OMB First to Final Action Recommendation Checklist 11-12-18

1052 C HANG ET AL .: J OURNAL OF AOAC I NTERNATIONAL V OL . 99, N O . 4, 2016

)LJXUH 'HJUDGDWLRQ SUR¿OHV RI GHJUDGDWLRQ WUHQG $ WKH SUR¿OHV of propachlor are shown as an example) over (a) 40 days and (b) 120 days. Determination days were plotted as horizontal ordinates; residue concentrations of pesticide were plotted as vertical ordinates.

There were 95 pesticides at a concn and 92 pesticides at b concn in accordance with degradation trend B, accounting for 35.1 and 33.9 of the 271 pesticides, respectively. Among them, 50 pesticides were in accordance with degradation trend B at both a and b concns. The k values from the degradation equations over 40 days were compared, showing that most of the 36 pesticides had higher k values at a concn versus b concn. Degradation trend C.— Degradation trend C was similar to degradation trend B; however, the difference was that the concentration of pesticides decreased logarithmically over 40 days (Figure 4). There were 7 and 10 pesticides in accordance with degradation trend C at a and b concns, respectively. It can be seen from the raw data that the concentrations of pesticides at day 5 or 10 day greatly differed from those on the ¿rst day. This logarithmic decrease may be considered the explanation for degradation trend C. Degradation trend D.— For degradation trend D, the concentration of pesticides presented as scatter points with R 2 values of <0.4 over 40 days, and most of the dropped trend could be ¿tted by exponential and logarithmical curves and a few ¿tted by polynomial curves over 120 days (Figure 5). At a concn, there were 23 pesticides in accordance with degradation trend D; among them, 15 pesticides decreased exponentially and 8 decreased logarithmically or polynomially over 120 days. At b concn, there were 31 pesticides in accordance with degradation trend D, and 23 pesticides decreased exponentially over 120 days. By comparison, it was found that 10 pesticides were in accordance with degradation trend D at both a and b concns. Degradation trend E.— Of the 271 pesticides, the ratios of pesticides in accordance with degradation trend E were third- ranked among the A–F aspects. The degradation pro¿les of 4,4ƍ-dibromobenzophenone over 40 and 120 days are shown as an example of degradation trend E in Figure 6a and b, respectively. For degradation trend E, the concentrations of pesticides decreased exponentially or logarithmically over 40 days, whereas no suitable equations could be used to ¿t the scatter points over 120 days. It can be seen from supplemental Tables 1 and 2 that there were 66 pesticides in accordance )LJXUH 'HJUDGDWLRQ SUR¿OHV RI GHJUDGDWLRQ WUHQG & H J dichlorofop-methyl) over (a) 40 days and (b) 120 days. Determination days were plotted as horizontal ordinates; residue concentrations of pesticide were plotted as vertical ordinates.

(at a concn) and supplemental Table 2 (at b concn). Degradation rate constants and their half-lives are also shown in supplemental Tables 1 and 2. By comparing the k values of a and b concns over 40 and 120 days, it can be found that most of the pesticides in trend A had higher k values over 40 days than over 120 days, except 12 and 19 pesticides showed the opposite at a and b concns, respectively. This ¿nding indicated that the concentration of most of the pesticides in type A dropped fast in ¿rst 40 days, whereas they decreased slowly in the remaining days. However, chlorfenapyr, bupirimate, fonofos, and furalaxyl had similar degradation equations over both 40 and 120 days. For these four pesticides, therefore, the degradation trend could be expressed by the degradation equations over 40 days. At a concn, the half-life of pesticides in degradation trend A ranged from 24.4–223.6 and 44.4–203.9 days according to the degradation equations over 40 and 120 days, respectively. Except for the previously mentioned four pesticides, the half-life of the other pesticides varied over 40 and 120 days, with the biggest difference being156.9 days. At b concn, the half-life of pesticides in degradation trend A ranged from 40.8 to 315.1 and 46.8 to 330.1 days, according to the degradation equations over 40 and 120 days, respectively. On the whole, either at a or b concn, there were great differences in half-lives over 40 and 120 days. Based on actual conditions, the half-life calculated by degradation equations over 120 days was considered to be reasonable. There were 28 pesticides in accordance with degradation trend A at both a and b concns. By comparing k values from their degradation equations over 120 days, 10 pesticides had higher k values at b concn than at a concn, whereas the remaining 18 pesticides showed the opposite. Degradation trend B— For degradation trend B, the concentration of pesticide in aged Oolong tea dropped faster over 40 days than over the remaining days. From the data in supplemental Tables 1 and 2, it was clear that the exponential equation was suitable for the ¿rst 40 days, whereas the logarithmical equation was suitable for 120 days. Taking chlorfenvinphos as an example, the degradation pro¿les of trend B are shown in Figure 3a and b for 40 and 120 days, respectively.

)LJXUH 'HJUDGDWLRQ SUR¿OHV RI GHJUDGDWLRQ WUHQG % H J chlorfenvinphos) over (a) 40 days and (b) 120 days. Determination days were plotted as horizontal ordinates; residue concentrations of pesticide were plotted as vertical ordinates.

)LJXUH 'HJUDGDWLRQ SUR¿OHV RI GHJUDGDWLRQ WUHQG ' H J cycluron) over (a) 40 days and (b) 120 days. Determination days were plotted as horizontal ordinates; residue concentrations of pesticide were plotted as vertical ordinates.