Anatol Kojło

Simultaneous spectrophotometric determination of nitrite and nitrate in a flow-injection system

Abstract A spectrophotometric flow-injection method based on a diazo-coupling reaction is proposed for the simultaneous determination of nitrite and nitrate. Nitrate is reduced to nitrite by using a reductor column which is formed by filling part of the sample loop with copperized cadmium. The flow system produces a signal of which the height of a shoulder in the ascending part of the peak corresponds to the nitrite concentration and the maximum of the peak corresponds to nitrate plus nitrite. The method is suitable for the simultaneous determination of both ions in natural waters. The detection limit is 0.1 mg 1−1 for nitrite and 0.5 mg 1−1 for nitrate. Up to 22 samples can be analyzed per hour with a relative precision of ca. 1–2%.

Flow-injection biamperometric determination of epinephrine

A flow-injection manifold is proposed for the determination of epinephrine. The experimental procedure is based on the indirect biamperometric detection of the drug by using Fe(III)-Fe(II) as an indicating redox system and a flow-through detector with two polarized Pt wire electrodes. The calibration graph is linear over the range 0.3-20 micrograms ml-1 of epinephrine. The relative standard deviation for the determination of 10 micrograms ml-1 of epinephrine is 1.5% (n = 25) and the sample throughput is 153 h-1. The method was applied to the determination of epinephrine in two commercially available pharmaceutical preparations.

Spectrofluorimetric flow injection determination of adrenaline with an iodine solid-phase reactor

Abstract A novel strategy for the preparation of solid-phase reactors by “impregnation” of a poly(vinyl chloride) coil with the reagent was carried out and applied to the fluorimetric flow injection determination of adrenaline. The calibration graph was linear over the range 5–25 mg l −1 of adrenaline, the reproducibility (R.S.D.) was 1.8% (15 replicates) and the sample throughput 32 h −1 .

Flow-injection biamperometry of phenothiazine derivatives

Abstract A flow-injection method for indirect amperometric determination of promazine and thioridazine using two polarized platinum electrodes was developed. Among seven different indicating systems examined, the most suitable for the determination of phenothiazine derivatives was found to be the redox system Fe(III)/Fe(II). The method developed was applied to several commercial pharmaceutical preparations.

Flow-injection ultraviolet spectrophotometric determination of sulphate in natural waters

Abstract The proposed method is based on measurement of the absorbance of the FeSO4+ complex cation at 355 nm. Sample-injection and reagent-injection procedures are described. Calibration graphs are linear in the ranges 25–600 and 10–150 mg l−1 sulphate, respectively. The main interference is from ultraviolet-absorbing organic compounds in the waters. Methods of eliminating the interference are discussed. Results for sulphate in river waters compare satisfactorily with those obtained by the gravimetric method. Depending on the pretreatment used, 10–30 samples can be analyzed per hour.

Immobilization of Hexacyanoferrate (III) for a Flow Injection-Spectrophotometric Determination of Promazine

Abstract An automated flow injection method for the determination of promazine is described. The method is based on the oxidation of promazine by hexacyanoferrate (III) and spectrophotometric monitorization of oxidized drug. The chemical and FIA variables were optimized. The calibration graph was linear over the concentration range 2,5–25 ppm of promazine hydrochloride. Some interfering substances were also investigated. The method was applied for the determination of promazine in pharmaceutical formulations.

Flow injection spectrophotometric determination of promazine

A method for the spectrophotometric determination of promazine by flow injection analysis is reported. The procedure is based on the reaction of promazine with molybdophosphoric acid. Concentrations of promazine in the range 1-25 ppm have been determined with a relative standard deviation of 1.8% at 10 ppm (n = 20). The method was applied to the determination of promazine in injections and compared favourably with an independent reference method based on spectrophotometry.

FIA-spectrophotometric determination of N-substituted phenothiazine derivatives by oxidation with a solid-phase reactor of manganese dioxide incorporated in polyester resin beads

The determination of several N-substituted phenothiazine derivatives was carried out by the reaction of the drug with managanese dioxide entrapped in a polymeric material in a packed-bed reactor; the oxidized drug was monitored at lambda(max). The calibration graph is linear over the range 5-50 mug/ml of phenothiazine derivatives with a relative standard deviation of 0.5-1% (at 10 mug/ml) and sample throughput of 40-48 h(-1). The influence of foreign compounds was studied and the method was applied to the determination of six different phenothiazine derivatives in pharmaceutical formulations.

Flow-Injection Biamperometry of Phenol

ABSTRACT A simple and rapid method determination of phenol is described, using a bromination reaction and biamperometric detection. The method is based on measurements of the intensity of current passing through two identical inert electrodes giving the concentration of phenol in samples. The sample is injected into a stream of carrier and merged with a stream of acidic bromine solution which brominates phenol in the reaction coil. A linear relationship between peak height and phenol concentration is observed in the range of 0.05 to 8 μg ml−1 of phenol. The relative standard deviation was 2.8% for analysis of 5μg ml−1 phenol and the sampling rate was 70 h−1

Indirect Potentiometric Determination of Chlorpromazine with an Oxidative Column In a Flow Injection System

Abstract A flow-injection method is proposed for the determination of chlorpromazine and other N-substituted phenothiazines. The procedure is based on the oxidation of analyte with lead dioxide entrapped into polymeric material in a packed-bed reactor. The oxidation of the drug yields soluble Pb2-, which is monitored by means of the lead ion selective electrode in the wall-jet configuration. The calibration graph is linear over the range of 0.01 – 2 μg ml−1 of chlorpromazine with relative standard deviation of 1.4% and sample throughput 20 h−1. The developed method was applied to the determination of chlorpromazine in pharmaceutical preparations.