Water and wastewater analysis – A guide manual by Central Pollution Control Board

Because of the increasing emphasis placed on verifying the accuracy and representativeness of data, greater emphasis is placed on proper sample collection, tracking and preservation techniques. Often laboratory personnel help in planning a sampling program, in consultation with the user of the test results. Such consultation is essential to ensure selection of right samples and application of analytical methods that provide a sound and valid basis for answering the questions that prompted the sampling and that will meet regulatory and/or project-specific requirements.

The document addresses the collection and preservation of water and wastewater samples; the general principles also apply to the sampling of solids or semi-solid matrices. It details how to obtain a sample that meets the requirements of the sampling program and handle it so that it does not deteriorate or become contaminated before it is analyzed.

Special precautions that are necessary for samples containing organic compounds and trace metals have been detailed. The details of collection vary with local conditions, so specific recommendations are not universally applicable. Sometimes it is more informative to analyze numerous separate samples instead of one composite so that variability, maxima, and minima can be determined.

Because of the inherent instability of certain properties and compounds, composite sampling for some analytes is not recommended where quantitative values are desired. In certain cases, such as for BOD, composite samples are routinely analysed by regulatory agencies.

When samples are collected from a river or stream, observed results may vary with depth, stream flow, and distance from each shore. The document details how the selection of the number and distribution of sites at which samples should be collected depends on study objectives, stream characteristics, available equipment, and other factors.

The information and guidelines contained here will provide necessary assistance to the Laboratories, State Pollution Control Boards and other bodies engaged in water and wastewater analysis.

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