Anal. Chem. 1987, 59, 65-69
65
Gas Chromatographic-Mass Spectrometric Analysis of Creosotes Extracted from Wooden Sleepers Installed in Playgrounds Wolfgang Rotard* and Wolfgang Mailahn
Institut fur Wasser-, Boden- und Lufthygiene des Bundesgesundheitsamtes, Corrensplatz 1, 0-1000 Berlin 33, West Germany
I n order to evaluate their hygienic risk, wood samples from sleepers (railroad cross ties) impregnated with coal tar creosote were taken from playgrounds and investlgated for hazardous compounds. The samples were extracted with ether, and acld-base-neutral separations were made on the creosote extracts. Water-soluble compounds were also isolated. Ail the fractions were lnvestlgated by capillary gas chromatography-mass spectrometry. Besldes phenbls in the acidic fractions and N-heterocyclic polynuclear aromatlc hydrocarbons (PAH) In the basic fractions, high amounts of neutral PAH and also, In several samples, high levels of carclnogenlc and cocarcinogenic PAH were determined.
Since the beginning of the construction of railways, wooden sleepers (railroad cross ties) have been impregnated once with coal tar creosote before being placed under the rails. Depending on the type of wood, amounts of creosote between 40 and 175 kg/m3 of wood are pressed into the sleepers by the vacuum-high-pressure method (1-3). Despite the different national standards and physical specifications for coal tar creosote, sleepers have a strong resistance to rotting and insects for several decades in zones of moderate climate (4-6). Even after more than 30 years of use, only a small decrease of creosote-in the sleepers has been found ( 4 , 5 ) . Discarded old sleepers are widely utilized as timber in horticulture. Experience has shown that creosotes contain carcinogenic compounds (3, and installation of disused sleepers in playgrounds is regarded as a health risk. On hot days creosote exudes from the surface of the old sleepers, which could still yield 10-20 kg of creosote each (4,5). Therefore contamination of children’s clothes and skin with subsequent absorption of hazardous compounds is possible. In order to evaluate the possible health risk, a variety of sleepers from playgrounds were analyzed. Analysis of coal tar and creosotes by gas chromatography (GC) and gas has been dechromatography-mass spectrometry (GC-MS) scribed (8-10). However, the extracts of old sleepers have been investigated by one working group, and only packed columns have been used ( 4 - 6 , l l ) . EXPERIMENTAL SECTION Sample Preparation and Extraction. Shavings were taken from defined parts of the surfaces of sleepers that had been installed in playgrounds. The density and the thickness of these shavings were determined by physical examination, and the type of wood was determined microscopically (Table I). About 5-7 g of shavings was accurately weighed, transferred into a 100-mL Soxhlet apparatus, and extracted with 180 mL of freshly distilled diethyl ether for 24 h. After filtration through anhydrous sodium sulfate, the solvent was evaporated by using an aspirator vacuum. The residue was weighed to determine the yield of ether-extractable material in the shavings (Table I). Acid-Base-Neutral (ABN) Separation and Cleanup. The residue was redissolved in 30 mL of distilled diethyl ether. This
solution was extracted four times with 10 mL of 1 N sulfuric acid. Additionally, the aqueous layer was extracted once with 5 mL of freshly distilled pentane, and the pentane layer was combined with the original ether layer. The acidic aqueous layer was treated with 45 mL of 1N sodium hydroxide solution and then extracted five times with 15 mL of diethyl ether. After being filtrated through anhydrous potassium carbonate and washed with ether, the extract was evaporated to determine the yield of basic organic compounds in the sleepers (fractions B 1-4 in the tables). The original ether-pentane layer was extracted four times with 10 mL of 1 N sodium hydroxide solution. Additionally, the alkaline aqueous layer was extracted with 5 mL of freshly distilled pentane, and the pentane layer was combined with the original organic extract. The alkaline aqueous layer was treated with 45 mL of 1N sulfuric acid and then extracted five times with diethyl ether. After being filtrated through anhydrous sodium sulfate and washed with ether, the solution was evaporated to determine the yield of acidic organic compounds in the sleepers (fractions A 1-4 in the tables). After being weighed, the residue was redissolved in a small amount of ether and then filtered through a column