Sample manipulation and apparatus useful in estimating surface and penetration residues of DDT in studies with leaves and fruits

Abstract

does not appear. First page follows. Introduction The consequences of DDT applied in the field have been intensively investigated at the University of California Citrus Experiment Station since 1943. Early in this investigation certain instances disclosed that DDT, as it was applied in the field in various experimental formulations, actually penetrated the fruit and leaf tissues. This indicated potential consumer hazards. Therefore, a detailed semiquantitative examination of surface residues and of the extent and degree of penetration resulting from such applications was undertaken. Materials examined in this program included fruit, and sometimes leaves, from mature apple, avocado, citrus, olive, peach, pear, and plum trees. At the present time a report of the analytical techniques developed empirically from the handling of many thousands of these samples, and a detailed description of some of the apparatus used may be of benefit to other investigators. (Carter and Hubanks (1946))4 recently presented a brief discussion of apparent “recoveries,” by analytical methods, of DDT added to dried plant material, including apples. Their results agree with those obtained by the techniques developed during the present investigation. Moreover, (Wichmann et al. (1946)) recently have thoroughly discussed the application of three methods for the quantitative determination of DDT as spray residues on fresh fruit, particularly apples and pears. Certain points of similarity between the techniques discussed by Wichmann et al., and those discussed in the present paper will be noted. It must be emphasized that certain of the manipulative procedures described in this report are only semiquantitative in nature.