Broad Spectrum Analysis of 109 Priority ... - ACS Publications

Mar 7, 2000 - EEC Council Directive on Pollution of the European. Union. Such Directive ... The European Union 76/464/CEE Directive1 and the Environ-...
58 downloads 0 Views 96KB Size
Download PDF
Anal. Chem. 2000, 72, 1430-1440

Broad Spectrum Analysis of 109 Priority Compounds Listed in the 76/464/CEE Council Directive Using Solid-Phase Extraction and GC/EI/MS Sı´lvia Lacorte,*,† Ingrid Guiffard,‡ Daniel Fraisse,‡ and Damia` Barcelo´†

Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain, and CARSO, Centre d’Analyse de Traces, Av, Jean Jaure` s, 69321 Lyon, France

A single multiresidue method was developed to determine 109 priority organic compounds included in the 76/464/ EEC Council Directive on Pollution of the European Union. Such Directive includes 132 priority pollutants with a broad spectrum of polarities to be analyzed in drinking and surface waters, with the aim to protect water quality. From this list, the compounds analyzed included benzidines, chloroanilines, chloronitrobenzenes, chloronitrotoluenes, chlorophenols, chloronitrotoluidines, PAHs, PCBs, pesticides, phenylurea, and triazine herbicides. The method was developed in four steps. First, automated off-line solid-phase extraction using polymeric sorbent Oasis 60 mg cartridges was optimized to trap 109 compounds. Second, gas chromatography coupled to mass spectrometry with electron impact ionization (GC/ EI/MS) was used in selected ion monitoring (SIM) mode for tentative identification of target analytes. Third, GC/ EI/MS under full scan conditions was used for spectrum identification and analyte confirmation. Last, quantification was performed from SIM chromatogram using surrogates and internal standard. This method offered excellent sensitivity and selectivity, and the preconcentration of 200 mL permitted the achievement of limits of detection at the low nanogram/liter level and recoveries between 70 and 120%. Such methodology was applied to determine 109 organic compounds in French surface waters, and several pollutants were detected at levels from ppt to ppb. This multiresidue method developed was highly reproducible and robust and permitted a high sample throughput. Over the past decade, the problem of diffuse pollution caused by industrial, agricultural, and human activities, accidental spills, and waste discharges has resulted in directives to control the sources of pollution, contribute to the protection of human salubrity, and to guarantee the utilization of natural resources. The European Union 76/464/CEE Directive1 and the Environmental Protection Agency of the United States (US EPA)2 have † ‡

IIQAB-CSIC. CARSO.

1430 Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

listed the more toxic and persistent pollutants, including some of their degradation products, and the maximum permissible levels in surface waters. Other recent directives such as the Integrated Pollution Prevention and Control (IPPC)3 and the Municipal Wastewater Treatment Directive4 have the objective to review and implement strategies and measures to control the sources of pollution and to establish practical rules and regulations to improve the quality of water. In Europe, Member States are encouraged to comply with Directive 76/464/CEE regarding dangerous substances discharged into surface waters. This Directive, also known as the EU Black List, considers 22 different chemical classes of pollutants which follow the general parameters of toxicity, persistence, and input and therefore are to be removed from community waters and discharges. It includes a total of 132 substances which are a priority in current European monitoring programs and are used in Europe as a base to estimate water quality. Table 1 lists the specific compound classes, and those included in the present method are marked in italics. Figure 1 shows the chemical structure of each family. We considered that a single multiresidue method capable of extracting and detecting all 109 priority organic compounds would improve the existing methodologies, in terms of cost and analysis time, used for routine surface and drinking water monitoring, The method proposed covers the analysis of organic pollutants which are formed due to the following three main human-activities. (1) Compounds generated from industrial processes and waste discharges, which are characterized as being toxic due to their mutagenic and carcinogenetic properties, (i) polyaromatic hydrocarbons (PAHs), which in the 76/464/CEE list are treated as a group and are ranked within the most toxic compounds in the CEE Priority Setting of substances dangerous for the aquatic environment.5 PAHs are introduced in the environment from both natural sources, e.g. incomplete combustion of organic matter (1) Directive 76/464/CEE, Dangerous Substances Discharged into the Environment, OJ no. L 129, Brussels, 1976. (2) Barcelo´, D. J. Chromatogr. 1993, 643, 117-143. (3) Directive 96/61/EC, Integrated Pollution Prevention Control, OJ no. L 257, Brussels, 1996. (4) Directive 91/271/EEC, Water Treatment and Purification, OJ no. L 135, Brussels, 1991. (5) Working Document M0498WDI, Priority Setting of Substances Dangerous for the Aquatic Environment, European Commission, 1999. 10.1021/ac991080w CCC: $19.00

© 2000 American Chemical Society Published on Web 03/07/2000

Table 1. Families of Compounds Included in the European Union Priority Pollutants List (Directive 76/464/CEE), Principal Method of Analysis and Main Sources method of analysis proposed compound class

extraction

analysis

main sources

amines benzidines chloroanilines chloroethers chloronitrobenzenes chloronitrotoluenes chlorophenols chlorotoluidines halogenated carboxyl compounds halogenated hydroxyl compounds inorganic metals miscellaneous (herbicides) organochloro pesticides organophosphorus pesticides organotin compounds phenoxyacid pesticides phenylurea compounds polyaromatic hydrocarbons polychloro biphenyls semivolatile halogenated compounds triazines volatile aromatics volatile halogenated organics

HS, SPE LLE, SPE LLE, SPE P-T, HS LLE, SPE LLE, SPE LLE, SPE LLE, SPE LLE, SPE P-T

GC/MS LC/EC, LC/MS GC/MS, LC/MS GC/MS GC/MS, LC/MS GC/MS, LC/MS LC/DAD, GC/MS GC/MS, LC/MS GC/ECD, GC/MS GC/MS ICP/MS LC/DAD, LC/MS GC/ECD, GC/MS LC/MS, GC/MS GC/AED, GC/MS LC/DAD, LC/MS LC/DAD, LC/MS LC/FLD, GC/MS GC/ECD, GC/MS GC/ECD, GC/MS LC/DAD, GC/MS GC/MS, GC/FID GC/MS, GC/ECD

derivative of petrochemicals dye, leather industry dye, leather industry industrial solvents industrial solvents industrial solvents paper, pulp, plastic industry paint and dye industry water treatment byproducts water treatment byproducts industry agriculture agriculture agriculture, domestic, terciary sector antifoulings, PVC stabilizers agriculture agriculture natural, anthropogenic sources industry, incineration plants solvents, additives agriculture, terciary sector solvents, industry water treatment byproducts

SPE, LLE LLE, SPE LLE, SPE LLE SPE, LLE SPE, LLE LLE, SPE LLE, SPE P-T, SPE SPE, LLE P-T, HS P-T, LLE

a Italic text denotes compounds included in the present method. b LLE, liquid-liquid extraction; SPE, solid-phase extraction; P-T, purge and trap; HS, headspace; LC, liquid chromatography; GC, gas chromatography; ICP, induced coupled plasma; DAD, diode array detector; EC, electrochemical detector; FLD, fluorescent detector; ECD, electron capture detector; FID, flame ionization detector; AED, atomic emission detector; MS, mass spectrometry.

