Flow-chemiluminescence: a growing modality of pharmaceutical analysis.

The present article deals with a review of the applications of the chemiluminescence to pharmaceutical analyses by using continuous-flow assemblies. A comprehensive study on the fundamentals of the chemiluminescence is also included.

Determination of phenylephrine hydrochloride by flow injection analysis with chemiluminescence detection.

A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80 degrees C. The calibration graph is linear over the range 0.03-8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.

Enhanced chemiluminescent determination of chloramphenicol and related nitro compounds by 'on-line' photochemical reaction.

The viability of tandem photochemical reaction-chemiluminescence detection was studied for a heterogeneous family of nitro compounds using chloramphenicol as a test substance. The 'on-line' chemical photodegradation of chloramphenicol was performed in a flow injection assembly by using a photoreactor consisting of a 725 cm x 0.5 mm id piece of PTFE tubing coiled around an 8 W low-pressure mercury lamp. Photodegraded chloramphenicol was detected by oxidizing photo-fragments from the parent compound and their subsequent reaction with a luminol-Co(II) system. The calibration graph was linear up to 3 x 10(-5) mol l-1 chloramphenicol, the limit of detection was 3 x 10(-9) mol l-1, the relative standard deviation was 1.8% for 2 x 10(-6) mol l-1 of the drug and the sample throughput was 60 h-1. The proposed method was used to determine chloramphenicol in pharmaceutical formulations and its application to other related nitro compounds was studied.

Indirect determination of paracetamol in pharmaceutical formulations by inhibition of the system luminol-H2O2-Fe(CN)3-(6) chemiluminescence.

After a large drug scanning, the system Luminol-H2O2-Fe(CN)6(3-) is proposed for first time for the indirect determination of paracetamol. The method is based on the oxidation of paracetamol by hexacyanoferrate (III) and the subsequent inhibitory effect on the reaction between luminol and hydrogen peroxide. The procedure resulted in a linear calibration graph over the range 2.5-12.5 microg ml(-1) of paracetamol with a sample throughput of 87 samples h(-1). The influence of foreign compounds was studied and, the method was applied to determination of the drug in three different pharmaceutical formulations.

FIA-AAS determination of salicylic acid by a solid-phase reactor of copper carbonate incorporated in polyester resin beads.

The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0-75 mug ml(-1) of salicylic acid, with a relative standard deviation of less than 1.5% and a sample throughout of 257 h(-1). The influence of foreign compounds was studied and the method was applied to the determination of salicylic acid content in two different pharmaceutical formulations.

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.

Fia-spectrophotometric determination of thiamine after UV-irradiation.

The determination of thiamine was carried out by UV-photodegradation in a single-line flow-injection assembly. The UV-photodegradation of thiamine was carried out in the coil of the injection valve, constituted of a PTFE tubing, half of its length being helically coiled around a UV lamp. A peak with two adjoining maxima was produced by injection, corresponding to the absorbance of the irradiated and non-irradiated sample. The analytical parameter is the difference between the two peaks, measured at 264 nm. The calibration graph is linear over the 1.2-30 mug/ml range of thiamine hydrochloride in 0.1M HCl. The influence of certain admixed substances was studied and the method was tested for the determination of thiamine in tablets.

Immobilization of reagents by polymeric materials. Determination of metamizol.

A method for immobilization of inorganic reagents, based on the dispersion of the reagent into an unsaturated polyester solution is applied to immobilization of lead dioxide. The obtained solid is of application in a flow-injection manifold for indirect atomic absorption determination of metamizol in pharmaceutical formulations. The procedure gives a linear calibration graph up to 6 ppm of metamizol with a relative standard deviation of 1.6% (3.0 mg/l) and a sample throughput of 72 hr(-1).

Device for data-acquisition from transient signals: kinetic considerations.

This paper reports on the evaluation and testing of a home-made device. Data-acquisition, treatment of transient signals and the hardware and software involved are discussed. Some practical aspects are developed in order to power the autonomy of procedures using the device. Kinetic and multi-signal calculations are considered in order to cover the actual tendencies in continuous-flow analysis. Somepractical advantages versus the use of classical chart recorders or commercial computerized-instrument devices are pointed out.

Determination of levamisole hydrochloride with HgI(2-)4 by a turbidimetric method and flow-injection analysis.

This paper is concerned with the use of ion-association compounds in the analysis of pharmaceutical samples by FIA. The usual extraction into an organic phase is avoided by using turbidimetric detection. Determination of levamisole with HgI(2-)(4) has been developed as a practical example: the experimental variables were optimized by the modified simplex method. The calibration graph is linear over the levamisole concentration range 7-32 microg ml . The reproducibility (rsd) and injection sample rate are 0.9% and 80/hr, respectively.

Favorable effects of the lipid-lowering and platelet antiaggregant Plafibride on the aging process of mice of the C57bl/6J strain.

It is known that an excessive intake of lipids and raised lipid levels in the blood accelerate many of the age-dependent pathologies. Therefore, it is probable that the administration of hypolipidemic agents delays to a certain degree the rate of aging. This concept has been experimentally tested in mice of the C57BL/6J strain treated with N-(2-p-chlorophenoxy) methylpropionil)-N'-morfolinomethylurea (Plafibride). The chemical was given in diet pellets at a dose of approximately 180 mg/kg body weight/day. There were no manifestations of toxicity despite the fact that treatment lasted 8 months. On the contrary, it seems that the aging process was favorably influenced since vigor and neuromuscular coordination were somewhat preserved in the treated mice in comparison to the controls. Moreover, old mice treated with Plafibride showed values for body and liver weights that were more similar to those of younger mice. These effects were especially evident in animals fed an hypercaloric diet enriched with fat and sucrose. The present experimental results suggest performing clinical studies for investigation of the effects of long-term treatment with Plafibride on the physiological and pathological manifestations of human aging.

Polarographic determination of proguanil and chlorhexidine.

The method is based on the cathodic wave obtained for chlorhexidine and proguanil in buffered aqueous dimethylformamide media. Concentrations up to 8 x 10(-5) and 6 x 10(-4)M, respectively, can be determined. The difference in behaviour at various pH values or in the presence of surface-active agents, is useful for characterization of both biguanides.

A compound of iron(II), phenylbiguanide and cyanide.

A spectrophotometric investigation has been made of the red water-soluble complex of phenylbiguanide with iron(II) in cyanide medium. The complex is found to have maximum absorbance at 520 nm. Use of the extension of the Asmus method to M(s)L(m)L'(n) complexes and of Koch and Ackermann's method suggests the formula [Fc(phenylbiguanide)(CN(4))](2-) for the red compound. Anlytical procedures for the detection of iron and cyanide are proposed.