Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-62 - General occupational health standards › Part G - CARCINOGENS (SPECIFIC) › Section 296-62-07389 - Appendix D - Sampling and analytical methods for ethylene oxide (nonmandatory)

Current through Register Vol. 24-14, July 15, 2024
(1) A
				number of methods are available for monitoring employee exposures to EtO. Most
				of these involve the use of charcoal tubes and sampling pumps, followed by
				analysis of the samples by gas chromatograph. The essential differences between
				the charcoal tube methods include, among others, the use of different desorbing
				solvents, the use of different lots of charcoal, and the use of different
				equipment for analysis of the samples. Besides charcoal, methods using passive
				dosimeters, gas sampling bags, impingers, and detector tubes have been utilized
				for determination of EtO exposure. In addition, there are several commercially
				available portable gas analyzers and monitoring units. This appendix contains
				details for the method which has been tested at the OSHA Analytical Laboratory
				in Salt Lake City. Inclusion of this method in the appendix does not mean that
				this method is the only one which will be satisfactory. Copies of descriptions
				of other methods available are available in the rulemaking record, and may be
				obtained from the OSHA Docket Office. These include the Union Carbide, Dow
				Chemical, 3M, and DuPont methods, as well as NIOSH Method S-286. These methods
				are briefly described at the end of this appendix.
(2) Employers who note problems with sample
				breakthrough using the OSHA or other charcoal methods should try larger
				charcoal tubes. Tubes of larger capacity are available. In addition, lower flow
				rates and shorter sampling times should be beneficial in minimizing
				breakthrough problems. Whatever method the employer chooses, he/she must assure
				himself/herself of the method's accuracy and precision under the unique
				conditions present in his workplace.
(3) Ethylene oxide:
(a) Method No.: 30.
(b) Matrix: Air.
(i) Target concentration: 1.0 ppm (1.8
				mg/m3)
(ii) Procedure: Samples are collected on two
				charcoal tubes in series and desorbed with 1% CS2 in
				benzene. The samples are derivatized with HBr and treated with sodium
				carbonate. Analysis is done by gas chromatography with an electron capture
				detector.
(iii) Recommended air
				volume and sampling rate: 1 liter and 0.05 Lpm.
(iv) Detection limit of the overall
				procedure: 13.3 ppb (0.024 mg/m3) (based on 1.0
				liter air sample).
(v) Reliable
				quantitation limit: 52.2 ppb (0.094 mg/m3) (based on
				1.0 liter air sample).
(vi)
				Standard error of estimate: 6.59% (see backup section 4.6 ).
(vii) Special requirements: Samples must be
				analyzed within fifteen days of sampling date.
(viii) Status of method: The sampling and
				analytical method has been subject to the established evaluation procedures of
				the Organic Method Evaluations Branch.
(c) Date: August 1981.
(d) Chemist: Wayne D. Potter
(e) Organic Solvents Branch, OSHA Analytical
				Laboratory, Salt Lake City, Utah
(f) General discussion:
(i) Background.
(A) History of procedure.
(I) Ethylene oxide samples analyzed at the
				OSHA laboratory have normally been collected on activated charcoal and desorbed
				with carbon disulfide. The analysis is performed with a gas chromatograph
				equipped with a FID (flame ionization detector) as described in NIOSH Method
				S286 (Ref. (3)(j)(i)). This method is based on a PEL of 50 ppm and has a
				detection limit of about 1 ppm.
(II) Recent studies have prompted the need
				for a method to analyze and detect ethylene oxide at very low
				concentrations.
(III) Several
				attempts were made to form an ultraviolet (UV) sensitive derivative with
				ethylene oxide for analysis with HPLC. Among those tested that gave no
				detectable product were: p-anisidine, methylimidazole, aniline, and
				2,3,6-trichlorobenzoic acid. Each was tested with catalysts such as
				triethylamine, aluminum chloride, methylene chloride and sulfuric acid but no
				detectable derivative was produced.