from natural processes (e.g. volcanic eruptions, fires) and anthropogenic sources (burning of fossil fuels, waste incineration, oil spill accidents, traffic, etc.);6 (ii) chlorophenols, which are generated in many industrial processes, e.g. manufacture of plastics, dyes, drugs and pulp industry, and also formed as degradation products of pesticides;7 (iii) polychlorinated biphenyls (PCBs), which after being used in many industrial applications for more than 40 years,8 were banned and their production was restricted. The chemical and thermal stability which made them interesting also made them refractory for the environment and they became ubiquitous and were bioaccumulated along the trophic chain; their widespread presence explains the interest and need of inclusion in monitoring programs; (iv) chloroanilines and benzidines occur in surface waters carrying industrial effluents from textile, dye, and leather manufacturing plants and also are formed from the degradation of herbicides;9 and (v) other chlorinated compounds, e.g. chloronitrobenzenes, chloronitrotoluenes, chloronitrotoluidines and chloronaphthalenes, which are used as solvent for oils, fat, pesticides, etc. (2) Compounds used in agriculture which are directed to increase crop production by eliminating insects pests and weeds are included. An older generation of pesticides, the so-called organochloro pesticides, are characterized as being highly toxic and persistent.10 Some compounds, e.g. heptachlor, hexachlo(6) Manoli, E.; Samara, C. TrAC, Trends Anal. Chem. 1999, 18 (6), 417-428. (7) Puig, D.; Barcelo´, D. TrAC, Trends Anal. Chem. 1996, 15 (8), 362-375. (8) Cairns, T.; Siegmund, E. G. Anal. Chem. 1981, 53, 1183A-1191A. (9) Lacorte, S.; Perrot, M. C.; Fraisse, D.; Barcelo´, D. J. Chromatogr. A 1999, 833, 181-194. (10) Barcelo´, D.; Hennion, M. C. In Trace Determination of Pesticides and Their Degradation Products in Water; Elsevier: Amsterdam, The Netherlands, 1997; pp 1-94.

Figure 1. Chemical structures of each family of organic compounds studied and, in parentheses, the number of compounds analyzed.

robenzene, endosulfan, and hexachlorocyclohexane (four individual isomers), are still candidate substances in the EU list of Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

1431

Table 2. Compounds Studied, Identification Number, Retention Time (tR) after GC/MS, Ion Monitored (m/z), Percentage of Recoveries at pH 7 and 2, Standard Deviation (STD), and Limits of Detection (LD, ng/L)a neutral fraction

acid fraction

compound

no.

tR (min)

m/z

%R

STD

LD

%R

STD

LD

cumene 2-chlorophenol 2-chloroaniline 2,4-dichlorophenol naphthalene 3-chloroaniline 4-chloroaniline 3-chlorophenol 4-chlorophenol hexachlorobutadiene 2-chloro-4-toluidine 1-chloro-3-nitrobenzene 2,6-dichloroaniline 1-chloro-4-nitrobenzene 1-chloro-2-nitrobenzene dichlorvos and trichlorfon 4-chloro-3-methylphenol 2-chloro-6-nitrotoluene 4-chloro-2-nitrotoluene 2,4-dichloroaniline 3,5-dichloronitrobenzene 2,5-dichloroaniline 2,3,5-trichlorophenol 2,3-dichloroaniline 2,4,6-trichlorophenol 2-chloro-3-nitrotoluene 2,4,5-trichlorophenol 4-chloro-3-nitrotoluene 2,5-dichloronitrobenezene 2,3,4-trichlorophenol 2,4-dichloronitrobenzene biphenyl 2,3,6-trichlorophenol 3,4-dichloronitrobenzene 2,3-dichloronitrobenzene 3,5-dichloroaniline 3,4-dichloroaniline mevinphos (Z)b mevinphos (E) 2-amino-4-chlorophenol 1-chloro-2,4-dinitrobenzene 1,2-dichloronaphthalene omethoate 4-chloro-2-nitroaniline demeton-S 3,4,5-trichlorophenol tributhyl phosphate R-hexachlorocyclohexane trifluraline hexachlorobenzene dimethoate demethon-O simazine β-hexachlorocyclohexane monolinuron pentachlorophenol atrazine lindane anthracene δ-hexachlorocyclohexane disulfoton PCB 28 propanil parathion-methyl heptachlor oxydemethon-methyl PCB 52 fenitrothion 1,2,3,4-tetrachloronaphthalene linuron

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 35 36 37 38 38 39 40 41 42 43 44 45 46 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70

9.37 12.17 18.57 20.41 21.01 21.91 22.05 22.13 22.13 22.69 23.06 23.18 23.54 23.63 24.00 24.58 26.00 26.47 26.76 27.64 27.63 27.72 27.84 28.54 28.64 28.79 28.90 28.96 29.19 29.27 29.56 29.74 29.94 30.13 30.63 30.76 31.89 32.36 32.48 33.29 37.26 37.47 38.46 38.65 39.71 39.71 40.80 42.08 42.18 42.43 43.30 43.30 43.86 44.04 44.02 44.16 44.28 44.32 45.07 46.08 46.07 48.25 48.46 49.05 49.12 50.32 51.14 51.57 51.61 51.65

105 128 127 162 128 127 127 128 128 225 141 157 161 157 157 109 142 154 154 161 145 161 196 161 196 171 196 171 145 196 191 154 196 145 145 161 161 127 127 143 202 196 156 172 88 196 99 219 306 284 87 88 201 219 61 266 200 219 178 219 88 256 161 109 100 109 292 109 266 61

45 86 100 81 102 96 65 74 coel 43 95 93 97 82 85 101 3 84 81 117 76 99 60 102 76 74 41 92 101 77 73 114 81 99 98 110 97 123 123 nd 89 nd 10 98 nd 81 111 112 53 72 101 25 147 153 119 nd 120 123 117 74 2 71 149 92 75 61.9 64.7 72 55 70

5.7 4.0 7.3 2.3 3.9 2.1 2.0 7.4 coel 10.6 0.7 2.8 9.0 2.8 6.3 9.0 4.1 6.7 4.2 11.2 3.8 4.9 2.6 1.9 8.5 6.3 0.2 8.6 2.7 0.8 3.1 10.8 7.3 4.6 0.8 8.7 9.5 24.9 24.9 nd 11.7 nd 4.0 10.3 nd 11.9 24.8 9.0 11.2 9.5 12.9 10.8 21 15.8 2.7 nd 14.7 14.1 14.2 2.8 0.5 19.6 22.7 4.5 19.0 5.6 6.2 6.9 6.1 1.1

7.1 4.5 6.1 7.6 1.6 2.6 5.1 19.1 coel 8.8 7.8 12.1 1.9 11.0 9.0 30.2 149 21.6 22.7 1.9 17.7 2.6 343 5.0 8.5 14.3 10.9 29.9 17.6 10.4 14.7 2.1 13.9 22.7 19.1 5.6 7.15 25.5 25.5 nd 61.7 nd 291.8 16.7 nd 46.4 11.0 7.4 15.3 4.7 16.9 159.1 6.55 6.5 10.5 nd 9.5 8.8 3.1 13.7 426.5 5.8 12.4 80.3 11.3 764.1 2.63 78.01 10.2 8.48

54 94 93 77 101 25 65 111 coel 49 93 100 100 86 86 106 96 84 83 103 82 100 112 112 106 97 99 104 110 107 83 114 106 110 116 127 128 121 121 nd 118 nd 12 118 nd 83 51 64 56 64 56 18 149 88 163 89 143 164 120 70 2 79 98 79 48 37 108 46 47 67

6.5 5.7 4.4 2.9 7.1 2.6 3.1 11.5 coel 5.4 9.5 9.0 4.6 4.4 7.4 1.8 11.5 0.6 7.6 9.9 7.3 1.06 4.9 4.7 3.5 4.5 9.8 5.5 8.4 3.1 10.7 1.4 3.3 11.3 19.1 14.3 7.3 27.7 27.7 nd 1.1 nd 4.4 9.9 nd 2.5 3.6 2.5 3.6 2.5 3.6 3.6 13.3 5.5 17.4 5.5 4.6 12.7 2.0 3.2 0.5 5.6 3.9 5.6 4.4 4.3 13.3 5.4 8.5 11.6

