QuEChERS-GC-MS method for rapid detection of 30 pesticide residues in tea leaves.

recently, the well-known Leighton green tea, jasmine tea, Tieguanyin bag bubble tea have been exposed to containing 17 kinds of banned pesticides.fact, this is the second time in a month that the international environmental
organization
Greenpeace has "difficult" tea to the domestic market. On April 11, it released the 2012 Tea Pesticide Survey Report, which claims that nine tea brands, including Wu Yutai, Zhang Yiyuan and Tianfu tea, have serious pesticide residues on more than 18 tea samples, not only have a variety of mixed pesticide residues, but also more than half of the samples detected the state's ban on the use of highly toxic pesticides in tea trees.this end, Moon Xu Technology introduced a rapid agricultural residue detection method, which uses QuEChERS-GC-MS, can quickly determine 30 kinds of pesticide residues in tea. In addition, The discussion of "correct view of tea farmers' residues" has also become a hot topic in the forum, see QuEChERS-GC-MS method to quickly determine 30 pesticide residues in tea 1 scope of application
applicable to the detection of various residual pesticides in tea (including
organic
chlorine, organophosphorus and so on).2 Extraction
5 g tea sample is placed in 50 mL plastic
centrifuge tube
, 10 mL ultra-pure water soaked 20 min and then added 10 mL acetylene, oscillating 5 min Then add the Welchrom
® QuEChERS salt analysis package (WEL-QE-04), shake quickly, oscillate 15 min, centrifuge 5 min at 4500 r/min, collect the liquid for purification.3 purification
take 1 ml extraction on the liquid added welchrom
®
QuEChERS 2ml purification tube WEL-
QC
-1402, shock vortex 2min so that the extract fully with adsorbent action, 10000rpm centrifugation 3min, take the liquid injection sample analysis.4
spectrometretography
mass spectrometrometrometromety
some4.1 chromatography conditionschromatography
: Welchrom
®
WM-5MS (30 m × 0.25 mm × 0.25
μ
m);
temperature warming procedure: 40 degrees C (1 min) 130
degrees C (0 min) 280 degrees C (5
min);
sample: 1.0
μ
L;
of the sample: no diversion sample, 1.5 min after opening the spool valve.4.2 Mass spectrometronic conditions
ionation mode: EI;
ionized energy: 70 ev;
assay: select ion monitoring mode (SIM);
ion source temperature: 230 degrees C;
four-stage bar temperature: 150 degrees C;
transmission line temperature: 280 degrees C;
solvent delay: 5 min.5 Experimental Results 5.1 GC-MS AssayFigure 1 30 Pesticide Residual Total Ion Flow ChromatographyChromatography Peaks by peak time in order: 1. Enemy grass, 2. Phenyl; 3. aniline; 4.tetrachloroylene; 5. phosphorus; 6. α-666;8.β-666;9.Zin;10.Pentachlor nitrobenzene;11. Tedinzin; 12. Grass Dazin; 13.δ-666; 14. Deline phosphorus; 15. Isopropylamine; 16. Grass-sweeping net; 17. Grass dan; 18. Metformin; 19. Isopropyl methamidophos; 20.Toxic; 21. chlorpyurethroid diethromethyl Esters; 22. Ester; 23. Grass is the enemy;24.isoprene net; 25. ethyl bromofropion parathion; 26. polybrominated pyridophos; 27.propylene bromide; 28. oxycycline; 29. oxycycline; 30.fluolycline 5.2 method recovery rate and precision.
the appropriate amount of pesticide mixing standard solution in the blank tea sample, according to the above pre-treatment steps and testing methods to determine the recovery rate of various pesticides. The results showed that the average recovery rate of 30 pesticides was 74% to 108%, and the RSD range was 0% to 10.38%.
.