of silica gel (5 g, 230 mesh, 1.5 cm i.d.) by washing with 100 mL of diethyl ether. The filtrate was evaporated to determine the loss of material (Table I). The original ether-pentane solution was filtered through anhydrous sodium sulfate, and after being washed with ether, the solution was evaporated to determine the yield of neutral organic compounds in the sleepers (fractions N 1-4 in the tables). The residue was dissolved in a small amount of ether and then filtered through a column of alumina (W 200, activity grade 2, 5 g, 1.5 cm i.d.) by washing with 100 mL of diethyl ether. The filtrate was evaporated to determine the loss of material (Table I). Extraction of Water-Soluble Compounds. About 1 g of shavings was stirred in 1L of water for 24 h at room temperature. After filtration over glass wool, the filtrate was extracted five times with 20 mL of dichloromethane (DCM). The organic layer was filtered through anhydrous sodium sulfate, washed with DCM, and then evaporated to determine the yield of water-soluble extractable material from the aqueous layer obtained from the sleepers (W 1-3 in the tables). Reference Materials and Calibrations. The external calibration and quantification were performed with the standard solution EPA 48214, which contained several PAH. Another standard solution of 21 PAH was prepared (Table 11). A standard solution containing six N-heterocyclic aromatic bases was prepared for the quantification of the basic extracts (Table 111). The absence of aminonaphthalenes in the basic extract was tested by spiking two aliquots of sample 1with etheral solutions of both 1-aminonaphthalene and 2-aminonaphthalene. A standard solution containing seven phenols and phthalic anhydride was prepared for the quantification of the acidic extracts (Table IV). Peak tailing of the phenols made it difficult to identify acidic components of high molecular weight. Since standards were not available for all methyl-, dimethyl-, and trimethylphenol isomers (Table VII) and all methyl-, dimethyl-, naphtho-, and dibenzoquinolinesand azapyrenes (Table VI) occurring in creosote, the response factors of the standards were also applied to isomers and to compounds of related structures. Standard solutions and sample extracts were injected successively to make quantitative determinations.
0003-2700/87/0359-0065$01.50/00 1986 American Chemical Society
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ANALYTICAL CHEMISTRY, VOL. 59, NO. 1, JANUARY 1987
Table 11. Components of the Neutral PAH Standard compound
i
VI
naphthalene 2-methylnaphthalene acenaphthene biphenyl fluorene dibenzofuran anthracene phenanthrene dibenzothiophen cyclopenta[deflphenanthrene
4m m
* m
U
ei
U
8
fluoranthene pyrene phenylnaphthalene chrysene benzo[ blfluoranthene benzo[k]fluoranthene benzo[e]pyrene benzo[a]pyrene perylene indeno[1,2,3-cdjpyrene dibenzo[a,h]anthracene
mol wt
integration mode
128 142 154 154 166 168 178 178 184 190 202 202 204 228 252 252 252 252 252 276 278
TIC TIC TIC TIC TIC TIC TIC TIC TIC TIC TIC TIC TIC M+ M+ M+ M+ M+ M+ M+ M+
m
3
ei
c)
!i
Table 111. Components of the N-Heterocyclic PAH Standard
.+
Y m
ei
compound
mol wt
integration mode
quinoline isoquinoline carbazole benzo[h]quinoline acridine dibenzo[f,h]quinoline
129 129 167 179 179 229
TIC/M+ TIC TIC TIC/M+ TIC/M+ M+
Y
a,
Table IV. Components of the Phenol Standard mol compound
wt
phenol 4-methylphenol 2,3-dimethylphenol 3-methoxyphenol 2,3,5-trimethylphenol 1-naphthol phthalic anhydride 4-phenylphenol
94 108 122
124 136 144 148 170
integration mode TIC TIC TIC TIC TIC M+ TIC M+
Narrow, intensive peaks a t lower retention times were integrated in the total ion chromatogram mode (TIC), while the broadened peaks at higher retention times were integrated in the selected ion chromatogram mode by using the molecular ion (M+). Gas Chromatograhic-Mass Spectrometric Equipment. GC-MS data were obtained with a HP 5995 A gas chromatograph-quadrupole mass spectrometer coupled to a HP 1000 computer. The gas chromatograph was equipped with a 50-m fused silica capillary column CP Si1 19 CB having a 0.2 mm i.d. and a 0.2 pm cyanopropylphenyl-methylpolysiloxane film (analogous to OV-1701). A Grob injector was used in splitless mode for 0.25 min a t an injection temperature of 280 "C. Helium was the carrier gas a t a pressure of 100 kPa. For oven temperature programs, see Figure 1-3 and Table VII. The GC-MS transfer line temperature was 280 " C , the temperature of the ion source and the analyzer was 180 "C. The electron impact ionization energy was 70 eV.
