A two-dimensional analysis of variance for the simultaneous quantitative determination of estradiol and its 4-14C isotopically labelled analogue with selected ion monitoring

Estradiol-17β and [4-14C]estradiol-17β in total mass amounts of 0, 10 and 20 pg per analysis in the presence of 1000 pg[2H8]estradiol as an internal standard were simultaneously quantitatively determined by gas chromatography mass spectrometry using the selected ion monitoring technique. The experiment was designed to investigate the two-dimensional error structure which facilitates the study and comparison of the variances and showed that in this concentration range the variance due to sample preparation is smaller than that due to the device. The deviations due to the device were shown to have a two-dimensional normal distribution. (author)