ABSTRACT
Objective@#To evaluate the dietary risk of neonicotinoid insecticides in market-sold vegetables in Guangzhou City, so as to provide insights into ensuring food safety for residents.@*Methods@#Forty-five samples of 21 kinds of vegetables were collected from supermarkets and farmer's markets in Guangzhou City from June to September in 2022, and 10 kinds of neonicotinoid insecticides were determined using liquid chromatography-mass spectrometry (LC-MS). The vegetable consumption was obtained through the survey of food consumption and nutrients intake of residents in Guangzhou City. The dietary risk was evaluated by calculating daily exposure and non-carcinogenic risk quotients of neonicotinoid insecticides. @*Results@#A total of 27 samples of vegetables were detected with neonicotinoid insecticides, and the detection rate was 60.00%. Among 10 kinds of neonicotinoid insecticides, 6 kinds were identified, including clothianidin, thiamethoxam, imidacloprid, acetamiprid, dinotefuranand and nitenpyram. The detection rates of clothianidin, thiamethoxam and imidacloprid were relatively high (26.67%, 11.11% and 6.67%), and some samples exceeded the standard, with the rate of 4.44%, 2.22% and 2.22%, respectively. The total exposure of neonicotinoid pesticides (IMIRPF) was 3 053.00 ng/g, and the contents and IMIRPF of imidacloprid were the highest in roots and tubers. The daily exposure of imidacloprid, acetamiprid, dinotefuran, clothianidin, thiamethoxam and nitenpyram was 34.58, 3.85, 1.20, 6.87, 7.19 and 0.86 ng/(kg·d). Non-carcinogenic risk quotients of imidacloprid, acetamiprid, dinotefuran, clothianidin, thiamethoxam and nitenpyram was 5.76×10-4, 0.55×10-4, 0.06×10-4, 0.69×10-4, 0.90×10-4 and 0.02×10-4, respectively, which was lower than 1; and the sum of non-carcinogenic risk quotients was 7.98×10-4, which was lower than 1. @*Conclusions@#The dietary risk of neonicotinoid pesticides is low in 21 kinds of market-sold vegetables in Guangzhou City; however, the contents of neonicotinoid insecticides in some vegetable samples exceed the standard. The supervision of vegetable markets should be strengthened.
ABSTRACT
@#Objective To screen a kind of solid culture medium without animal-derived materials for resuscitating Streptococcus pneumoniae(Spn).Methods Spn 19F was selected for the preliminary screening of 9 kinds of formula culture media without animal-derived materials,and then other 23 serotypes of Spn were cultured for verification.The effect of the selected medium on the hereditary stability of various serotypes was identified by strain identification and capsular polysaccharide antigen gene sequence analysis of the 15-generation strains.The strains resuscitated by this medium were fermented according to the production procedure,and the culture situation and the yield and quality of capsular polysaccharide antigen were analyzed to determine the production applicability of the screened medium.Results The number of viable bacteria of various types of Spn was desired after 11～15 h of incubation on the selected solid medium and there was no difference in strain identification and antigen gene sequence between the final 15 generation and the control(strains cultured in sheep blood solid medium).After fermentation and culture of the strain resuscitated by this medium,the cell growth and the capsular polysaccharide production increased slightly,and all the related verification indicators of capsular polysaccharide met the requirements in Chinese Pharmacopoeia(Volume Ⅲ,2020 edition).Conclusion The selected solid culture medium without animal-derived materials has good applicability and can replace blood-derived culture medium for the resuscitation of Spn strain for vaccine production.