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Anal. Chem. 1984, 56,2134-2137
(22) Howard, A. G.; Mills, G. A. Int. J . Environ. Anal. Chem. 1983, 74, 43. (23) Stenberg, U.; Alsberg, T.; Blomberg, T.; Wannman, T. "Polynuclear Aromatic Hydrocarbons"; Jones, P. W., Leber, P., Eds.; Ann Arbor Science: Ann Arbor, MI, 1979; p 313. (24) Vassllarus, D. L.; Kong, R. C.; Later, D. W.; Lee, M. L. J . C h r o ~ t o g r . 1982, 252. 1.
(25) Tong, H. Y.; Sweetman, J. A,; Karasek, F. W.; Jellum, E.; Thorsrud, A. K. J. Chromatogr., in press.
for review February 16, 1984. Accepted May 21, 1984.
Development and Validation of an Air Monitoring Method for 1,3=Dichloropropene, trans - 1,2,3-Trichloropropene, cis- 1,2,3-Trichloropropene, 1,1,2,3-Tetrachloropropene, 2,3,3-Tr ic hlor0-2-p ropen- 1-0I, and 1,1,2,2,3-Pentachloropropane Mark A. Leiber and Howard C. Berk* Research Department, Monsanto Agricultural Products Company, 800 North Lindbergh Boulevard, St. Louis, Missouri 63167
A procedure for the sensitive and specific determination of 1,3dlchloropropene, c/s-1,2,3-trlchloropropene, traffs-1,2,3trlchloropropene, 1,1,2,3-tetrachloropropene, 2,3,3-trlchloro2-propen-1-01, and 1,1,2,2,3-pentachloropropane In air has been developed and evaluated. Tenax-GC sampling tubes were used for sample collection followed by solvent desorption and sample analysts by ceplllary GC/ECD. The method was laboratory valldated for the range 1 ppb to 6 ppm and overall average recoveries were 98 % at the parts-permllllon level and 106% at the parts-per-bllllon level for all analytes except 1,3-dlchloropropene. For 1,3-dlchloropropene the range was 0.4-4.0 ppm with a mean recovery of 100 %. The pooled CVs ranged from 0.03 to 0.09. Fleld tests were conducted at a productlon plant.
of a variety of organic compounds (1-11). Tenax has been shown to be efficient in trapping chlorinated hydrocarbons (2, 3,6-8). Solvent desorption of specific compounds from Tenax-GC has also been shown to be a useful technique (4, 5). For analysis, electron capture detection has been well documented as a selective and sensitive gas chromatographic detection system in connection with industrial hygiene methodology (12-14). The combination of the resolution of capillary columns and the sensitivity of electron capture detection has been found to be a powerful technique for the quantitation of organohalides (15). In this work we utilized Tenax-GC as the solid adsorbent to retain the series of chloropropenes and chloropropanes outlined above. The analysis technique involved desorption of the Texax-GC with isooctane a t 90 O C and then analysis by capillary GC with electron capture detection.