RESULTS AND DISCUSSION The yield of ether-extractable material in the sleeper s a m ples from playgrounds varied from 8.9 to 15% of total weight (Table I). The neutral extracts always were the major fractions in the ABN separations, while the amounts of bases did not
ANALYTICAL CHEMISTRY, VOL. 59, NO. 1, JANUARY 1987
67
Table V. Important Compounds in the Neutral Extracts of the Samples 1-4 and the Total Extract of Sample 5 (see Figure 1) concentration in the shavings, gg/g N2 N3 N4
mol
peak no. 1 2
3 4 5 6 7 8 9 10 11 12
13 14 15 16 17 18
compound
wt
N1
naphthalene acenaphthene dibenzofuran fluorene dibenzothiophene phenanthrene + anthracene cyclopenta[deflphenanthrene phenylnaphthalene fluoranthene pyrene chrysene + triphenylene benzo[b]fluoranthene+ benzoLj1fluoranthene benzo[k]fluoranthene benzo[a]fluoranthene benzo[e]pyrene benzo[a]pyrene perylene indenowrene
128
365 865 990 1380 1420 14755 1500 1033 12418 5592 5599 1222 940 166 721 867 231 322
154 168 166 184 178 190 204 202 202 228
252 252 252 252 252 252 276
179 742 627 1811 1291 19892 3917 2140 23067 11683 12950 2316 1930 419 1300 1573 371 354
392 973 561 1849 978 13973 2722 726 10138 3258 3397 408 303 289
6.4 44 23 58 22
1005 418
5 80
134 147 185 84 1473 101 833 553 266
5141 2249 3325 307 360
221
239 47
100
22
210 183 32
30.8 43.8
Table VI. Important N-Heterocyclic Aromatic Compounds in the Basic Extracts of Samples 1-4 (Figure 2) peak no.
a
concentration in the shavings p g / g B2 B3
mol compound
wt
B1
quinoline isoquinoline methylquinolinesa
129 129 143
dimethylquinolinesa
157
benzo [hlquinoline acridine azapyrenesb (azafluoranthene) naphthaquinolinesc (benzoacridine)
179 179 203
30.5 8.2 42.3 (7 peaks) 31.5 (7 peaks) 50.4 27.5 115 (6 peaks) 125.1 (6 peaks)
229
B4
7.8 20.8 (4 peaks) 8.9 (2 peaks) 23.2 13.3 23.8 (4 peaks)
3.6 1.3 4.6 (2 peaks)
4.2 (6 peaks) 19.3 15.0 (4 peaks) 32.5 (3 peaks)
Quantified with quinoline standard. Quantified with acridine standard. Quantified with dibenzoV,h]quinolinestandard. lcountsl 6
90000-
PIPAH ilC
I
PI B TIC
2517-252 7omu
iminl
Figure 1. (a) Total lon chromatogram of the neutral extract of sample 1 (Table VI. (b) Mass chromatogram of m / e 252. Temperature program was as follows: 30 OC (2 mln), 25 OC/mIn to 250 OC, isothermal 10 min, 3 OC/min to 280 OC, isothermal 10 min, 2 OClmin to 300 OC, isothermal 24 min.
exceed 0.5% of total weight and the amount of acids also remained under 2 %. The yield of ether-extractable material in the firewood sample was low. The high-resolution gas chromatographic profile of the neutral fraction 1 (Figure 1, Table V) from sample 1 was similar to those from samples 2-5. Phenanthrene and anthracene were the substances having the highest concentrations in samples 1, 3, and 5, while in samples 2 and 4 fluoranthene was the compound in highest concentration. The carcinogenic and noncarcinogenic isomers of benzofluoranthenes and benzopyrenes were detected in all
Figure 2. Total ion chromatogram of the basic extract of sample 1 (Table VI). Temperature program was as follows: 30 OC, 20 OC/min to 200 OC, 3 'Clmin to 260 OC, isothermal 20 min.
