Simultaneous Determination of Valsartan and Hydrochlorothiazide in Tablets by High-Performance Liquid Chromatography

ABSTRACT

A method for the simultaneous determination of valsartan and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 5.0-10.0 μg ml^?1 for valsartan and 0.5-2.0 μg ml^?1 for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 1.0 μg ml^?1 for valsartan and 0.05 μg ml^?1 for hydrochlorothiazide.     

Liquid chromatographic method to follow-up ceftazidime and pyridine in portable elastomeric infusion pumps over 24 h

Portable infusion pumps are an interesting solution to continue outpatient parenteral antimicrobial therapy (OPAT) at the patient's home. However, the use of ceftazidime for such applications is challenging in view of its relatively poor stability in solution. In this study, elastomeric infusion pumps with 6 or 7 g of ceftazidime were deflated over 24 h in an oven at 33°C while ceftazidime and its degradation product, pyridine, were regularly monitored. Hereto, a fast and sensitive liquid chromatographic (LC) method has been developed using a Kinetex^® C18 (150 × 3 mm, 2.6 μm) column with gradient elution. Ammonium formate 20 mM and acetonitrile (ACN) were mixed in a ratio of 98:2 v/v for mobile phase A and 85:15 v/v for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was set at 0.4 mL/min. The solution with a starting dose of 6 g ceftazidime was found to be degraded 10% after an average of 19 h 11 min so that an administration of 6 g to the patient was not reached. For the solution with a starting dose of 7 g of ceftazidime, 10% degradation was observed after an average of 18 h 42 min. However, by starting from a higher dose, an average of 6.56 g of ceftazidime could be administered over 24 h. In addition, 1.0% of pyridine versus ceftazidime pentahydrate with sodium carbonate (=mixture for injection) was formed over 24 h.     

High-Performance Liquid Chromatographic Assay for Chlorquine and its Two Major Metabolites,Desethylchloroquine and Bidesethylchloroquine in Biological Fluids

Abstract

A high-performance liquid chromatography (HPLC) method for the determination of chloroquine and its two major metabolites in biological fluids is described. Hydroxychloroquine is used as an internal standard (I.S.). Drug, metabolites and I.S. were extracted as bases with diethyl ether by a single step procedure. After drying and evaporation of the organic phase, the residue was dissolved into the mobile phase and injected into the chromatographic system. Separation was performed using a normal phase column (Inertsil sill with mixture of acetonitrile, methanol and ammonia as mobile phase. The detection was carried out by fluorescence measurement : excitation wavelength was set at 325 nm and emission at 380 nm. The limit of detection was near 3.7 ng ml^?1 for chloroquine and metabolites. No chromatographic interference could be detected by endogenous compounds or other antimalarial drugs. Because of the good accuracy of the method, concentrations were determinated with a relative standard deviation lower than 7% at the 25 ng ml^?l level for all substances.

An excellent precision was obtained over the range of concentrations tested, 25–1000ng ml^?l. This method can be applied to therapeutic, pharmacokinetic and epidemial studies.     

Quantification of Suramin by Reverse-Phase Ion-Pairing High-Performance Liquid Chromatography

Abstract

A specific and sensitive method has been developed for the separation and quantification of suramin and trypan blue (internal standard) in human plasma. Plasma samples were extracted by centrifugation after the addition of ion-pairing reagent (tetra-butylammonium phosphate, TRAP) and methanol. Extracts were injected directly onto a reverse-phase ion-pairing HPLC system with 5 mM TBAP in the mobile phase. There was nearly 100% extraction efficiency after 3 cumulative extracts of each sample. The limit of quantitation was 0.5 μg/ml at a detection wavelength of 313 nm. Analysis of 3 post-therapy samples from a patient with AIDS was used to determine a plasma half-life for suramin of at least 3 weeks.     

Simultaneous Determination of Diazepam and its metabolites in Plasma by High-Performance Liquid Chromatography

Abstract

A reversed phase high-performance liquid chromatographic method (HPLC) for the simultaneous determination of diazepam and its three active metabolites, nordazepam, oxazepam and temazepam, in plasma was proposed. The compounds were isolated by solid-phase extraction. The chromatographic mobile phase was metanol-water (55:45, v/v) at a flow rate of 1 mL/min. UV detection was performed concurrently at 240 and 254 nm.     

Simultaneous Determination of Food-Related Amines by High-Performance Liquid Chromatography

Abstract

Ten amines found in marine foods, dimethylamine, trimethylamine, trimethylamine oxide, ammonia, urea, histamine, cadaverine, putrescine, spermine and spermidine were separated by HPLC using an ion-moderated partition column. Optimum resolution and sensitivity were obtained using 0.003N sodium hydroxide as the mobile phase and UV detection at 208 nm.     