EXPERIMENTAL SECTION The development of appropriate air monitoring methods for all Monsanto herbicides and the key intermediates used in their production is an ongoing program in Monsanto Agricultural Products (MAP) Research. The methods are utilized to define the levels of these materials in work place air and to assure there are no locations where there may be unacceptable worker exposure to chemicals of concern. In addition to providing assurance that good industrial hygiene practices are followed at all manufacturing facilities, these air monitoring procedures may also be used to assess plant fugitive emissions when the need arises. Triallate, S-(2,3,3-trichloroally1)diisopropylthiocarbamate, is the active ingredient in FAR-GO herbicide which is used to control wild oats in wheat, barley, peas, and lentils. In the manufacture of triallate several chloropropenes and chloropropanes are used as process intermediates. In this study a method was developed to define the levels of 1,3-dichloropropene, cis-1,2,3-trichloropropene,trans-1,2,3-trichloropropene, 1,1,2,3-tetrachloropropene,2,3,3-trichloro-2propen-1-01, and 1,1,2,2,3-pentachloropropanein work place air. Tenax-GC, a polymer of 2,6-diphenyl-p-phenylene oxide, has been reported to be an effective absorbent for the analysis 0003-2700/84/0356-2134$01.50/0
Reagents. 1,3-Dichloropropene, cis-1,2,3-trichloropropene, trans-1,2,3-trichloropropene, 1,1,2,3-tetrachloropropene, 2,3,3trichloro-2-propen-l-ol, and 1,1,2,2,3-pentachloropropanewere obtained from Monsanto Agricultural Products Co. (St. Louis, MO). 1,3,5-Tribromobenzenewas obtained from Eastman Organic Chemicals,Rochester, NY. 2,2,4-Trimethylpentane (isooctane) was MCB-pesticidegrade. Tenax-GC (60-80 mesh) from Applied Science Laboratories, Inc., was used as the solid sorbent and no preparation or cleaning was needed. Apparatus. Air sampling pumps (Model P4000) were from E. I. du Pont de Nemours and Co., Inc. The gas chromatographwas a Varian Model 3700 GC, equipped with a Varian 8000 series autosampler, a 63Nielectron capture detector, an SE-30 30 m X 0.25 mm fused silica open tubular capillary column obtained from J and W Scientific, and a Hewlett-Packard 3390A recording integrator. High purity nitrogen was used as the carrier gas for the analyses. To generate standard parts per million level test atmospheres, a standards generator from Analytical Instruments Development, Inc. (Model 350), equipped with three chamber temperature settings was used. The chamber was operated at 50 "C for 1,3dichloropropene, trans-1,2,3-trichloropropene, and cis-1,2,3-trichloropropene and at 70 "C for 1,1,2,2,3-pentachloropropane, 1,1,2,3-tetrachloropropene, and 2,3,3-trichloro-2-propen-l-o1. Diffusion tube neck inside diameters used were as follows: 1,30 1984 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 56, NO. 12, OCTOBER 1984
3 mm I.D.
6 mm I.D.
t.3/8+ Figure 1. Configuration of the glass sampling tube.
dichloropropene, 1 mm; trans-1,2,3-trichloropropene,2 mm; cis-1,2,3-trichloropropene,2 mm; 1,1,2,3-tetrachloropropene,6 mm; 2,3,3-trichloro-2-propen-l-ol, 3 mm; and 1,1,2,2,3-pentachloropropane, 6 mm. Filtered nitrogen was used as the diluting gas. For statically generating parts-per-billion levels of these materials in air, a gas chromatograph injection port whose temperature was set at 100 "C and whose carrier flow was set at 10 mL/min was used. A General Eastern Model 400C relative humidity/temperature monitor was used in the humidity studies. A Cole-Parmer Mark I hot plate (Model 4800) fitted with a vial block was used for heating vials during desorption. Preparation of Sampling Tubes (See Figure 1). The collection tubes were prepared by joining two tubes together with the following dimensions: tube number 1 , 3 in. X 1/4 in. 0.d. X 3 mm id.; tube number 2,3 in. X 3/8 in. 0.d. X 6 mm i.d. To pack the tube, a glass wool plug was inserted through the larger tube into the smaller tube a distance of about 1 to ll/zin. Tenax-GC (160 mg) was added to fill the tube in the direction of the larger end. Another glass wool plug was inserted in the larger diameter end to separate the front section from the backup section. Another 40 mg of Tenax-GC was added followed by a final glass wool plug. The section of the tube which contained 40 mg of Tenax-GC was designated as the backup section and it was this end of the tube which was attached to the sampling pump. The prepared collection tubes were capped tightly until used to prevent contamination. Air