samples (12). Significantly higher concentrations of carcinogens were found in samples 1 and 2. Quinoline, isoquinoline, and the methyl-substituted isomers were detected in the basic extracts of samples 1, 2, and 4. Higher condensed aromatic bases such as benzoacridines and naphthoquinolines (molecular weight 229) were detected in samples 1 and 4 (Figure 2, Table VI). Besides benzoquinoline and acridine, several compounds with a molecular weight of 203, probably isomers of azapyrene and azafluoranthene, were found in all samples (13). In the gas chromatograms of both spiked basic aliquots of sample 1,the aminonapththalenes gave longer retention times than the isomers of methylquinolines. The mass chromato-
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ANALYTICAL CHEMISTRY, VOL. 59, NO. 1, JANUARY 1987
Table VII. Important Substances in the Acidic Extracts of Samples 1-4n mol compound
A1
wt
phenol methylphenols
108
dimethylphenols
122
trimethylphenols
136
1.2
phthalic anhydride 1-naphthol 4-phenylphenol
148 144 170
2.1
94
concentration in the shavings, pg/g A2 A3
A4
8.0
37.8 (2 peaks) 20.3 (3 peaks)
1.7 1.5
0.48
2.0
4.6 (3 peaks) 5.4 (2 peaks) 1.3 2.05
16.9 (5 peaks) 7.8 (2 peaks) 5.1 7.7
0.8
0.5
aTemperature program: 30 "C, 30 "C/min to 150 "C, 5 "C/min to 250 "C, isothermal 24 min. Table VIII. Important Substances in the Aqueous Extracts of Samples 1-3 (See Figure 3)
peak no.
i
1
'5
2
3 4 5
6 7 8
9 10 11 12
13 14 i6
:3
32
3+
36
38
10
12
LL
+6Imml 18
Flgure 3. (a) Exerpt of the total ion chromatogram of the aqueous extract of sample 1 (Table VIII). (b) Exerpt of the mass chromatogram of m l e 252, benzo[b]- and benzo[j]fluoranthene just can be identified and quantified. Temperature program was as follows: 30 OC, 30 OC/min to 200 OC, 4 OC/min to 296 OC, 0.2 OC/min to 300 O C , isothermal 20 min.
grams of m l e 143 showed that no aminonaphthalenes were detectable in the original basic extracts of samples 1-4. In the acidic extracts of samples 1,2, and 3, especially the isomers of methylphenols and dimethylphenols were detected, while the presence of phthalic acid was inferred from its anhydride detected in samples 1 and 2 (Table VII). Only a few volatile substances were detected in the acidic extract of sample 4. The water solubility of creosote compounds was investigated to evaluate the health risk of skin contact with wet sleepers and the contamination of the surrounding soil. In the aqueous extracts of samples 1-3, high amounts of phenols and N-heterocyclic aromatics in relation to neutral aromatics were found. The concentrations of neutral aromatics decreased with the increase in molecular weights (Table VIII). Some compounds like benzothiophene and anthraquinone were also observed in the aqueous extracts. They also should have been present in the neutral extracts but were probably masked by other components. Benzofluoranthenes were found only in sample 1, while in the aqueous extracts of samples 2 and 3 such PAH with a molecular weight of 252 and above were no longer detectable (Figure 3, Table VIII). As the yield of water-soluble material in sample 4 was very small, the extract was not investigated any more. It was observed that the response factors of some compounds with related structures varied within & E % . Smaller
15 16 17
compound phenol methylphenols naphthalene benzothiophene quinoline acenaphthene dibenzofuran fluorene dibenzothiophene phenanthrene anthracene benzo[h]quinoline acridine carbazole fluoranthene pyrene benzo[b]fluoranthene + benzo[t9]fluoranthene
mol wt
94 108 128 134 129 154
168 166 184 178 178 179 179 167 202 202 252
concentration in water (pg/L) from 1 g of shavings w1 w2 w 3 5.5
43.2 44.5
11.7 30.2 42.9 51 39.8 23.0 89.6 12.8 10.0 2.7 58.9 25.4 10.1
88.9 5.6 7.6 107 92.7 120 17.8 119 8.6
52.9 1.6
23.2 16.9 30.8 6.5 60.9 2.3 17.7 4.3 13.4 0.9 50 8.6 13.3 15.3 6.3 4.7
4.5
deviations in the response factors were observed for acenaphthene, fluorene, and dibenzofuran. A deviation range of f l l % was found for phenanthrene, fluoranthene, and pyrene. The total deviation range for the quantification was about f30%. Longer retention times increased the detection limit; therefore, the detection limit was about 1-2 ng in the lower retention range and 2-3 ng in the higher retention range.