4.9 3.4 1.3 2.7 0.7 8.7 26.6 2.5 coel 8.3 4.2 10.8 1.2 10.0 5.02 14.5 15.2 7.6 12.5 1.1 9.2 1.1 2.1 1.2 1.6 5.1 1.6 10.9 9.4 1.8 11.3 1.3 1.3 11.4 9.6 0.6 0.7 1.8 1.8 nd 29.7 nd 300.0 12.7 nd 45.1 7.3 4.4 2.6 1.3 30.7 110.7 2.0 2.3 6.8 20.3 4.6 2.6 1.4 4.6 11.7 6.0 6.3 105.7 21.3 312.3 1.6 51.7 7.1 12.0

1432 Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

Table 2 (Continued) neutral fraction

acid fraction

compound

no.

tR (min)

m/z

%R

STD

LD

%R

STD

LD

aldrine malathion fenthion parathion-ethyl isodrine bentazone fluoranthene o,o′-DDE R-chlordane benzidine R-endosulfan o,p′-DDE PCB 101 γ-Chlordane dieldrin p,p′-DDE PCB 77 o,p′-DDD endrin β-endosulfan PCB 118 p,p′-DDT o,p′-DDT PCB 153 triazophos p,p′-DDD pyrazon PCB 138 PCB 126 3,3′-dichlorobenzidine PCB 180 azinphos-methyl PCB 169 azinphos-ethyl coumaphos benzo(b)fluoranthene benzo(k)fluoranthene benzo(a)pyrene indeno(1,2,3-cd)pyrene benzo[ghi]perylene

71 72 73 74 75 76 77 78 79 80 81 82 83 79 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109

51.90 52.94 53.49 53.49 54.26 nd 55.43 55.98 57.23 58.00 58.02 58.01 58.19 57.88 59.92 60.38 60.69 60.88 61.37 62.07 62.55 63.21 63.33 64.07 64.75 65.60 65.62 65.81 66.33 68.83 70.04 70.94 71.23 73.17 75.20 75.57 75.70 77.01 81.09 81.79

66 173 109 109 193 198 202 246 373 184 195 246 326 373 79 246 292 235 281 195 326 235 235 360 161 235 221 360 326 252 394 132 362 132 362 252 252 252 276 276

54 103 coel 82 63 nd 101 nd 220 6 101 63 68 nc 97 73 69 63 103 90 77 59 47 84 82 34 98 81 85 101 84 76 83 74 51 57 75 57 61 48

4.5 10.5 coel 9.2 3.9 nd 3.7 nd 6.5 0.5 5.6 5.6 8.8 nc 5.3 7.2 8.1 5.3 3.2 7.2 8.7 5.5 2.3 10.8 0.7 5.2 2.1 7.2 6.8 2.2 4.7 10.1 4.4 2.1 8.6 8.6 8.0 4.6 7.1 8.6

33.4 19.6 coel 43.2 11.5 nd 0.5 nd 51.9 68.4 24.6 3.4 1.9 nc 13.5 3.9 1.5 9.5 42.5 30.5 2.6 10.5 13.5 1.7 26.0 17.8 14.1 5.4 10.3 5.7 6.5 50.1 4.9 30.7 37.8 1.07 5.5 11.1 6.6 8.1

42 47 coel 81 44 nd 81 nd 43 2 92 45 42 nc 88 89 77 48 89 94 42 44 30 84 38 46 84 46 45 82 44 63 42 42 35 29 35 31 29 35

7.4 5.8 coel 3.7 5.8 nd 3.7 nd 4.3 1.4 2.4 2.9 4.1 nc 2.4 2.8 1.4 5.4 2.8 1.4 4.8 8.2 6.3 7.9 2.3 3.9 7.9 10.2 4.8 10.2 4.5 12.9 6.3 7.1 5.3 9.5 5.1 11.2 12.8 11.8

20.4 3.3 coel 16.5 13.9 nd 0.5 nd 24.0 64.1 13.5 4.7 1.5 nc 8.8 1.5 1.3 4.7 15.6 13.0 3.3 3.9 10.8 1.5 20.7 11.9 29.4 1.6 2.6 3.6 2.9 43.6 4.0 27.2 9.8 4.5 3.7 6.3 2.6 12.6

a

nd, not detected; nc, not calibrated; coel, coelution. b Mevinphos was quantified as the sum of the two isomers.

toxic substances, while other chlorinated insecticides, such as DDT and its metabolites, aldrin, dieldrin, endrin, and isodrin, are considered as “historic” pollution cases. However, their adverse effects toward wildlife, persistence in the environment, and widespread occurrence led to regulatory compliance. In the last 40 years, OC pesticides have been increasingly replaced by more polar, less persistent pesticides, which are represented by organophosphorus pesticides, phenylurea, triazine, and phenoxyacid herbicides. Due to their intrinsic specificity, the fact that they are rapidly degraded after application, and that they are rarely accumulated in the trophic chain, modern pesticides are widely used to combat different pests.11 (3) Compounds used in the tertiary sector are difficult to classify and it is also difficult to control their use, but due to the large amounts globally used, they represent an important and increasing source of water pollution. Many pesticides are used for mosquito and rodent control in public transports, in touristic

areas, for domestic use, in greenhouses, in cementeries, in aquaculture, in golf courses, as antifoulings, etc. For the analysis of these priority pollutants, a substantial number of analytical procedures have been developed and are applied in current monitoring programs. In general, the analytical methods proposed by the EU are family specific (Table 1) and are based on an efficient sample extraction or preconcentration, e.g. liquidliquid extraction (LLE) or solid-phase extraction (SPE), followed by the chromatographic determination,12 e.g. diode array detection, fluorimetric, or mass spectrometry detection for liquid chromatography and generally gas chromatography with mass spectrometry for the analysis of the more volatile/apolar compounds. The purpose of this paper is first to demonstrate that a single polymeric SPE cartridge of Oasis 60 mg can be used to extract more than 100 organic compounds of different physicochemical properties, including polar analytes, by preconcentrating 200 mL of water. This method compromises extraction and sensitivity,

(11) Fielding, M.;Barcelo´, D.; Helweg, A.; Galassi, S.; Tortensson, L.; Van Zoonen, P.; Wolter, R.; Angeletti, G. In: Pesticides in Ground and Drinking Water; Water Pollution Research Report; Commission of the European Communities, Brussels, 1992; pp. 1-136.

(12) Lacorte, S.; Puig, D.; Barcelo´, D. Sample Handling and Analysis of Organic Pollutants (Pesticides and Phenols) in Water Matrixes by HPLC in Handbook of HPLC; Katz, E., et al., Eds.; Marcel Dekker: New York, 1998; Chapter 29.

Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

1433

since with 1 L, sensitivity increases but losses of the more polar compounds occur, and in addition, the preconcentration time is 5 times longer. The second purpose was to optimize GC/EI/MS so that we were able to unequivocally identify (with full scan) and quantify (SIM, with an appropriate surrogate and internal standard) all the target analytes. And, third, this paper shows that the method can be used for the survey of the 132 substances in real surface and wastewaters from France, on a routine basis. To our knowledge, such multiresidue methodology has not been published before in the literature and the present paper provides useful information to all laboratories involved in the determination of organic pollutants in surface waters in Europe. EXPERIMENTAL SECTION Chemicals and Reagents. Table 2 lists all the compounds studied. All standards were of high purity (99.9%) and were purchased from Promochem (Wesel, Germany). Mother solutions were prepared in dichloromethane (weight by weight) at a concentration of 1000 µg/mL. Many of the compounds studied have significant toxicity; therefore, precautions have to be taken into account while preparing and manipulating standards (prepare standards in the hood, use gloves and mask, and, in general, follow good laboratory practices). A working solution containing all 109 compounds was prepared in acetonitrile at a concentration of 5 ng/µL. This solution was used for spiking water samples. Acetonitrile was a gift from Baker (Deventer) and dichloromethane was purchased from SDS (Peypin, France). Normapur chloridric acid was from Prolabo. Pure HPLC grade water was generated with a Maxima Ultrapure Water (Elga, S. A.). Oasis 60 mg solid-phase extraction cartridges were from Waters. Sample Collection. Two liters of surface water samples were collected with Pyrex borosilicate bottles and were immediately stored at 5 °C, in the dark for a maximum of 7 days. The total organic carbon (TOC) content of these samples was of below 20 mg C/L. Samples were filtered through glass fiber filters of 0.45 µm (Whatman, England) and afterward were extracted as depicted below. Sample Preparation. For method development, drinking water was used. 1 L of water was spiked with the 109 compounds at a concentration of 1-2 ng/mL. At the same time, a surrogate solution containing nitrobenzene-d5, 2-fluorobiphenyl, and pterphenyl-d14 in absolute alcohol at a concentration of 39.2 ng/µL was added to the water sample at a concentration of 1 ng/mL. The concentration of the analytes and the surrogate in the final extract was between 0.5 and 1 ng/µL. Sample Extraction. Samples were extracted with the automated system ASPEC XL (Gilson, Villiers-le-Bel, France). For each sample, 200 mL was extracted at neutral pH, and 200 mL was acidified with 2N HCl to pH 2. Oasis 60 mg cartridges (Waters) (3 mL of syringe volume) were conditioned with 6 mL of dichloromethane, 6 mL of acetonitrile, and 6 mL of HPLC water. Samples were percolated through the cartridge at a flow rate of 6 mL/min. Immediately after, cartridges were rinsed with 1 mL of HPLC water at a flow rate of 30 mL/min. Cartridges were dried by passing nitrogen through them at a flow rate of 3 mL/min during 20 min. Elution was carried out with 2.5 mL of acetonitriledichloromethane (1:1) and 3.2 mL of dichloromethane, pushing at each step the residual solvent by applying air at a flow rate of 3 mL/min. After elution, the extract was transferred to vials and 1434

Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

the excess of solvent was evaporated under a gentle stream of nitrogen to an extract weight of 500 µg. Exact concentration was corrected by solvent density (dichloromethane). The internal standard anthracene d10 (100 µL) was added to the final extract, which produced a concentration of 1 ng/µL. Instrumentation. GC/MS analysis were performed with gas chromatograph HP6890 connected to a mass spectrometer HP 5973 (Hewlett-Packard, Waldbronn, Germany). The mass spectrometer was operated in the electron impact ionization mode with an ionizing energy of 70 eV and an emission current of 300 µA. The ion source temperature was 230 °C. A HP-5MS (30 m × 0.25 mm i.d. with 0.25 µm film thickness) containing 5% phenyl methyl siloxane (model HP 19091S-433) was programmed from 40 (keeping this temperature for 2 min) to 175 °C at 3 °C/min (keeping this temperature for 4 min), from 175 to 240 °C at 3 °C/min, and to 320 °C at 7 °C/min (keeping this temperature for 10 min). The total analysis time was 93 min and the equilibration time 3 min. Helium was used as the carrier gas at 7 psi. The injection volume was of 1 µL and the splitless mode was used. Chromatograms were recorded under time-scheduled selected ion monitoring (SIM) using 10 acquisition windows for each group of compounds as follows: (1) from 0 to 22.6 min, m/z 50, 99, 105, 112, 127, 128, and 162; (2) from 22.6 to 25.6 min, m/z 94, 109, 141, 157, 161, and 225; (3) from 25.6 to 32.4 min, m/z 142, 145, 154, 161, 171, 172, 191, and 196; (4) from 32.4 to 40.4 min, m/z 88, 127, 143, 156, 172, 196, 202, and 330; (5) from 40.4 to 43 min, m/z 99, 141, 142, 219, 284, and 306; (6) from 43 to 47.3 min, m/z 61, 87, 88, 162, 178, 188, 200, 201, 219, 230, and 266; (7) from 47.3 to 55.2 min, m/z 61, 66, 100, 109, 161, 173, 193, 198, 256, 266, and 292; (8) from 55.2 to 63.9 min, m/z 79, 184, 195, 202, 235, 244, 246, 281, 292, 300, 326, 353, and 373; (9) from 63.9 to 68.3 min, m/z 161, 221, 231, 235, 326, 334, and 360 and (10) from 68.3 to 94 min, m/z 132, 252, 276, 362, 368, 394, and 404. The dwell time was set at 100 ms and the scanning rate was of 1 scan/ s. Full scan conditions (from 50 to 400 amu) were also used. All extracts were all injected in SIM, for quantitative purposes and by scan mode, to confirm the presence of each analyte. Quantification. The surrogate nitrobenzene-d5 was used to evaluate the response of compounds eluting from cumene to 2,4dichloronitrophenyl, 2-fluorobiphenyl for compounds eluting from biphenyl to heptachlor, and p-terphenyl-d14 for the rest of the compounds (see Table 2). Anthracene-d10 was used for quantification. The linearity of the system was determined by performing a calibration curve at 0.05, 0.1, 0.5, 1, and 2 µg/mL. The instrument detection limit was calculated taking a signal-to-noise ratio of 3, using the lowest concentration of the calibration curve. RESULTS AND DISCUSSION Multiresidue Extraction. Multiresidue methods for routine water monitoring are specially recommended to save time and reduce the cost of analysis. However, in the present case, method development was relatively complex, due to the fact that compounds of different polarities, solubilities, volatilities, and pKa values had to be simultaneously extracted and analyzed. From the 132 priority pollutants (or families) included in the “Black List”, we selected all GC amenable compounds. Compounds included in the list and not analyzed were metamidophos, phoxim, and 2,4,6trichloro-1,3,5-triazine, since they can only be detected by HPLC or by GC with derivatization due to their high polarity. Volatile

Figure 2. GC/EI/MS chromatogram in selected ion monitoring (SIM) of (A) a standard mixture at 1 µg/mL and (B) sample C, after SPE of 200 mL of surface water. Identification numbers and exact retention times are specified in Table 2.

compounds, organometallics and organotins were not analyzed either since these analytes need a specific method of analysis. In the present study, one item that had to be faced was the choice of a universal sorbent for the simultaneous extraction of all 109 compounds and the choice of a detection technique capable of determining these compounds at the low µg/L level. Oasis 60 mg SPE cartridges, containing polymeric N-pyrrolidone styrene divinylbenzene sorbent, was used for its capabilities to retain both basic and neutral analytes, and because it is designed to trap compounds in its ionic form. Table 2 shows the mean recovery values (n ) 3) of 109 compounds from 200 mL of drinking water spiked at 1 ng/mL. From the results obtained, it is demonstrated that a single Oasis 60 mg cartridge that is normally used to trap a specific chemical class (10-20 compounds) can be used to absorb more than 100 compounds without increasing sample manipulation. In this first experiment, we preconcentrated waters under neutral and acid conditions to determine extraction efficiency. As can be observed, similar recoveries were obtained from both conditions, indicating that the sorbent chosen has the ability to sustain compounds of different acid/basic characteristics. This fact is specially relevant for multiresidue analysis, indicating that the two-step elution was suitable to recover satisfactorily (percentage recovery between 70 and 120%, for at least one condition) 77 out of the 109 compounds and detect another 25 (recoveries between 50 and 70%). These data suggests that 60 mg of sorbent has enough capacity to trap an amount of analytes of more than 20 µg. A general remark to be made is that neutral conditions are preferred to analyze the organophosphorus and organochlorine pesticides, PAHs and PCBs. For some of these compounds, the percentage of recovery under acidic conditions was 40% lower. However, if chlorophenols are the main concern, extraction at pH 2 is recommended (especially trichlorophenols), although they were also recovered from the neutral extracts. 4-Chloro-3-methylphenol and pentachlorophenol were only recovered from the acid fraction, while 2-amino 4-chlorophenol was not recovered since derivatization is needed prior to GC/MS. GC/