Simultaneous Determination of Pioglitazone and Glimepiride by High-Performance Liquid Chromatography

A rapid and accurate HPLC method has been developed for simultaneous determination of pioglitazone and glimepiride. Chromatographic separation of the two pharmaceuticals was performed on a Cosmosil C₁₈ column (150 mm × 4.6 mm, 5 m) with a 45:35:20 (v/v) mixture of 0.01 m triammonium citrate (pH adjusted to 6.95 with orthophosphoric acid), acetonitrile, and methanol as mobile phase, at a flow rate of 1.0 mL min^–1, and detection at 228 nm. Separation was complete in less than 10 min. The method was validated for linearity, accuracy, precision, limit of quantitation, and robustness [1, 2]. Linearity, accuracy, and precision were found to be acceptable over the ranges 2.50–30.00 g mL^–1 for pioglitazone and 0.10–10.00 g mL^–1 for glimepiride.     

Simultaneous Separation and Determination of Different Polar Flavonoids in Multiflora Fruit by Reverse-Phase High-Performance Liquid Chromatography

Abstract

A method for the determination of different polar flavonoids from multiflora fruit by reverse-phase high-performance liquid chromatography (HPLC) is presented in this article. Chromatographic separation of these flavonoids was performed over a Diamonsil C₁₈ column (200 mm × 4.6 mm × 5 µm) using gradient elution with an isopropanol–methanol–water mixture at 25°C, at a flow rate ranging from 0.5 to 1.5 mL/min and detection at 360 nm. The flavonoids could be separated within 6 min; the recovery was between 96% and 104%, and the relative standard deviation was 1.6–2.6%. This method allows rapid detection of flavonoids.     

Estimation of Alprazolam and Sertraline in Pure Powder and Tablet Formulations by High-Performance Liquid Chromatography and High-Performance Thin-Layer Chromatography

Abstract

This article describes validated high-performance liquid chromatographic (HPLC) and high-performance thin-layer chromatographic (HPTLC) methods for simultaneous estimation of alprazolam (ALZ) and sertraline (SER) in pure powder and tablet formulation. The HPLC separation was achieved on a Nucleosil C18 column (150 mm long, 4.6 mm i.d., and 5-µm particle size) using acetonitrile and phosphate buffer (50 + 50 v/v), pH 5.5, as the mobile phase at a flow rate of 1.0 mL/min at ambient temperature. The HPTLC separation was achieved on an aluminum-backed layer of silica gel 60 F₂₅₄ using acetone/toluene/ammonia (6.0:3.0:1.0, v/v/v) as the mobile phase. Quantification with the HPLC method was achieved with ultraviolet (UV) detection at 230 nm over the concentration range 3–18 µg/mL for both drugs with mean recovery of 101.86 ± 0.21 and 100.57 ± 0.31% for ALZ and SER, respectively. Quantification in HPTLC was achieved with UV detection at 230 nm over the concentration range of 400–1400 ng/spot for both drugs with mean recoveries of 101.32 ± 0.15 and 100.38 ± 0.51% for ALZ and SER, respectively. These methods are rapid, simple, precise, sensitive, and are applicable for the simultaneous determination of ALZ and SER in pure powder and formulations.     

反相高效液相色谱对DABTH—氨基酸的分离与鉴定

应用反相高效液相色谱(RP-HPLC)技术,采用等度洗脱。对20种标准DABTH-氨基酸进行了分离与鉴定,灵敏度达到pmol水平;并以溶菌酶为模式蛋白,经手工DABITC/PITC双偶联方法对其N端部分序列进行Edman降解,其降解产物DABTH-氨基酸用RP-HPLC技术进行了鉴定,蛋白质微量序列分析的灵敏度达到nmol水平.     

Simultaneous Quantification of Puerarin and Daidzein in Rat Plasma by High-Performance Liquid Chromatography with Post-Column Modification and Fluorescence Detection

A sensitive HPLC method based on post-column modification and fluorescence detection has been developed for determination of puerarin and daidzein in rat plasma. Chromatographic separation was performed on a C₈ column with a linear gradient prepared from 0.5% aqueous acetic acid and 0.5% acetic acid in acetonitrile, delivered at a flow rate of 0.8 mL min⁻¹. Naringin was used as the internal standard. It was necessary to use acetic acid in the mobile phase to achieve good separation, but this led to fluorescence signal suppression, because puerarin and daidzein have native fluorescence at pH 8.0–9.0. To enhance the sensitivity, post-column modification with alkaline buffer was adopted. After this modification, detection sensitivity for puerarin and daizein increased more than 500-fold and 600-fold, respectively, compared with direct fluorescence detection. Signal-to-noise ratios for detection for puerarin were more than 150 times better than for UV detection after use of the same method of sample preparation. This sensitive analytical method was successfully used to determine pharmacokinetic data for puerarin and daidzein in rat plasma after oral administration of a single dose of Puerariae radix extract containing puerarin (approx. 8.4 mg) and daizein (approx. 5.9 mg) to male SD rats.     

