Objective An analytical method for rapid screening and confirmation of multiple pesticide residues in vegetable and fruit was established according to GB 2763-2014 national food safety standard-maximum residue limits for pesticides in food,using ultra performance liquid chromatography-Q-time of flight mass spectrometry (UPLC-Q-TOF-MS).Methods Pesticide residues in vegetable and fruit were screened by comparing the accurate mass,isotope distribution and abundance in the accurate mass database,and confirmed by comparing with the spectra in the spectra library or by the spectral analysis method.Results The method was verified by spiked samples,and all pesticides were detected at the addition level of 10.0 and 50.0 μg/kg.The recovery of 90％ of the pesticides was in the range of 70％-120％,with relative standard deviation (RSD) ≤ 20％ (n =5).The method was applied to screen pesticides in 30 samples of vegetables and fruits.Twenty-seven pesticides were found and 2 samples exceeded the limit.Conclusion The method was sensitive,accurate and reproducible.Hundreds of pesticides in GB 2763-2014 could be screened and confirmed in a short period of time even without standard substance.It could provide an effective method for food safety control.

Objective To investigate the characteristic of MRS in patients suffered diffuse axonal injury (DAI)in acute and suba-cute stage,and the correlation between MRS changes and the severity of disease.Methods We reported MRI and proton magnetic resonance spectroscopy studies of 3 6 head-inj ured patients in acute and subacute stage.Proton magnetic resonance spectra were ac-quired from the white matter and gray matter of bibateral frontal lobe that on conventional MRI appeared normal by using 2D MRSI at 3.0T MRI .30 volunteers as contronl were studied at the same time.Results In patient group,N-acetylaspartate/creatine ratios were (2.14±0.15)and (1.71±0.08)choline/creatine ratios were(1.35±0.13)and (1.03±0.08)for the white matter and the gray matter,respectivily.The brain N-acetylaspartate/creatine ratio was reduced and the choline/creatine ratio was increased in pa-tient group compared with the controls.The increase in the choline/creatine ratio was significant even in the moderate and severe in-j ured groups.Furthermore,there was a significantly correlation between the severity of head inj ury and the N-acetylaspartate/cho-line ratio,and changes in patients with metabolite ratios of the GCS score had a strong correlation.Conclusion We conclude that DAI patients with normal conventional imaging manifestations of the frontal lobe appear metabolite ratio change,suggesting the existence of local cerebral inj ury,and it has a strong correlation between the prognosis and MRS changes.MRS may provide an useful method that can tell us the severity of the brain inj ury in patients with DAI .