Ultraviolet irradiation limitations

These instruments employ a continuous flow of persulfate solution to promote oxidation prior to ultraviolet irradiation, and have a low system blank and low detection limit. Since all reactions take place in the liquid phase, problems suffered by combustion techniques, such as catalyst poisoning, reactor corrosion, and high-temperature element burnouts, are obviated. However, the ultraviolet-promoted chemical oxidation technique is not designed to handle particulate-containing samples, and tends to give incomplete oxidation for certain types of compounds such as cyanuric acid. 

The initial batch of Ara mutants was isolated from a Thr" Ara" Leu parent strain on EMB L-arabinose agar plates subsequent to ultraviolet irradiation [1]. A limited number were induced by 2-amino-purine [25]. 

In practice, such ozone celts are extensively automated to control the process cycle (Fig. 5< 14(b)) and may incorporate ultraviolet facilities. Current applications include those sectors of the pharmaceutical and fineultra-pure water for critical synthetic steps or to meet stringent purity limits. In such applications, the electrolytic route to ultra-pure water, via ozone generationf is competing against the more traditional methods of sterile filtration (e.g. ultra-filtration), ultraviolet irradiation and the use of conventional air-phase corona-discharge ozonizers. 

Tao et al. [658] have described a procedure in which antimony and arsenic were generated as hydrides and irradiated with ultraviolet light. The broad continuous emission bands were observed in the ranges about 240-750 nm and 220 - 720 nm, and the detection limits were 0.6 ng and 9.0 ng for antimony and arsenic, respectively. Some characteristics of the photoluminescence phenomenon were made clear from spectroscopic observations. The method was successfully applied to the determination of antimony in river water and seawater. The apparatus used in this technique is illustrated in Fig. 5.16. 

Grimbaldeston MA, Nakae S, Kalesnikoff J. Tsai M, Galli SJ Mast cell-derived interleukin-10 limits skin pathology in contact dermatitis and chronic irradiation with ultraviolet B. Nat Immunol 2007 8 1095-1104. 

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