Document wxa3EQ5wZ729E11R8NZZ74e3

PESTICIDES IN SOIL "Apparent" Organochlorine Insecticide Contents of Soils Sampled in 19101 B. E. Frazkr, G. Chesters, and G. B. Lee .! ' ABSTRACT A total ol 34 soil samples taken in Wisconsin between 1909 and 1911 were extracted for organcchlorine insecticides and analyzed by gas chromatography on 3 columns,--a mixed QF-1 /IV-17 column; a mixed QF-1/DC-200 column; and a diethylcnc glycol succinate column.-] The samples had been stored continuously since collection in tightly sealed glass jars end presumably were free of inter-icide contamination. Of the 34 samples 32 showed some "apparent" insecticide residues on ui least one oj the columns. Hecause peaks)corTcsrpcr.dir.Kg to r.a.i.Luhi, or vunuchiorine insecticides on cl| /iromatograms from one column did not recur on other columns, it was concluded that the peaks arose from co-extracted indigenous soil components. Peaks corresponding to heplachlor epoxide on the QF-1 /OV-17 column and to aldrir. on the QF-1 fDC-200 column provided greatest interference in chromatographic determination. Introduction to be interfering compounds (3). Extraction and an alytical procedure: suitable for organochlorine insecti cide determinations in soils must be able to disprove "apparent" residues when used on soils known to be free of insecticide residues. In the routine analysis of soil samples for insecticides it is advantageous if methods can be designed to elimi nate cleanup. Partitioning and Florisil cleanup steps ate used but contamination from indigenous soil rnmnnnontc rv,2y rt;t; v-c present (2), and a con firmatory analysis is necessary. This investigation on insecticide-free samples was de signed to determine the extent of interference with in secticide determination arising from indigenous soil components. Insecticide-free soils were obtained from a collection of 34 soil samples collected between 1909 and 1911 and stored in tightly stoppered glass jars since that time. Multicolnnm gas chromatography has been used suc cessfully to determine qualitatively and quantitatively the content of organochlorine insecticides in soils: how ever, the method has not been tested extensively using soil samples known to be free of insecticides. The chromatogram of one uncontaminated soil revealed small interfering peaks, suggesting that concentrated soil ex tracts may show "apparent" insecticides where none exist (7). In another investigation, five uncontaminated soil samples gave gas chromatographic responses" to y-BHC, aldrin, and endrin (2). One response which was apparently caused by y-BHC was in fact caused! by sulfur. By use of mu'ticolumn gas chromatography, aldrin-like compounds found in plant materials proved 1 From the Deportment of Soil Science, University of Wisconsin, Madi son, Wis. 53706. ' Vol. A, No. 2, September 1970 Methods and Materials The soils (Table 1) consisted of samples with a wide range of textural class; their organic matter content ranged from 1.0% to 7.9%. An unpublished report on the soil samples indicates that organic matter was de termined by a chromic acid wet oxidation method, but details of the procedure are not available. The textural class was obtained by observation. Although the descrip tion of the methodology is inadequate, it is believed that these data rre as reliable as data which might be obtained presently on 60-year-old samples. The organochlorine insecticides--y-BHC, heptachlor and its epoxide, aldrin, dieldrin, endrin, ;>,p'-DDD, p,p'DDT, and p.p'-methoxychlor--used as standards were those described earlier (4). . 67 . _ i DSW 203297 STLCOPCB4053118 Sample No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 TABLE 1.--Properties of soil samples used Soil Series Texture Ontonagon Miami Fayette Miami1 Dubuque Plainfield Tania , Tama Morley Plano Oshkosh Plano Ontonagon Oshkosh Miami Goodman Fox Fox Warsaw Casco Piainfield Plano Oshkosh Warsaw Huntsville Miami Plainfield Tam- . Oshkosh Payette Plainfield Hixton { ornira 1 jtlochhrim . clay tilt loam silt loam Silt loam silt loam . sand silt loam silt loam silt loam silt loam silt loam silt loam clay clay loam silt loam silt loam silt loam silt loam silt loam sandy loam sand silt loam silt loam sandy loam silt loam silt loam sand silt loam clay 1 .am silt loam sand . fine sandy loam silt lo;-m gravelly loam " ' -i - Percent Organic Matter -- 3.4 22 1.4 2.4 1.8 . 