Validation of analytical methods and laboratory procedures for chemical measurements

Method validation is a key element in the establishment of reference methods and in the assessment of a laboratory's competence in producing reliable analytical data. Hence, the scope of the term "method validation" is wide, especially if one bears in mind the role of Quality Assurance/Quality Control (QA/QC). The paper puts validation in the context of the process generating chemical information, introduces basic performance parameters included in the validation processes, and evaluates current approaches to the problem. Two cases are presented in more detail: the development of European standard for chlorophenols and its validation by a full scale collaborative trial and the intralaboratory validation of a method for ethylenethiourea by using alternative analytical techniques.