Sample handling procedures, field studies

This assay was validated In a field study which examined assay performance and compared data obtained on the same samples by GC analysis. These data have been published (12), and to our knowledge, Is the first study of Its kind which addresses procedural error and data handling for real world samples In Immunoassay for pesticides. Thus, It seems appropriate to reiterate some of the salient points here. 

A study of mercury in Lake Michigan found levels near 1.6 pM (1.6 X 10 12 M), which is two orders of magnitude below concentrations observed in many earlier studies.5 Previous investigators apparently unknowingly contaminated their samples. A study of handling techniques for the analysis of lead in rivers investigated variations in sample collection, sample containers, protection during transportation from the field to the lab, filtration techniques, chemical preservatives, and preconcentration procedures.6 Each individual step that deviated from best practice doubled the apparent concentration of lead in stream water. Clean rooms with filtered air supplies are essential in trace analysis. Even with the best precautions, the precision of trace analysis becomes poorer as the concentration of analyte decreases (Box 5-2). 

The GLP principles are a managerial concept defining the organizational processes and conditions under which laboratory and field research is planned, performed, monitored, recorded, and reported. They were designed to ensure that sampling and analytical procedures and results are complete and of known, documented quality. When a study is GLP compliant, an auditor, regulator, or analyst should be able to review the smdy some years after its completion and easily determine what work was done, when, where, by whom, and with what equipment and methods who supervised the study what results were obtained and whether there were any problems encountered and, if so, how they were handled. Considerable effort and dedication in planning, support, and implementation is required to achieve this standard of documentation and attention to detail. Successful implementation of GLP provides reliable data for which the precision, accuracy, comparability, and completeness is known. 

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