Seawater analysis, assessment

Dimethvlsulfide. In this section we discuss the analytical techniques which have been used to determine the concentration of DMS in marine air. Unlike the determination of DMS in seawater, the analysis of DMS in air is complicated by the presence of atmospheric oxidants which can cause variable and often severe sampling losses of DMS. For this reason, a number of different techniques have been used to determine atmospheric DMS and the accuracy of data reported in the literature is often difficult to assess. 

The determination of iodine in seawater helps in understanding the marine environment. A variety of analytical methods have been proposed for the quantitative determination of iodine in seawater. This chapter discusses the methods employed for the separation and determination of iodine in seawater. These methods include capillary electrophoresis (CE), ion chromatography (IC), high-performance hquid chromatography (HPLC), gas chromatography (GC), spectrophotometry, ion-selective electrode, polar-ography, voltammetry, atomic emission spectrometry (AES), and neutron activation analysis (NAA). The advantages and hmitations of these methods are also assessed and discussed. Since iodine is present in the ocean at trace levels and the matrices of seawater are complex, especially in estuarine and coastal waters, the methods developed for the... 

To fully assess the practical, real-world applicability of this automated online chemical pretreatment method, accuracy, detection capability, and stability tests were carried out. Accuracy was evaluated by analyzing a seawater certified reference material. The average of four separate analyses of the NASS 5 ocean seawater are shown in Table 20.4. All the data generated are well within the error of the certified values except for zinc, which is approximately three-fold higher. It is well-recognized that zinc is a notoriously difficult element to determine by ICP-MS because of contamination issues. For that reason, it is likely that the NASS 5 certified reference material (CRM) was contaminated with zinc from an external source before or during the analysis. 

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