Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
38, Number 12, December 2000, pp. 521-527
Use
of Micellar Mobile Phases for the Chromatographic Determination of Clorazepate,
Diazepam, and Diltiazem in PharmaceuticalsMayte
Gil-Agustí[1], Samuel Carda-Broch[2], M. Celia García-Alvarez-Coque[2],
and Josep Esteve-Romero[1]
[1]Àrea de Química Analítica, Universitat Jaume I, 12006,
Castelló, Spain and
[2]Departament de Química Analítica, Universitat de València,
46100, Burjassot, Spain
An
ODS-2 column, a micellar mobile phase of high elution strength containing 0.1M
sodium dodecyl sulfate and 3% (v/v) butanol, and ultraviolet detection at 230
nm are used for the determination of either of two benzodiazepines (clorazepate
and diazepam) and a benzothiazepine (diltiazem) in pharmaceuticals. The procedure
is shown to be competitive against conventional chromatography with methanol–water
mobile phases, especially for diltiazem. The composition of the micellar mobile
phase is selected using a predictive strategy based on an accurate retention
model and assisted by computer simulation. Calibration graphs are linear at
least in the 2.5 to 20 µg/mL, 4 to 20 µg/mL, and 5 to 40 µg/mL
ranges for clorazepate, diazepam, and diltiazem, respectively. The intra- and
interday repeatabilities (%) are clorazepate (1.7, 5.2), diazepam (0.43, 3.7),
and diltiazem (0.36, 3.1). Limits of detection are well below the concentrations
of the drugs found in the commercial pharmaceutical preparations analyzed. The
drug contents evaluated with the proposed procedure are compared with the declared
contents given by the manufacturers. The achieved percentages of label claim
are usually between 95 and 104%.
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