Sampling. Sampling at parts-per-million levels in the laboratory was accomplished using the standards generator. The set of diffusion tubes were placed in the permeation chamber and equilibrated at the appropriate temperature. The rate of diffusion was monitored daily and collections were not begun until the rate became constant. A collection tube was attached to a sampling pump with a short piece of Tygon tubing such that the back section (40 mg) was closest to the pump. The "sample" outlet of the standard generator was connected to the sampling tube via a glass line (with a "T vent" to allow for overflow of the standards generator output) and a short length of Tygon tubing. The standard generator's "vent' outlet was closed off. Air concentrations were varied by nitrogen dilution with constant dif-
2135
fusion rate and constant pump sampling rate and time. A 10-L air sample was collected at a rate of 200 mL/min. Laboratory sampling in the parts-per-billion range was accomplished by inserting a sampling tube into a gas chromatograph injection port (the collection tube design is ideally suited for this). A 10-pL aliquot of an isooctane solution at the desired concentration was injected and the injector was allowed to flush for approximately 5-10 min. The tube was then removed from the injector and allowed to cool. The sampling tube was then attached to a P4000 pump and a 10-L air sample was pulled through the tube at a rate of 200 mL/min. Field samples in production facilities were obtained by using the P4000 pumps. For field experiments with spiked tubes, the spike was applied using this flash loading procedure. Analysis. After sampling was done for a measured period of time, the 160 mg front section was emptied into an 8-mL vial containing 5 mL of desorbing solution (isooctane containing 4.000 pg/mL 1,3,5-tribromobenzene). The 40-mg back section was treated similarly. The vials were then heated at 90 "C for 15 min and allowed to stand overnight. After centrifugation, an aliquot of the resulting solution was injected onto the gas chromatograph and quantitated by peak height by using the tribromobenzene as an internal standard. Tribromobenzene was chosen because it is a halocarbon compound which produces a good response using electron capture detection. It is also readily available and has a retention time which clearly separates it from the compounds of interest. Tribromobenzene is not used in the manufacturing process and would therefore not be subject to any background interferences. For gas chromatographic analysis, the nitrogen flow rate was adjusted to 30 psi. Injection volumes were 0.1 pL for partsper-million levels and 0.5 pL for parts-per-billion levels utilizing a 1-pL syringe. The splitter was operated at a ratio of 101. The integrator chart speed was 0.5 cm/min. The injector temperature was set at 250 "C. The electron capture detector was operated at 350 "C. The oven temperature was programmed from 50 "C to 135 "C at a rate of 7 deg/minute. For representative chromatograms, see Figures 2 and 3.
RESULTS AND DISCUSSION For generating parts-per-million levels of 1,3-dichloropropene, cis-1,2,3-trichloropropene,trans-1,2,3-trichloropropene, 1,1,2,3-tetrachloropropene, 2,3,3-trichloro-2propen-1-01, and 1,1,2,2,3-pentachloropropaneduring validation, the Analytical Instruments Development, Inc. (AID), Model 350 standards generator worked very well. Early attempts at generating dynamic test atmospheres via injection into a mixing bulb/glass tube apparatus at ambient air temperatures were not successful due to insufficient vaporization. The compounds tended not to completely vaporize and therefore they were not fully dispersed into the air stream. The AID Model 350 features a chamber which can be held at a constant elevated temperature in order to raise the vapor pressure of the compound of interest. Because these compounds have generally low ambient vapor pressures, the use of a heated, constant temperature chamber was found to be necessary. Three chamber temperature settings (30 "C, 50 "C, and 70 "C) were available for use and temperature choice was made under consideration of production of a suitable rate of vaporization and avoidance of possible decomposition of standards as evidenced by discoloration. Because slow discoloration over time of the three lower boiling chloropropenes occurred a t the 70 "C setting, the standards generator was operated a t 50 "C for 1,3-dichloropropene, cis-1,2,3-trichloropropene, and trans-1,2,3-trichloropropene. For 1,1,2,3-tetrachloropropene, 2,3,3-trichloro-2-propen-l-ol, and 1,1,2,2,3-pentachloropropane, the standards generator was operated at 70 "C. At concentration levels of 1and 10 ppb, a convenient method for spiking the collection tubes was found to be via a flash loading technique utilizing the injection port of a Varian 3700 GC. The production of specific parts-per-billion levels in the
