A technique Is proposed for the quantitative determination of constituents In complex mixtures characterized by gas chromatography data. The technique Is partial least squares In latent variables (PLS) and the data to which It Is applied are gas chromatograms of the Aroclors 1242, 1248, 1252, and 1260. In addition the problem Is formulated as one of classification and calibration and a sample of used transformer oil from a waste dump Is classified as to Its origin.

Bluegills (Lepomis macrochirus Rafinesque) and largemouth bass (Micropterus salmoidesLacepede) were exposed to two applications of Dursban©, an organophosphorus insecticide, at the recommended rates for mosquito control of 0.05 or 0.01 lb of active ingredient/A in experimental 0.! acre ponds. Residues of Dursban in water ! day after the applications ranged from 2.39 parts per billion (ppb) in the highest treatment to 0.97 ppb in the low treatment. Cumulative mortality in the untreated ponds during 63 days of observation was approximately 1% of the total population of each species of fish. Cumulative mortality of fishes during the same period in ponds treated at 0.0! lb/A was 3% for bluegills and 10% for bass, whereas the corresponding mortalities for the high application rate (0.05 lb/A) were 55% for bluegills and 46% for bass. Uptake of Dursban by fishes produced maximum residue values of 3.82 parts per million (ppm) in bluegills and 2.55 ppm in bass within ! to 3 days after application of the insecticide at 0.05 lb/A. These residues decreased greatly within 2 weeks to less than 0.4 ppm and were undetectable after 4 weeks. Both species of fish taken from the ponds treated at 0.05 lb/A exhibited more than 80% inhibition of brain acetylcholinesterase activity as compared to fish from untreated ponds; fishes from these ponds had not recovered normal acetylcholinesterase activity 28 days after application of the insecticide. Histological examination of tissues from bluegills and largemouth bass exposed to Dursban did not show conclusive evidence for pesticide-induced pathology. The high treatment reduced the total number of insects colonizing plate samplers by three-fourths, eliminated caddisflies, and severely reduced mayfly populations. We believe that the results of this investigation confirm the inadvisability, as suggested on product labels, of using Dursban at the current recommended rates of application for mosquito control in habitats where valuable fishery resources are to be protected. SMITH, G. 1966. Basic studies on Dursban insecticide. Down to Earth 22(2): 3-7. Dow Chemical

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