BMF 96 - 13C-labelled internal standards for toxicology

Quantitation of an analyte is usually accomplished by measuring the response obtained relative to an internal standard (IS). These are used to compensate for loss of analyte during sample preparation and for variation in mass spectrometric analysis (i.e. ionization efficiency and subtle variations in MS analysis). The assumption is that IS losses will be similar to losses of analyte. If a known quantity of IS is added to the unknown sample prior to any manipulations, the ratio of IS to analyte remains constant, because the same fraction of each is lost in any operation.


Find out more about the properties on an ideal IS, and the relative advantages and disadvantages of deuterated vs 13C labelled variants in our latest newsletter; BMF 96