CONCLUSIONS In the creosote extracts of several samples considerable yields of carcinogenic PAH as benzo[a]pyrene, benzo[b]fluoranthene, and benzolilfluoranthene were detected. The carcinogenic effect of creosote not only is caused by carcinogens, which are active as single substances, but is heavily increased by a large number of cocarcinogens that are inactive as single substances (14). Although an occurrence of skin cancer has not been reported from workers in creosote-impregnation plants (15-17), allergic skin reactions by sensitive persons have been observed among plant workers and even among railway workers who laid sleepers (17). On playgrounds with installed sleepers the possibility of allergic reactions to creosote has to be regarded as the main health risk, especially if little wounds and scratches on children's skin are contaminated. As little children often put their fingers into the mouth, an intake of creosote into the digestive system is possible if their fingers are contaminated.
Anal. Chem. 1987, 59, 69-74
As a result of theae investigations, the Federal Health Office has recommended avoiding the installation of discarded old sleepers as playground equipment for the prevention of these health risks (18). Registry No. PhOH, 108-95-2; naphthalene, 91-20-3; acenaphthalene, 208-96-8; dibenzofuran, 132-64-9; fluorene, 86-73-7; dibenzothiophene, 132-65-0;phenanthrene, 85-01-8; anthracene, 120-12-7; cyclopenta[deflphenanthrene, 203-63-4; phenylnaphthalene, 3546571-5; fluoranthene, 206-44-0; pyrene, 129-00-0; chrysene, 218-01-9;triphenylene, 217-59-4;benzo[blfluoranthene, 205-99-2; benzovlfluoranthene, 205-82-3;benzo[k]fluoranthene, 207-08-9; benzo[a]fluoranthene, 203-33-8; benzo[e]pyrene, 19297-2; benzo[a]pyrene, 50-32-8;perylene, 198-55-0;indenopyrene, 72254-06-9; quinoline, 91-22-5; isoquinoline, 119-65-3;benzo[h]quinoline, 230-27-3; acridine, 260-94-6; azafluoranthene, 8912645-4; phthalic anhydride, 85-44-9; 1-naphthol, 90-15-3; 4phenylphenol, 92-69-3; benzothiophene, 11095-43-5; carbazole, 86-74-8. LITERATURE CITED (1) Metzner, W.; Bellmann, H. Ullmnns €nzyk/opasdie der technischen Chemk; Verlag Chemle: Weinheim, West Germany, 1976; Vol. 12, pp 865-702.
89
(2) Hunt, G. M.; Garret, 0.Wood Presetvation, 3rd ed.;McGraw-Hill: New York 1967. (3) Rueping, M. U.S. Patent 709799, 1902. See also Wassermann, C. German Patent 138933, 1902. (4) Petrowitz, H. J.; Becker, G. Materklpriifung 1964, 6, 461-470. (5) Petrowitz, H. J.; Becker, 0.Materklpriifung 1965, 7, 325-330. (6) Petrowitz. H. J.; Becker, G. Holz Roh-Werkst. 1976, 34, 315-322. (7) Henningsson, B. Holz Roh-Werkst. 1983, 47, 471-475. (8) Borwitzky, H.; Schomburg, G. J. Chromatogr. 1979, 770, 99-124. (9) Aiben, K. Anal. Chem. 1980, 5 2 , 1625-1628. (10) Nestler, F. H. M.; Anal. Chem. 1974, 46, 46-53. (11) McNeii, D.; Vaughan, G. A. Rec. Annu. Conv. Br. Wood Preserv. ASSOC. 1884, 1-22. (12) Grimmer, G.; Jacob, J.; Naujack, K.-W.; Dettbarn, G. Anal. Chem. 1983, 55, 829-900. (13) Lee, M. L.; Novotny, M.; Bartle, K. Analytical Chemlstfy of Polycyclic Aromatic Compounds ; Academic Press: New York, Oxford, 1981. (14) Jacob, I.; Karcher, W.; Wagstaffe, P. J.; Fresenius' Z . Anal. Chem. 1984, 377, 101-114. (15) Heller, I. J. Ind. wg. 1930, 12, 169-197. (16) Flicklnger, C. W.; Lawrence, A. W. Proc. Annu. Meet. Am. WoodPreserv. Assoc. 1982, 11-28. (17) Willeitner, H.; Dieter, H. 0. Holz Roh-Werkst. 1984, 42, 223-231. (18) Public Relations Service of the Federal Health Office, news item of August 9th, 1984.
