Interlaboratory analytical comparison of fatty acid concentrations in serum or plasma.
BACKGROUND
There are a large number of clinical studies focusing on the measurement of individual fatty acids in serum or plasma; however, few studies have focused on the interlaboratory comparisons of these measurements. The National Institutes of Standards and Technology (NIST), in collaboration with the National Institutes of Health Office of Dietary Supplements (NIH-ODS) and the Centers for Disease Control and Prevention (CDC), has initiated a quality assurance program for assessing and improving the comparability of individual fatty acid measurements in serum and plasma.


METHODS
This is a performance-based study so participants are encouraged to use their laboratory's methods for the quantification of the individual fatty acids that they typically measure in the unknown serum or plasma samples along with a control material. The control materials used to date are SRM 1950 Metabolites in Human Plasma and SRM 2378 Fatty Acids in Frozen Human Serum.


RESULTS
To date, two studies of the Fatty Acid Quality Assurance Program (FAQAP) have been completed with 11 and 14 participants, respectively. The agreement among the laboratories for individual fatty acids was within 20% for 70% of the data submitted. Laboratories were also requested to run triplicate analyses for each unknown sample. The precision of the individual laboratory data was generally good, with relative standard deviations <20%.


CONCLUSIONS
The results from the first two exercises indicate the need for additional assessment of the comparability among laboratories doing these measurements. Future studies will be conducted with the goals of increasing the number of participating laboratories, increasing awareness of the need to use control materials, and improving the comparability among laboratories.
Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. Electronic address: Michele.schantz@nist.gov.
Michele M
MM
Schantz
Nutritional Biomarkers Branch/Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
Carissa D
CD
Powers
Nutritional Biomarkers Branch/Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
Rosemary L
RL
Schleicher
Office of Dietary Supplements, National Institutes of Health, Bethesda, MD 20892, USA.
Joseph M
JM
Betz
Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Office of Dietary Supplements, National Institutes of Health, Bethesda, MD 20892, USA.
Stephen A
SA
Wise
D000328:Adult; D001774:Blood Chemical Analysis; D005227:Fatty Acids / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
D005227:Fatty Acids
Fatty acids; Interlaboratory study; Plasma; SRM 1950; SRM 2378; Serum
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