Page 25 - Volume 6, Issue 2, July 2013

Biodegradation of diazinon by epiphytic yeasts

73

m/z were used for the quantification of di-

azinon and IMP, respectively. After the for-

tification of 250 mL flasks containing 50 mL

mineral salts medium with diazinon and

IMP, the obtained recoveries for the two

compounds ranged from 85.2 to 100%, val-

ues which were accepted according to SAN-

CO Document 2011/ 12495 (Table 1). Relative

standard deviations (RSDs) values ranged

from 0.34 to 3.55 %, all lower to 20%, also

accepted. Validation results of tomato fruits

sprayed with 0.05 0.1 and 0.5 μg/mL diazi-

non gave average recoveries from 97.6% to

102% and mean RSDs from 1.7% to 4.7% (Ta-

ble 1), respectively. The limit of quantifica-

tion (LOQ) was set for both substrates in the

lowest validation level, 0.05 μg/mL and the

limit of detection (LOD) was calculated to be

0.02 μg/mL. The above results indicate the

efficiency of the analytical methods for the

Figure 1.

Determination of diazinon and its metabolite 2-isopropyl-6-methyl-4-pyridinol (IMP) in the LC-MS/MS chro-

matographic system with ESI (+) during a time period of 10 days. The determination of the two compounds was achieved

with the MRMs 305.1> 169.1 m/z and 305.1>96.6 m/z for diazinon and 153> 84 m/z and 153>70 m/z for IMP.