In this study, three simple and accurate spectrophotometric methods for simultaneous determination of pyriproxyfen and chlorothalonil residues in cucumbers and cabbages grown in experimental greenhouse were studied. The first method was based on the zero-crossing technique measurement for first and second derivative spectrophotometry. The second method was based on the first derivative of the ratio spectra. However, the third method was based on mean centering of ratio spectra. These procedures lack any previous separation steps. The calibration curves for three spectrophotometric methods are linear in the concentration range of 1–30 μg·mL⁻¹ and 0.5–7 μg·mL⁻¹ for pyriproxyfen and chlorothalonil successively. The recoveries ranged from 82.12–97.40% for pyriproxyfen and 81.51–97.04% for chlorothalonil with relative standard deviations less than 4.95% and 5.45% in all instances for pyriproxyfen and chlorothalonil, respectively. The results obtained from the proposed methods were compared statistically by using one-way ANOVA, and the results revealed there were no significant differences between ratio spectra and mean centering methods with the zero-crossing technique. The proposed methods are successfully applied for the simultaneous estimation of the residue of both pesticides in cucumber and cabbage samples.

中文翻译：

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三种不同的分光光度法同时测定黄瓜和卷心菜样品中的吡rip草酚和氯噻酮残留量

在这项研究中，研究了三种简单而准确的分光光度法同时测定实验性温室中黄瓜和卷心菜中吡虫杀酚和百菌清残留量的方法。第一种方法是基于用于一阶和二阶分光光度法的过零技术测量。第二种方法基于比率光谱的一阶导数。但是，第三种方法是基于比率光谱的平均居中。这些过程缺少任何先前的分离步骤。三个分光光度法的标准曲线是线性的在1-30的浓度范围 μ克·ML ^-1和0.5-7  μ克·ML ^-1依次用于吡ip昔芬和百菌清。吡ip昔芬的回收率范围为82.12–97.40％，百菌清的回收率范围为81.51–97.04％，在所有情况下，吡虫啉和百菌清的相对标准偏差分别小于4.95％和5.45％。使用单向方差分析对从所提出的方法获得的结果进行统计比较，结果表明比率光谱和采用零交叉技术的均值居中方法之间没有显着差异。所提出的方法已成功应用于黄瓜和卷心菜样品中两种农药残留的同时估算。