C. Gómez Benito

Photochemical derivatization and spectrofluorimetric determination of chlorpromazine by flow injection

Abstract The flow-injection spectrofluorimetric determination of chlorpromazine was carried out by on-line photoderivatization, in which the PTFE tubing in the injection valve loop was helically coiled around the UV lamp. An aqueous solution was used as the carrier stream. The influence of foreign compounds was studied and the method was applied to the determination of chlorpromazine in pharmaceutical formulations.

Flow-injection spectrofluorimetric determination of paracetamol

Abstract A flow-injection spectrofluorimetric determination of paracetamol is reported, based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anion-exchange resin, the fluorescence being enhanced with N,N′-dimethylformamide. Concentrations of paracetamol in the range 0.04–17.60 mg l−1 are determined with a relative standard deviation of 1.5%. The injection rate is 25 samples h−1. The influence of foreign species and the determination of paracetamol in several pharamaceutical formulations are also reported.

Flow-injection analysis-spectrophotometric determination of nitrite and nitrate in water samples by reaction with proflavin

A flow-injection manifold is proposed for determination of nitrite based on the reaction with 3,6-diamino acridine (proflavin sulfate) in hydrochloride acid medium. The assembly is adapted for nitrate determination by including a reductive column filled with copperized cadmium. The influence of foreign substances is also studied. The method gives a linear calibration graph over the range 0·06-4 mg 1−1 nitrite, with an RSD <0.5%. The method was applied to nitrite and nitrate determinations in either waste water or coastal marine water samples.

Photochemical derivatization and fluorimetric determination of reserpine in a flow-injection assembly

Abstract The fluorimetric flow-injection determination of reserpine was achieved with the drug being derivatized on-line by photoreaction. PTFE tubing was helically coiled around a germicide lamp located between the injection valve and detector. Two analytical procedures are proposed using either dilute acetic acid or pure methanol as the carrier stream. The influence of foreign compounds was studied and the method was applied to the determination of reserpine in pharmaceutical formulations.

Continuous-flow spectrophotometric determination of sulfadiazine by diazotisation with in situ preparation of nitrite

Abstract Nitrite is prepared in situ for the determination of sulfadiazine. The method is based on solid-phase reduction of copperized cadmium of nitrate; the nitrite reagent merges with the sample stream in hydrochloric acid medium and the resulting mixture is injected into the water carrier, pure distilled water, and then merges with the N-(1-naphthyl)ethylendiamine reagent and is measured spectrophotometrically at 542.0 nm. The calibration graph is linear over the range 0.5–50 μg ml−1 sulfadiazine, mid-range R.S.D. = 0.3% (n = 5) and sample throughput 72 h−1. The procedure is applied to sulfadiazine determination in a pharmaceutical formulation and to in vitro dissolution studies of two different pharmaceutical formulations. The method makes the frequent preparation of the unstable nitrite solution unnecessary; the physical and chemical characteristics as well as the life-span of the solid-phase reactor are also studied.

Photochemical Derivatization and Fluorimetric Determination of Promethazine in a FIA Assembly

Abstract The flow injection fluorimetric determination of promethazine is carried out by on-line photoderivatization. The PTFE tubing is helically coiled around the lamp. An analytical procedure is proposed by using aqueous solution as carrier stream: the calibration graph is linear over the range 0.05 - 20 ppm. The influence of foreign compounds is studied and the method is applied to promethazine determination in pharmaceutical formulations.

FIA—fluorimetric determination of thiamine☆

Abstract A flow injection-fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1–4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.

Determination of promethazine hydrochloride with bromophenol blue by a turbidimetric method and flow injection analysis

Abstract A flow injection analysis procedure for the turbidimetric determination of promethazine is proposed. The sample solution is injected directly into the carrier reagent stream, which is composed of 1.16 × 10 −3 M bromophenol blue at pH 1.20. The calibration graph is linear over the range 25–197 ppm of promethazine. The influence of some foreign substances was also investigated. The method is applied to promethazine determination in a pharmaceutical formulation.

Determination of fluphenazine hydrochloride in a flow assembly incorporating cerium(IV) arsenite as a solid-bed sector

Abstract Cerium(IV) arsenite is used as a strong oxidizing solid-bed reactor in an unsegmented flow assembly. The solid was synthesized as homogeneous size particles with the suitable physico-chemical properties to resist the continuous-flow with good reactivity. The resulting manifold is proposed for the analytical determination of fluphenazine in pharmaceutical preparations by means of the fluorimetric monitoring of the oxidized drug. A linear calibration graph is obtained over the range 0.05–100 ppm of fluphenazine hydrochloride.

Spectrofluorimetric determination of emetine by flow injection using barium peroxide and UV derivatization

Abstract The flow-injection spectrofluorimetric determination of emetine was carried out by photoderivatization in the presence of barium peroxide, in a flow-injection assembly in which the PTFE tubing in the injection valve is helically coiled around the lamp. The sample solution merges with a barium peroxidephosphoric acid solution and then the resulting mixture is irradiated; pure distilled water is used as a carrier stream. The calibration graph is linear over the range 0.05–50 μ g ml −1 of emetine dihydrochloride. The influence of foreign compounds was studied and the method was applied to the determination of emetine in injection and human urine samples.