Anal. Chem. 1981, 53, 1541-1543 (25) Kadish, K. M. "The Chemical Physics of Biologically Important Inorganic Chromophores"; VOl. 1, Lever, A. B. p., @aY, H. 8.3 Ed% in press. (26) Kadish, K. M.; Rhodes, R. K. Inorg. Chem., in press.
RECEIVED for review February 27,1981.
Accepted April 17,
1541
1981. The authors wish to gratefully acknowledge the suppofi of this research in part by the National Science Foundation (Grant CHE-7921536), the National Institutes of Health (Grant GM 2517-02), and the Robert A. Welch Foundation (Grant E-680).
Analysis of Fish and Sediment for Volatile Priority Pollutants Michael H. Hiatt U S .Environmental Protection Agency, Environmental Monitoring Systems Laboratmy, P.O. Box 75027, Las Vegas, Nevada 89 7 74 The U.S. Environmental Protection Agency's (EPA's) water quality monitoring and hazardous waste monitoring programs require analysis of a variety of samples for volatile organic compounds. The samples analyzed are primarily sediments, soils, water, and fish. Determination of the volatile priority pollutants in water samples is routinely accomplished with acceptable results in accordance with the EPA-recommended Method 624 (1). However, the EPA-recommended procedures for the determination of volatile priority pollutants in sediment and fish (2-4) produce unacceptable results, as evidenced in other studies ( 5 , 6 ) by low spike recoveries and high detection limits. An improved method was required for the Agency's monitoring programs. The vaporization of volatile organic compounds from a sample under vacuum and subsequent condensation in a super-cooled trap seemed an ideal approach when compared to other methods available (5-7). Cryogenic concentration has been used successfully for the determination of tritiated methane and the radioisotopes of krypton and xenon (8) and appeared to be applicable to the determination of volatile organic compounds in hiolid matrices. Another advantage of vacuum extraction was that i t did not require elevated temperatures or the addition of reagents which could produce unwanted byproducts due to sample degradation. I n this method volatile organic compounds are vaporized from the fish or sediment matrix under vacuum and are condensed in a purging trap cooled by liquid nitrogen. The purging trap is transferred to a conventional purge and trap device where the concentrate is treated as a water sample and is analyzed as described in Method 624 ( I ) . With this method, the average recovery of volatile organic compounds from samples spiked a t the 25 pg/kg level was found to be 94% for sediments and 74% for fish tissue.
EXPERIMENTAL SECTION Samples. Sediments and fish samples previously found to contain less than detectable levels of volatile priority pollutants were used as matrices for this study. Spiked samples were prepared by placing 10 g of isediment or ground fish into a 125-mL septum vial and adding the compounds to be studied (Tables 1-111). Two separate additions were necessary to add the organic compounds. The first addition was 10 pL of a water solution that contained acrolein and acrylonitrile (1pg/pL), which are more stable in water than methanol. The second injection was 5 pL of a methanol solution that contained 250 ng (50 ng/pL) of the remaining volatile organic compounds. The spiked samples were sealed with a Teflon-lined septum cap and sonicated for 5 min. The sample vials were then sealed in cans containing activated charcoal and stored overnight in a freezer. Apparatus. A diagram of the apparatus for vacuum extraction and cryogenic concentration is shown in Figure 1. The vacuum extractor can be assembled from materials normally available in the laboratory. The low pressure necessary for extraction is supplied by a vacuum pump capable of producing a torr
vacuum and a flow rate of 25 L/min. The concentrator traps (25 mL Tekmar purging tubes or equivalent)are used for condensing the volatile vapors and transferring the extract to the purge and trap device. The concentrator trap is connected to the transfer lines of the vacuum extractor with l/a in. compression fittings and graphite ferrules. The transfer lines are made of glass-lined 1/4 in 0.d. stainless steel tubing. Gastight valves (Vl-V4), Nupro B-4BKT, are connected with compression fittings and graphite ferrules. The 125-mL septum vial containingthe sample aliquot is connected to the system with a one-hole rubber stopper pierced with the 1/4 in 0.d. tubing. A liquid nitrogen cold trap is placed between the vacuum