Carmen Martínez-Lozano

Simultaneous determination of doxorubicin, daunorubicin, and idarubicin by capillary electrophoresis with laser-induced fluorescence detection.

The separation and simultaneous determination of doxorubicin, daunorubicin and ida‐rubicin was investigated using capillary electrophoresis with laser‐induced fluorescence detection. Because the three anthracycline antibiotics were similar in structure and mass, careful manipulation of the electroosmotic flow and electrophoretic mobilities was required. A buffer consisting of 100 mM borate, adjusted to pH 9.5, containing 30% acetonitrile was found to provide a very efficient and stable electrophoretic system for the analysis of the three anthracyclines. The method was applied to the determination of three anthracyclines in serum samples. Responses were linear in the range of 10 — 500 ng·mL−1 and the detection limits were lower than 0.9 ng·mL−1.

Simultaneous determination of propranolol and pindolol by synchronous spectrofluorimetry

The simultaneous determination of propranolol and pindolol using synchronous fluorescence spectrometric techniques is described. The method involves measuring the natural fluorescence of these drugs in a 50% (v/v) ethanol-water medium using zero and first derivative synchronous spectrofluorimetry. Under the optimum conditions, the linear determination ranges of propanolol and pindolol are ca. 0.02-1.0 and 0.04-1.2 mug ml(-1), respectively. The results showed that propranolol and pindolol can be determined simultaneously when the concentration ratio of propranolol to pindolol varies from 1:100 to 50:1 in the mixed sample. The method has been satisfactorily applied to the determination of propranolol and pindolol in urine samples and propranolol in pharmaceutical preparations.

Flow-injection chemiluminometric determination of ascorbic acid based on its sensitized photooxidation

The chemiluminescent reaction, in alkaline solution, of lucigenin with the products from the photooxidation of ascorbic acid sensitized by toluidine blue has been studied. A flow-injection configuration is proposed for the determination of ascorbic acid over a concentration range of 1 × 10−9 −3 × 10−4 M with a throughput of 80 samples/h. The method has been used for the simple and rapid determination of ascorbic acid in pharmaceuticals, fruit juices, soft drinks and blood serum.

Successive determination of thiamine and ascorbic acid in pharmaceuticals by flow injection analysis.

A simple and rapid fluorimetric method for the determination of mixtures of thiamine and ascorbic acid is proposed. The procedure is based on the oxidation with mercury(II) of the B1 and C vitamins to form thiochrome (TC) and quinoxaline derivate, respectively. Both reaction products exhibit fluorescence at the same wavelengths (lambdaex = 356 and lambdaem = 440 nm). The procedure is optimised in a flow injection (FI) system and applied with excellent results in the determination of B1 and C vitamins in commercial pharmaceutical preparations. The calibration graphs were linear over the range 2-100 microg ml(-1) for thiamine and 5-100 microg ml(-1) for ascorbic acid. The throughput was 25 samples per hour.

Flow-injection fluorimetric determination of penicillamine and tiopronin in pharmaceutical preparations

Two flow-injection methods for the fluorimetric determination of penicillamine and tiopronin are proposed. The procedures are based on the oxidation of these drugs by thallium(III). In hydrochloric acid medium the fluorescence of thallium(I) formed in the oxidation of penicillamine or tiopronin is monitored using excitation and emission wavelengths of lambda ex = 227 nm and lambda em = 419 nm respectively. Linear calibration graphs were obtained between 3 x 10(-7) and 8 x 10(-6) M for penicillamine and between 8 x 10(-7) and 2 x 10(-5) M for tiopronin with sampling frequencies of 90 and 45 samples h-1 respectively. The relative standard deviations were in the ranges 0.48-0.29% for penicillamine and 1.04-0.31% for tiopronin. The applicability of the method to the determination of both drugs in pharmaceutical preparations was demonstrated by investigating the effect of potential interferences and by analysis of commercial preparations.

Flow-injection extraction-spectrophotometric method for the determination of ranitidine in pharmaceutical preparations

The spectrophotometric determination of trace amounts of ranitidine was carried out by liquid-liquid extraction using bromothymol blue with a flow system. The determination of ranitidine in the range of 1 x 10(-5) - 1 x 10(-4) mol l(-1) was possible with a sampling frequency of 40 samples h(-1). The method was satisfactorily applied to the determination of ranitidine in pharmaceutical preparations and the recovery was quantitative and no interferences from excipients were observed.

Flow-injection fluorimetric determination of trimeprazine and trifluoperazine in pharmaceutical preparations

A flow-injection configuration for the fluorimetric determination of trimeprazine and trifluoperazine is proposed. The procedure is based on oxidation of the drugs by cerium(IV). The fluorescence of cerium(III) formed in the oxidation of trimeprazine or trifluoperazine is monitored. Lineal calibration graphs were obtained between 2 x 10(-7) and 1 x 10(-5)M for both trimeprazine and trifluoperazine with a sampling rate of 60 samples/hr. The relative standard deviations were over the ranges 0.78-1.16 and 0.84-0.97% for trimeprazine and trifluoperazine respectively. The applicability of the method to determination of trimeprazine and trifluoperazine was demonstrated by investigating the effect of potential interferences and by analysis of commercial pharmaceutical preparations.

Flow injection fluorimetric determination of thiamine and copper based on the formation of thiochrome

The reaction, involving the oxidation of thiamine by copper(II) in basic solutions to fluorescent thiochrome, has been adapted to the determination of thiamine by flow-injection analysis. Linear calibration graphs are obtained between 0.30 and 6.02 mug/ml with a sampling rate of 50 samples/hr and a relative standard deviation of 0.53%. This reaction has also been adapted to the determination of copper(II) over the range 0.5-5.0 mug/ml. The applicability of both methods for determination of thiamine and copper is demonstrated by investigating the effect of potential interferences and by the analysis of real samples (pharmaceuticals for thiamine and ores and alloys for copper).

Determination of epinephrine, norepinephrine dopamine and L-dopa in pharmaceuticals by a photokinetic method

A study of the photochemical reaction of the Rose Bengal (RB)-ethylenediaminetetraacetic acid system in the presence of epinephrine, norepinephrine, dopamine and L-dopa is presented. The rate of photoreduction of RB is dramatically retarded by small amounts of these catecholamines, which have an inhibitory effect on the excited state of RB, which is the activator of the process. Optimum conditions for the determination of catecholamines in the range of concentration between 5 x 10(-6) and 1 x 10(-4) mol dm-3 are described. The proposed method has been applied with excellent results to the determination of catecholamines in pharmaceuticals.

Direct determination of ranitidine and famotidine by CE in serum, urine and pharmaceutical formulations

A simple and sensitive capillary electrophoresis method using UV detection has been developed for the direct determination of ranitidine (RANT) and famotidine (FAMT) in serum, urine and pharmaceutical formulations. A buffer consisting of 60 mM phosphate buffer adjusted to pH 6.5 was found to provide a very efficient and stable electrophoretic system for the analysis of both drugs. The detection limits obtained were 0.088 microgram ml(-1) for RANT and 0.16 microgram ml(-1) for FAMT.