High-performance liquid chromatographic assay for nanogram determination of chlorpromazine and its comparison with a radioimmunoassay.

A specific and sensitive high-performance liquid chromatographic (HPLC) method for the quantitative determination of plasma chlorpromazine concentrations is described. The procedure is capable of determining 1 ng of chlorpromazine/ml and is adequate for following plasma concentration-time profiles after 7-mg single intravenous doses. After a simple organic extraction of the drug and an internal standard (mesoridazine) from plasma, the organic layer was transferred to a vial and evaporated to dryness at 55 degrees under nitrogen. The residue was dissolved in 200 microliters of HPLC grade acetonitrile. Aliquots (70-100 microliters) were chromatographed, and the drug was quantitated in the range of 1-15 ng/ml of plasma using a fixed-wavelength UV detector. Plasma concentrations determined by the method were compared with those obtained by a previously reported radioimmunoassay specific for chlorpromazine and N-desmethylchlorpromazine. The two methods agreed favorably with a correlation coefficient of 0.993 and a slope of 0.994.

High-performance liquid chromatographic determination of isoniazid and 1-isonicotinyl-2-lactosylhydrazine in isoniazid tablet formulations.

A high-performance liquid chromatographic procedure is presented for the simultaneous determination of isoniazid and 1-isonicotinyl-2-lactosylhydrazine (I) in isoniazid tablet formulations. An aliquot of a diluted aqueous tablet extract is introduced onto a microparticulate cyanopropyl bonded-phase column using a valve-loop injector and chromatographed using a mobile phase of acetonitrile--0.01 M, pH 3.5 aqueous acetate buffer (5:95). Compound I can be determined at levels as low as 0.5% of the isoniazid label claim. The relative standard deviations are 0.4 and 0.7% for the simultaneous determination of isoniazid and I, respectively. Seven commercial tablet formulations contained 93.8--97.0% of the labeled isoniazid amounts and 0.3--5.8% of I, expressed as equivalent isoniazid relative to the labeled isoniazid level.

Stability-indicating high-performance liquid chromatographic determination of chlorpropamide, tolbutamide, and their respective sulfonamide degradates.

A quantitative high-performance liquid chromatographic method for the determination of chlorpropamide, tolbutamide, and their respective hydrolysis products, p-chlorobenzenesulfonamide and p-toluenesulfonamide, in solid dosage forms was developed. The method is stability indicating and can be used to determine the sulfonamide hydrolysis product and the intact drug in the presence of minor degradates. Method reproducibility, demonstrated by repeated injections of a calibration standard, was 1.21%. The lower limit of quantitation of the hydrolysis products, p-chlorobenzenesulfonamide and p-toluenesulfonamide, was 0.2 microgram/5-microliter injection. The accuracy of the method for intact drugs was determined by comparison of the HPLC results to those obtained by the appropriate USP or BP assays. The mean of the results obtained by the two methods differed by 0.7% for chlorpropamide and 0.3% for tolbutamide. Pure drug samples were spiked with amounts of the hydrolysis products ranging from 20 to 120% of the intact content. The mean percent recovery for p-chlorobenzenesulfonamide was 98.6%; for p-toluenesulfonamide, it was 100.6%. A qualitative TLC procedure for the detection of chlorpropamide, p-chlorobenzenesulfonamide, dipropylurea, propylurea, n-propylamine, tolbutamide, p-toluenesulfonamide, dibutylurea, butylurea, and n-butylamine is also described.

Simultaneous determination of procainamide and N-acetylprocainamide in plasma by high-performance liquid chromatography.

A sensitive, specific, high-performance liquid chromatographic procedure is described for the simultaneous determination of procainamide and its metabolite, N-acetylprocainamide, in plasma. Basic plasma (2.0 ml), containing pheniramine maleate as an internal standard, is partitioned with methylene dichloride. The organic extract is concentrated to between 0.3 and 0.5 ml, and 100-microliter aliquots are chromatographed on a microparticulate silica gel column using 0.1% acetic acid-20% 0.1 M ammonium acetate in acetonitrile as the mobile phase. With a fixed-wavelength (254-nm) UV detector, both compounds can be quantitated in the 0.1-8.0-microgram/ml of plasma range.

Simultaneous determination of reserpine and hydrochlorothiazide in two-component tablet formulations by high-performance liquid chromatography.