pump and concentrator trap in order to prevent condensation of pump oil vapors in the concentrator trap. The helium line and pressure gauge are connected at a junction in the transfer line between the sample and V2 and are used primarily to test the apparatus for leaks. The helium used is 99.999% pure, and normally because of the small quantities used, it is not necessary to purify further. If it is desired, however, a gas filter trap can be added to the helium line to ensure purity. An ultrasonic cleaner, Branisonic 12, is used to agitate the sample during extraction. Procedure. The vacuum extractor must be airtight and free of moisture before an extraction can be started. A clean 125-mL septum vial is connected, the vacuum pump started, and V2 to V4 are opened to evacuate the apparatus. The elimination of line condensation is accomplished by warming the transfer lines while evacuating the system. Heating tape is effective in creating even transfer line temperatures and can be used continuously during extraction. The vacuum extractor is pressurized with helium by closing V3 and opening V1. The apparatus is then leak-tested by applying soapy water on all connections and making the appropriate adjustments when leaks are located. When the apparatus is airtight, close V1 and open V3. Heat the transfer lines and concentrator trap for 5 min to eliminate any contamination from previous extraction at parts-per-billion concentration. The system is now ready for sample extraction. To begin the extraction process close V2 (V3 and V4 remain open), cool the concentratortrap with a liquid nitrogen bath, and replace the empty 125-mL vial with the sample vial. Disconnect the vacuum source by closing V3. Open V2 to permit vapors from the sample vial to reach the concentrator trap. The sample vial is then immersed in the ultrasonic water bath. The equilibrium temperature generated in the ultrasonic bath is 50 "C.Therefore the bath is initially fiiled with 50 O C water and that temperature maintained by continuous ultrasonic operation. After 5 min of ultrasonic agitation the vacuum source is connected by opening V3. The lower pressure hastens the transfer of volatile compounds from the sample to the super-cooled concentrator trap. After 15 min of vacuum close V3 and open V1 to fill the system with helium until atmospheric pressure is obtained. Close V1 and V2 to isolate the concentrate. The sample extraction is now complete and the concentrate is ready for transfer to a purge and trap device. The concentrate can be held in the liquid nitrogen bath for up to an hour prior to analysis. Disconnect the sample concentrator trap from the vacuum extractor and connect it to the purge and trap device. Some outgassing is observed when the sample extract is melted;
This article not subject to U.S. Copyright. Published 1981 by the American Chemical Society
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ANALYTICAL CHEMISTRY, VOL. 53, NO. 9, AUGUST
1981
Table I. Percent Spike Recoveries for Volatile Priority Pollutants from Sediment Matrices with Three Analytical Methods
chloromethane bromomethane vinyl chloride chloroe th ane methylene chloride trichlorofluoromethane 1,l-dichloroethene 1,l-dichloroethane trans-l,2-dichloroethene chloroform 1,2-dichloroethane 1,1,l-trichloroethane carbon tetrachloride acrylonitrile bromodichloromethane 1,2-dichloropropane trans-l,3-dichloropropene trichloroethene benzene dibromochloromethane 1,1,2-trichloroethane cis- 1,3-dichloropropene bromoform tetrachloroethene 1,1,2,2-tetrachloroethane toluene chlorobenzene ethylbenzene av compd recovery e
a 25 ppb spikes, Not determined.
f
vacuum extractiona
direct purge and trap of diluted sample@
modified purge and trap with thermal desorption f,g
9 8 i 22 8 6 i 24 108+ 35 1 0 6 i 27 LCb 80i 8 82i 9 101 i: 7 9 2 1 10 1 0 2 i 11 9 6 i 17 106 i 11 100 i 1 3 89i 8 96i 8 96 i 4 91 i 6 98+ 6 94 + 4 9 8 i 10 98i 5 922 7 9oi 9 104 c 1 3 98i 8 102 i 4 101 i 5 97i 5 96i 7
97 i 16 69+ 15 114 i 27 101 i 1 9 9 8 i 18 ND e 87 f 21 87 i 1 7 88i 24 88 i 1 9 90 f 34 7 8 2 21 94 i 28 ND 88i 37 ND ND 73 i 23 59 i 24 7 0 i 29 86 i 34 ND 7 0 i 29 57 i 21 9 O i 27 3 5 i 24 ND ND 8 2 i 18
91 i 13 77 i 1 5 87 i 24 76 i 20 77+ 17 103 i 37 84 i 20 84 i 29 78 i 3 2 77 i 35 81 i 3 1 93 + 1 3 l o o t 33 ND 93 i 24 88i 18 71 i 21 99 i 1 2 83 f 1 0 87 + 33 77 i 3 5 71 i 21 79 i 4 1 38 c 76 6 0 i 33 77 + 88 81 + 1 3 80i 8 8 3 i 10
Laboratory contamination of fish prevented generation of valid data. Reference 7. g 27 ppb spikes.
