ABSTRACT
A laboratory is expected to be able to specify the quality of its data in quantitative terms. This requires the existence of some degree of quality assurance. Quality assurance is a definite plan for laboratory operation that specifies standard procedures that help to produce data with defensible quality and reported results with a high level of confidence. Quality control is a mechanism established to control errors. It is a set of measures within a sample analysis methodology to assure that the process is in control. Quality assessment is the mechanism to verify that the system is operating within acceptable limits. It is the overall system of activities whose purpose is to provide assurance that the overall quality control job is being done effectively. Sample custody is the process of protecting the samples collected and analyzed. The satisfactory quality of analytical data may be characterized by accuracy, precision, and bias.