(IV) The next derivatization attempt was to
				react ethylene oxide with HBr to form 2-bromoethanol. This reaction was
				successful. An ECD (electron capture detector) gave a very good response for
				2-bromoethanol due to the presence of bromine. The use of carbon disulfide as
				the desorbing solvent gave too large a response and masked the 2-bromoethanol.
				Several other solvents were tested for both their response on the ECD and their
				ability to desorb ethylene oxide from the charcoal. Among those tested were
				toluene, xylene, ethyl benzene, hexane, cyclohexane and benzene. Benzene was
				the only solvent tested that gave a suitable response on the ECD and a high
				desorption. It was found that the desorption efficiency was improved by using
				1% CS2 with the benzene. The carbon disulfide did not
				significantly improve the recovery with the other solvents. SKC Lot 120 was
				used in all tests done with activated charcoal.
(B) Physical properties (Ref. (3)(j)(ii) -
				(iv)):
(I) Synonyms: Oxirane; dimethylene
				oxide; 1,2-epoxy-ethane; oxane;
				C2H4O; ETO;
(II) Molecular weight: 44.06;
(III) Boiling point: 10.7°C
				(51.3°);
(IV) Melting point: --
				111°C;
(V) Description:
				Colorless, flammable gas;
(VI)
				Vapor pressure: 1095 mm. at 20°C;
(VII) Odor: Ether-like odor;
(VIII) Lower explosive limits: 3.0% (by
				volume);
(IX) Flash point (TOC):
				Below 0°F;
(X) Molecular
				structure: CH2 --
				CH2;
(ii) Limit defining parameters:
(A) Detection limit of the analytical
				procedure. The detection limit of the analytical procedure is 12.0 picograms of
				ethylene oxide per injection. This is the amount of analyte which will give a
				peak whose height is five times the height of the baseline noise. (See backup
				data section (3)(i)(i).)
(B)
				Detection limit of the overall procedure.
(I)
				The detection limit of the overall procedure is 24.0 ng of ethylene oxide per
				sample.
(II) This is the amount of
				analyte spiked on the sampling device which allows recovery of an amount of
				analyte equivalent to the detection limit of the analytical procedure. (See
				backup data section (3)(i)(ii).)
(C) Reliable quantitation limit.
(I) The reliable quantitation limit is 94.0
				nanograms of ethylene oxide per sample. This is the smallest amount of analyte
				which can be quantitated within the requirements of 75% recovery and 95%
				confidence limits. (See backup data section (3)(i)(ii).)
(II) It must be recognized that the reliable
				quantitation limit and detection limits reported in the method are based upon
				optimization of the instrument for the smallest possible amount of analyte.
				When the target concentration of an analyte is exceptionally higher than these
				limits, they may not be attainable at the routine operating parameters. In this
				case, the limits reported on analysis reports will be based on the operating
				parameters used during the analysis of the samples.
(D) Sensitivity.
(I) The sensitivity of the analytical
				procedure over a concentration range representing 0.5 to 2 times the target
				concentration based on the recommended air volume is 34105 area units per
				ug/mL. The sensitivity is determined by the slope of the calibration curve (see
				backup data section (3)(i)(iii)).
(II) The sensitivity will vary somewhat with
				the particular instrument used in the analysis.
(E) Recovery. The recovery of analyte from
				the collection medium must be 75% or greater. The average recovery from spiked
				samples over the range of 0.5 to 2 times the target concentration is 88.0% (see
				backup section (3)(i)(iv)). At lower concentrations the recovery appears to be
				nonlinear.
(F) Precision
				(analytical method only). The pooled coefficient of variation obtained from
				replicate determination of analytical standards at 0.5X, 1X and 2X the target
				concentration is 0.036 (see backup data section (3)(i)(v)).
(G) Precision (overall procedure).
(I) The overall procedure must provide
				results at the target concentration that are 25% or better at the 95%
				confidence level. The precision at the 95% confidence level for the fifteen day
				storage test is plus or minus 12.9% (see backup data section
				(3)(i)(vi)).
(II) This includes an
				additional plus or minus 5% for sampling error.
