Micellar liquid chromatographic determination of five antianginals in pharmaceuticals.

A procedure was developed for the determination of five antianginals (diltiazem, nadolol, nifedipine, propranolol and verapamil), using hybrid micellar mobile phases of sodium dodecyl sulphate (SDS) and pentanol, a C18 column and UV detection. All possible combinations of antianginals were resolved and determined using a mobile phase of 0.05 M SDS-5% pentanol with an analysis time of 9 min. Repeatabilities and intermediate precision were evaluated at four different drug concentrations in the 2-20 microg/ml (n=5) range. Limits of detection were in the range 0.028 microg/ml for diltiazem and 0.130 microg/ml for verapamil. The range of the limit of quantitation was from 0.092 to 0.431 microg/ml for the same compounds. Antianginal drugs were studied in pharmaceuticals with no interference from related compounds. The results of the analyses of pharmaceuticals formulations were in agreement with the declared compositions.

Direct determination of verapamil in urine and serum samples by micellar liquid chromatography and fluorescence detection.

Verapamil, a calcium channel antagonist, is one of the most commonly prescribed drugs in the treatment of hypertension. In this work, it was determined in serum and urine samples by a sensitive and precise chromatographic procedure without any pre-treatment step in a C18 column using a micellar mobile phase of 0.15M sodium dodecyl sulfate and 5% pentanol at pH 7. Fluorescence detection set at 230 nm (excitation) and 312 nm (emission) was used. Verapamil is eluted at 12.5 min with no interference by the protein band or endogenous compounds. Linearities (r > 0.998), as well as intra- and inter-day precision, were studied in the validation of the method. LODs were also calculated to be 11.0, 18.5 and 20.2 ng/mL in micellar solution, serum and urine, respectively. Recoveries in the biological matrices were in the 97-99% range. Drug excretion in urine was studied in a volunteer receiving treatment for hypertension, and verapamil, as an unchanged drug, was separated from other metabolites. The procedure developed can be useful in the field of toxicology and clinical analysis.

Rapid determination of acetaminophen in physiological fluids by liquid chromatography using SDS mobile phase and ED detection.

Acetaminophen is determined in serum and urine samples by a rapid, sensitive, and precise chromatographic method without any pretreatment step in a C18 column using a pure micellar mobile phase of 0.02M sodium dodecyl sulfate at pH 7. Acetaminophen is eluted in less than 5 min with no interference of the protein band. The use of electrochemical and UV detection is compared. Linearities (r > 0.999), as well as intra- and interday precision, are studied in the validation of the method. Limits of detection (LOD) are also calculated to be 0.56, 0.83, and 0.74 ng/mL in micellar solution, serum, and urine using electrochemical detection. The developed micellar liquid chromatographic method is useful for the quantitation of acetaminophen in serum and urine. Recoveries in the biological matrices are in the 98-107% range and results are compared with those obtained using a reference method. Drug excretion (in urine) and serum distribution are studied in several healthy volunteers, and no interference from metabolites is found. The developed procedure can be applied in routine analyses, toxicology, and therapeutic monitoring.

Micellar liquid chromatography determination of some biogenic amines with electrochemical detection.

A simple and reliable liquid chromatographic procedure is successfully applied to the simultaneous determination of the biogenic amines, dopamine, serotonin, their metabolites (homovalinic acid (HVA) and hydroxyindoleacetic acid (HIAA)) as well as tyramine in serum samples. After an optimization procedure using a C18 column, the mobile phase selected was 0.15 M sodium dodecyl sulfate buffered at pH 3, in which the serum samples were directly injected and the analysis time for the five substances was less than 12 min. The use of electrochemical (ED) and ultraviolet (UV) detection was compared. The limits of detection of the biogenic amines studied were drastically improved using ED detection. Repeatability and intermediate precision were tested at three different concentrations and the relative standard deviations were below 1.5% for most assays. Finally, the method was successfully applied to the determination of biogenic amines in serum samples.