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.
Borschel
M W
MW
Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47907.
Kirksey
A
A
Hamaker
B R
BR
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