Study On The Residual Analysis Of Jinggangmycin In Rice

Jinggangmycin, the most widely used fungicide in China, is the most effective agent in controlling the sheath blight of rice plants with no drug resistance and low toxicity. However, it is toxic and might be harmful to human being when accumulated in high concentration during the continued large-scale of use. This dissertation focuses on the study of residual analysis of Jinggangmycin in paddy water, soil, rice, rice husk, paddy plant and stalk. The main results are as follows:(1) The paddy water sample was adjusted to pH3.5, the analyte was collected with strongly acidic cation exchange column of D072, followed by ethanol and a phosphate buffer (pH3.5) used for the removal of impurities. The column was then eluted with1mol·L-1aqueous ammonia-ethanol (4:1, v:v), the eluate was then concentrated to dryness on a rotary evaporator, the residue was reconstituted of phosphate buffer (pH7.0), and20uL portion was injected onto the HPLC system for Jinggangmycin A quantification. The average recovery of Jinggangmycin A in water sample was from77.75%to83.00%with a relative standard deviation (RSD, n=5) from6.7%to12.4%. The limit of detection (LOD) was0.05mg·L-1for water sample.(2) The soil sample was extracted with a phosphate buffer (pH7.0), the obtained soil extraction was adjusted to pH3.5, the analyte was collected with strongly acidic cation exchange column of D072, followed by a phosphate buffer (pH3.5) and ethanol used for the removal of impurities. The column was then eluted with1mol·L-1aqueous ammonia-ethanol (4:1, v:v), the effluent was concentrated and applied to a macroporous adsorbent resin column of x-5(10g) for further cleanup, phosphate buffer (pH3.5) was selected as eluate. The eluate was then concentrated to dryness on a rotary evaporator, the residue was reconstituted of phosphate buffer (pH7.0), and20uL portion was injected onto the HPLC system for Jinggangmycin A quantification. The average recovery of Jinggangmycin A in soil sample was from78.74%to86.26%with a relative standard deviation (RSD, n=5) from7.1%to9.8%. The limit of detection (LOD) was0.05mg·kg-1for soil sample.(3) The rice sample was extracted with90%methanol, the obtained rice extraction was adjusted to pH3.5, the analyte was collected with strongly acidic cation exchange column of D072, followed by ethanol and a phosphate buffer (pH3.5) used for the removal of impurities. The column was then eluted with1mol·L-1aqueous ammonia-ethanol (4:1, v:v), the effluent was concentrated and applied to a macroporous adsorbent resin column of x-5(10g) for further cleanup, phosphate buffer (pH3.5) was selected as eluate. The eluate was then concentrated to dryness on a rotary evaporator, the residue was reconstituted of phosphate buffer (pH7.0), and20uL portion was injected onto the HPLC system for Jinggangmycin A quantification. The average recovery of Jinggangmycin A in rice sample was from75.36%to78.60%with a relative standard deviation (RSD, n=5) from7.1%to11.1%. The limit of detection (LOD) was0.05mg·kg-1for rice sample.(4) The rice husk sample was extracted with90%methanol, the obtained rice husk extraction was adjusted to pH3.5, the analyte was collected with strongly acidic cation exchange column of D072, followed by ethanol and a phosphate buffer (pH3.5) used for the removal of impurities. The column was then eluted with1mol·L-1aqueous ammonia-ethanol (4:1, v:v), the effluent was concentrated and applied to a macroporous adsorbent resin column of x-5(10g) for further cleanup, phosphate buffer (pH3.5) was selected as eluate. The eluate was then concentrated to dryness on a rotary evaporator, the residue was reconstituted of phosphate buffer (pH7.0), and20uL portion was injected onto the HPLC system for Jinggangmycin A quantification. The average recovery of Jinggangmycin A in rice husk sample was from79.31%to88.38%with a relative standard deviation (RSD, n=5) from8.1%to11.4%. The limit of detection (LOD) was0.05mg·kg-1for rice husk sample.(5) The paddy plant sample was extracted with90%methanol, the obtained paddy plant extraction was adjusted to pH3.5, the analyte was collected with strongly acidic cation exchange column of D072, followed by ethanol and a phosphate buffer (pH3.5) used for the removal of impurities. The column was then eluted with1mol·L-1aqueous ammonia-ethanol (4:1, v:v), the effluent was concentrated and applied to a macroporous adsorbent resin column of x-5(10g) for further cleanup, phosphate buffer (pH3.5) was selected as eluate. The eluate was then concentrated to dryness on a rotary evaporator, the residue was reconstituted of phosphate buffer (pH7.0), and20uL portion was injected onto the HPLC system for Jinggangmycin A quantification. The average recovery of Jinggangmycin A in paddy plant sample was from83.29%to86.48%with a relative standard deviation (RSD, n=5) from6.7%to11.8%. The limit of detection (LOD) was0.05mg·kg-1for paddy plant sample sample.(6) The paddy stalk sample was extracted with90%methanol, the obtained paddy plant extraction was adjusted to pH3.5, the analyte was collected with strongly acidic cation exchange column of D072, followed by ethanol and a phosphate buffer (pH3.5) used for the removal of impurities. The column was then eluted with1mol·L-1aqueous ammonia-ethanol (4:1, v:v), the effluent was concentrated and applied to a macroporous adsorbent resin column of x-5(10g) for further cleanup, phosphate buffer (pH3.5) was selected as eluate. The eluate was then concentrated to dryness on a rotary evaporator, the residue was reconstituted of phosphate buffer (pH7.0), and20uL portion was injected onto the HPLC system for Jinggangmycin A quantification. The average recovery of Jinggangmycin A in paddy stalk sample was from80.34%to89.23%with a relative standard deviation (RSD, n=5) from6.7%to11.8%. The limit of detection (LOD) was0.05mg·kg-1for paddy stalk sample.(7) The obtained results showed that all the add recoveries and relative standard deviation of Jinggangmycin A are within the allowable range of pesticide residue testing guidelines. The selected method meets the technical requirements for the analysis and detection of pesticide residues, and can be applied to Jinggangmycin residue test on rice.