Environ. Sci. Technol. 1992, 26, 921-925
McDonald, D. G. Can. J. Fish. Aquat. Sci. 1988,45, 1575. (53) Bertsch, P. M.; Herbert, B.; Layton, W. J. Abstracts of Papers, 201st National Meetings of the American Chemical Society, Atlanta, GA, 1991; American Chemical Society: Washington, DC, 1991; COLL 55. (54) Dickson, W. Verh. Int. Ver. Limnol. 1978, 20, 851. (55) Dickson, W. Vatten 1983, 39, 400. (56) Nyberg, P. Philos. Trans. R. SOC.London, B 1984,305,549. (57) Weatherly, N. S.; Rutt, G. P.; Thomas, S. P.; Ormerod, S. Water, Air, Soil Pollut. 1991, 55, 345. (58) Playle, R. C.; Wood, C. M. J. Comp. Physiol., B 1989,159, 527.
Bottero, J. Y.; Axelos, M.; Tchoubar, D.; Cases, J. M.; Fripiat, J. J.; Fiessinger, F. J. Colloid Interface Sci. 1987,
117, 47. Tsai, P. P.; Hsu, P. H. Soil Sci. SOC.Am. J. 1984,48, 59. Hsu, P. H. Clays Clay Miner. 1988, 36, 25. Kinraide, T. B.; Parker, D. R. Plant Cell Enuiron. 1989,
12, 419. Wood, M.; Cooper, J. E. Soil Biol. Biochem. 1984,16,571. Wood, M.; Cooper, J. E. Soil Biol. Biochem. 1988,20, 95. Kinraide, T. B. Plant Physiol. 1988, 88, 418. Moore, D. P. In The Plant Root and its Environment; Carson, E. W., Ed.; University Press of Virginia: Charlottesville, VA, 1974; Chapter 6. Grauer, U. E.; Horst, W. J. Plant Soil 1991, 127, 13. Driscoll, C. T., Jr.; Baker, J. P.; Bisogni, J. J., Jr.; Schofield, C. L. Nature (London) 1980, 284, 161. Kane, D. A,; Rabeni, C. F. Water Res. 1987,21, 633. Havas, M. Can. J. Fish. Aquat. Sci. 1985, 42, 1741. Wood, C. M.; Playle, R. C.; Simons, B. P.; Goss, G. G.;
Received for review October 21, 1991. Revised manuscript received January 31, 1992. Accepted February 6, 1992. P.M.B. was partially supported by Contract DE-ACO9-76SR00819 between the University of Georgia and the U.S. Department of Energy.
Analyte Stability Studies Conducted during the National Pesticide Survey Davld J. Munch" US. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268
Chrlstopher P. Frebls Computer Sciences Corporation, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268
Since it is generally impossible to analyze field samples immediately upon collection and sample extraction, demonstration of the stability of the analytes in both the aqueous and organic solvent (extract) matrices is essential in all environmental surveys. The US.Environmental Protection Agency (EPA) has recently completed the National Pesticide Survey (NPS). Analyte stability studies of both well water samples and final extracts were important components of this survey. The primary focus of these studies was to demonstrate the stability of the analytes for the maximum sample and extract holding times that would be permitted during the survey. Up to 100% loss was observed for 26 out of the 147 compounds spiked into well water samples which had been biologically inhibited and stored at 4 "C for 14 days. Analyte stability was demonstrated for 121 analytes, in stored well water samples. Analytes generally remained stable in stored sample extracts. H
Introduction
