A NEW CONCEPT IN SAMPLE PRESERVATION?POISONING AND DEPOISONING

The reliability of analytical test data is judged all too frequently by the type of method used and by the procedural skill of the analyst. How ever, valid characterization of an aqueous sample, whether a waste water, process water, or natural water, is equally dependent on procurement of a representative aliquot or sample and positive preservation of sample quality during storage. Accepted methods of water and wastewater analyses are collectively outlined in "Standard Methods,"1 which includes a brief description of theory, interferences, and precision and accuracy for each test. "Standard Methods" also includes a short and very inadequate section on sampling procedures and sample preservation. Tarazi et al.2 discussed at length a comparison between two common sample collection procedures, the grab method and the flow-weighted com posite method. They concluded that sampling methodology significantly affected subsequent analytical results. Sample preservation during storage, though of obvious significance to the final test results, has not been ade quately researched. Classically, preser vation methods for samples containing organics have been based in whole or in part on microbiologists, findings regarding the inhibition of microbial