小麦和土壤中环丙唑醇残留消解动态及膳食摄入评估

Analysis of wheat and soil cyproconazole dissipation under field conditions and risk for dietary residue intake

为评价环丙唑醇在小麦生产上应用的安全性,通过建立乙腈提取、氮磷检测器检测方法对小麦籽粒、植株和土壤样品中环丙唑醇的残留量进行检测,研究了小麦籽粒、植株和土壤中环丙唑醇的残留及其消解动态,并对小麦中的残留量进行风险评估。结果表明,环丙唑醇在小麦籽粒、植株及土壤空白样品中的添加回收率为79.2%~95.6%,相对标准偏差为1.9%~10.0%,最小检出量为8.2×10？12 g,在小麦籽粒、植株及土壤中的最低检测浓度均为0.05 mg·kg？1,乙腈提取、氮磷检测器检测方法重现性好,准确度、精密度高,可满足环丙唑醇在小麦上的残留分析要求。2010年和2011年,河南省、黑龙江省和江苏省3地环丙唑醇在小麦植株和土壤中的消解半衰期分别为3.0~5.5 d、18.1~34.5 d;不同施药次数、施药量及采样间隔,环丙唑醇在小麦籽粒中的最终残留量均≤0.415 mg·kg？1。采收间隔期为14 d和21 d时,不同施药次数、施药剂量和采收间隔期,环丙唑醇在小麦植株、小麦籽粒和土壤中的残留量差异均不显著;采收间隔期为7 d,有效成分108 g？hm-2施药2次与有效成分162 g？hm-2施药3次时小麦植株、小麦籽粒和土壤中的残留量之间均存在显著性差异。普通人群环丙唑醇的国家估算每日摄入量为0.000 109 9 mg,占日允许摄入量的0.5%左右,按本试验方式进行施药,通常不会对一般人群健康产生不可接受的风险。

Currently, there is little research on the assessment of dissipation and dietary intake of cyproconazole in wheat and soil under field conditions. This paper developed a sensitive and simple method of analysis of cyproconazole based on gas chromatography with nitrogen-phosphorus detector（GC-NPD）. Calibration curves were derived for cyproconazole by plotting peak area against concentration range of 0.05-2.0 mg·L-1 in a linear equation（y=266 482 x ＋ 2 296.7） with a correlation coefficient of r2=0.999 7. The limit of quantification（LOQ）, defined as minimum spike level, was 0.05 mg·kg-1. The average recoveries of five replicates fortified at 0.05-0.2 mg·kg-1 were in the range of 79.2%-95.6% for soil, wheat crop and wheat grain and with relative standard deviation（RSD） range of 1.9%-10.0%. Based on the developed method, the dissipation and terminal residues of cyproconazole in wheat and soil in three experiment fields respectively in Henan, Jiangsu, and Heilongjiang Provinces were investigated under field conditions. The effects of application frequency, dosage and pre-harvest interval on terminal residues were also discussed. Based on first-order kinetic equations, half-life of dissipation of cyproconazole in wheat（3.0-5.5 days） was much shorter than in soil（18.1-34.5 days） in three experimental fields. The sequence of residue level was wheat grain soil wheat plant; which were respectively 0.415 mg·kg-1, 0.696 mg·kg-1 and 5.670 mg·kg-1. Final residues of cyproconazole in wheat grains was less than 0.415 mg·kg？1 under different application times, doses and pre-harvest intervals. When pre-harvest interval was 14 and 21 days, cyproconazole residues in wheat plants, grains and soil were not significant different among different application times, doses. However, when harvested at 7 days after application, residues in wheat plants, grains and soil were significantly different between 108 g？hm-2 cyproconazole spraying 2 times and 162 g？hm-2 cyproconazole spraying 3 times. Acceptable daily intake（ADI） of cyproconazole was 0.02 mg for per kilogram body weight. The supervised trial median residue（STMR） in wheat grain was 0.05 mg·kg-1 and the estimated ADI of cyproconazole was 0.000 109 9 mg？kg？1（body weight）. Risk assessment analysis for supervised residue trial suggested that potential health risk posed by cyproconazole was insignificant. Comparison using the one-way Duncan analysis showed that when pre-harvest interval was 14-21 days, dosage and frequency of cyproconazole application had no effect on terminal residues. When pre-harvest interval was 7 days, dosage and frequency had a critical effect on terminal residues. The results showed that cyproconazole use was comparably safe under recommended application methods. This provided a guideline for safe and reasonable use of cyproconazole.