The U.S. Environmental Protection Agency (EPA) has recently completed the National Pesticide Survey (NPS). This Rurvey was the first nationally based, statistically valid study of the occurrence of pesticides in drinking water wells. During the NPS, 1349 drinking water wells were sampled and analyzed for 127 different pesticides or related compounds, using eight different analytical methods. Sampling and analyses were conducted over approximately a 2-year period. The results of the NPS were released in November 1990 ( I ) . The following six analytical methods were developed for use in the NPS. Information concerning the development and implementation of the analytical methods used in this survey were previously reported (2).Four of these methods have since been promulgated for use in drinking water compliance monitoring (3, 4). NPS method 1 (EPA 507): Determination of nitrogen phosphorous containing pesticides in ground water by gas chromatography with a nitrogen phosphorous detector [39 0013-936X/92/0926-0921$03.00/0
analytes, final extraction solvent methyl tertiary butyl ether (MTBE)]. NPS method 2 (EPA 508): Determination of chlorinated pesticides in ground water by gas chromatography with an electron capture detector (25 analytes, final extraction solvent MTBE). NPS method 3 (EPA 515.1): Determination of chlorinated acids in ground water by gas chromatography with an electron capture detector (13 analytes, final extraction solvent MTBE). NPS method 4: Determination of pesticides in ground water by high performance liquid chromatography with an ultraviolet detector (16 analytes, final extraction solvent methanol). NPS method 5 (EPA 531.1): Measurement of N-methyl carbamoyloximes and N-methyl carbamates in ground water by direct aqueous injection HPLC with post-column derivatization (10 analytes). NPS method 6: Determination of ethylene thiourea (ETU) in ground water by gas chromatography with a nitrogen-phosphorous detector (1analyte, final extraction solvent ethyl acetate). In addition to using the six analytical methods developed specifically for the NPS, samples collected for this survey were analyzed using two previously developed EPA methods. EPA method 504: 1,2-Dibromoethane and 1,2-dibromo-3-chloropropane in water by microextraction and gas chromatography (1,2-dichloropropane and cis- and trans-1,3-dichloropropenewere added to the scope of the method, final extraction solvent hexane). EPA method 353.2: Nitrogen, nitrate-nitrite, colorimetric, automated, cadmium reduction. Experimental Section
Methods Development. A limited preservation study was conducted during methods development. Samples of a groundwater from central Ohio were acquired for these experiments. To inhibit biological degradation, 10 mg of
0 1992 American Chemical Soclety
Environ. Sci. Technol., Vol. 26, No. 5, 1992 921
Table I. National Pesticide Survey Analysis of Composite Time Storage Samplesn analyte alachlor ametryn atraton atrazine bromacil butachlor butylate carboxin chlorpropham cycloate diazinon dichlorvos diphenamid disulfoton disulfoton sulfone disulfoton sulfoxide
EPTC ethoprop fenamiphos fenarimol fluridone hexazinone merphos methyl paraxon metolachlor metribuzin mevinphos MGK 264 molinate napropamide norflurazon pebulate prometon prometryn pronamide propazine simetryn simazine stirofos tebuthiuron terbacil terbufos terbutryn triademefon tricyclazole vernolate aldrin a-chlordane y-chlordane chlorneb chlorobenzilate chlorothalonil DCPA 4,4’-DDD 4,4’-DDE 4.4’-DDT dieldrin endosulfan I endosulfan 11 endosulfan sulfate endrin endrin aldehyde etridiazole wHCH B-HCH 6-HCH Y-HCH heptachlor heptachlor-epoxide hexachlorobenzene methoxychlor cis-permethrin 922
no. obs
av % rec
SO
SO
SD SO
no. obs E14
20 17 16 20 16 16 19 17 15 17 6 18 17 8 8 8 16 19 19 18 18 17 17 20 17 18 17 20 17 15 18 17 18 18 8 18 18 17 20 18 17 9 20 18 18 17