MS permitted the distinction of the two isomers of mevinphos, which were quantified in conjunction to obtain the 120% recovery. In general, the low recovery or no recovery of analytes can be explained by (i) excessive retention upon the polymeric SPE sorbent, as represented by some PCBs, DDTs and its derivatives, aldrine, isodrine, and coumaphos, which in general were recovered at 50%. Higher recoveries could be obtained by eluting with 100% hexane, but this represents that more than one fraction should be collected due to poor solvent miscibility with the other solvents used. Alternatively, C18 sorbent would provide better recoveries of these compounds, but that would mean more than one preconcentration per sample. As a result, none of these options is suitable for carrying out one single multiresidue analysis. (ii) Poor retention of polar pesticides degradation products, e.g. omethoate, caused by breakthrough due to its high water solubility and low octanol-water partition coefficient (Kow around 0.17) also leads to recovery problems. Percolation of lower sample volumes would lead to better recoveries, but at the expenses of sensitivity. Demeton-S and demeton-O were not recovered due to a combination of breakthrough and degradation. In contrast, its degradation product, oxydemeton-methyl was recovered in 62 and 37% in the neutral and acidic fraction, respectively. Similarly, disulfoton was not recovered in any of the fractions due to the fact that this compound is very rapidly degraded in water solution and disulfoton sulfoxide and sulfone, their corresponding oxygen analogues, and diethylthiophosphate are formed by metabolism or chemical degradation;13 (iii) Volatilization throughout the sample preparation step, specially for semivolatile compounds also brings about low or no recovery. Cumene, hexachlorobutadiene, and chloronaphthalenes were lost during sorbent drying and sample evaporation, so poor recoveries were obtained. An alternative of SPE is LLE, but losses during sample evaporation arise.14 The recommended method is purge (13) Lacorte, S.; Lartiges, S.; Garrigues, P.; Barcelo´, D. Environ. Sci. Technol. 1995, 29 (2), 431-438. (14) Barcelo´, D.; Hennion, M. C. Anal. Chim. Acta 1995, 318, 1-41.

Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

1435

Table 3. Compounds Studied Grouped in Chemical Classes, Instrument Detection Limits (IDL, pg) Obtained with GC/EI/MS, Molecular Weight (Mw), and the Three Most Abundant Fragment Ions of Each Studied Compounda m/z compounds benzidines benzidine 3,3′-dichlorobenzidine chloroanilines 2-chloroaniline 3-chloroaniline 4-chloroaniline 2,6-dichloroaniline 2,4-dichloroaniline 2,5-dichloroaniline 2,3-dichloroaniline 3,5-dichloroaniline 3,4-dichloroaniline 4-chloro-2-nitroaniline chloronitrobenzenes 1-chloro-3-nitrobenzene 1-chloro-4-nitrobenzene 1-chloro-2-nitrobenzene 3,5-dichloronitrobenzene 2,5-dichloronitrobenezene 2,4-dichloronitrobenzene 3,4-dichloronitrobenzene 2,3-dichloronitrobenzene 1-chloro-2,4-dinitrobenzene chloronitrotoluenes 2-chloro-6-nitrotoluene 4-chloro-2-nitrotoluene 4-chloro-3-nitrotoluene 2-chloro-3-nitrotoluene chlorophenols 2-chlorophenol 2,4-dichlorophenol 3-chlorophenol 4-chlorophenol 4-chloro-3-methylphenol 2,3,5-trichlorophenol 2,4,6-trichlorophenol 2,4,5-trichlorophenol 2,3,4-trichlorophenol 2,3,6-trichlorophenol 2-amino-4-chlorophenol 3,4,5-trichlorophenol pentachlorophenol chlorotoluidines 2-chloro-4-toluidine miscellaneous biphenyl tributhyl phosphate trifluraline propanil bentazone pyrazon organochloro pesticides hexachlorobenzene R-hexachlorocyclohexane β-hexachlorocyclohexane lindane δ-hexachlorocyclohexane heptachlor aldrin isodrine o,o′-DDE R-chlordane R-endosulfan o,p′-DDE γ-chlordane dieldrin p,p′-DDE o,p′-DDD endrin β-endosulfan p,p′-DDD o,p′-DDT p,p′-DDT 1436

IDL

Mw

4.66 5.21

184 252

0.40 0.88 0.96 0.19 0.60 0.65 0.64 1.67 3.23 14.8

127 127 127 161 161 161 161 161 161 172

1.50 1.72 1.44 1.68 0.32 6.15 4.88 4.63 4.07

1

2

3

92 (11) [C6H6N]+ 126 (12) [C6H5NCl]+

184 (100) [M]+ 252 (100) [M]+

65 (23) [C5H5]+ 65 (27) [C5H5]+ 65 (28) [C5H5]+ 90 (26) [M - HCl2]+ 90 (16) [M - HCl2]+ 90 (25) [M - HCl2]+ 90 (29) [M - HCl2]+ 90 (23) [M - HCl2]+ 90 (19) [M - HCl2]+ 90 (50) [126 - HCl]+

92 (18) [M - Cl]+ 92 (20) [M - Cl]+ 92 (20) [M - Cl]+ 126 (8) [M - Cl]+ 126 (11) [M - Cl]+ 126 (10) [M - Cl]+ 126 (16) [M - Cl]+ 126 (13) [M - Cl]+ 126 (12) [M - Cl]+ 126 (73) [M - NO2]+

127 (100) [M]+ 127 (100) [M]+ 127 (100) [M]+ 161 (100) [M]+ 161 (100) [M]+ 161 (100) [M]+ 161 (100) [M]+ 161 (100) [M]+ 161 (100) [M]+ 172 (100) [M]+

157 157 157 191 191 191 191 191 202

75 (76) [M - NO2 - HCl]+ 75 (100) [M - NO2 - HCl]+ 75 (100) [M - NO2 - HCl]+ 109 (69) [M - NO2 - HCl]+ 109 (100) [M - NO2 - HCl]+ 109 (100) [M - NO2 - HCl]+ 109 (98) [M - NO2 - HCl]+ 109 (100) [M - NO2 - HCl]+ 75 (100) [M - 2NO2 - Cl]+

111 (100) [M - NO2]+ 111 (96) [M - NO2]+ 111 (83) [M - NO2]+ 145 (100) [M - NO2]+ 145 (97) [M - NO2]+ 161 (96) [M - NO]+ 145 (100) [M - NO2]+ 145 (100) [M - NO2]+ 110 (67) [M - 2NO2]+

157 (63) [M]+ 157 (78) [M]+ 157 (75) [M]+ 191 (72) [M]+ 191 (83) [M]+ 191 (85) [M]+ 191 (86) [M]+ 191 (98) [M]+ 202 (94) [M]+

2.18 3.12 2.31 2.72

171 171 171 171

89 (95) [C7H5]+ 89 (100) [C7H5]+ 89 (100) [C7H5]+ 89 (100) [C7H5]+

126 (54) [M + H - NO2]+ 126 (53) [M + H - NO2]+ 125 (62) [M - NO2]+ 125 (71) [M - NO2]+

154 (100) [M - OH]+ 154 (91) [M - OH]+ 171 (96) [M]+ 171 (96) [M]+

0.64 1.18 12.0 11.6 1.39 3.19 3.26 6.68 3.46 7.05 10.5 9.62 10.8

128 162 128 128 142 196 196 196 196 196 143 196 264

64 (41) [M - Cl - CHO]+ 63 (32) [98 - Cl] 65 (26) [C5H5]+ 65 (34) [C5H5]+ 77 (46) [C6H5]+ 97 (45) [M - 2Cl - CHO]+ 97 (50) [M - 2Cl - CHO]+ 97 (43) [M - 2Cl - CHO]+ 97 (45) [M - 2Cl - CHO]+ 97 (47) [M - 2Cl - CHO]+ nd 97 (33) [M - 2Cl - CHO]+ 165 (35) [M - 2HCl - CHO]+

