California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 7 - General Industry Safety Orders › Group 16 - Control of Hazardous Substances › Article 110 - Regulated Carcinogens › Appendix D - Sampling and Analytical Method for Ethylene Oxide

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
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.
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.
ETHYLENE OXIDE METHOD NO. : 30
Matrix: Air.
Target Concentration: 1.0 ppm (1.8
						  mg/m3).
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.
Recommended Air Volume and Sampling Rate: 1 liter and
						  0.05 Lpm.
Detection Limit of the Overall Procedure: 13.3 ppb
						  (0.024 mg/m3) (Based on 1.0 liter air
						  sample).
Reliable Quantitation Limit: 52.2 ppb (0.094
						  mg/m3) (Based on 1.0 liter air sample).
Standard Error of Estimate: 6.59%.
Special Requirements: Samples must be analyzed within
						  15 days of sampling date.
Status of Method: The sampling and analytical method
						  has been subjected to the established evaluation procedures of the Organic
						  Method Evaluations Branch.
1. General Discussion.
1.1 Background.
1.1.1 History of Procedure.
In studies to develop a method for the analysis of EtO
						  at very low concentrations, it was found that the reaction of EtO with HBr
						  (hydrobromic acid) gave a derivative, 2-bromoethanol, readily detectable by an
						  ECD (electron capture detector) due to the presence of the bromine. Of solvents
						  tested for their response on the ECD and their ability to desorb EtO from the
						  charcoal, benzene was the only solvent tested that gave a suitable response on
						  the ECD and a high desorption. The desorption efficiency was improved by using
						  1% CS2 (carbon disulfide) with the benzene.
1.1.2 Physical Properties.
See Section
						  5220, Appendix B.
1.2 Limit Defining Parameters.
1.2.1 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.
1.2.2 Detection Limit of the Overall Procedure.
The detection limit of the overall procedure is 24.0
						  nanograms of ethylene oxide per sample. 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.
1.2.3 Reliable Quantitation Limit.
The reliable quantitation limit is 94.0 nanograms of
						  ethylene oxide per sample. This is the smallest amount of analyte which can be
						  quantiated within the requirements of 75% recovery and 95% confidence
						  limits.
It must be recognized that the reliable quantitation
						  limit and detection limit 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. The limits reported on analysis reports
						  must be based on the operating parameters used during the analysis of the
						  samples.
1.2.4 Sensitivity.
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 [MICRO]g/mL. The
						  sensitivity is determined by the slope of the calibration curve.
The sensitivity will vary somewhat with the particular
						  instrument used in the analysis.
1.2.5 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%. At lower concentrations the
						  recovery appears to be non-linear.
1.2.6 Precision (Analytical Method Only).
The pooled coefficient of variation obtained from
						  replicate determinations of analytical standards at 0.5X, 1X and 2X the target
						  concentration is 0.036.
1.2.7 Precision (Overall Procedure).
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 15-day storage test is plus or
						  minus 12.9%.
This includes an additional plus or minus 5% for
						  sampling error.
1.3 Advantages.
1.3.1 The sampling procedure is convenient.
1.3.2 The analytical procedure is very sensitive and
						  reproducible.
1.3.3 Reanalysis of samples is possible.
1.3.4 Samples are stable for at least 15 days at room
						  temperature.
1.3.5 Interferences are reduced by the long GC
						  retention time of the derivative.
1.4 Disadvantages.
1.4.1 Two tubes in series must be used because of
						  possible breakthrough and migration.
1.4.2 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.
1.4.3 The use of benzene as the desorption solvent
						  increases the hazards of analysis because of the potential carcinogenic effects
						  of benzene.
1.4.4 After repeated injections there can be a buildup
						  of residue formed on the electron capture detector which decreases
						  sensitivity.
1.4.5 Recovery from the charcoal tubes appears to be
						  nonlinear at low concentrations.
2. Sampling Procedure.
2.1 Apparatus.
2.1.1 A calibrated personal sampling pump whose flow
						  can be determined within plus or minus 5% of the recommended flow.
2.1.2 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 3-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.
2.2 Reagents.
2.2.1 None required.
2.3 Sampling Technique.
2.3.1 Immediately before sampling, break the ends of
						  the charcoal tubes. All tubes must be from the same lot.
2.3.2 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.
2.3.3 The tubes should be placed in a vertical position
						  during sampling to minimize channeling.
2.3.4 Air being sampled should not pass through any
						  hose or tubing before entering the charcoal tubes.
2.3.5 Seal the charcoal tubes with plastic caps
						  immediately after sampling. Also, seal each sample with OSHA seals
						  lengthwise.
2.3.6 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.
2.3.7 Transport the samples (and corresponding
						  paperwork) to the lab for analysis.
2.3.8 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.
2.4 Breakthrough.
2.4.1 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 [MICRO]g of ethylene
						  oxide. Upon saturation of the tube it appeared that the water may be displacing
						  ethylene oxide during sampling.
2.5 Desorption Efficiency.
2.5.1 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 non-linear.
2.5.2 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.
2.6 Recommended Air Volume and Sampling Rate.
2.6.1 The recommended air volume is 1.0 liter.
2.6.2 The recommended maximum sampling rate is 0.05
						  Lpm.