ANALYTICAL CHEMISTRY, VOL. 56, NO. 12, OCTOBER 1984
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Table I. Results for Validation of Chloropropenes/anes at Parts-per-Million Levelsa 1,3-dichloropropene mean recovery CV rangeb ppm rangec
R2 total no. of samples'
100%
0.01-0.035 0.4-4.0 0.996 39
trans-1,2,3trichloropropene
cis-1,2,3trichloropropene
1,1,2,3-tetrachloropropene
102% 0.023-0.044 0.5-5.0 0.995 39
99 % 0.022-0.047 0.5-3.0 0.995 39
100% 0.032-0.072 0.5-6.0 0.989 34
2,3,3-trichloro-2propen-1-01
1,1,2,2,3-penta. chloropropane
88% 0.062-0.10 0.5-3.0 0.983 34
97 % 0.027-0.062 0.5-5.0 0.985 34
"Lab validation was done with a dynamic standards generator. "he range of coefficients of variation for all concentration levels. cEach chloropropene/ane was validated at five different concentration levels in air in the range indicated. dThe proportion of variation in the calculated air concentration that was accounted for by the relationship between calculated and measured air concentration expressed in a regression line. eAt each concentration level, at least six and not more than eight validation samples were taken. Table 11. Results for Validation of Chloropropenes/anes at Parts-per-Billion Levelsa
recovery at 1 ppb recovery at 10 ppb CVb at 1 ppb CVb at 10 ppb
trans-1,2,3trichloropropene
cis-1,2,3trichloropropene
1,1,2,3-tetrachloropropene
2,3,3-trichloro-2propen-1-01
1,1,2,2,3-pentachloropropane
116% 106% 0.037 0.038
110%
105% 0.029 0.034
110% 103% 0.025 0.024
106% 100% 0.038 0.034
106% 103% 0.0045 0.039
Lab validation was done using the injection port loading method. bCoefficientof variation. Eight validation samples were taken per level. desired range by the AID generator could not be accomplished with more than one compound a t a time. The flash loading procedure facilitated control of concentrations by simply making solutions of known concentrations of the materials of interest. In addition, synergistic effects a t very low levels could be assessed. Assessing the capacity of the Tenax-GC and simulation of a real world situation was accomplished by pulling 10-L of air through the tube after injection port loading. Validation of the method at parts-per-billion levels was facilitated by using the flash loading procedure. Tenax collection tubes were designed in such a manner as to both accommodate a large volume of Tenax and be inserted into a gas chromatograph injection port for the purpose of flash loading. Because dichloropropene and pentachloropropane were not retained on Tenax as well as the other chloropropenes, a large volume of Tenax was needed to bring breakthrough down to a minimum. Because of this large volume requirement, a tube with a large inside diameter was needed. On the other hand, a smaller diameter tube was needed for the purpose of using the injection port loading method when validating at parts-per-billion levels or when spiking the sampling tubes. The result was a sampling tube made by joining two tubes of different inside diameters. Validation. The method was laboratory validated by generating at least six samples at each of six levels in the range 1ppb to 6 ppm for a 20-L air sample. The results are summarized in Tables I and 11. Overall average recoveries were 98% a t the parts-per-million level and 106% at the partsper-billion level. When the Analytical Instruments Development, Inc., standards generator was used, recoveries were determined from diffusion rates of diffusion tubes. Coefficients of variation or relative standard deviations for the method ranged between 0.03 and 0.09. Recoveries of chloropropenes/anes a t parts-per-billion levels were generally above 100% probably because quantitation became more difficult at levels near the limit of detection. 1,3-Dichloropropene was not validated in the 1-10 ppb range because of an interference found in the chromatograms at the same retention time. This interfering response was found in the blank samples and is caused by the isooctane desorbing solution. This interference was found to affect quantitation only at levels below 0.5 ppm (see Figures 2 and 3).
