| Analysis method of common benzimidazole fungicides which contain carbendazim, benomyl and thiabendazole was studied on samples of six typical kinds of fruits—apple, peach, citrus, grape, strawberry and banana. With new established method, Carbendazim and thiabendazole residues were determined in 213 apple samples and 47 grape samples collected from main production regions and markets in 2005, 2006 and 2007.Main results of the analysis method study are as follows:1,Dispersive-SPE and HPLC analytical method was successfully developed for the qualitative and quantitative analysis of the benzimidazole fungicide residues—carbendazim, benomyl and thiabendazole. The parameters of the method were further optimized and identified with the above mentioned 6 kinds of typical fruit, it showed good linear relation for the fungicides concentrations ranging from 0.01mg/kg～3.0 mg/kg with correlation coefficients﹥0.999, the recovery rate was between 88%～104.7%, and relative standard deviation <4.2%. Precision, accuracy and repeatability of the mended method all satisfied the demand. The new method (dispersive-SPE and HPLC) was compared with other 4 commonly used standard methods in the world for carbendazim determination, it showed obvious advantage in high accuracy, low cost of economy and time. Based on the results, a relative method draft standard was written.2,The compound of dispersive sorbent PSA and C18 was studied for mending the method, it reduced the carbendazim recovery rate from 110% to 91.8%～104.7% and heightened the thiabendazole recovery rate from 17%～44% to 88%～102%.3,Matrix effect of carbendazim was discovered, and a suitable method was used to solve the problem.Main results of the fungicide residues status study are as follows:1,The eligible rate of apples was very high, so the safety status is good for the market. In 2005, carbendazim residues detection rate was 63.5%, thiabendazole residues detection rate was 16.4%. And in 2006, carbendazim residues detection rate was 16.4%, thiabendazole residues detection rate in domestic samples was none. Carbendazim detection rate was higher than thiabendazole detection rate in domestic samples, but the situation was opposite in abroad samples. In Gala, 0.162mg/kg and 0.153mg/kg carbendazim average residues were detected in domestic and abroad samples respectively, which were obviously higher compared with other varieties. 0.622mg/kg thiabendazole average residues in Gala was also higher than the average residues in other varieties.2,Detection rate of carbendazim in grape was 68.1%, but no one is over the MRL, so it is safe. Detection rate of thiabendazole in grape was 31.9%, and all of them are below the Japan MRL 3mg/kg, but over the EU MRL 0.05mg/kg. |