99 100 112 100 98 99 88 90 98 94 84 96 99 83 88 90 94 99 95 100 95 96 79 109 99 95 97 87 96 103 98 91 96 95 27 97 96 98 105 94 102 50 98 98 104 90
2.6 5.1 6.9 2.5 4.2 5.7 2.8 4.2 5.2 3.4 4.5 4.0 4.6 6.3 5.1 7.7 3.0 2.4 6.0 7.8 9.1 4.8 3.3 3.8 4.5 4.1 4.2 4.2 3.2 6.1 5.6 3.8 4.7 4.4 4.2 4.3 5.4 4.8 3.9 5.5 4.4 6.0 3.0 5.1 6.1 4.0
16 17 16 15 18 16 16 18 15 18 7 18 18 8 8 8 18 16 15 18 18 17 17 16 17 18 18 16 18 15 18 17 18 18 8 18 18 17 16 18 17 5 16 18 18 18
21 20 20 21 19 21 20 20 20 21
79 91 96 96 113 74 111 92 88 91 91 96 89 93 93 92 107 92 99 95 111 96 92 95 126 98
3.5 6.7 6.6 3.9 12.1 3.9 9.2 12.6 7.7 11.3 6.1 5.6 7.3 9.8 6.7 8.8 9.8 3.5 8.5 9.4 5.4 5.7 4.7 4.6 21.9 14.1
28 28 28 28 26 26 28 28 28 28 28 28 28 28 28 28 28 27 28 26 28 28 28 28 28 28
21 21
21 20 21 21 20 20 20 20 21 20 21 19 20 21
Envlron. Scl. Technol., Vol. 26, No. 5, 1992
av % rec
SD
no. obs
E14
E14
SI4
4.0 6.5 7.8 3.7 3.3 6.5 2.5 2.5 3.4 3.3 14.0 3.4 3.9 4.7 5.5 4.1 2.6 3.8 8.8 4.7 7.2 4.9 6.3 6.2 5.7 3.4 3.2 4.3 2.6 8.4 4.5 3.0 3.2 3.5 3.2 3.2 3.6 5.7 5.0 3.8 7.0 1.9 4.9 3.5 4.3 3.7
19 18 18 19
19 15 16 18 18 18 19 17 18 18 17 18 16 16 17 18 18 8 18 18 17 19 18 18 8 19 18 18 17
0 93 97 90 98 96 93 86 106 100 94 93 85 94 104 99 91 95 94 0 96 93 97 101 93 103 1 96 94 97 88
5.8 6.6 6.3 5.4 10.0 4.8 6.9 10.9 9.0 17.8 7.2 7.4 9.2 9.2 10.9 9.3 5.0 3.9 5.1 6.1 4.9 4.6 5.3 4.4 21.7 15.5
22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22
81 89 92 100 107 72 108 95 89 100 97 94 82 95 96 96 117 97 98 93 117 75 94 91 131 114
Method I 100 102 114 100 98 99 87 92 98 94 81 97 98 84 90 92 92 100 95 102 100 99 91 115 101 97 98 88 94 105 100 90 97 97 27 98 96 98 106 95 106 35 99 99 103 88 Method 2 84 100 105 99 118 71 115 109 102 100 97 99 93 103 99 96 114 97 104 91 117 99 95 97 144 111
18
17 17 17 16 18 5 18 18 8 8 8 18
av rec SI*
SD
97 100 113 102 94 101 88 84 97 91 21 86 106
3.1 5.6 5.7 3.7 2.9 6.7 2.4 2.7 4.5 3.3 4.0 4.7 3.6 0.2 3.2 0.4 2.6 2.9 4.7 3.4 5.8 5.0 3.4 6.5 5.2 2.8 3.3 2.7 2.8 7.9 3.5 3.0 3.0 3.0 0.02 2.9 3.3 4.6 5.5 6.2 5.9 3.3
1 1
s14
4.1
5.6 4.3 3.0 4.5 6.5 6.4 7.6 10.8 7.4 7.0 11.3 8.8 14.5 5.6 5.5 8.3 11.1
6.0 11.7 11.0 6.5 4.8 5.7 7.2 3.2 4.8 4.7 18.7 16.5
p-value vs
s 1 4 vs
so
0.506 0.414 0.414 0.498 0.806 0.855 0.634 0.412 0.910 0.901 0.871 0.493 0.889 0.705 0.424 0.638 0.475 0.273 0.936 0.443 0.141 0.326 0.163 0.058 0.358 0.255 0.670 0.752 0.461 0.467 0.308 0.753 0.690 0.415 0.897 0.738 0.845 0.948 0.272 0.930 0.164 0.677 0.580 0.702 0.752 0.501
0.356 0.728 0.715 0.592 0.128 0.553 0.823 0.052 0.543 0.207 0.005 0.000 0.070 0.000 0.000 0.000 0.664 0.220 0.299 0.692 0.692 0.549 0.388 0.176 0.671 0.597 0.094 0.016 0.324 0.886 0.779 0.524 0.511 0.432 0.001 0.523 0.320 0.703 0.024 0.710 0.769 0.001 0.129 0.164 0.032 0.388
0.063 0.181 0.295 0.172 0.024 0.773 0.239 0.043 0.077 0.033 0.058 0.206 0.260 0.059 0.128 0.013 0.532 0.063 0.536 0.320 0.048 0.871 0.131 0.887 0.006 0.043
0.622 0.436 0.271 0.093 0.553 0.761 0.537 0.660 0.762 0.060 0.124 0.385 0.140 0.678 0.280 0.084 0.069 0.146 0.660 0.821 0.300 0.000 0.220 0.109 0.565 0.009
Table I (Continued) analyte
no. obs
av % rec
SD
SO
SO
SO
no. obs
av % rec
av rec
SD
s 1 4
SI4
E14 VI So
12.2 4.5 3.7
22 22 22
110 109 105
20.0 5.6 4.8
0.006 0.348 0.452
0.081 0.007 0.767
Si4
vs So
20
94 100 106
16.3 4.1 5.9
28 28 28
17 20 20 15 20 12 20 19 19 20 16 18 16 20 19 20 20
82 100 99 12 99 100 99 99 96 98 87 90 107 85 84 100 102
