| Wolfberry is rich in many kinds of nutrients,which has high nutritional value and medicinal value.In recent years,the planting area of wolfberry is expanding rapidly.China has become the main production and consumption place of wolfberry products in the world.Many diseases and insect pests such as rust mite,gall mite,wood louse,naked thrips,mealybug and aphid often occur at the same time or alternately in the growth process of wolfberry,so it is very difficult to control them.At present,chemical control is the main way,but due to farmers'nonstandard use of drugs,it has brought huge hidden dangersthe to the quality and safety of Chinese wolfberry products.Pesticide has stable chemical properties,high fat solubility,long residue period,easy to deposit,which is a serious threat to human health.Most pesticides will decompose through biodegradation,photolysis,chemical oxidation and plant metabolism,but there will still be a small amount of pesticide residues in plants and soil.This not only has a serious adverse effect on the quality of wolfberry,but also has a huge potential harm to human health.It also brings higher and higher requirements and new challenges to the detection technology of pesticide residues.In recent years,the safety of Chinese wolfberry medicine has been concerned.Pesticide residue has become the main factor affecting the quality and safety of Chinese wolfberry,and to a certain extent,it affects the modernization and internationalization of Chinese wolfberry industry.(1)A method for the determination of 107 pesticide residues in wolfberry by acetate-buffered salt extraction and Sin-QuEChERS nano column purification coupled with ultra performance liquid chromatography tandem mass spectrometry was established.The extraction effects of three different types of buffer salts and the purification effects of different solid-phase extraction columns were compared,and the linearity,matrix effect,analysis limits,precision,stability and accuracy were validated,which verifies the satisfactory performance of this new method.The experimental results showed that in the multiple reaction monitoring mode(MRM),107 pesticides can be well separated,the linear range was between 2-1000?g/kg,the correlation coefficient was greater than 0.990,the detection limit(LODs)and the limit of quantification(LOQs)were in the range of 0.14-1.91?g/kg and 0.46-6.37?g/kg,respectively.The recovery of analytes at three fortification levels(10?g/kg,50?g/kg,100?g/kg)ranged from 63.3-123.0%,72.0-118.6%,and 67.0-118.3%,respectively,with relative standard deviations(RSDs)below 15.0%.The precision of the method was high(intra-day 0.6-9.4%,n=5 and inter-day 0.8-12.6%,n=5),and the stability was good(RSD<11.7%,n=7).The proposed method was applied to the analysis of fifty wolfberry samples collected from supermarkets,pharmacies and farmers'markets in different cities of Shandong Province.One hundred percent of the samples analyzed included at least one pesticide,and a total of 26 pesticide residues was detected in fifty samples,which mainly were insecticides and bactericide.Several pesticides with higher detection rates were 96%for acetamiprid,82%for imidacloprid,54%for thiophanate-methyl,50%for blasticidin-S,42%for carbendazim,42%for tebuconazole and 36%for difenoconazole in wolfberry samples.This method is sensitive,rapid,simple and reliable,and does not need complex purification process.It is suitable for the rapid detection of pesticide residues in wolfberry,which provides basis for the research on the risks to wolfberry health.(2)Different deep eutectic solvents with choline chloride as hydrogen bond acceptor,urea,glycerol,phenol and glucose as hydrogen bond donors were used as extractants to extract various pesticides from wolfberry.The prepared deep eutectic solvent was characterized by FTIR,and its viscosity and density were measured.The parameters such as DES type and proportion,extraction temperature,DES volume,THF volume,vortex time,ultrasonic time,centrifugal rate and centrifugal time were optimized.The target substance was quantitatively detected by liquid chromatography tandem mass spectrometry.The results showed that the linear relationship of 10pesticides in wolfberry was good in the range of 0.05-50?g/kg,and the linear correlation coefficient R~2 was greater than 0.9997.The detection limit(LOD)and quantitative limit(LOQ)of the method were 0.0088-0.5952?g/kg and 0.0294-1.9814?g/kg,respectively.The recovery of 10 pesticides at three fortification levels(0.2?g/kg,2.0?g/kg and 20.0?g/kg)ranged from 79.8-99.4%,82.3-101.8%and88.5-102.4%,respectively,with relative standard deviations(RSDs)below 15.0%,which met the requirements of multiple pesticides residue detection.The method had good stability(RSD<12.3%,n=7).And the precision of the method was high,which were 1.6-11.5%(n=5)and 1.4-9.3%(n=5),respectively.The method was used to screen pesticide residues in wolfberry samples that sold in different cities of Shandong Province.The results showed that one hundred percent of the samples analyzed included at least one pesticide.Among them,the detection rate of myclobutanil and chlorpyrifos was as high as 100%,and the detection rates of fipronil,fipronil-desulnyl and fipronil-sulfone were also high(93.75%).The method is green and environment-friendly,and the use of organic reagents is almost zero.It shows good application prospects in the detection of pesticide residues and other pollutants. |
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