Simultaneous Determination of Selected Veterinary Antibiotics and their Main Metabolites in Fish and Mussel Samples by High-Performance Liquid Chromatography with Diode Array-Fluorescence (HPLC-DAD-FLD) Detection

A reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantitative determination of 11 antibiotics (drugs) and the main metabolites of five of them in fish tissue and mussel samples were developed, optimized, and validated. The analytes belong to four different classes of antibiotics (sulfonamides, tetracyclines, penicillin, and amphenicols). The analyzed compounds were sulfadiazine and its N⁴-acetylsulfadiazine metabolite; sulfamethazine and its N⁴-acetylsulfamethazine; sulfamerazine and its N⁴-acetylsulfamerazine; sulfamethoxazole; trimetroprim; amoxicillin and its main metabolite amoxicilloic acid; ampicillin and its main metabolite ampicilloic acid; chloramphenicol; thiamphenicol; oxytetracycline; and chlortetracycline. For HPLC analysis, diode array and fluorescence detectors were used. The separation of the analyzed compounds was conducted by means of a C₁₈ (150 mm × 4.6 mm I.D., particle size 5 µm) analytical column with LiChrospher® C₁₈ (4 mm × 4 mm, particle size 5 µm) guard-column. Analyzed drugs were determined within 35 minutes using formic acid 0.1% in water and acetonitrile in gradient elution mode as the mobile phase. The method was applied to the determination of the analytes in tissue of hake (Merluccius merluccius), anchovy (Engraulis encrasicolus), mussel (Mytltus sp.), and wedge sole (Solea solea). The proposed method was also evaluated by a laboratory assay consisting of the determination of the targeted analytes in samples of Cyprinus carpio that were previously administered controlled doses of the antibiotics.     

Quantitation of Toremifene and its Major Metabolites in Human Plasma by High-Performance Liquid Chromatography Following Fluorescent Activation

Abstract

A highly sensitive reverse-phase high-performance liquid chromatography assay utilizing fluorescence activation has been developed for the quantitative analysis of the anti-estrogenic compound toremifene and its major metabolites, 4-hydroxy-toremifene and N-desmethyl-toremifene. Plasma samples containing various quantities of toremifene and its metabolites were spiked with an internal standard (nafoxidine), extracted with 2% n-butanol in hexane, and irradiated with high intensity ultraviolet light (254 nm). Aliquots of the extracted plasma components were then injected onto a C-18 reversed phase column and eluted isocratically with a mobile phase of water and triethylamine in methanol. Fluorescence of toremifene, its metabolites, and internal standard was measured at an excitation wavelength of 266 nm. -The sensitivity of this assay was 8.0, 15.0 and 5.0 ng/mL for toremifene, N-desmethyl-toremifene and 4-hydroxy-toremifene, respectively. Linearity was achieved for the concentration range of 25 to 400 ng/mL for all the compounds, with correlation coefficients of greater than 0.994. The assay presented is highly specific, very sensitive and demonstrates reproducible linearity throughout a wide range of clinically relevant plasma toremifene concentrations.     

Quantitation of Purines and Pyrimidines in Human Serum by High-Performance Liquid Chromatography

Abstract

A high-performance liquid chromatography assay was developed for the purpose of examining xanthine, hypoxanthine, uridine, thymidine, allopurinol, and oxypurinol in serum of patients with advanced carcinoma treated with methorexate and 5-fluorouracil. After the addition of an internal standard, serum samples were extracted of purines and pyrimidines with trichloroacetic acid and neutralized with tert-amine. Aliquots of the extracted serum were injected onto a C18 reverse-phase column and purines and pyrimidines were eluted with a gradient of MeOH/H₂O and KH₂PO₄ solutions. Absorbance was detected with a variable-wavelength UV spectrophotometer at 254 nm and 280 nm. This assay can be readily applied to quantitate baseline and treatment-induced variations in serum purine and pyrimidine levels which may correlate with clinical response and/or toxicity in patients with cancer.     