(iii) Advantages.
(A) The sampling procedure is
				convenient.
(B) The analytical
				procedure is very sensitive and reproducible.
(C) Reanalysis of samples is
				possible.
(D) Samples are stable
				for at least fifteen days at room temperature.
(E) Interferences are reduced by the longer
				GC retention time of the new derivative.
(iv) Disadvantages.
(A) Two tubes in series must be used because
				of possible breakthrough and migration.
(B) The precision of the sampling rate may be
				limited by the reproducibility of the pressure drop across the tubes. The pumps
				are usually calibrated for one tube only.
(C) The use of benzene as the desorption
				solvent increases the hazards of analysis because of the potential carcinogenic
				effects of benzene.
(D) After
				repeated injections there can be a buildup of residue formed on the electron
				capture detector which decreases sensitivity.
(E) Recovery from the charcoal tubes appears
				to be nonlinear at low concentrations.
(g) Sampling procedure.
(i) Apparatus.
(A) A calibrated personal sampling pump whose
				flow can be determined within plus or minus 5% of the recommended
				flow.
(B) SKC Lot 120 Charcoal
				tubes: Glass tube with both ends flame sealed, 7 cm long with a 6 mm O.D. and a
				4-mm I.D., containing 2 sections of coconut shell charcoal separated by a 2-mm
				portion of urethane foam. The adsorbing section contains 100 mg of charcoal,
				the backup section 50 mg. A 3-mm portion of urethane foam is placed between the
				outlet end of the tube and the backup section. A plug of silylated glass wool
				is placed in front of the adsorbing section.
(ii) Reagents.
None required.
(iii) Sampling technique.
(A) Immediately before sampling, break the
				ends of the charcoal tubes. All tubes must be from the same lot.
(B) Connect two tubes in series to the
				sampling pump with a short section of flexible tubing. A minimum amount of
				tubing is used to connect the two sampling tubes together. The tube closer to
				the pump is used as a backup. This tube should be identified as the backup
				tube.
(C) The tubes should be
				placed in a vertical position during sampling to minimize channeling.
(D) Air being sampled should not pass through
				any hose or tubing before entering the charcoal tubes.
(E) Seal the charcoal tubes with plastic caps
				immediately after sampling. Also, seal each sample with OSHA seals
				lengthwise.
(F) With each batch of
				samples, submit at least one blank tube from the same lot used for samples.
				This tube should be subjected to exactly the same handling as the samples
				(break, seal, transport) except that no air is drawn through it.
(G) Transport the samples (and corresponding
				paperwork) to the lab for analysis.
(H) If bulk samples are submitted for
				analysis, they should be transported in glass containers with Teflon-lined
				caps. These samples must be mailed separately from the container used for the
				charcoal tubes.
(iv)
				Breakthrough.
The breakthrough (5% breakthrough) volume for a 3.0
				  mg/m3 ethylene oxide sample stream at approximately
				  85% relative humidity, 22°C and 633 mm is 2.6 liters sampled at 0.05 liters
				  per minute. This is equivalent to 7.8 µg of ethylene oxide. Upon
				  saturation of the tube it appeared that the water may be displacing ethylene
				  oxide during sampling.
(v)
				Desorption efficiency.
(A) The desorption
				efficiency, from liquid injection onto charcoal tubes, averaged 88.0% from 0.5
				to 2.0 x the target concentration for a 1.0 liter air sample. At lower ranges
				it appears that the desorption efficiency is nonlinear (see backup data section
				(3)(i)(ii)).
(B) The desorption
				efficiency may vary from one laboratory to another and also from one lot of
				charcoal to another. Thus, it is necessary to determine the desorption
				efficiency for a particular lot of charcoal.
(vi) Recommended air volume and sampling
				rate.
(A) The recommended air volume is 1.0
				liter.
(B) The recommended maximum
				sampling rate is 0.05 Lpm.
(vii) Interferences.
(A) Ethylene glycol and Freon 12 at target
				concentration levels did not interfere with the collection of ethylene
				oxide.