Flgure 2. Capillary gas chromatogram for injection of 0.1 pL of a solution containing 9.08 pQ/mLof 1,Wichloropropene (a), 11.90 pg/mL trans-l,2,3-trichloropropene (b), 11.90 pg/mL cis-1,2,3-trichloropropene (c), 14.71 pg/mL 1,1,2,3-tetrachloropropene(d), 13.37 pg/mL 2,3,3-trichloro-2-propen-l-ol (e), 17.70 pg/mL l11,2,2,3-pentachloropropane (f), and 4.0 pg/mL trlbromobenzene (g), internal standard (equivalent to a 10-L air sample containing 1 ppm of each chloropropendane). I
I
c
f
Figure 3. Caplllary gas chromatogram for injection of 0.5 pL of a solution Containing 0.11 9 pg/mL trans-l,2,3-trlchloropropene (a), 0.11 9 pg/mL cis-l,2,3-trichloropropene (b), 0.147 pglmL 1,1,2,3-tetrachloropropene (c), 0.134 pg/mL 2,3,3-trlchloro-2-propen-l-ol (d), 0.17 pg/mL lI1,2,2,3-pentachloropropane (e), and 4.0 pglmL tribromobenzene (f), internal standard (equivalent to a 10-L air sample containing 10 ppb of each chloropropenelane). The first several peaks arise from the isooctane desorbing solution.
ANALYTICAL CHEMISTRY, VOL. 56, NO. 12, OCTOBER 1984
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Table 111. Results for High Humidity Study“
mean recovery no. of samples
cv
1,3-dichloropropene
trans-1,2,3-
cis-1,2,3-
1,1,2,3-tetra-
2,3,3-trichloro-2-
trichloropropene
trichloropropene
chloropropene
propen-1-01
1,1,2,2,3-pentachloropropane
93 % 7 0.051
101% 7 0.068
100% 7 0.054
110% 6 0.079
92% 6 0.080
93 % 6 0.044
High humidity studies were done at 96.5% relative humidity. Concentration was 1 ppm in air. Table IV. Results for Five-Day Storage Study 1,3-dichloropropene ppm level recovery
no. of samples
cv
2.0 104% 6
0.072
trans-1,2,3trichloropropene 3.0 105% 6 0.048
1,1,2,3-tetrachloropropene
2,3,3-trichloro-2-
trichloropropene 1.5 101% 6 0.047
2.0 84.6% 5 0.046
1.0 83% 5 0.072
cis-1,2,3-
The backup sections of all validation samples were analyzed as well and some dichloropropene and some pentachloropropane were found in the backup sections. For pentachloropropane, in the range between 1.6 and 5 ppm, the amount found in the backup section was between 9% and 17% of the total. For dichloropropene, in the range between 1.6 and 4.4 ppm., the amount found in the backup section was between 6% and 23% of the total. Because some of the dichloropropene and pentachloropropane was found in the backup section, it was necessary to use the full 200 mg of Tenax-GC for efficient collection of all six compounds. Humidity Studies. For solid sorbents, increased humidity often results in an increase in breakthrough; Le., the water competes with active sites. Although Tenax-GC is known to be hydrophobic (3),two of the compounds were affected by an increase in humidity. Under conditions of high humidity, (96.5% relative humidity) the amount found in the backup was 21 % and the section for 1,1,2,2,3-pentachloropropane amount found in the backup section for 1,3-dichloropropene was 50%. Although this is a significant percentage, total recovery was still good (93% for both). High humidity did not affect the other chloropropenes significantly (see Table 111). Breakthrough of 1,3-dichloropropeneto the backup section could be caused by the greater volatility of 1,3-dichloropropene relative to the other chloropropenes. 1,1,2,2,3-Pentachloropropane is not as well retained because of its lack of a double bond. Storage Effects. Since immediate desorption or analysis of desorbed solutions is not always possible, definition of the effect of storage was necessary. For storage studies, tubes were loaded with chloropropenes/anes collected from the standards generator and then were desorbed after 5 days of storage. Five day storage caused some migration to the backup section for 1,3-dichloropropene (30%) and for 1,1,2,2,3-pentachloropropane (13%). Total recovery was not significantly affected for either and 5-day storage did not affect recovery of the other chloropropenes. See Table IV for details. Field Tests. The performance of this method was evaluated at an industrial location where chloropropenes and chloropropanes are associated with the manufacture of triallate. Approximately 75 samples were taken including blank and spiked samples. Spiked samples, at 10 ppb, 100 ppb, and 1 ppm, were made by using the injection port loading procedure mentioned previously. The average recovery for trans-1,2,3-trichloropropene at the 10 ppb level was 81% and all other average recoveries were above 90%. It was determined during field testing that air must be pulled through
propen-1-01
1,1,2,2,3-pentachloropropane 2.0 103% 5 0.028
spiked sampling tubes immediately after spiking. Otherwise, the chloropropenes/anes are not sufficiently adsorbed onto the Tenax. No problems with the method were found during field testing.