1.1 4.1 7.9 2.7 5.2 2.6 5.7 3.0 1.7 2.3 3.3 3.7 1.5 5.3 2.3 1.8 6.2 2.1 2.9 7.6 1.5 1.3 4.3 3.9 4.4 1.7 1.5 2.3 2.1 A Packard Model 7620 gas-liquid chromatograph was used for analysis of organcehlorinr. in^v-ticides. Gas chromatographic conditions were: carrier gas, v.'hh flow rate of 125 m'/hiinuie; r,H-foil electron-capture detector at 210 C, 50 volts; column temperature, 190 C; inlet ternpciaturc, 235 C; outlet temperature, 225 C. The three types of columns were: (1) 2 parts 105e QF-I, 1 part 3% OV-17 on 60/S0 mesh Gas Chrom Q (2 meters x 4 mm I.D.); (2) 1 part 1757 QF-1, 1 part 11% DC-200 on 60/80 mesh Gas Chrom Q (;2 meters X 4 mm I.D.); and (30 1057 dietheylene glycol suc cinate (DGS) on 60/S0 mesh Gas Chrom Q (1 meter X 4 mm I.D.). The instrument incorporates; the use of glass columns and on-column injection to avoid sample, degradation resulting from contact of the sample with metal surfaces. Air-dried soil from the surface 20 cm was extracted in quantities of 100 g or 50 g (when a limited amount was available) with 200 ml'of a 41:59 Shelly B:acetoneazeotropic mixture using a Soxhlet technique in all glass apparatus (5). Cone miration of the extract to 25 ml was achieved by forced air evaporation at 40 C. For samples 1-9 inclusive a fivefold dilution of the 25 ml concentrated extract was required for quantitative gas ehiomatogiaphy. Tire concentrated extracts were not subjected to any method of cleanup. 6S _ Results and Discussion Using three column chromatography most of the soil extracts gave peaks corresponding to organocblo- rine insecticides. On the QF-1 /OV-1T column, 32 of 34 samples apparently showed measurable quantities of "hcptachlor epoxide," and 24 samples contained ``hepta- chlor"; peaks comparable to y-BHC, aklrin, and diekhin were found in a few samples (Table 2). On the QF-1/ DC-200 column 20 of 34 samples apparently contained measurable quantities of "aldrin" with slight interfer ence from "rBHC" and "dieldrin." A low degree of confusion between organoehlorine insecticides and in digenous soil components was found on the DGS column; small amounts of "y-BHC." and "hcptachlor epoxide" would have been reported if this column had been used exclusively. No indigenous soil components which would interfere with determination of ernlrin, p.p'-DDD, p,p'-DDT, or p,p'-methoxychlor were found on any of the columns. Major interferences (>100 ppb) were found for "hcptachlor epoxide" in soil samples 1-8 inclusive on the QF-l/OY-17 column and for "aldrin" in samples 1, 2, 5, and 6 on the QF-1/DC- 200 column. Chromatograms of the Skeliy. Biacetone extract of sample 9 on each of the three columns are shown in Fig. 1, 2, and 3. This sample was chosen because it was qualitatively similar to the other soil samples while showing a moderate amount of imerferer.ee with iu- PeSTICI DES hI.ONITOR1 NG JOURNAL ! DSW 203298 TABLE 2.--"Apparent" organochlorine insecticide contents o{ air-dried soils sampled in 1910 Sample No. Heptacklok Epoxide 1 823 2 *07 3 742 4 696 5 364 6 373 7 188 8 156 9 51 10 49 11 43 12 40 13 33 14 28 15 25 16 20 17 19 18 14 19 9 20 8 21 7 22 7 23 7 24 4 25 4 26 4 27 3 28 3 29 2 30 2 31 2 32 1 33 0 34 C 4*Apparent" Insecticide Contents in PPB os Columns QF-l/OV-17 QF-1 /DC-700 HeptaChlox VBHC Aldjun Dieldrin BHC Aldrin Dieldrin 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 40 0 0 0 0 0 0 0 0 0 0 0 0 0 DGS -BHC Heftachlor Epoxide 00 40 00 90 90 30 00 00 20 02 00 03 22 30 30 00 00 20 00 00 46 00 04 00 00 21 00 00 C0 00 00 00 30 20 secticide determination (Table 2). Extensive contam ination by "hcptachlor epoxide" and slight contamina tion by "y-BHC" and "hcptachlor" are indicated on the QF-1/ON7-17 column (Fig. 1). "Aldrin" is the apparent contaminant found on the QF-1 /DC-200 col umn (Fig. 2) while a small amount of "y-B.HC" was found on the DGS column (Fig. 3). Interfering peaks were classed as those which had a retention time (Rt) equal to R, 30 seconds of that of the standard in secticide. With a larger discrepancy in R,-value, it is