A high-performance liquid chromatographic procedure is presented for the simultaneous determination of reserpine and hydrochlorothiazide in two-component tablet formulations. An aliquot of a tetrahydrofuran extract of the tablet, containing polylythiazide as an internal standard, is chromatographed on a microparticulate silica gel column using a mobile phase of 0.01% (v/v) diethylamine, 5% (v/v) chloroform, and 18% (v/v) 2-propanol in n-hexane. The relative standard deviations are 1.2 and 0.6% for the simultaneous determination of reserpine and hydrochlorothiazide, respectively. Seven commericial tablet formulations were found to contain 92.7--101.0% and 98.3--101.4% of the labeled amounts of reserpine and hydrochlorothiazide, respectively.

High-performance liquid chromatographic determination of perphenazine and amitriptyline hydrochloride in two-component tablet formulations.

A rapid, precise, and accurate high-performance liquid chromatographic procedure is presented for the simultaneous determination of perphenazine and amitriptyline hydrochloride in two-component tablet formulations. An aliquot of a methanolic extract of the tablet, containing trifluoperazine hydrochloride as an internal standard, is chromatographed on a nitrile bonded phase microparticulate column using a 0.005 M ammonium acetate-methanol (20:80) mobile phase. Quantitation is by peak area. The relative standard deviations for the procedure are 0.34 and 0.54% for the simultaneous determination of perphenazine and amitriptyline, respectively. Eight commercial tablet formulations were analyzed and found to contain 96.5-101.5 and 96.5-103.3% of the labeled amounts of perphenazine and amitriptyline hydrochloride, respectively.

Analysis of prednisolone in plasma by high-performance liquid chromatography.

A sensitive, specific high-performance liquid chromatographic procedure for the determination of prednisolone in plasma is described. The organic solvent extract from plasma is chromatographed on a silica gel column using a mobile phase of 0.2% glacial acetic acid, 6% ethanol, 30% methylene chloride in n-hexane on a high-performance liquid chromatograph fitted with an ultraviolet dector (254 nm). Quantitation of plasma samples containing 25 ng/ml prednisolone is reported. Metabolites and endogenous hydrocortisone do not interfere with prednisolone. The determination of prednisolone concentration in plasma following administration of a 10-mg single oral dose to a human subject is described.

High-performance liquid chromatographic determination of chlordiazepoxide and major related impurities in pharmaceuticals.

A rapid, precise, forward-phase (adsorption) high-performance liquid chromatographic procedure is presented for the determination of chlordiazepoxide and two common impurities, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide and 2-amino-5-chlorobenzophenone, in commercial formulations and for the determination of the benzophenone in the chlordiazepoxide drug substance. The method involves simultaneous quantitation of chlordiazepoxide and the 1,3-dihhydro impurity, followed by quantitation of the benzophenone from a separate sample extract using a second mobile phase. A single microparticulate silica gel column is used throughout. Nitrazepam and o-dinitrobenzene are the internal standards, Quantitation is by peak area using a computing integrator, except that the peak due to the benzophenone is quantitated by peak height. The described procedure is of equivalent precision, but superior accuracy, to the BP 1973 spectrophotometric procedure for the analysis of chlordiazepoxide in chlordiazepoxide formulations. Quantitation of the 1,3-dihydro and the benzophenone impurities at levels as low as 6.3 and 0.9 ng, respectively, is demonstrated.

Combined assay, identification, and foreign related steroids test for methandrostenolone by high-speed liquid chromatography.

A high-speed liquid chromatographic system is described, which can be used for the simultaneous identification of the anabolic steroid methandrostenolone and its impurities and the quantitation of each of these compounds. Separation is effected by adsorption chromatography on a slurry-packed microparticulate silica gel column.

Simultaneous high-speed liquid chromatographic determination of tetracycline and rolitetracycline in rolitetracycline formulations.

A rapid, precise high-speed liquid chromatographic procedure for the simultaneous determination of tetracycline and rolitetracycline in rolitetracycline formulations is described. Samples are dissolved in water, chilled to 0 degrees, and chromatographed on a pellicular cation-exchange resin, The specificity of this method represents a significant improvement over present analytical procedures, which fail to differentiate between rolitetracycline and its hydrolysis product, tetracycline, in these formulations.

Separation and detection of tetracyclines by high-speed liquid chromatography.

The high-speed liquid chromatographic behavior of 15 tetracyclines on anion- and cation-exchange columns is described and illustrated by typical separations of a number of tetracycline derivatives on several systems, as well as by the resolution of tetracycline from its degradation products epi-, epianhydro-, and anhydrotetracycline. These serve as a basis for a rapid, convenient, and precise method for the direct detection of the tetracycline antibiotics and their degradation products.