CONCLUSION The use of Tenax-GC as an adsorbent, coupled with capillary GC separation and electron capture detection is a powerful method for the selective quantitation of 1,3-di1,1,2,3chloropropene, cis- and trans-1,2,3-trichloropropene, tetrachloropropene, 2,3,3-trichloro-2-propen-l-ol, and 1,1,2,2,3-pentachloropropanein air. Because of the affinity of Tenax-GC for a variety of unsaturated and chlorinated organic compounds, it is likely that this method could be extended to a variety of other materials.
ACKNOWLEDGMENT Preliminary development work on this project was done by J. D. Fuhrman and B. V. Owens. Helpful suggestions were supplied by R. K. Beasley. Registry No. 1,3-Dichloropropene, 542-75-6; cis-1,2,3-trichloropropene, 13116-57-9;trans-1,2,3-trichloropropene, 1311658-0; 1,1,2,3-tetrachloropropene,10436-39-2; 2,3,3-trichloro-2propen-l-ol,3266-39-5;1,1,2,2,3-pentachloropropane, 16714-68-4; Tenax-GC, 24938-68-9.
LITERATURE CITED (1) Sakodynskli, K.; Panlna, L.; Klinskaya, N. Chromatographia 1979, 7, 339-344. (2) Brown, R. H.; Purnell, C. J. J. Chromatogr. 1978, 778, 79-90. (3) Billings, W. N.; Bldleman, T. F. Environ. Sci. Techno/., 1980, 14, 679-683. (4) Stampfer, J. F.; Hermes, R. E. Am. Ind. Hyg. Assoc. J . 1981, 42, 699-706. (5) Bishop, R. W.; Ayers, T. A.; Rinehart, D. S. Am. Ind. Hyg. Assoc. J. 1981, 42, 586-589. (6) Kawata, K.; Vemura, T.; KlFune, I.; Tomlnaga, Y.; Oikawa, K. Bunseki Kagaku 1982, 31 453-457. (7) Krost, K. J.; Pellizzarl, E. D.; Walburn, S. G.; Hubbard, S. A. Anal. Chem. 1082, 54, 810-817. (8) Pellizzarl, E. D. Environ. Scl. Techno/. 1982, 76, 781-785. (9) Matienzo, L. J.; Hensler, C. J. Am. rnd. Hyg. Assoc. J . 1982, 4 3 , 838-844. (10) Hanson, R. L.; Clark, C. R.; Carpenter, R. L.; Hobbs, C. H. Environ. Sci. Techno/. 1983, 17, 701-705. (11) Elceman, G. A.; Karasek, F. W. J. Chromatogr. 1980, 200, 115-124. (12) Langvandt, P. W.; Nestrick, T. J.; Hermann, E. A.; Braun, W, H. J. Chromatogr. 1978, 153, 433-477. (13) Langhorst, M. L.; Melcher, R. G.; Kallos, G. L. Am. Ind. Hyg. Assoc. J. 1981, 42, 47-55. (14) Lewis, R. G.; MacLeod, K. E. Anal. Chem. 1982, 5 4 , 310-315. (15) Eklund, G.; Josefsson, 6 . ;Roos, C. M. “Recent Advances in Capillary Gas Chromatography”; Bertsch, W., Jennings, W. G., Kaiser, R. E., Eds.; Verlag: Heidelberg; 1981; pp 533-550. ~
RECEIVED for review March 7, 1983. Accepted May 21, 1984.
