Application On Solid Phase Micro-Extraction For Determintion Of Pesticide Residues In Aquatic Vegetables

Aquatic vegetables have exposed to pesticides less than other types of vegetables because of its unique living environment such as rivers, lakes and swamps and have conquered customers of both domestic and abroad with special flavor and beneficial elements. However, it is urgent and important to detect pesticide residues in aquatic vegetables for the environment of aquatic vegetables have changed and its pollution is increasingly serious.Solid phase micro-extraction(SPME) integrate a number of sample handling operations such as extraction, preconcentration, and sample introduction for instrumental analysis into a single step. In this paper, SPME was picked to detect the trace residues of pesticides in aquatic vegetables combined with equipment such as gas chromatography(GC), high performance liquid chromatography(HPLC) and gas chromatography mass spectrometry(GC-MS). Insecticides, fungicides and herbicides that are used to lotus root, water chestnut and zizania aquatica including a total of15kinds of commonly used pesticides had detected. The main works were described as follows:1Multi-residue determination of pesticides in lotus root by SPME combined with GC.It was the first time to introduce SPME to detection of pesticide residues in lotus root. The extraction parameters were optimized and the response surface analysis (RSA) was introduced to assess extraction conditions. The optimized extraction protocol was as follows:65μm-PDMS/DVB,40℃of the extraction temperature,41min of the extraction time,25%(W/V) NaCl in concentration, pH7.5with agitation at455rpm, and250℃of desorption temperature,5min of desorption time. Under this optimized conditions, the recovery of pesticides including Isoprocarb, Acetochlor, Metolachlor, Haloxyfop-R-methyl, Oxadiazon, Buprofezin, Fluazifop-p-butyl, Quizalofop-p-ethyl, Difenoconazole, Azoxystrobin ranged from76.17%to137.15%, relative standard deviation(RSD) ranged from1.15%to12.83%, the limit of detection(LOD) was less than 0.03μg/g. This method can meet the requirements of international maximum residue limit.2Determination of trace pesticide residues in water chestnut by SPME combined with GC-MS.It was the first time to detect trace pesticide residues in water chestnut using SPME in conjunction with GC-MS, and7parameters were optimized too. The optimized extraction protocol was as follows:65μm-PDMS/DVB,30℃of the extraction temperature,40min of the extraction time,10%(W/V) NaCl in concentration with agitation at650rpm, and270℃of desorption temperature,5min of desorption time. Under these optimized conditions, the recovery of4pesticides including Chlorpyrifos, Flusilazole, Chlorfenapyr, Fluazifop-p-butyl ranged from70.78%to134.14%, the RSD was less than12.10%, the LOD was less than8.0ng/g. The method can meet the requirements of international maximum residue limit.3Determination of Imidacloprid and Carbendazim in Zizania aquatica by SPME combined with HPLC.SPME combined with HPLC was chosen to detect the Imidacloprid and Carbendazim residues in Zizania aquatica.7parameters were optimized too. The optimized extraction protocol was as follows:65μm-PDMS/DVB;50min of extraction temperature,40℃of extraction time,750rpm of stirring speed,28%(W/V) of concentration of NaCl with9min of static desorption time. The recovery of Imidacloprid and Carbendazim ranged from83.27%to120.03%, the RSD was less than6.81%, the LOD was less than0.05μg/g. Otherwise, the great linear correlation were obtained that are greater than0.9945in4.0μg/g-80.0μg/g. The method can meet the requirements of international maximum residue limit.