13.3 5.3 7.8 7.5 4.6 11.8 6.1 4.3 5.7 5.5 13.6 5.2 17.1 4.9 6.8 4.7 4.3
Method 16 19 19 15 19 11 19 19 18 19 15 19 15 19 18 19 19
3
acifluorfen 2,4-DB bentazon chloramben 2,4-D dalapon DCPA acid metabolites dicamba 3,5-dichlorobenzoicacid dichlorprop dinoseb 5-hydroxy dicamba 4-nitrophenol PCP picloram 2,4,5-T 2,4,5-TP
70 101 102 19 103 98 99 101 107 104 85 81 107 81 85 104 106
8.4 5.7 7.7 2.9 4.8 6.9 4.1 4.7 7.6 5.4 6.2 7.8 11.8 4.6 5.9 5.0 4.9
18 20 20 16 20 13 20 20 20 18 16 20 16 19 20 19 20
77 104 108 12 104 99 102 101 103 106 81 86 102 86 83 106 109
9.4 10.8 8.1 4.4 6.8 10.6 7.2 6.3 8.1 7.4 14.6 8.6 14.8 6.1 8.3 7.4 6.9
0.150 0.569 0.295 0.182 0.376 0.702 0.898 0.629 0.122 0.127 0.565 0.468 0.970 0.352 0.799 0.172 0.332
0.381 0.216 0.013 0.662 0.171 0.893 0.299 0.413 0.175 0.056 0.140 0.650 0.281 0.749 0.832 0.052 0.071
atrazine dealkylated Barban carbofuran phenol cyanazine diuron fenamiphos sulfone fenamiphos sulfoxide fluometuron 3-ketocarbofuran phenol linuron metribuzin DA metribuzin DADK neburon pronamide metabolite propanil propham Swep
24 29 27 29 24 21 24 29 28 29
82 91 94 93 93 93 93 91 90 91 79 17 89 97 94 93 94
4.0 6.6 6.6 4.3 5.2 7.7 5.7 3.9 3.9 4.1 4.3 0.5 3.5 5.6 5.1 3.8 6.2
Method 23 25 25 25 23 22 23 25 25 25 25 1 26 23 23 25 23
4 81 85 93 88 92 95 93 85 83 85 74 18 84 96 93 86 91
3.8 4.8 7.2 3.7 3.5 6.1 4.3 4.6 3.6 3.2 6.7 2.8 3.5 3.6 3.2 3.1 4.0
23 28 28 27 23 22 23 27 28 28 28 1 28 23 23 28 23
81 85 83 87 93 91 91 86 84 86 73 21 84 98 94 87 93
4.4 3.3 6.3 4.6 4.6 5.3 5.8 3.2 3.5 3.7 4.5 1.1 2.9 4.3 4.3 3.3 5.0
0.457 0.164 0.371 0.200 0.177 0.508 0.592 0.074 0.070 0.153 0.171
0.349 0.063 0.005 0.080 0.327 0.483 0.298 0.092 0.056 0.094 0.058
0.189 0.555 0.433 0.126 0.115
0.145 0.777 0.427 0.069 0.170
aldicarb aldicarb sulfone aldicarb sulfoxide Baygon carbaryl carbofuran 3-hydroxycarbofuran methiocarb methomyl oxamyl
39 39 39 39 39 39 39 39 39 39
100
102 100 100 97 100 99 94 103 98
4.8 4.2 4.7 3.6 3.0 3.8 3.8 2.7 4.1 3.9
39 39 39 39 39 39 39 39 39 39
97 100 99 100 97 100 99 95 96 93
3.0 2.9 3.4 2.3 2.4 2.3 2.3 2.2 3.6 2.9
ETU
27
91
5.0
Method 6 27 90
4.6
26
77
4.8
0.532
0.000
Method 504 29 96 29 102 29 89 29 94 29 94
6.3 8.6 7.4 5.7 9.2
36 36 36 36 36
91 90 90 84 87
4.8 5.1 5.6 4.2 6.5
0.954 0.008 0.184 0.457 0.012
0.013 0.110 0.061 0.000 0.000
10
103
1.7
trans-permethrin propachlor trifluralin
20 21
29 1
29 23 24 29 24
EDB DBCP l,2-dichloropropane cis-1,3-dichloropropene trans-1,3-dichloropropene
33 33 33 33 33
97 94 95 98 102
7.2 6.1 7.2 6.1 8.0
nitrates
11
104
3.0
105 104 108
p-value
no. obs SI4
SD
E14
Method 5 0 0 0 0 0 0 0 0 0 0
0.084 0.140 0.314 0.962 0.978 0.970 0.648 0.824 0.027 0.046
Method 353.2 0
0.700
Key: So, unstored sample; E14, extract stored 14 days; S14, sample stored 14 days; p-value, observed significance level.
HgC1, was added to each liter of sample. Samples collected for analyses using method 5 were preserved by use of a monochloroacetic acid buffer instead of HgC12. Replicate samples were fortified with method analytes and then analyzed after 0,14, and 28 days of storage. The extracts obtained during the analyses of the day 0 samples were also analyzed after 14, and 28 days of storage.
Survey. Clean sample bottles containing the appropriate chemical preservative were prepared and sent to each sampling site. Samples collected for analyses using method 5 were preserved with a monochloroacetic acid buffer, and for method 353.2 with diluted sulfuric acid. Maintaining a pH of