20 ppb spikes.
Reference 5.
Table 11. Percent Spike Recoveries for Volatile Priority Pollutants from Fish Matrices with Three Analytical Methods
vacuum extraction chloromethane bromomethane vinyl chloride chloroethane methylene chloride trichlorofluoromethane 1,l-dichloroethene 1,l-dichloroethane trans-l,2-dichloroethene chloroform 1,2-dichloroethane 1,l,l-trichloroethane carbon tetrachloride bromodichloromethane 1,2-dichloropropane truns-l,3-dichloropropene trichloroethene benzene dibromochloromethane 1,1,2-trichloroethane cis-1,3-dichloropropene bromoform tetrachloroethene 1,1,2, %tetrachloroethane toluene chlorobenzene ethylbenzene av compd recovery e
a 25 ppb spikes. Not determined.
85.1 22 1 2 6 i 75 6 4 i 11 6 9 i 22 LCb 995 2 74 i 8 90 i 6 86 i 9 107 i 3 1 92i 5 92i 8 91 i 9 64 i 11 54 i 7 52i 9 6 5 i 11 57 i 1 0 56 i 9 66 i- 7 54 i 9 ND e ND 61 i 1 0 ND 64 i 1 5 ND 76 i 20
direct purge and trap of diluted sample C,d
direct purge or trap of diluted sarnplepg
NDe ND 25i 9 21 i 5 ND ND 59 i 1 9 33i 9 3 3 i 11 382 13 ND 60 i 18 95 i 40 44 i 1 3 3 6 i 11 ND 41+ 8 37 i 25 42i 8 42i 7 ND 51i- 8 55 i 1 2 4 8 i 15 53 i 14 32i 8 3 5 i 12 44 i 16
78h 71 65 70h 22 54 62 69 49 81 79 58 50 67 73 65 59 68 65 77 74 62 48 71 66 68 60 64 i 1 2
Laboratory contamination of fish prevented generation of valid data. 20 ppb spikes. 200 ppb spikes. 800 ppb spikes. Reference 6, precision data were not available.
therefore, the extract should be kept frozen until the concentrator trap is attached to the purge and trap device. Warm the concentrator trap walls to loosen the extract and allow the ring of
Reference 5.
ice formed during condensation to drop to the bottom of the trap. To this partially melted extract add 5 mL of distilled deionized water containing the internal standards recommended in Method
ANALYTICAL CHEMISTRY, VOL.
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frozen extracts which should yield reproducible purging efficiencies.
Valve 1
He
RESULTS AND DISCUSSION Preliminary data, obtained with the method described, have shown excellent spike recoveries for sediment samples and a general improvement of spike recoveries for fish samples compared to results reported for other methods (Tables I and
11).
Figure 1. Vacuum extractor.
