ABSTRACT
Quality Assurance (QA)/Quality Control (QC) measures are necessary during field sampling as well as in laboratory procedures. QA refers to the activities which allow us to demonstrate that a certain quality standard has been met at a stated confidence level. QC refers to procedures that lead to statistical control of the measurement process and provide the desired accuracy of the measurement. Guidance in developing standard operating procedure protocols can be obtained from such organizations as the American Society for Testing and Materials, The United Kingdom Accreditation Service, and the United States Environmental Protection Agency. Determination of accuracy and precision is the most important step in generating high-quality data. Accuracy is determined by analyzing samples of known concentration and comparing the measured value to the known, true value. Control charts provide a graphical display of statistical control and can also be used to monitor the variability of repetitive measurements.
