QUALITY-CONTROL LEVEL - AN ALTERNATIVE TO DETECTION LEVELS

Existing methods for the determination of reporting limits (e.g., MDL, LOD, etc) are based on a binary procedure that determines that lowest concentration of an analyte that is either detected or not detected within specified confidence limits. There is no assessment of the accuracy or precision of the results detected. An alternative procedure is presented, the Quality Control Level which determines the lowest concentration that meets the data quality objects of the data user in term of the minimum acceptable precision and accuracy. To examine this hypothesis, a series of 15 soils and aqueous liquids were prepared with successively smaller concentrations of 16 toxic regulated elements. The range of the concentrations were over four orders of magnitude for both. Each of these liquids and soils were analyzed eight times and the accuracy and precision of each analyte was measured against concentration. This paper will show that it is possible to use a quality control approach to reporting levels.