Interlaboratory and intralaboratory variabilities in the Environmental Lead Proficiency Analytical Testing (ELPAT) program.
Schlecht PC; Song R; Groff JH; Feng HA; Esche CA
Am Ind Hyg Assoc J 1997 Nov; 58(11):779-786
Interlaboratory and intralaboratory variability in the Environmental Lead (7439921) Proficiency Analytical Testing (ELPAT) program was examined. The ELPAT program was administered by the American Industrial Hygiene Association in cooperation with NIOSH and the Environmental Protection Agency (EPA) and was designed to evaluate and improve the performance of laboratories conducting analyses associated with lead abatement. All laboratories interested could participate in the program either to practice or to obtain accreditation for performing lead analysis of paint chip, soil, or dust wipe samples. Paint chip, soil, and dust wipe samples containing lead at four unlabeled concentrations were sent to the participating laboratories each calendar quarter. In 1997 there were about 400 laboratories participating in the ELPAT program. Data on the mean lead concentrations in the three sample matrices and the total relative standard deviations (RSDs) obtained during the first 14 rounds, approximately 3 years, of the program were analyzed by a correlation model to determine whether the interlaboratory or the intralaboratory RSDs contributed most to the total variance in the data (total RSD). The correlation model used a variance component matrix approach to separate the interlaboratory from the intralaboratory contributions to the total RSD. The approach was also used to investigate the contributions of the interlaboratory and intralaboratory variance in the results obtained with the three analytical methods used most commonly in the ELPAT program: the NIOSH-7082/7102 sample preparation technique with flame atomic absorption spectrometry (FAA) and the EPA-SW846-305A sample preparation technique used with FAA or with inductively coupled plasma/atomic emission spectroscopy. The interlaboratory RSD made a larger contribution to the total RSD than the intralaboratory RSD, the ratio being approximately 1.7 to 1. The 1.7 ratio did not vary significantly with the lead content of the samples. The authors conclude that interlaboratory variability contributes more to the total variability in the ELPAT program data than intralaboratory variability, although the contribution of intralaboratory variability is important.
NIOSH-Author; Heavy-metals; Chemical-analysis; Laboratory-work; Performance-capability; Quality-standards; Mathematical-models; Statistical-analysis;
Author Keywords: correlation coefficient; interlaboratory relative standard deviation; intra laboratory relative standard deviation; relative standard deviation; variance components
American Industrial Hygiene Association Journal