Table 111. Percent Spike Recoveries for Volatile Priority Pollutants from Water IJsing Vacuum Extraction %
concn,a ppb chloromethane bromomethane vinyl chloride chloroethane methylene chloride trichlorofluorome thane 1,l-dichloroethene 1,l-dichloroethane truns-l,2-dichloroethene chloroform 1,2-dichloroethane 1,1,l-trichloroethane carbon tetrachloride acrylonitrile bromodichlorome thane 1,2-dichloropropane
25
av compd recovery
1 0 5 + 22 1 1 O i 23 83i 12 103 t 16 126 i 22 9 9 i 18 98+ 5 96+ 5 98i 5 93i 8 98 i 1 0 104 + 9 1 0 2 i 10
100 25
truns-l,3-dichloropropene
trichloroethene benzene dibromochlorome thane 1,1,2-trichloroethane cis-l,3-dichloropropene bromoform tetrachloroe thene 1,1,2,2-tetrachloroethane toluene chlorobenzene ethyl benzene 2-chloroethyl vinyl etheir acrolein
recovery
100
85 i 13 108i 10 104i 7 109 i 9 1051 9 106 i 7 1 0 2 i 11 95+ 8 109 i 9 104 f 14 105i 9 9oi 9 106 i 7 101 i 7 103 k 5 9 4 i 5OC 113 i 76c 102i 8
aThe organic compounds were added to 2 mL of water which represents the water content of 10 g of sediment. Recoveries oE spikes were calculated by comparing vacuum extracted determinalion to determinations where spikes were added directly to the purge and trap device. These recoveries are results for three separate analyses on four different days. Average of three analyses on the same day. 624 ( I ) . The purge and itrap procedure is then performed in accordance with a modified Method 624 ( I ) . In the modified procedure the extract solution is purged with the concentrator trap immersed in an ice water bath for 5 min followed by immersion in a 55 O C water bath for an addit.iona1 7 min. This modification provides reproducible conditions for melting the
Recovery studies were performed by using freshly boiled, distilled, deionized water to which 250 ng of each of the volatile priority pollutants were added. A study using 2-mL water aliquots and extraction times that varied from 5 min to 1h indicated that extractions from water were essentially complete after 5 min. Varying the volume of water from 1 to 3 mL had no detected effect on spike recoveries. Acrolein and acrylonitrile were added only to the sediments studied. No acrolein was recovered from the spiked sediments which suggests that there is either a strong acrolein-sediment interaction or degration of the acrolein added. This finding appears to be consistent with other studies (5, 7) which also did not report any acrolein recovered. Acrolein, however, was extracted from water solutions added to the sample vial with a good recovery (Table 111). This suggests that the spiking procedure with overnight storing allowed ample time for sediment-volatile organic compound interactions t o occur prior to testing the method. This vacuum extraction method is an improvement over existing procedures and has immediate application to environmental analysis. It gives uniformly high recoveries for the individual volatile organic compounds (Tables I and 11) and appears to be free of interferences due to sediment matrices and moisture content. The method should be reliable for the variety of sediment matrices encountered in environmental monitoring. We are presently conducting a more thorough study to gain additional information on the effects of sample matrix, sample concentration, and spiking techniques. The detailed results of this study will be reported a t a later date.
LITERATURE CITED Fed. Regist. 1979, 44 (No.233), 69532-69539. United States Environmental Protection Agency. Sampling and Anaiysis for Screening of Fish for Priority Pollutants. "Analysis of Fish for Volatile Organics by Head Space Analysis"; US. Environmental Monitoring and Support Laboratory-Cincinnati: Cincinnati, OH, Aug 23, 1977; p 14. United States Environmental Protection Agency. Interim Methods for the Sampling and Analysis of Priority Pollutants in Sediments and Fish Tissue. "The Analysis of Sediments for Volatile Organics by Head Space Analysis"; U.S. Environmental Monitoring and Support Laboratory-CincinnatI: Cincinnati, OH, Aug 23, 1977; p 18. "The Analysis of Fish for Volatile Organics by Head Space Analysis"; US. Environmental Monitoring and Support Laboratory-CincinnatI: Cincinnati, OH, undated; p 21. Biazevich, J. U S . Environmental Protection Agency, Region X, Manchester, WA, personal communication, 1980. Easiy, D. M.; Kieopfer, R.D.; Carasea, A. W. "The Analysis of Volatile Organic Compounds in Fish"; U S . Environmental Protection Agency Region VI1 Laboratory: Kansas City, KS. Spies, David N. "Determination of Purgeabies Organics in Sediment Using a Modified Purge and Trap Technique"; US. Environmental Protection Agency Region 11: Edision, NJ, Oct IO, 1980. United States Environmental Protection Agency. Handbook of Radiochemical Analytical Methods: Environmental Monitoring Systems Laboratory-Las Vegas: Las Vegas, NV, Feb 1975; pp 55-69.
RECEIVED for review December 22,1980. Accepted May 19, 1981.