tFleved that the insecticide would be resolved satisfac torily from the indigenous soil contaminant. From examination of Table 2, it can be seen that the "apparent" insecticide residues in the soil arise from indigenous compounds which display cliromatographic characteristics similar to a particular organochlorine insecticide. However, the characteristic is unique to one' of the columns and not displayed on either of the other two columns. The use of a combination of any two of the three columns described would reveal satisfactorily any chromatographic discrepancies arising from co-extraction of naturally occurring soil com ponents, i Six of the samples indicated small amounts of "hcptachlor epoxide',' on the DGS column which might be considered confirmatory for the "hcptachlor epoxide" found on the QF-l/OV-17 column. However* no peaks Voi.. A, No. 2, September 1970 corresponding to hcptachlor epoxide were found on the QF-1/DC-200 column, and it is not believed that this discrepancy would lead to confusion if only two columns were used since the quantities of "hcptachlor epoxide" on DGS arc extremely small; the highest amount was 6 ppb for sample 21. In Tabic 1 the samples are arranged in decreasing order of "apparent" insecticide contamination based on the "hcptachlor epoxide" peak shown on the QF-l/OV-17 column. No relationship was found between "apparent" insecticidal contamination (Table 2) and the soil prop erties described in Table 1. On each of the three columns a large peak was found which' displayed an Revalue greater than that for p,p'methoxychlor on the QF-l/OV-17 and QF-1/DC-200 columns which are relatively nonpolar. However, on the. relatively polar DGS column, the peak had a short Revalue (comparable to that of dieldrin and endrin on the DGS column) which would interfere with insecti cide determination (Fig. 3). This peak was found to result from the forced air evaporation of the soil extracts using Tygon tubing to blow air over the extracts. Small amounts of Tygon must have been dissolved by the Skclly Btacelone solvent during this procedure since Skclly B was capable of extracting the material from Tygon in less than 10 seconds (Fig. 3). , r---------- ------------ 69 1 DSW 203299 STLCOPCB4053120 Approved by the Director, Research Division, Colltge of Agricultural and Life Sciences. University of Wisconsin, Madison, *Wis. This investigation was supported in part by the U.S. Department of Agri culture, ARS Contract No. 12-14-100-S154(14) and the" U.S. De partment of the Interior, Office of Water Resources Research Proj ect No. B-016-WIS. * See Appendix for chemical names of compounds mentioned in this paper. FIGURE 2.--Gas chromatograms oj crgar.oclilorine insecti cide standards and the Shelly B: acetone extract of soil sample 9 on c QF-1 /DC-200 LITERATURE CITED (!) Bowman, M. C., H. C. Young, ar.d W. F. Bartliel. 1965. Minimal concentrations of aldrin, dicldrin, and heptachlor in soil for control of White-Fringed Beetles as de termined by parallel gas chromatographic and biological assays. J. Econ. Entomol. 58:896-902. (2) De Vries, D. M., R. D. Collins, and R. T.'Rossi. 1968. What is a residue--or analytical artifacts? Symposium on the science and technolog} of residual insecticides in food production with special reference to aldrin and dicldrin. Shell Oil Company. (S) Goodwin, E. S., R. Goulden, and }. G. Reynolds. 1961. Rapid identification and determination of residues of chlorinated pesticides in crop by gas-liquid chromatog raphy. Analyst 86:697,709. (4) Pionke, II. B., J. G. Konrad, G. Chesters, and 1). E. Armstrong. 1968. Extraction of organochlorine and organophosphatc insecticides from lake waters. Analyst 93:363-367. (5) Pionke, 11. B., G. Chesters, and D. E. Armstrong. 1968. Extraction of chlorinated hydrocarbon insecticides from soils: Agron. J. 60:289-292. FIGURE 1.--Gas chromatograms of organochlorine insecti cide standards and the Shelly B: acetone cxtrr.ct cf soil sample 9 on a QF-1 /OV-17 column FIGURE 3.--Gas chromatograms of organochlorir.c insecti cide standards and the Shelly B: acetone extract of soil sample 9 ar.d Tygon tubing on a DCS column 70 Pesticides Monitoring Journal DSW 203300 j STLCOPCB4053121