Population distributions and intralaboratory reproducibility for fat-soluble vitamin-related compounds in human serum.

Concentrations of alpha- and beta-carotene, lycopene, beta-cryptoxanthin, zeaxanthin, lutein, alpha-, gamma-, and delta-tocopherol, retinol, and retinyl palmitate have been determined in over 1400 human sera from two epidemiological studies. Complete adult population distributions for these analytes, and for a chromatographically defined "total carotenoids" component, are detailed as data-defined histograms. The distributions for retinol and alpha-tocopherol concentrations are much narrower than those for the other analytes. Information provided by analysis of control samples facilitated intercomparison of the two studies and provided univariate and bivariate estimates of the intra-laboratory measurement reproducibility. The utility of an analytical measurement is shown to be dependent on both the measurement uncertainty and the distribution of the analyte within the population.