚在25min内出峰,峰面积RSD均小于4%;线性范围分别为2.45～39.17、1.61～25.76、1.58～25.28 mg/L;检出限(S/N=3)分别达139、34、24μg/L,回收率分别为96%～101%、98%～102%、96%～102%。     

Determination of aerobic-anaerobic metabolism-related compounds in a Chaoborus flavicans population by infusion ion trap mass spectrometry of extracts of individual larvae

In a daily migration, the aquatic larvae of Chaoborus flavicans (a phantom midge) alternate oxygen-saturated and anoxic lake strata. To investigate this cycle, larvae were collected at a natural environment, and acetate, propionate, pyruvate, lactate, glycerol, phosphate, maleate, succinate, glucose and citrate were determined. Each larva was homogenized with 200 microL water and deproteinized with a spin-filter; 50 microL aliquots were mixed with 50 microL of a buffer containing 80 mM propylamine, 20 mM HCl and 0.06 mM 2,4-dihydroxybenzoic acid (internal standard) in methanol. The extracts were infused in an electrospray ionization ion-trap mass spectrometer. The limits of detection for the [M-H](-) peaks ranged from 2 microM for pyruvate and lactate to 200 microM for acetate and glycerol. The MS(2) ion-trap spectra obtained at pH 7 (ammonium acetate buffer) were used to distinguish maleate (cis-2-butenedioic), which gave [M-CO(2)-H](-) (m/z 71), from fumarate (trans-2-butenedioic), which showed first a loss of water yielding an instable peak at m/z 97. The compounds involved in the aerobic-anaerobic adjustment of the metabolism were revealed by linear discriminant analysis. Acetate, citrate, glucose, maleate (which decreased during the daytime), and particularly succinate (which increased), showed the maximal discrimination power between the day- and night-time samples.     

Ion chromatography determination of trace level bromate by large volume injection with conductivity and spectrophotometric detection after post column derivatisation

Bromate is a well known by-product produced by the ozonisation of drinking water; the allowed concentration for human consumption has to be regulated to the low microg l(-1) range. A direct injection, ion chromatographic method was developed using a tetraborate eluent with serially connected conductivity and spectrophotometric detection. Bromate was detected after post-column reaction with fuchsin at 520 nm. Sample capacity was investigated by injecting large volumes (up to 6 ml) using a high total hardness and chloride tap water. Linear correlation of bromate response with volumes from 1 ml to 6 ml was demonstrated, the main limitation being the overlapping of the chloride peak with bromate. Up to 1.5 ml sample can be injected without any pre-treatment. With more than 1.5 ml injection volume, a sample pre-treatment with a cartridge in Ag and H form, followed by a 10 min degassing in an ultrasonic bath, was needed. This method was validated by analysing secondary reference materials and real samples from a drinking water treatment plant. The method was linear from the limit of quantification to 20 microg l(-1). Reproducibilities in tap water were 18% (5 microg l(-1), n=12) and 21% (1 microg l(-1), n=4) respectively for 1.5 and 6 ml injection volumes with conductivity detection, and 17% at 0.5 microg l(-1) (n=9) with spectrophotometric detection. Calculated detection limits were 0.5 microg l(-1) (6 ml) ahd 2 microg l(-1) (1.5 ml) for conductivity detection and 0.3 microg l(-1) (1.5 ml) for spectrophotometric detection.     

Reaction kinetics of solid-state cyclization of enalapril maleate investigated by isothermal FT-IR microscopic system

To investigate the reaction kinetics of the solid-state degradation process of enalapril maleate, a Fourier transform infrared microspectroscope equipped with thermal analyzer (thermal FT-IR microscopic system) was used. The isothermal stability study was conducted at 120-130 degrees C for 1-2 h and changes in the three-dimensional plots of the IR spectra of enalapril maleate with respect to heating time were observed. The study indicates that the bands at 1649, 1728, and 1751 cm(-1) assigned to intact enalapril maleate gradually reduced in peak intensity with heating time. However, the peak intensities at 1672 and 1738 cm(-1) (due to enalapril diketopiperazine (DKP) formation) and at 3250 cm(-1) (corresponding to water formation) gradually increased with heating time. The solid-state diketopiperazine formation and the degradation process of enalapril maleate via intramolecular cyclization were found to be simultaneous. The isothermal decomposition curves were sigmoidal and were characterized by induction and acceleration periods, indicating the presence of autocatalytic solid-state decompositions. Moreover, the power-law equation (n = 1/4) was found to provide the best fit to the kinetics of decomposition. This isothermal FT-IR microscopic system was easily used to investigate the degradation of enalapril maleate and the concomitant formation of DKP. The solid-state reaction of enalapril maleate required an activation energy of 195+/-12 kJ/mol to undergo the processes of decomposition and intramolecular cyclization.     

Sodium Coumarin 6-Sulfonate,A Fluorometric Ion-Pairing Reagent for Tertiary Amines. Application to the Determination of Chlorpheniramine Maleate

Abstract

A study of sodium coumarin 6-sulfonate as a fluorescent ionpair reagent indicated that it could be useful in the analysis of tertiary amines such as chlorpheniramine maleate. The physical properties of the coumarin sulfonate that make it suitable as a fluorescent ion-pair reagent for basic drugs are its high relative quantum yield (0.76) and its acidity (pKa of ?7.66). Methylene chloride containing 5% n?pentanol was used to extract the coumarinchlorpheniramine ion-pair from aqueous solution. It was found that a 10^?2 M coumarin concentration yielded a 92% recovery of chlorpheniramine at pH 5. Following phase separation, the coumarin species was completely ionized by the addition of tetrabuty1 ammonium hydroxide to the organic phase. After irradiation for 30 min using long wavelength ultraviolet light (365 nm), the fluorescence intensity of the sample was measured using excitation and emission wavelengths of 400 and 540 nm, respectively. Comparison of fluorescence data of spiked aqueous samples to that of a chlorpheniramine maleate standard curve performed concurrently gave drug concentration in the samples. The calibration curve was linear in the 50–1000 ng/ml range (0.13 ? 2.6 × 10 ^?6 M). The procedure allowed the determination of chlorpheniramine maleate with an accuracy of 4–6% and a precision of 2–6% RSD (relative standard deviation). The minimum detectable concentration of drug (S/N = 2) that can be assayed by this method is 50 ng/ml of the maleate salt (35.3 ng/ml of chlorpheniramine free base).