92 (12) [M - HCl]+ 98 (28) [M - Cl - CHO]+ 107 (100) [M - Cl]+ 160 (37) [M - HCl]+ 132 (42) [M - Cl - CHO]+ 132 (30) [M - Cl - CHO]+ 160 (38) [M - HCl]+ 132 (33) [M - Cl - CHO]+ nd 133 (40) [M - Cl - CO]+ 202 (20) [M - Cl - CHO]+

128 (100) [M]+ 162 (100) [M]+ 128 (100) [M]+ 128 (100) [M]+ 142 (94) [M]+ 196 (100) [M]+ 196 (100) [M]+ 196 (100) [M]+ 196 (100) [M]+ 196 (100) [M]+ nd 196 (100) [M]+ 266 (100) [M]+

1.27

141

77 (35) [C6H5]+

106 (100) [M - Cl]+

141 (92) [M]+

0.13 0.83 1.13 3.15 nd 2.79

154 266 335 217 240 221

99 (100) [H4PO4]+ 264 (83) [290 - C2H2]+ 57 (38) [C3H5O]+ nd 77 (100) [C6H5]+

76 (18) [C6H4]+ 155 (24) [C4H12PO4]+ 290 (16) [M - C2H5O]+ 161 (100) [M - C3H5O]+ nd 105 (25) [M - C8H6N]+

154 (100) [M]+ 211 (10) [P (OH) 2 (OBu) 2]+ 306 (100) [M - C2H5]+ 217 (20) [M]+ nd 221 (71) [M]+

0.57 1.49 1.02 1.03 1.13 1.82 1.39 0.90 0.60 nq 3.93 1.02 nq 3.77 0.37 0.90 16.8 4.49 1.39 1.65 1.23

282 291 291 291 291 371 362 362 316 410 407 316 410 378 316 318 378 407 318 352 352

142 (34) [M - 4Cl]+ 111 (48) [M - 5Cl]+ 109 (800) [M - 5Cl]+ 111 (55) [M - 5Cl]+ 109 (100) [M - 5Cl]+ 100 (100) ni 66 (100) [C5H6]+ 66 (75) [C5H6]+ 176 (30) [M - 4Cl]+ 237 (30) [M - 5Cl]+ 207 (100) ni 176 (26) [M - 4Cl]+ 237 (26) [274 - Cl]+ 79 (100) [C2H4ClO]+ 176 (35) [M - 4Cl]+ 165 (30) [235 - 2Cl]+ 197 (73) ni 195 (100) ni 165 (44) [235 - 2Cl]+ 165 (40) [235 - 2Cl]+ 165 (33) [235 - 2Cl]+

249 (22) [M - Cl]+ 181 (95) [M - 3Cl]+ 181 (98) [M - 3Cl]+ 181 (100) [M - 3Cl]+ 181 (64) [M - 3Cl]+ 237 (50) [M - 4Cl]+ 91 (53) ni 193 (100) [M - C5H6 - 3Cl]+ 246 (100) [M - 2Cl]+ 274 (26) [M - 4Cl]+ 239 (84) ni 246 (100) [M - 2Cl]+ 272 (25) [M - 4Cl]+ 263 (33) ni 246 (100) [M - 2Cl]+ 199 (12) [235 - HCl]+ 237 (100) [M - HCl - 3Cl]+ 207 (78) ni 199 (17) [235 - HCl]+ 199 (16) [235 - HCl]+ 199 (10) [235 - HCl]+

284 (100) [M]+ 219 (100) [M - 2Cl]+ 219 (100) [M - 2Cl]+ 219 (79) [M - 2Cl]+ 219 (42) [M - 2Cl]+ 272 (92) [M - 3Cl]+ 263 (30) [M - C5H6 - Cl]+ 263 (50) [M - C5H6 - Cl]+ 318 (43) [M]+ 373 (100) [M - Cl]+ 277 (58) ni 318 (34) [M]+ 373 (100) [M - Cl]+ 279 (23) [M - C5H6 - Cl]+ 318 (80) [M]+ 235 (100) [M - CHCl2]+ 265 (53) [M - CHCl2CH2O]+ 237 (79) ni 235 (100) [M - CHCl2]+ 235 (100) [M - CCl3]+ 235 (100) [M - CCl3]+

Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

Table 3 (Continued) m/z compounds

IDL

organophosphorus pesticides dichlorvos 1.36 trichlorfon 1.38 mevinphos (Z) 2.71 mevinphos (E) 2.71 omethoate 3.68 demeton-S-methyl 5.72 dimethoate 2.47 demethon-O 7.53 disulfoton 2.24 parathion-methyl 9.35 oxydemeton-methyl 125.8 fenitrothion 10.5 malathion 2.88 fenthion 10.0 parathion-ethyl 7.26 triazophos 10.74 azinphos-methyl 27.37 azinphos-ethyl 10.28 coumaphos 0.86 phenylurea pesticides monolinuron 2.40 linuron 4.58 PAHs naphthalene 1.65 anthracene 0.17 fluoranthene 0.38 benzo[b]fluoranthene 1.02 benzo[k]fluoranthene 1.12 benzo[a]pyrene 3.54 indeno [1,2,3-cd]pyrene 1.12 benzo[ghi]perylene 1.53 PCBs PCB 28 0.22 PCB 52 0.38 PCB 101 0.36 PCB 77 1.13 PCB 118 0.38 PCB 153 0.49 PCB 138 0.58 PCB 126 1.28 PCB 180 1.14 PCB 169 1.16 b SVHC hexachlorobutadiene 0.29 1,2-dichloronaphthalene 0.29 1,2,3,4-tetrachloronaphthalene 0.79 triazines simazine 1.56 atrazine 1.01 volatile amines cumene 0.22 a

Mw

1

2

3

220 256 224 224 213 230 229 214 274 263 246 277 330 278 291 313 317 345 362

79 (25) [(CH3O)POH]+ 79 (100) [(CH3O)POH]+ 109 (25) [(CH3O)2PO]+ 109 (25) [(CH3O)2PO]+ 79 (43) [(CH3O)POH]+ 60 (36) [C2H4S]+ 87 (100) [SCH(CON)]+ 60 (35) [C2H4S]+ 88 (100) [C4H8S]+ 109 (100) [(CH3O)2PO]+ 109 (100) [(CH3O)2PO]+ 109 (90) [(CH3O)2PO]+ 93 (58) [(CH3O)2P]+ 109 (45) [(CH3O)2PO]+ 97 (85) [P(SH)2]+ 161 (100) [(C8H7N3)O]+ 77 (89) [C6H5]+ 77 (60) [C6H5]+ 109 (79) [(C2H5O)PSH]+

109 (100) [(CH3O)2PO]+ 109 (91) [(CH3O)2PO]+ 127 (100) [(CH3O)2P(OH)2]+ 127 (100) [(CH3O)2P(OH)2]+ 110 (100) [(CH3O)2POH]+ 88 (100) [M - (CH3O)2PS(OH)]+ 93 (60) [(CH3O)2P]+ 88 (100) [M - (CH3O)2PO(OH)]+ 97 (29) [P(SH)2]+ 125 (90) [(CH3O)2PS]+ 125 (59) [(CH3O)2PS]+ 125 (100) [(CH3O)2PS]+ 127 (77) [173 - (C2H5O)H]+ 125 (50) [(CH3O)2PS]+ 109 (92) [(C2H5O)PSH]+ 172 (42) ni 132 (80) [C6H4CH2N3]+ 132 (100) [C6H4CH2N3]+ 226 (84) [M - (C2H5O)2PO]+

