APPLICATION OF LC-MS
Determination of vitamin D3in poultry feed supplements using MS
Vitamin D is an essential constituent in human and animal nutrition. Livestock diets deficient in vitamin D can cause growth abnormalities.
Traditional GC/MS analysis methods for vitamin D in feed extracts require extensive and time-consuming sample preparation and derivatization prior to analysis. Atmospheric pressure chemical ionization with ion trap detection provides a sensitive analytical method without the need for extensive sample preparation and derivatization. Further, the multiple-stage MS capability of the ion trap eliminates the need for chromatographic separation, greatly speeding analyses.
Flow injection analysis of a poultry feed extract yields a peak at m/z 385 suggesting the presence of vitamin D
Isolation and fragmentation of the precursor ion at m/z 385 is inconclusive. The full scan product ion spectrum shows a prominent peak at m/z 367 representing the loss of a single water mole- cule but little other fragmentation (Figure)
Isolation and fragmentation of the ion at m/z 367 yields a full scan MSspectrum (Figure A) rich in structurally specific product ions. This spectrum is an excellent. match with a similar analysis of a pure standard (Figure B) and conclusively confirms the presence of vitamin D3
Detection of phenylurea herbicides
Many of the phenylurea herbicides are very similar and difficult to distinguish with a UV detector (Figure ). Monuron and diuron have one benzene ring and differ by a single chlorine. Chloroxuron has two chlorines and a second benzene ring attached to the first by an oxygen. The UV-Vis spectra are similar for diuron and monuron, but different for chloroxuron. When analyzed using electrospray ionization on an LC/MS system, each compound has a uniquely identifiable mass spectrum.
Detection of low levels of carbaryl in food
Pesticides in foods and beverages can be a significant route to human exposure. Analysis of the carbamate pesticide carbaryl in extracts of whole food by ion trap LC/MS/MS proved more specific than previous analyses by HPLC fluorescence and single-quadrupole mass spectrometry. The protonated carbaryl molecule (m/z 202) was detected in full scan mode using positive ion electrospray. A product ionat m/z 145 (Figure ) generated by collision- induced dissociation provided confirmation of carbaryl and was used for subsequent quanti- tative analysis. Ion trap analysis was more sensitive than previous analysis using a single-quadrupole mass spectrometer operating in scanning mode and more sensitive than fluorescence detection.
Ion trap LC/MS/MS also con- firmed false positives in the HPLC fluorescence analysis caused by a co eluting compound. Based on the MS/MS spectrum of the co eluting compound, a possible structure was assigned as shown in Figure .
[agilent.com& Michael Linscheid. Westmorel, D.G]
- Basics of LC/MS by Agilent technology available at URL agilent.com accessed on 15/7/2011. Pg.no:4-6; 20-32.
- Lee, M.S. Kerns, E.H. LC/MS application in drug development. New Jersey: Milestone Development Services Pennington. Pg.no:235-242
- Michael Linscheid. Westmorel, D.G. International union of pure and applied chemistry. vol-66. No: 9. Printed in Great Britain.
- Snyder, L.R. Dolan, J.W. High performance gradient elution the practical application of the linear-solvent-strength model. A john Wiley & sons publication. Pg.no:326-328
- Watson, D.G. Pharmaceutical analysis a text book for pharmacy student and pharmaceutical chemist. Published by Churchill Livingstone. Pg.no:186-188.
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