2.7 Interferences.
2.7.1 Ethylene glycol and Freon 12 at target
						  concentration levels did not interfere with the collection of ethylene
						  oxide.
2.7.2 Suspected interferences should be listed on the
						  sample data sheets.
2.7.3 The relative humidity may affect the sampling
						  procedure.
2.8 Safety Precautions.
2.8.1 Attach the sampling equipment to the employee so
						  that it does not interfere with work performance.
2.8.2 Wear safety glasses when breaking the ends of the
						  sampling tubes.
2.8.3 If possible, place the sampling tubes in a holder
						  so the sharp end is not exposed while sampling.
3. Analytical Method.
3.1 Apparatus.
3.1.1 Gas chromatograph equipped with a linearized
						  electron capture detector.
3.1.2 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, 0.1% Carbowax 1500
						  on 100/120 Supelcoport.
3.1.3 An electronic integrator or some other suitable
						  method of measuring peak areas.
3.1.4 Two milliliter vials with Teflon-lined
						  caps.
3.1.5 Gas tight syringe--500 L or other convenient
						  sizes for preparing standards.
3.1.6 Microliter syringes--10 L or other convenient
						  size for diluting standards and 1 L for sample injections.
3.1.7 Pipets for dispensing the 1%
						  CS2 in benzene solvent. The Glenco 1 mL dispenser is
						  adequate and convenient.
3.1.8 Volumetric flasks--5 mL and other convenient
						  sizes for preparing standards.
3.1.9 Disposable Pasteur Pipets.
3.2 Reagents.
3.2.1 Benzene, reagent grade.
3.2.2 Carbon disulfide, reagent grade.
3.2.3 Ethylene oxide, 99.7% pure.
3.2.4 Hydrobromic acid, 48% reagent grade.
3.2.5 Sodium carbonate, anhydrous, reagent
						  grade.
3.2.6 Desorbing reagent, 99%
						  benzene/1%CS2.
3.3 Sample Preparation.
3.3.1 The front and back sections of each sample are
						  transferred to separate 2-mL vials.
3.3.2 Each sample is desorbed with 1.0 mL of desorbing
						  reagent.
3.3.3 The vials are sealed immediately and allowed to
						  desorb for one hour with occasional shaking.
3.3.4 Desorbing reagent is drawn off the charcoal with
						  a disposable pipet and put into clean 2-mL vials.
3.3.5 One drop of HBr is added to each vial. Vials are
						  resealed and HBr is mixed well with the desorbing reagent.
3.3.6 About 0.15 gram of sodium carbonate is carefully
						  added to each vial. Vials are again resealed and mixed well.
3.4 Standard Preparation.
3.4.1 Standards are prepared by injecting the pure
						  ethylene oxide gas into the desorbing reagent.
3.4.2 A range of standards are prepared to make a
						  calibration curve. A concentration of 1.0 [MICRO]L 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.
3.4.3 One drop of HBr per mL of standard is added and
						  mixed well.
3.4.4 About 0.15 grams of sodium carbonate is carefully
						  added for each drop of HBr (a small reaction will occur).
3.5 Analysis.
3.5.1 GC Conditions.
Nitrogen flow rate--10mL/min.
Injector Temperature--250°C
Detector Temperature--300°C
Column Temperature--100°C
Injection size--0.8 [MICRO]L
Elution time--3.9 minutes
3.5.2 Peak areas are measured by an integrator or other
						  suitable means.
3.5.3 The integrator results are in area units and a
						  calibration curve is set up with concentration vs. area units.
3.6 Interferences.
3.6.1 Any compound having the same retention time of
						  2-bromoethanol is a potential interference. Possible interferences should be
						  listed on the sample data sheets.
3.6.2 GC parameters may be changed to circumvent
						  interferences.
3.6.3 There are usually trace contaminants in benzene.
						  These contaminants, however, posed no problem of interference.
3.6.4 Retention time data 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.
3.7 Calculations.
3.7.1 The concentration in g/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.
3.7.2 The amount of analyte in each sample is corrected
						  for desorption efficiency by use of a desorption curve.
3.7.3 Analytical results (A) from the two tubes that
						  compose a particular air sample are added together.
3.7.4 The concentration for a sample s calculated by
						  the following equation:
EtO, mg/m3 = (A x B) /
						  C
where:
A = [MICRO]g/mL
B = desorption volume in milliliters
C = air volume in liters.
3.7.5 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 = molecular weight of EtO.
3.8 Safety Precautions
3.8.1 Ethylene oxide and benzene are potential
						  carcinogens and care must be exercised when working with these
						  compounds.
3.8.2 All work done with the solvents (preparation of
						  standards, desorption of samples, etc.) should be done in a hood.
3.8.3 Avoid any skin contact with all of the
						  solvents.
3.8.4 Wear safety glasses at all times.
3.8.5 Avoid skin contact with HBr because it is highly
						  toxic and a strong irritant to eyes and skin.
1.
						  Editorial correction moving NOTE and HISTORIES 1-7 to precede Appendix A of
						  section 5220 (Register 99, No. 28). For
						  prior history of Appendices, see section
						  5220.