(B) Suspected interferences
				should be listed on the sample data sheets.
(C) The relative humidity may affect the
				sampling procedure.
(viii) Safety precautions.
(A) Attach the sampling equipment to the
				employee so that it does not interfere with work performance.
(B) Wear safety glasses when breaking the
				ends of the sampling tubes.
(C) If
				possible, place the sampling tubes in a holder so the sharp end is not exposed
				while sampling.
(h) Analytical method.
(i) Apparatus.
(A) Gas chromatograph equipped with a
				linearized electron capture detector.
(B) GC column capable of separating the
				derivative of ethylene oxide (2-bromoethanol) from any interferences and the 1%
				CS2 in benzene solvent. The column used for validation
				studies was: 10 ft x 1/8 inch stainless steel 20% SP-2100, .1% Carbowax 1500 on
				100/120 Supelcoport.
(C) An
				electronic integrator or some other suitable method of measuring peak
				areas.
(D) Two milliliter vials
				with Teflon-lined caps.
(E) Gas
				tight syringe -- 500 µL or other convenient sizes for preparing
				standards.
(F) Microliter syringes
				-- 10 µL or other convenient sizes for diluting standards and 1 µL
				for sample injections.
(G) Pipets
				for dispensing the 1% CS2 in benzene solvent. The Glenco
				1 mL dispenser is adequate and convenient.
(H) Volumetric flasks -- 5 mL and other
				convenient sizes for preparing standards.
(I) Disposable Pasteur pipets.
(ii) Reagents.
(A) Benzene, reagent grade.
(B) Carbon disulfide, reagent
				grade.
(C) Ethylene oxide, 99.7%
				pure.
(D) Hydrobromic acid, 48%
				reagent grade.
(E) Sodium
				carbonate, anhydrous, reagent grade.
(F) Desorbing reagent, 99% Benzene/1%
				CS2.
(iii) Sample preparation.
(A) The front and back sections of each
				sample are transferred to separate 2-mL vials.
(B) Each sample is desorbed with 1.0 mL of
				desorbing reagent.
(C) The vials
				are sealed immediately and allowed to desorb for one hour with occasional
				shaking.
(D) Desorbing reagent is
				drawn off the charcoal with a disposable pipet and put into clean 2-mL
				vials.
(E) One drop of HBr is added
				to each vial. Vials are resealed and HBr is mixed well with the desorbing
				reagent.
(F) About 0.15 gram of
				sodium carbonate is carefully added to each vial. Vials are again resealed and
				mixed well.
(iv)
				Standard preparation.
(A) Standards are
				prepared by injecting the pure ethylene oxide gas into the desorbing
				reagent.
(B) A range of standards
				are prepared to make a calibration curve. A concentration of 1.0 µL of
				ethylene oxide gas per 1 mL desorbing reagent is equivalent to 1.0 ppm air
				concentration (all gas volumes at 25°C and 760 mm) for the recommended 1
				liter air sample. This amount is uncorrected for desorption efficiency (see
				backup data section (3)(i)(ii), for desorption efficiency
				corrections).
(C) One drop of HBr
				per mL of standard is added and mixed well.
(D) About 0.15 grams of sodium carbonate is
				carefully added for each drop of HBr (a small reaction will occur).
(v) Analysis.
(A) GC conditions.
Nitrogen flow rate -- 10mL/min.
Injector temperature -- 250°C
Detector temperature -- 300°C
Column temperature -- 100°C
Injection size -- 0.8 µL
Elution time -- 3.9 minutes
(B) Peak areas are measured by an integrator
				or other suitable means.
(C) The
				integrator results are in area units and a calibration curve is set up with
				concentration vs. area units.
(vi) Interferences.
(A) Any compound having the same retention
				time of 2-bromoethanol is a potential interference. Possible interferences
				should be listed on the sample data sheets.
(B) GC parameters may be changed to
				circumvent interferences.
(C) There
				are usually trace contaminants in benzene.
These contaminants, however, posed no problem of
				  interference.
