1) BASF SE, Agricultural Solutions, APE/MB, Speyerer Strasse 2, 67117 Limburgerhof, Germany, 2) TÜV Rheinland Agroisolab GmbH, TÜV Rheinland-Gruppe, Germany Journal of Agricultural and Food Chemistry (2011), V59 (9), pp 4365–4370, doi: Isotopic Fingerprinting for the Authenticity Control of Crop Protection Active Compounds using the Representative Insecticide Fipronil Philipp Weller (1), Markus Boner (2), Hilmar Foerstel (2), Horst Becker (1), Benjamin Peikert (1) and Wolfgang Dreher (1) Isotopic fingerprinting was evaluated for its potential to generate characteristic fingerprints of crop protection products in an extensive survey, using the insecticide Fipronil. One hundred and twenty batches of Fipronil from the BASFproduction site in France were analyzed for the isotope ratios of δ13C, δ15N, and δ34S. Samples spanned a production time of four years and were analyzed by elemental analysis, coupled to isotope ratio mass spectrometry (EA/IRMS). A number of Fipronil samples from other sources were analyzed in the same manner and were compared to the samples from BASF by means of multivariate data analysis. The isotopic fingerprint was sufficiently specific to differentiate between Fipronil from BASF production and Fipronil from other producers. This suggests that isotopic fingerprinting is suitable for the authenticity control of active compounds in crop protection products. It is anticipated that this technique will deliver great benefit in the defense against counterfeits and illegal parallel imports.