RECEIVED for review March 10, 1986. Resubmitted August 18, 1986. Accepted August 26, 1986.
Analytical Potential of Continuous Precipitation in Flow Injection-Atomic Absorption Configurations Pilar Martinez-Jimenez, Mercedes Gallego, and Miguel ValcBrcel* Department of Analytical Chemistry, Faculty of Sciences, University of Cbrdoba, Cbrdoba, Spain
The incorporation of a continuous precipitation unit built into flow injection manifolds Is presented and discussed, in order to show its analytical potential in the development of indirect automatic atomic absorption methods. The preclpitate is formed by InJecUng an ankn (analyte) into a carrier containing a cation (reagent) and is retained on a stalniess-steel filter. Two unsegmented flow configurations, one of which involves the dissoiutlon of the retained precipitate, have been tested. Three types of precipitates encountered in gravimetric procedures have been considered in this work crystalline (calcium oxalate), curdy (silver chloride), and gelatinous (ferric hydroxide). By continuous precipitation, chloride and oxalate could be determined in the range 3-100 pg/mL and 5-90 pg/mL, respectively, with a relative standard deviation between 2 and 5 %. The sampling frequency ranges between 10 and 50 h-'.
T o extend the scope of application of atomic absorption spectrometry (AAS) and to increase the sensitivity achievable for elements directly unsuitable for trace analysis, much attention has been devoted to the development of indirect methods for such elements (1-3). The application of these methods to the determination of nonmetal elements and organic compounds involves carrying out a suitable chemical reaction. One of these is based on the reaction of an anion with a solution of a cation a t an adequate concentration to yield an insoluble compound. The cation is then measured either in the filtrate or in the precipitate. Precipitates of analytical interest have very different physical properties, which determine both their analytical applicability and the 0003-2700/67/0359-0069$0 1.50/0
optimum experimental conditions for their formation. Precipitates are classified as gelatinous or flocculent, curdy, and crystalline (41, and representative examples of these types are ferric hydroxide, silver chloride, and calcium oxalate, respectively. The hydrous oxide of iron is a precipitate that has an indefinite composition and may be represented as Fez03.H20,but for simplicity is usually formulated as Fe(OH)3 and called ferric hydroxide ( 4 ) . No reference has been found in the literature about the application of this preecipitate using U S detection. Pinta (5) had previously determined chloride using a large excess of silver nitrate; chloride in the precipitate was indirectly determined by AAS in the 5-100 pg/mL range. Menache (6) had previously used the calcium oxalate system to determine oxalic acid in urine. In this method, oxalate is precipitated from urine with excess calcium at pH 5. Calcium in the precipitate is determined indirectly by AAS, substracting excess calcium measured in the supernate from the overall amount of calcium present and added to the urine sample. This method permits routine determinations of oxalate between 17 and 186 pg/mL, at a rate of 30 samples/day. The flow injection analysis (FIA) technique is a major alternative to manual methods of analysis (7,8). The advantages of the AAS-FIA association have been recently praised by several authors (9, IO). Indirect methods may also appear more attractive when the necessary chemical and possibly physical manipulation of the sample can be reduced to filling and injecting the contents of a sample loop. Thus, the incorporation of a continuous separation system (ion exchange, liquid-liquid extraction, etc.) offers numerous advantages. We have recently made use of the AAS-FIA association in conjunction with liquid-liquid extraction as a separation technique for the indirect determinations of perchlorate in human 0 1986 American Chemical Society
