Sunday, November 01, 2009
Figure 6 results were obtained in other acquisition modes, including neutral loss (74 mass units), which corresponds to a cleavage typically observed for one subclass of ß-agonist compounds, and full-scan mode performed simultaneously with MRM mode (dual-scan MRM matrix monitoring). The Xevo TQ MS in neutral loss acquisition mode appears promising for the development of generic screening approaches for detecting new ß-agonist structures belonging to predefined subfamilies.
6 - Specific extracted chromatograms of terbutaline obtained from a
urine sample extract spiked at 20 pg/g acquired in a) UPLC (ESI+)/MS
(dualscan MRM matrix monitoring), b) UPLC (ESI+)/MS/MS (MRM 226.1 >
152.1), and c) UPLC (ESI+)/MS (neutral loss 74).
For this analysis, ESI in positive mode was used to detect a peptide specific to the recombinant form of the bovine growth hormone. This ionization mode served as a “soft” ionization technique that is optimal for peptides. The ionization of the N-terminal peptide rbST leads to two main forms (z = 2 and z = 3). Main transitions and related conditions were optimized using IntelliStart software.
Some of the transitions generated by the software were those usually monitored for this compound (913.36 > 1047.7 and 774.27) and are known with respect to amino acid sequence and consequently were very specific for the target molecule. IntelliStart also proposed intense fragments corresponding to smaller ions (251.21, 175.09, 169.11, 141.12, and 120.09) that had not yet been identified or considered that were potentially specific to the peptide of interest (Figure 7). Application of the developed acquisition method to spiked bovine serum (5 ng peptide on column) led to very specific detection of the peptide without any interference on the chromatogram (Figure 7). Observed sensitivity and signal-to-noise ratios were very good when using the Xevo TQ for detecting expected levels of the protein in animal serum.
Figure 7 - Extracted MRM chromatogram overlay (with offset) of serum spiked with growth hormone N-terminal tryptic peptide (5 ng on column equivalent). Also overlaid is a dual scan-MRM (matrix monitoring) total ion chromatogram (TIC) showing a high-matrix background.
In summary, the sensitivity provided by the Xevo TQ MS allowed the determination of corticosteroids at the required MRL and offered a solution to the problem of lack of methodology in highly complex matrices, such as liver. Further, this sensitivity in neutral loss mode facilitates the development of new generic screening approaches in this field applied to corticosteroids and ß-agonist analysis.
A high degree of specificity and sensitivity was also observed for the analysis of recombinant bovine somatotropin. Use of IntelliStart software on the Xevo TQ MS enabled the discovery of MRM transitions not previously considered for this analysis.
- JECFA/70/SC. Summary and conclusions of the 70th Meeting of Joint FAO/WHO Expert Committee of Food Additives, Oct 21–29, 2008, Geneva, Switzerland.
- André, F.; Le Bizec, B.; Montrade, M.-P.; Maume, D.; Monteau, F.; Marchand, P. Developments in residue assay and metabolism study of growth promoters by mass spectrometric analysis. The Analyst1994, 119, 2529–35.
- Pinel, G.; André, F.; Le Bizec, B. Discrimination of recombinant and pituitary derived bovine, porcine and human growth hormones by peptide mass-mapping. J. Agric. Food Chem. 2004, 52(3), 407–14.
- De Brabander, H.; Le Bizec, B.; Pinel, G.; Antignac, J.P.; Verheyden, K.; Mortier, V.; Courtheyn, D.; Noppe, H. Review. Past, present and future of mass spectrometry in the analysis of residues of banned substances in meat-producing animals. J. Mass Spectrom. 2007, 42(8), 983–98.
- Le Breton, M.H.; Rochereau-Roulet, S.; Pinel, G.; Bailly-Chouriberry, L.; Rychen, G.; Jurjanz, S.; Goldmann, T.; Le Bizec, B. Direct determination of recombinant bovine somatotropin in plasma from a treated goat. Rapid Comm. Mass Spectrom. 2008, 22, 3130–6.
- Antignac, J.P.; Le Bizec, B.; Monteau, F.; Poulain, F.; André, F. Multi-residue extraction-purification procedure for corticosteroids in biological samples for efficient control of their misuse in livestock production. J. Chromatogr. B2001, 757, 11–19.
- Montrade, M.P.; Le Bizec, B.; Monteau, F.; Siliart, B.; André, F. Multi-residue analysis for ß-agonistic drugs in urine of meat producing animals by gas chromatography mass spectrometry. Anal. Chim. Acta1993, 275, 253–68.
- Antignac, J.P.; Le Bizec, B.; Monteau, F.; Poulain, F.; André, F. Collision-induced dissociation of corticosteroids in electrospray tandem mass spectrometry and development of a screening method by high performance liquid chromatography/tandem mass spectrometry. Rapid Comm. Mass Spectrom. 2000, 14, 33–9.
Mr. Monteau, Dr. Antignac, Dr. Pinel, and Prof. Le Bizec are with Laboratoire d’Etude des Résidus et Contaminants dans les Aliments (LABERCA), Ecole Nationale Vétérinaire de Nantes (ENVN), Nantes Cedex, France. Dr. Silcock and Dr. Hancock are with Waters Corp., Atlas Park, Simonsway, Manchester M22 5PP, U.K.; tel.: +44 0 161 435 4100; e-mail: email@example.com.