Ion interaction reagent reversed-phase high-performance liquid chromatography determination of anti-tuberculosis drugs and metabolites in biological fluids.

New methods of ion interaction reagent (IIR) RP-HPLC are presented for the determination of anti-tuberculosis drugs and their metabolites, singly or in multi-component mixtures, in biological fluids. The following analytes are considered: isoniazid, ethionamide, pyrazinamide, morphazinamide, p-aminosalicylic acid, nicotinic and isonicotinic acids. Aqueous solutions of three different ion interaction reagents are alternatively or comparatively used as the mobile phases, namely: (A) 5.00 mM octylamine at pH 3.00 for o-phosphoric acid, (B) 5.00 mM octylamine at pH 8.00 for o-phosphoric acid, and (C) 5.00 mM 1,6 diaminohexane at pH 6.00 for o-phosphoric acid. The response linearity between peak area and analyte concentration is verified for all the analytes in the concentration range within the determination limits and 2.00 mg/l. Detection limits are always lower than 82 microg/l for standard solutions; in the analysis of samples of rat serum, rat plasma and human serum, the matrix effect is negligible, the detection limits are always lower than 94 microg/l and the average recovery yield is always greater than 96%.

Determination of creatinine in human serum. Statistical intercalibration of methods.

An intercalibration of methods was performed in the determination of creatinine in human plasma. Jaffè, enzymatic creatinine-deaminase (CRDI) and ion-interaction reagent high-performance liquid chromatography (HPLC) methods were employed and the results were compared using a parametric t-test for multiple samples and non-parametric Mann-Whitney, Wilcoxon and Friedman tests. The comparison did not show a statistically significant difference in the use of the three methods. The ion-interaction HPLC procedure is proposed as a reference method for creatinine assays.

High-performance liquid chromatography of food colours and its relevance in forensic chemistry.

The forensic interest in the use of food colours is related to health rights and safeguard of the consumer, as established in national legislations. The regulations related to food dyes consider the health of human beings and the adulteration of foodstuffs and economic needs connected with quantitative restrictions on imports. Efficient analytical methods are required for evaluating toxicity and authenticity or adulteration, in order (a) to determine whether there are synthetic dyes present in foods and whether they are permitted, (b) to determine the levels, (c) to confirm the absence of added dyes in foods where they are not declared and (d) to check on the stability of dyes during processing and storage. Recent HPLC methods for the identification and determination of natural and synthetic dyes and of carcinogenic amines contained as impurities in synthetic dyes are reviewed.

Quantification of theophylline in human plasma by reversed-phase ion-interaction high-performance liquid chromatography and comparison with the TDx fluorescence polarization immunoassay procedure.

A new method for the determination of theophylline (1,3-dimethyl-1H-purine-2,6-dione) in human plasma is described, free from interference by theobromine (3,7-dimethyl-1H-purine-2,6-dione) and caffeine (1,3,7-trimethyl-1H-purine-2,6-dione). The method makes use of ion-interaction reversed-phase high-performance liquid chromatography (octylamine-orthophosphate being the interaction reagent and a C18 reversed-phase column the stationary phase) with spectrophotometric detection at 274 nm. The quantitative results obtained in the analysis of samples of plasma from patients undergoing treatment with theophylline were compared with those obtained for the same samples with the TDx fluorescence polarization immunoassay procedure (using the Abbot Therapeutic Drug Monitoring system), which is generally employed in hospitals and clinical laboratories. Statistical F-test and t-test for multiple samples were applied to the data obtained by the two methods. The results showed no significant difference between the two methods at the 95% confidence level.

Separation of reduced and oxidized glutathione in a pharmaceutical preparation by ion-interaction reversed-phase HPLC.

A new method is presented for the simultaneous determination of reduced and oxidized glutathione by ion-interaction reversed-phase HPLC with octylamine orthophosphate as the interaction reagent, 5-microns Spherisorb ODS-2 as the stationary phase and UV detection at 230 nm. Lower limits of detection of 2.50 micrograms ml-1 have been achieved for both the oxidized and the reduced forms. The method has been applied in the analysis of a commercial pharmaceutical preparation.

[Environment and biology of the population in the determination of blood lead levels]. / Ambiente e biologia di popolazione nel determinare i livelli ematici di piombo.

The survey presented is an attempt to explain the reasons for the higher average lead concentrations in the blood of certain groups living in two mountain valleys than encountered in residents of Turin and other towns in the Province. To this end the influence of several environmental, individual and genetic variables was investigated.