(D) Retention
				time date on a single column is not considered proof of chemical identity.
				Samples over the 1.0 ppm target level should be confirmed by GC/Mass Spec or
				other suitable means.
(vii) Calculations.
(A) The concentration in µg/mL for a
				sample is determined by comparing the area of a particular sample to the
				calibration curve, which has been prepared from analytical standards.
(B) The amount of analyte in each sample is
				corrected for desorption efficiency by use of a desorption curve.
(C) Analytical results, A, from the two tubes
				that compose a particular air sample are added together.
(D) The concentration for a sample is
				calculated by the following equation:
ETO, mg/m3
=
AXB
C
where:
A
=
MICROg/mL
B
=
desorption volume in milliliters
C
=
air volume in liters.
(E)
				To convert mg/m3 to parts per million (ppm) the
				following relationship is used:
ETO, ppm
=
mg/m3 x 24.45
44.05
where:
mg/m3
=
results from 3.7.4
24.45
=
molar volume at 25°C and 760 mm Hg
44.05
=
air volume in liters.
(viii) Safety precaution
(A) Ethylene oxide and benzene are potential
				carcinogens and care must be exercised when working with these
				compounds.
(B) All work done with
				the solvents (preparation of standards, desorption of samples, etc.) should be
				done in a hood.
(C) Avoid any skin
				contact with all of the solvents.
(D) Wear safety glasses at all
				times.
(E) Avoid skin contact with
				HBr because it is highly toxic and a strong irritant to eyes and
				skin.
(i)
				Backup data.
(i) Detection limit data.
The detection limit was determined by injecting 0.8 µL
				  of a 0.015 µg/mL standard of ethylene oxide into 1% CS2 in benzene. The
				  detection limit of the analytical procedure is taken to be 1.20 x
				  10-5
												µg per injection. This is equivalent to
				  8.3 ppb (0.015 mg/m3) for the recommended air
				  volume.
(ii) Desorption
				efficiency. Ethylene oxide was spiked into charcoal tubes and the following
				recovery data was obtained:
Amount
spiked (MICROg)
Amount recovered (MICROg)
Percent
recovery
4.5
4.32
96.0
3.0
2.61
87.0
2.25
2.025
90.0
1.5
1.365
91.0
1.5
1.38
92.0
.75
6525
87.0
.375
.315
84.0
.375
.312
83.2
.1875
.151
80.5
.094
.070
74.5
Note:
At lower amounts the recovery appears to be
								nonlinear.
(iii) Sensitivity data. The following data
				was used to determine the calibration curve:
Injection
0.5 x .75
MICROg/mL
1 x 1.5
MICROg/mL
2 x 3.0
MICROg/mL
1. . . . . . . . . .
30904
59567
111778
2. . . . . . . . . .
30987
62914
106016
3. . . . . . . . . .
32555
58578
106122
4. . . . . . . . . .
32242
57173
109716
X. . . . . . . . . .
31672
59558
108408
Slope = 34.105.
(iv) Recovery. The recovery was determined by
				spiking ethylene oxide onto lot 120 charcoal tubes and desorbing with 1%
				CS2 in Benzene. Recoveries were done at 0.5, 1.0, and
				2.0 X the target concentration (1 ppm) for the recommended air volume.
Percent Recovery
Sample
0.5x
1.0x
2.0x
1. . . . . . . . . .
88.7
95.0
91.7
2. . . . . . . . . .
83.8
95.0
87.3
3. . . . . . . . . .
84.2
91.0
86.0
4. . . . . . . . . .
88.0
91.0
83.0
5. . . . . . . . . .
88.0
86.0
85.0
X. . . . . . . . . .
86.5
90.5
87.0
Weighted average = 88.2
(v) Precision of the analytical procedure.
