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A simplified protein precipitation and filtration procedure for determining serum vitamin B6 by high-performance
Michael E Rybak1, Christine M Pfeiffer
1Nutritional Biomarkers Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA. mrybak@cdc.gov
Abstract:
Protein precipitation followed by centrifuge filtration was tested as a simplified sample preparation procedure for quantifying pyridoxal 5'-phosphate (PLP) and 4-pyridoxic acid (4PA) in serum by high-performance liquid chromatography. Serum samples (n=160) were prepared by both centrifuge filtration and an established technique using traditional supernatant extraction with manual filtration. Bland-Altman bias analysis (95% confidence levels [CLs]) of the results showed a -1.3 (-2.2, -0.5)% difference in PLP values and a -6.2 (-7.3, -5.2)% difference in 4PA values using the simplified sample preparation. These deviations were found to be well within allowable biases on the basis of biologic variation.
