Stable Isotope Dilution Assay

In case of available stable isotope standards, the stable isotope dilution assay (SIDA) is the method of choice for targeted metabolomics.

Advantage

The advantage of SIDA is, that in principle the analyte itself is used as internal standard. The only difference is that the internal standard is isotopically labeled, so that the standard has a higher molecular weight. The internal standard is added at the beginning of the sample preparation so that it corrects for losses during sample preparation and compensates matrix effects during the mass spectrometric analysis. The peak ratio of analyte and isotopically labeled standard is used for quantitation.

Disadvantage

Not all standards are commercially available. This problem can be overcome by total- or semi-synthesis of isotopically labeled compounds or by biosynthetic production on completely ¹³C-labled culture medium.

Literature Example

Kleigrewe, K.; Niehaus, E. M.; Wiemann, P.; Tudzynski, B.; Humpf, H. U., New approach via gene knockout and single-step chemical reaction for the synthesis of isotopically labeled fusarin c as an internal standard for the analysis of this fusarium mycotoxin in food and feed samples. J. Agric. Food Chem. 2012, 60, 8350-5