Sampling for Dissolved Ion Analyses

Sampling procedures for determining the amounts of dissolved ions should be discussed with the relevant laboratory. Commonly, half-liter plastic bottles are adequate. Occasionally a separate bottle is needed, to which a few drops of pure acid are added to secure low pH in order to prevent precipitation of some ions, such as carbonates. For Si02 analyses, addition of known amounts of distilled water is recommended to avoid precipitation of silica as a result of cooling of the water. 

Separate samples are commonly collected for H2S determination. To these a fixative agent is added, each laboratory preferring its own material. 

The details of a sampling expedition have to be worked out with the laboratory staff in advance, and the proper (clean) bottles have to be obtained. In addition to being clean, bottles should be rinsed in the sampled water before taking samples. 

Always label the samples in the field—never rely on your memory— and make sure the labels are complete. 

Marcel Dekker, Inc. 270 Madison Avenue, New York, New York 10016 

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