Chemistry of nonaqueous titration of chlopromazine.

The chemistry of the red color formed during perchloric acid titration of chlorpromazine hydrochloride in acetic acid in the presence of mercuric acetate is discussed. Addition of ascorbic acid prevents the color formation and allows titration using a crystal violet end-point. Ascorbic acid addition also sharpens the potentiometric end-point. Ascrobic acid and its oxidation product, dehydroascorbic acid, being neutral to perchloric acid, do not interfere with the titration.

Nonaqueous titration of sulfates of quinine and quinidine using barium acetate.

A nonaqueous titrimetric method is proposed for determining the diastereomeric sulfates of quinine and quinidine. The sulfuric acid content of the alkaloid salts is precipitated, in the form of barium sulfate, with acetous barium acetate solution before the liberated alkaloid is titrated; the necessary calculations are provided. A favorable characteristic of the proposed procedure is the accuracy, speed, and ease of performance. The mean percent recoveries (p = 0.05) obtained with the proposed method for the sulfates of quinine and quinidine were 98.84 +/- 1.00 and 99.74 +/- 1.27, respectively, compared with 100.73 +/- 1.44 and 100.82 +/- 1.16, respectively, when the BP 1968 procedure was applied.

Determination of phenothiazines by charge-transfer complex formation with chloranilic acid.

A rapid and sensitive spectrophotometrc method has been developed for the microdetermination of some phenothiazine derivatives as the pure substances and in different dosage forms. The method depends on the formation of stable donor-acceptor complexes between phenothiazines and chloranilic acid in an acetonitrile-2-propanol solvent mixture. The resulting intensely purple chloranilic acid radical anion possesses a characteristic absorption maximum at 515 nm. Beer's law is obeyed over the concentration ranges 1-6, 1-10 and 5-30 mug ml for prochlorperazine dimaleate, trifluoperazine dihydrochloride and thiethylperazine dihydrochloride, with apparent molar absorptivities of 7.76 x 10(4), 1.95 x 10(4) and 6.64 x 10(3) 1. mole(-1).cm(-1), respectively. Statistical comparison of the results with those of an official method shows excellent agreement and indicates no significant difference in precision.

Fluorimetric determination of aminoglycoside antibiotics using lanthanide probe ion spectroscopy.

The application of probe ion fluorimetry has succeeded in the microdetermination of six aminoglycoside antibiotics: neomycin, streptomycin, gentamicin, tobramycin, amikacin and kanamycin as sulfate salts in pure form and in some pharmaceutical preparations. The method is based on the reaction of Eu(3+) ions with aminoglycosides through amino and hydroxy groups. Such interactions enhance the intensity of the 616 nm fluorescence emission of the Eu(3+) ion. The fluorescence at 592 nm comes from a non-hypersensitive transition and is not affected by the ligand which is bound to the probe ions. The intensity ratio R, defined as I (592)I (616) was used to determine the amount of free and bound europium ions. A linear relationship between bound europium ions and aminoglycoside was found within the concentration ranges 20-100 ppm for neomycin, 5-60 ppm for streptomycin, and 10-70 ppm for gentamicin, tobramycin, amikacin, and kanamycin as sulfate salts. The percentage recoveries ranged from 99.22 to 101.07, with standard deviations ranging from +/- 1.5 to +/- 4.38. The relative stability constants ranged from 5 x 10(3) to 2 x 10(4). The optimum reaction conditions were studied and the results obtained compared favourably with the fluorimetric method using fluorescmine reagent.

Europium(III) ion probe spectrofluorometric determination of diclofenac sodium.

A new method has been devised for the determination of diclofenac sodium in bulk and in pharmaceutical preparations using Eu3+ ions as the Fluorescent probe. The technique was built around the hypersensitive property of the transitions of the fluorescent probe ion, Eu3+, at 616 nm. This is normally a forbidden transition, but the interaction with diclofenac sodium, which contains a carboxylic group, makes the transition allowed and enhances the intensity of its fluorescence emission. The Eu3+ fluorescence emission at 592 nm comes from a non-hypersensitive transition and is not affected by ligation. The intensity ratio, R, defined as I592/I616, was used as a measure of the percentage of bound probe ions. Diclofenac and Eu(III) forms a (1:1) molar complex. The relative stability constant of the complex was found to be 10(5). A linear relationship between bound Eu3+ and the concentration of diclofenac sodium was found for concentrations from 10 to 200 micrograms ml-1, with a recovery percentage of 100.22 +/- 2.27. The method shows a good agreement with a spectrophotometric method.

Gas chromatographic assay of methyltestosterone in tablets.

A simple gas chromatographic procedure has been developed for the determination of methyltestosterone in bulk powders and in tablets. Two new silyl ether derivatives of methyltestosterone have been prepared using dimethylethylsilylimidazole (DMESI) and dimethylisopropylsilylimidazole (DMiPSI). The method is accurate and selective for methyltestosterone within the concentration range 0.1-1.5 micrograms microliters-1.

Sensitive colorimetric determination of copper (II) ions in some chemicals and multivitamins.

A sensitive and selective colorimetric method has been devised for the micro-determination of copper (II) ions in pure form, some chemicals and multivitamin preparations. The method depends on the formation of stable blue complexes in ammonia medium peaking at 615 nm between copper (II) ions, oxalyldihydrazide and one of the following aldehydes: 4-nitrobenzaldehyde, 2-nitrocinnamaldehyde and formaldehyde with minimum detection limits 0.1, 0.16 and 1.1 ppm, respectively. Several metal ions do not interfere. The optimum reaction conditions were studied and the results obtained were favorably comparable to the diethyldithiocarbamate method.

Assay of certain oral contraceptive formulations by gas chromatography-mass spectrometry-selected ion monitoring.

The combined technique of gas chromatography--mass spectrometry--selected ion monitoring (GC-MS-SIM) has been employed for the nanogram level determination of ethinyloestradiol, mestranol, norgestrel and norethisterone in various oral contraceptive formulations. Steroids were assayed as their DMES-or methoxime DMES ether derivatives in the presence of ethisterone as the internal standard. The method is accurate, specific and suitable for single tablet assay.

Gas chromatography and mass spectrometry of dimethylethylsilyl ether derivatives of norethisterone metabolites in plasma.

Metabolites isolated from human plasma after oral administration of norethisterone were assayed as their novel dimethylethylsilyl ether derivatives by gas chromatography--mass spectrometry--ion selective monitoring. The major metabolite is 3 alpha, 5 alpha-tetrahydronorethisterone. The unchanged drug is present in a measurable amount even after 8 h of drug administration. The method is accurate, precise and highly sensitive.