185 (18) [M - Cl]+ 221 (6) [M - Cl]+ 192 (26) [M - (CH3O)H]+ 192 (26) [M - (CH3O)H]+ 156 (98) [CH2(CH3O)2P(OH)S]+ 125 (43) [(CH3O)2PS]+ 170 (14) ni 274 (19) [M]+ 263 (91) [M]+ 169 (100) [M - C2H5SO]+ 277 (79) [M]+ 173 (100) [M - (CH3O)2PS2]+ 278 (100) [M]+ 291 (100) [M]+ 257 (30) ni 160 (100) [C6H4CH2CON3]+ 160 (77) [C6H4CH2CON3]+ 362 (100) [M]+

153 (75) [M - C2H7NO]+ 187 (19) [M - C2H7NO]+

214 (10) [M]+ 248 (20) [M - H]+

101 (12) [C8H5]+ 126 (22) [C10H6]+ 126 (30) [C10H6]+ 126 (24) [C10H6]+ 138 (25) [C11H6]+ 138 (34) [C11H6]+

128 (100) [M]+ 178 (100) [M]+ 202 (100) [M]+ 252 (100) [M]+ 252 (100) [M]+ 252 (100) [M]+ 276 (100) [M]+ 276 (100) [M]+

150 (25) [M - 3Cl]+ 220 (81) [M - 2Cl]+ 184 (29) [M - 4Cl]+ 110 (10) [C6H3Cl]+ 184 (10) [M - 4Cl]+ 218 (16) [M - 4Cl]+ 218 (22) [M - 4Cl]+ 184 (15) [M - 4Cl]+ 252 (29) [M - 4Cl]+ 218 (20) [M - 4Cl]+

186 (56) [M - 2Cl]+ 255 (17) [M - Cl]+ 256 (58) [M - 2Cl]+ 220 (46) [M - 2Cl]+ 254 (42) [M - 2Cl]+ 290 (59) [M - 2Cl]+ 290 (70) [M - 2Cl]+ 254 (36) [M - 2Cl]+ 324 (76) [M - 2Cl]+ 290 (43) [M - 2Cl]+

256 (100) [M]+ 292 (100) [M]+ 326 (100) [M]+ 292 (100) [M]+ 326 (100) [M]+ 360 (100) [M]+ 360 (100) [M]+ 326 (100) [M]+ 396 (100) [M]+ 360 (100) [M]+

260 190 (43) [M - 2Cl]+ 196 126 (29) [M - 2Cl]+ 264 194 (29) [M - 2Cl]+

225 (100) [M - Cl]+ 161 (15) [M - Cl]+ 229 (14) [M - Cl]+

260 (34) [M]+ 196 (100) [M]+ 266 (100) [M]+

201 173 (43) [M - C2H4]+ 215 173 (25) [M - C3H6]+

186 (67) [M - CH3]+ 200 (100) [M - CH3]+

201 (100) [M]+ 215 (61) [M]+

120 77 (16) [C6H5]+

105 (100) [M - CH3]+

120 (31) [M]+

214 61 (100) [C2H7NO]+ 249 61 (100) [C2H7NO]+ 128 178 202 252 252 252 276 276 256 290 324 292 324 356 356 324 392 358

nd ) not detected. ni ) not identified. b SVHC) Semi volatile halogenated compounds

and trap or closed loop stripping, followed by GC/MS.15 (iv) Finally, compounds not GC amenable, e.g. bentazone and benzidine, for which a previous derivatization step is required or otherwise LC techhniques should be used, have poor or no recoveries.16 Gas Chromatography/Mass Spectrometry. GC/EI/MS is nowadays the most used technique for environmental analysis, (15) EPA Method 524.2, Revision 4.0, Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry, Environmental Monitoring Systems Laboratory, Environmental Protection Agency, Cincinnati, OH 45268, 1992. (16) Chiron, S.; Papilloud, S.; Haerdi, W.; Barcelo´, D. Anal. Chem. 1995, 67, 7(9), 1637-1642.

since it permits one to achieve LOD at the nanogram/liter range and compounds can be easily identified through library search. With the GC conditions optimized, a single run in GC/EI/MS permitted the multiresidue analysis of all 109 compounds, and it offered good sensitivity and selectivity. Figure 2A displays the GC/ EI/MS total ion chromatogram of a standard mixture at 1 ng/µL using the HP-5MS column. Characterization of all 109 compounds was performed before establishing the time-scheduled SIM conditions. Table 3 depicts the three main ions of each compound, their relative abundance and the tentative characterization. GC/ EI/MS generated the [M]+ ion as base peak for most families of compounds (e.g. benzidines, chloroanilines, chlorophenols, PAHs, Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

1437

PCBs and chloronaphthalenes) or other diagnostic ions formed by the loss of group-specific components corresponding to OH, CH3, C2H4, or chlorine atoms, depending on the molecule type. Chlorinated compounds exhibited losses of chlorine atoms, giving an ion at m/z 92 for chloroanilines and at m/z 126 for dichloroanilines, corresponding to [M - Cl]+. Organochloro pesticides exhibited losses of 2-5 chlorine atoms, giving characteristic fragments. Chlorinated compounds could be easily identified from the scan chromatogram by following its chlorine pattern. Chloronitrobenzenes underwent strong fragmentation under EI and produced characteristic fragment ions corresponding to losses of the nitro group and chlorine atoms. 2-Chloro-6-nitrotoluene and 4-chloro-2-nitrotoluene exhibit [M - OH]+ instead of [M]+ due to a McLafferty rearrangement, indicating a nitro group adjacent to a methyl group. Organophosphorus pesticides produced [M]+ for some phosphorothioates, but other compounds fragmented to produce diagnostic fragment ions as base peaks, indicating the functional group structure for each class of pesticides, e.g. parathion-methyl and -ethyl formed an ion at m/z 109, corresponding either to [(CH3O)2PO]+ or [(CH3CH2O)PSH]+ and fenitrothion at m/z 125 [(CH3O)2PS]+. For other compounds, e.g. disulfoton, malathion, and azinphos methyl and ethyl, the base peak corresponded to structure-characteristic fragments. For the phenylurea pesticides monolinuron and linuron, the base peak corresponded to a fragment ion at m/z 61 [C2H7NO]+, which was used for quantification purposes despite the low mass. In general, the combination of both diagnostic and molecule-characteristic ions permitted an easy identification of target pesticides in surface water matrixes.17 As can be seen from Table 3, in most cases the molecular ion was the base peak and it was the ion chosen for the SIM program (indicated in Table 2). Even though the EPA recommends the use of three ions for confirmation and quantification of target analytes,18 in the present protocol a single ion per compound was selected to avoid a decrease in sensitivity due to the large number of ions scanned. In the present case, by selecting the appropriate ion of each compound and by retention time comparison, automatic identification of the analytes was possible and no coelutions occurred (except for 3- and 4-chlorophenol and parathion-ethyl and fenthion), and quantification was accurately performed from the SIM chromatogram. The corresponding scan chromatogram permitted the confirmation of specific analytes by the different fragment ions formed and by comparison with an authentic standard. A similar criteria is reported by Gilbert et al..19 The double-injection mode was very useful for the unequivocal identification of target analytes in drinking and surface waters, where often matrix interferences and the low analyte concentration make identification and quantification difficult. Quality Assurance. The first task was to select appropriate compounds to be used as surrogates and internal standard, because they are needed in a GC/EI/MS multiresidue analysis to ensure method performance and robustness. To verify the (17) Lacorte, S.; Molina, C.; Barcelo´, D. Anal. Chim. Acta 1993, 281, 71-84. (18) EPA Method 525.1: Determination of Organic Compounds in Drinking Water by Liquid-Solid Extraction and Capillary Column GC/MS. Revision 2.2, Environmental Monitoring Systems Laboratory, US EPA, Cincinnati, OH 45268, 1991; p 323. (19) Gilbert, J.; Startin, J. R.; Crews, C. Pestic. Sci. 1987, 18, 273-290.

