Determination of L-cysteine origin on the basis of its delta N-15 values

International audienceThe majority of L-cysteine is obtained industrially by hydrolysis of animal materials, such as poultry feathers. Despite widespread belief, there is little evidence that human hair is used as a source material and its use is explicitly banned in the European Union (2000/63/EC decision). We developed an isotope ratio mass spectrometric (EA-IRMS) method to determine carbon and nitrogen isotopic ratio in cysteine preparations and related compounds, e.g. cystine and carbocysteine. A threshold relying on the N-15/N-14 was established to differentiate between hair and feathers; a value below 6.6% indicates a poultry feathers origin. Global uncertainty of measurement was found to be 0.1% for delta N-15 (sample size of 0.5-1.8 mg)

High Throughput Identification and Quantification of Anabolic Steroid Esters by Atmospheric Solids Analysis Probe Mass Spectrometry for Efficient Screening of Drug Preparations

Recent developments in ambient mass spectrometry (AMS), such as atmospheric solids analysis probe (ASAP) mass spectrometry, open a whole new range of possibilities to screen for drug preparations. In this study, the potential of ASAP for the rapid identification and quantification of anabolic steroid esters has been evaluated. These compounds are known to be used both in human and in food producing animals to enhance performances and to improve the rate of growth, respectively. Using a triple quadrupole (QqQ) MS instrument, mechanism of ionization and fragmentation in both positive and negative mode were studied for a range of 21 selected steroid esters (based on testosterone, estradiol, nandrolone, and boldenone) which highlighted common neutral mass loss of 96.1, thus allowing rapid screening in minutes to reveal steroid ester presence with minimal sample preparation. Ester identification is further achieved through an efficient 2 min workflow on a QqQ MS instrument. Moreover, the use of isotope labeled internal standards permitted the quantification of the corresponding steroid esters in selected reaction monitoring (SRM) mode, for the first time in ASAP. This approach was successfully applied for characterization of oily commercial preparations. These results open new perspectives in hormone (and drug) rapid analysis by ASAP-MS in the near future

Germination Stimulants of Phelipanche ramosa in the Rhizosphere of Brassica napus Are Derived from the Glucosinolate Pathway

International audiencePhelipanche ramosa is a major parasitic weed of Brassica napus. The first step in a host-parasitic plant interaction is stimulation of parasite seed germination by compounds released from host roots. However, germination stimulants produced by B. napus have not been identified yet. In this study, we characterized the germination stimulants that accumulate in B. napus roots and are released into the rhizosphere. Eight glucosinolate-breakdown products were identified and quantified in B. napas roots by gas chromatography mass spectrometry. Two (3-phenylpropanenitrile and 2-phenylethyl isothiocyanate [2-PEITC1) were identified in the B. napus rhizosphere. Among glucosinolate-breakdown products, P ramosa germination was strongly and specifically triggered by isothiocyanates, indicating that 2-PEITC, in particular, plays a key role in the B. napus P ramosa interaction. Known strigolactones were not detected by ultraperformance liquid chromatography tandem mass spectrometry, and seed of Phelipanche and Orobanche spp. that respond to strigolactones but not to isothiocyanates did not germinate in the rhizosphere of B. napus. Furthermore, both wild-type and strigolactone biosynthesis mutants of Arabidopsis thaliana Atccd7 and Atccd8 induced similar levels of P ramosa seed germination, suggesting that compounds other than strigolactone function as germination stimulants for P ramosa in other Brassicaceae spp. Our results open perspectives on the high adaptation potential of root-parasitic plants under host-driven selection pressures