This short review provides the recent progresses on continuous monitoring of atmospheric ozone. The analytical performance is defined in US-EPA 40 CFR Part 53, and Federal Equivalent Method for ozone adopts an ultraviolet photometry to meet the definition. Chemical monitoring systems including spectrophotometry with dye bleaching, chemiluminescence, and bioluminescence have been developed to satisfy the analytical performance. Changes in the electric resistance of semiconductors are also utilized for the measurements. Some of the proposed instruments have been applied to the monitoring of ozone in the ambient air, and reliable results are demonstrated.

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Utilizing the methodology of sequential injection (SI) analysis, a novel automated method was developed for the rapid determination of 6-thioguanine (6-TG) and 6-mercaputopurine (6-MP) which are well-known antimetabolic drugs. The method involved a direct amperometric detection of these compounds by using an electrochemically activated carbositall electrode (CSE). The linear dynamic ranges of 0.1 – 100 and 0.2 – 200 µg mL^-1, with the detection limits (S/N =3) of 0.03 and 0.06 µg mL^-1, were obtained for 6-TG and 6-MP, respectively. Sampling rate – 70 h^-1, sample volume – 500 µL. The applicability of the proposed SI-amperometric system was demonstrated by analysing the thiopurine drugs with good recoveries (98.8 – 102.0 %) and reproducibility of the electrode response (RSD < 2.0 %). The method can be useful for automated dissolution testing of thiopurine antimetabolic drugs.

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In this tutorial review, the principle of on-line sample concentration by evaporation through a Nafion membrane tubing and its application to post-column concentration of anions by ion chromatography are described. As solution flows through the Nafion membrane tubing, drying nitrogen gas flows outside it to remove the solvent. The removal rate was increased with increasing sample residence time, drying gas flow rate, and device temperature. With the concentrator, the detection sensibility was improved, and the lower detection limit was obtained compared to that without the concentrator. The optimized system has successfully been applied to the determinations of perchrolate in atmospheric aerosol and orotic acid in urinary samples.

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