1438

Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

suitability of the surrogates nitrobenzene-d5 (eluting at 16.76 min), 2-fluorobiphenyl (29.53 min), and p-terphenyl d14 (60.62 min), their recoveries were calculated from the calibration curve using anthracene-d10 as internal standard. The recovery of nitrobenzened5 (75%), 2-fluorobiphenyl (82%), and p-terphenyl-d14 (88%) in spiked drinking water indicated no losses of these compounds during sample manipulation. The method was validated by establishing the quality parameters associated with the overall procedure. Spike experiments were performed in drinking water, which is one of the matrixes proposed by the EU for water surveillance. Response factors were determined using the integrated peak area of the base peak ion of each compound versus that of the internal standard, and values close to 1 indicated a similar behavior. For quantification, a five-point calibration curve was constructed for each compound using anthracene-d10 as internal standard. Coefficients of correlation were in most cases close to 0.99, the system was linear over a concentration range of 0.05-2 µg/mL, and instrument detection limits are shown in Table 3. By preconcentrating 200 mL of water spiked at 1 ng/mL, the overall recoveries of 70-100% indicated that no breakthrough occurred and standard deviations of triplicate analysis were in most cases between 1 and 9%, indicating good accuracy and robustness. The method limits of detection are indicated in Table 2 and in general were a few nanograms/liter. With this method it was possible to quantify most of the priority organic pollutants at the levels required by the EU, which are below 0.1 µg/L in drinking water. Surface Water Monitoring. The multiresidue method developed was used in a pilot study carried out in France in order to accomplish EU 76/464/CEE Directive concerning the survey of 132 target pollutants in surface water. Different water matrixes were sampled, including drinking, sea, river, and waste water. Samples were analyzed for the 109 compounds as depicted above. From 20 samples analyzed, only a few were positive. Table 4 shows the concentration of several pollutants in surface waters in three samples quantified from the SIM chromatogram using internal standard. Confirmation was always performed from the scan chromatogram. Sample A contained a high concentration (72.7 µg/L) of pentachlorophenol, along with trace levels of several PAHs, cumene, and tributhyl phosphate. Ion chromatograms (obtained under SIM mode of operation) are shown in Figure 3. This case represents a typical case of industrial contamination. Specifically, pentachlorophenol is widely used as an insecticide, general herbicide, wood preservation agent, and glue and in a wide variety of industrial applications, and according to the 76/ 464/CEE Directive,1 the maximum allowable concentration for this compound in surface water should be of 10 µg/L. Therefore, actions should be made to reduce the concentration of this compound, which is described as toxic and persistent. Sample B was characterized by the presence of PAHs at trace levels, but fenitrothion and tributhyl phosphate were detected at levels of 2.6 and 13.1 µg/L, respectively. Fenitrothion is widely used in crop protection, although this compound was eliminated from the United States National Pesticide Survey (US NPS) because it presumably degradates under environmental conditions, shown by its half-life of 2 20 and 6 days,21 depending on the environmental conditions. However, it can generate more toxic and persistent degradation products such as fenitrooxon and the

Table 4. Compounds Detected in Three Surface Waters (samples A, B, and C) in µg/L, after Preconcentration of 200 mL of Water at pH 7 and 2 with Oasis 60 mg Cartridges Followed by GC/EI/MS A compound

acid

cumene 0.04 2,4-dichlorophenol naphthalene 0.22 2,4,6-trichlorophenol tributhyl phosphate 0.62 trifluraline HCB pentachlorophenol 72.7 anthracene PCB 52 fenitrothion 1,2,3,4-tetrachloronaphthalene fluoranthene 0.02 o,p′-DDE PCB 101 p,p′-DDE PCB 77 o,p′-DDD PCB 118 PCB 153 p,p′-DDD benzo[b]fluoranthene benzo[k]fluoranthene benzo[a]pyrene

B

C

neutral

acid

0.09

0.11

10.8

2.62

13.1

neutral acid 0.56

0.39

5.68 1.04 0.52 0.36

6.02 1.33 0.08 0.13

0.26 0.31

0.19 0.08

0.60 0.22 0.49 0.25 0.53 0.25 0.68 0.10 0.15 0.64 0.45 0.23 0.39

0.38 0.05 0. 26 0.19 0.22 0.10 0.56 0.09 0.09 nd 0.41 0.23 0.34

2.82

S-methyl isomer of fenitrothion.20 These compounds should be taken into consideration in future monitoring programs. In addition, the presence of tributhyl phosphate in water is common due to its stability and widespread use as fire retardant plasticizers and as industrial hydraulic fluids for the replacement of PCBs.22 Sample C represents a typical case of diffuse industrial pollution, where chlorinated phenols, PAHs, PCBs, and DDT metabolites abound. We note here that the extraction efficiency can vary when changing from drinking water to real environmental samples. Under acidic conditions, humic acids are protonated and increase their hydrofobic character, which leads to higher interactions with the more apolar compounds, and lower recoveries are found. This explains the differences in concentration of trifluraline, PCB 52, fluoranthene and p,p′-DDD in sample C (Table 3) between the neutral and acidic extracts. Figure 2B shows the GC/EI/MS traces corresponding to the preconcentration of 200 mL of water. The presence of chlorophenols, which are included in the US EPA list of priority pollutants,23 and PAHs are indicators of industrial effluents spill or contamination by runoff. Although PCBs and DDT derivatives are at trace levels, their detection in water indicates illegal use of these compounds in some part of Europe. From these results, we can state that the method developed permits us to follow large-scale monitoring studies with unequivocal identification and quantification of target analytes. (20) Lacorte, S.; Barcelo´, D. Environ. Sci. Technol. 1994, 28, 8(6), 1159-1163. (21) Oubin ˜a, A.; Ferrer, I.; Gasco´n, J.; Barcelo´, D. Environ. Sci. Technol. 1995, 29, 1246-1251. (22) Go´mez-Belincho´n, J. I.; Grimalt, J. O.; Albaige´s, J. Chemosphere 1998, 17 (11), 2189-2197. (23) EPA Method 8041: Phenols by Gas Chromatography: Capillary Column Technique, Washington, DC, 1995; pp 1-28.

Figure 3. GC/EI/MS ion chromatograms in selected ion monitoring (SIM) showing the presence of several organic compounds (in order of elution) detected in sample A after SPE of 200 mL of surface water.

CONCLUSIONS In summary, we have described in this paper a single procedure based in SPE using polymeric cartridges and GC/EI/ MS for the identification of 109 priority pollutants included in the EU Black List. The excellent method performance, as regarding recovery efficiency, LD, and reproducibility, indicates that the automated protocol proposed is especially suitable for routine monitoring programs. The double GC/EI/MS analysis in SIM and scan mode permitted an accurate quantification of target analytes and the unequivocal identification through mass spectra and library confirmation, respectively. This multiresidue approach permits one to follow EU regulations in terms of the number of analytes that can be simultaneously analyzed in different types of waters (drinking, surface, waste, etc.). The overall time and expense of analysis is reduced and represent an advantage over specific family methods. The advantage of the present method is that with a single extraction it is possible to recover satisfactorily 77 out of 109 compounds and detect another 25. The monitoring program launched by the EU on water quality and management and the technique developed are intended to promote the knowledge of the compounds that are being released into environmental waters. With the multianalyte data obtained, it will be possible to establish temporal and spatial distributions of organic pollutants in the environment and to update existing regulations. Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

1439

ACKNOWLEDGMENT Gilson (Villiers-le-Vel, France) is acknowledged for the loan of the extraction system ASPEC XL. S.L. acknowledges the ministry of Spain (grant PF 37.745.208) for financial support. This work has been supported by the Environmental and Climate Program INEXSPORT (Wastewater Cluster) [ENV4-CT97-

1440

Analytical Chemistry, Vol. 72, No. 7, April 1, 2000

0476], BIOTOOLS [IC15-CT98-0138], and CICYT [AMB972083-CE]. Received for review September 20, 1999. Accepted January 5, 2000. AC991080W