Harmonized guidelines for the use of recovery information in analytical measurement

Abstract

Synopsis: ISO, IUPAC and AOAC INTERNATIONAL have co-operated to produce agreed protocols or guidelines on the "Design, Conduct and Interpretation of Method Performance Studies" [1] on the "Proficiency Testing of (Chemical) Analytical Laboratories" [2] and on "Internal Quality Control in Analytical Chemistry Laboratories" [3]. The Working Group that produced these protocols/guidelines was asked to prepare guidelines on the use of recovery information in analytical measurement. Such guidelines would have to outline minimum recommendations to laboratories producing analytical data on the internal quality control procedures to be employed. A draft of the guidelines was discussed at the Seventh International Symposium on the Harmonization of Quality Assurance Systems in Chemical Laboratory, sponsored by IUPAC/ISO/AOAC INTERNATIONAL, held in Orlando, USA, 4-5 September 1996. Proceedings from that Symposium are available [4]. The purpose of these guidelines is to outline the conceptual framework needed for considering those types of analysis where loss of analyte during the analytical procedure is inevitable. Certain questions cannot be satisfactorily addressed, and hence remain irreducibly complex, unless such a conceptual framework is established. The questions at issue involve (a) the validity of methods for estimating the recovery of the analyte from the matrix of the test material, and (b) whether the recovery estimate should be used to correct the raw data to produce the test result. The types of chemical analysis most affected by these considerations are those where an organic analyte is present at very low concentrations in a complex matrix. "Protocol for the Design, Conduct and Interpretation of Method Performance Studies", W. Horwitz, Pure Appl. Chem. 60, 855- 864 (1988), revised, 67, 331-343 (1995). "The International Harmonized Protocol for the Proficiency Testing of (Chemical) Analytical Laboratories", M. Thompson and R. Wood, Pure Appl. Chem. 65, 2123-2144 (1993). (Also published in J. AOAC International 76, 926-940 (1993). "Harmonized Guidelines for Internal Quality Control in Analytical Chemistry Laboratories", M. Thompson and R. Wood, Pure Appl. Chem. 67, 49-56 (1995). "Quality Assurance for Analytical Laboratories", edited M. Parkany, Royal Society of Chemistry, London, UK, 1996.