A micromethod for determination of plasma pyridoxal phosphate and its use in assessment of storage stability of the vitamer.
A widely used macromethod employing tyrosine apodecarboxylase for measurement of pyridoxal phosphate (PLP) concentration in 0.5-1.0-ml plasma was modified to a microscale utilizing 0.1-ml plasma. Mean PLP levels in 12 plasma samples were 160.6 +/- 32.8 pmol/ml (mean +/- SD) when analyzed by the macromethod, and were not significantly different compared to those obtained by the micromethod (158.4 +/- 28.2 pmol/ml). Results of the two methods were significantly correlated (r = +0.97, p less than 0.001). Plasma PLP concentrations of 11 samples determined by the micromethod (means = 151.8 +/- 30.0 pmol/ml) were similar and significantly correlated (r = +0.95, p less than 0.001) to levels measured in the same samples 1-2 years earlier (means = 145.1 +/- 26.2 pmol/ml). This suggests that plasma PLP content of the samples was stable for up to 2 years of storage when the micromethod was utilized for analysis. The strong significant correlation between macro- and micromethods attests that the micromethod is a reliable alternative to the macromethod. The micromethod is useful in instances where only small samples of plasma are available for measurement of PLP.
Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47907.
M W
MW
Borschel
A
A
Kirksey
B R
BR
Hamaker
D001774:Blood Chemical Analysis / Q000379:methods; D002648:Child; D006801:Humans; D011732:Pyridoxal Phosphate / Q000097:blood*; D011736:Pyridoxine / Q000097:blood; D026681:Vitamin B 6 Deficiency / Q000097:blood*
D011732:Pyridoxal Phosphate; D011736:Pyridoxine