				The following data was used to determine the precision of the analytical
				method:
Concentration
0.5 x .75
MICROg/mL
1 x 1.5
MICROg/mL
2 x 3.0
MICROg/mL
Injection
.7421
.7441
.7831
.7753
.7612
1.4899
1.5826
1.4628
1.4244
1.4899
3.1184
3.0447
2.9149
2.9185
2.9991
Average Standard Deviation
.0211
.0674
.0998
CV. . . . . . . .
.0277
.0452
.0333
CV
=
3(.0277)2  + 3
								(.0452)2 + 3
								(.0333)2
3 + 3 + 3
CV + 0.036
(vi)
				Storage data. Samples were generated at 1.5 mg/m3 ethylene oxide at 85%
				relative humidity, 22°C and 633 mm. All samples were taken for twenty
				minutes at 0.05 Lpm. Six samples were analyzed as soon as possible and fifteen
				samples were stored at refrigerated temperature (5°C) and fifteen samples
				were stored at ambient temperature (23°C). These stored samples were
				analyzed over a period of nineteen days.
Percent Recovery
Day analyzed
Refrigerated
Ambient
1. . . . . . . . . . . .
87.0
87.0
1. . . . . . . . . . . .
93.0
93.0
1. . . . . . . . . . . .
94.0
94.0
1. . . . . . . . . . . .
92.0
92.0
4. . . . . . . . . . . .
92.0
91.0
4. . . . . . . . . . . .
93.0
88.0
4. . . . . . . . . . . .
91.0
89.0
6. . . . . . . . . . . .
92.0
6. . . . . . . . . . . .
92.0
8. . . . . . . . . . . .
92.0
8. . . . . . . . . . . .
86.0
10. . . . . . . . . . .
91.7
10. . . . . . . . . . .
95.5
10. . . . . . . . . . .
95.7
11. . . . . . . . . . .
90.0
11. . . . . . . . . . .
82.0
13. . . . . . . . . . .
78.0
13. . . . . . . . . . .
81.4
13. . . . . . . . . . .
82.4
14. . . . . . . . . . .
78.5
14. . . . . . . . . . .
72.1
18. . . . . . . . . . .
66.0
18. . . . . . . . . . .
68.0
19. . . . . . . . . . .
64.0
19. . . . . . . . . . .
77.0
(vii) Breakthrough data.
(A) Breakthrough studies were done at 2 ppm
				(3.6 mg/m3) at approximately 85% relative humidity
				at 22°C (ambient temperature). Two charcoal tubes were used in series. The
				backup tube was changed every ten minutes and analyzed for breakthrough. The
				flow rate was 0.050 Lpm.
Tube No.
Time
(Minutes)
Percent breakthrough
1. . . . . . . . . . . . . . . .
10
(1)
2. . . . . . . . . . . . . . . .
20
(1)
3. . . . . . . . . . . . . . . .
30
(1)
4. . . . . . . . . . . . . . . .
40
1.23
5. . . . . . . . . . . . . . . .
50
3.46
6. . . . . . . . . . . . . . . .
60
18.71
7. . . . . . . . . . . . . . . .
70
39.2
8. . . . . . . . . . . . . . . .
80
53.3
9. . . . . . . . . . . . . . . .
90
72.0
10. . . . . . . . . . . . . . .
100
96.0
11. . . . . . . . . . . . . . .
110
113.0
12. . . . . . . . . . . . . . .
120
133.9
1
None.
(B)
				The 5% breakthrough volume was reached when 2.6 liters of test atmosphere were
				drawn through the charcoal tubes.
(j) References.
(i) "NIOSH Manual of Analytical Methods," 2nd
				ed. NIOSH: Cincinnati, 1977; Method S 286.
(ii) "IARC Monographs on the Evaluation of
				Carcinogenic Risk of Chemicals to Man." International Agency for Research on
				Cancer: Lyon, 1976; Vol. II, p. 157.
(iii) Sax., N.I. "Dangerous Properties of
				Industrial Materials," 4th ed.; Van Nostrand Reinhold Company, New York, 1975;
				p. 741.
(iv) "The Condensed
				Chemical Dictionary," 9th ed.; Hawley, G.G., ed.; Van Nostrand Reinhold
				Company, New York, 1977; p. 361.