Simultaneous Quantification of Seven Caffeoylquinic Acids in Ecotypes of Blumea balsamifera at Various Life Stages by High-Performance Liquid Chromatography

Blumea balsamifera is a traditional Chinese medicine containing various bioactive caffeoylquinic acids and usually used for the treatment of rheumatism, eczema, and dermatitis. An accurate and reliable high-performance liquid chromatography method was established for simultaneous determination of 5-O-caffeoylquinic acid, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 1,3-di-O-caffeoylquinic acid, 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 4,5-di-O-caffeoylquinic acid in B. balsamifera. The method was rigorously verified and was successfully applied to simultaneous quantification of seven caffeoylquinic acids in four ecotypes of B. balsamifera at five life stages. The results showed that the highest concentrations of seven compounds were present in September, October, and November, indicating that the optimal harvest time of B. balsamifera is in the autumn. Therefore, this method is suitable for the quantification of the seven compounds and quality control for B. balsamifera.     

Determination of Arbutin,Niacinamide, and Adenosine in Functional Cosmetic Products by High-Performance Liquid Chromatography

A reversed-phase high-performance liquid chromatography method using a diode array detector at 260 nm was developed and validated for the determination of arbutin, niacinamide, and adenosine in cosmetics. The analytes were extracted using methanol and deionized water. The separations were performed on a C₁₈ column with gradient elution. At the optimized conditions, the limits of detection for arbutin, niacinamide, and adenosine were 0.75, 0.12, and 0.01 µg/mL, respectively. The average recoveries were between 98.1% and 107.5%. The method was used to analyze thirty cosmetics.     

Analysis of Triorganotin Compounds by High-Performance Liquid Chromatography with Reverse-Pulse Amperometric Detection

High-performance liquid chromatography (HPLC) coupled with the reverse-pulse amperometric (RPA) detection method has been developed for the analysis of triorganotin compounds in aqueous solutions. The major advantage of RPA vs. conventional amperometric detection is its ‘in situ’ elimination of interference from dissolved oxygen in the chromatographic eluent; therefore, no extra chemicals or apparatus are required for oxygen removal. With a Partisil-10 SCX column and an eluent of methanol/0.01 M sodium acetate buffer (70:30, pH 5.5), the four triorganotins, viz., trimethyl-, triethyl-, tripropyl-, and tributyltin, can be totally separated. Detection by RPA was performed with a static dropping mercury electrode with an initial potential of ?1.15 V and a final potential of +0.15 V. The absolute detection limit (S/N = 3) ranged from 12 ng of tributyltin (as tin) to 0.3 μg of trimethyltin (as tin). Applications of the method to the analysis of trace tributyltin in marine antifoulant leachate and sea water are described.     

Determination of 19 Preservatives in Various Matrices by High-Performance Liquid Chromatography

A simple and sensitive high-performance liquid chromatography (HPLC) method was developed for the determination of 19 preservatives in cosmetic matrices. The composition of the mobile phase was optimized as a gradient to achieve a lower detection limit when compared to previously validated methods, and sample preparation conditions were investigated to optimize separation of the 19 preservatives. A C18 column was used with methanol, 0.05 mol/L ammonium acetate buffer, and water as the mobile phase under gradient elution conditions. Preservatives in cosmetics were extracted with 70% methanol using an ultrasonicator, after which they were analyzed with an HPLC-photodiode array detector. All preservatives were separated within 55 min. The recoveries ranged from 94.9% to 102.8%, with relative standard deviations of less than 3.2% and no correlation coefficients lower than 0.9986. Additionally, the developed method has a low detection limit, which makes it possible to analyze trace levels of compounds in various cosmetic and ingredient matrices.     

Simultaneous Determination of Hydrochlorothiazide and Propranolol Hydrochloride in Tablets by High-Performance Liquid Chromatography

Abstract

A simple and stability indicating HPLC procedure is described for the simultaneous determination of hydrochlorothiazide and propranolol hydrochloride in tablet formulations. Potential degradation products of both drugs and synthesis impurities of hydrochlorothiazide were separated, making the determination stability indicating for both drugs and selective for hydrochlorothiazide. All compounds were chromatographed on a cyanopropylsilane column, eluted with a 15:85 mixture of acetonitrile: 0.05 M ammonium phosphate (pH 3.0) and detected at 290 m. Excellent interlaboratory precision and recovery data were obtained. Linearity studies were carried out using peak area measurements. Detector response to the concentration of each drug was confirmed. The method was applied to dosage forms containing 25 mg of hydrochlorothiazide and 40 or 80 mg of propranolol hydrochloride.     

Simultaneous Determination of Succinic Acid and Water-Soluble Vitamins by Ion-Pair High-Performance Liquid Chromatography

A procedure is proposed for the determination of succinic acid, riboxin, nicotinamide, and riboflavin by ion-pair HPLC with UV detection. Owing to the addition of an ion-pair modifier to the mobile phase and the selection of gradient elution conditions, the optimal retention and resolution of peaks of the components to be determined are achieved. Specificity, linearity, accuracy, and precision of the developed procedure are proved on an example of the determination of active substances in the Cerebronorm® preparation.