||100 ppm (410 mg/m3)|
||Samples are collected by drawing air through glass sampling
tubes containing coconut shell charcoal coated with
4-tert-butylcatechol. Samples are desorbed with
toluene and analyzed by GC using a flame ionization detector.|
|Recommended air volume
and sampling rate:
|3 L at 0.05 L/min|
|Reliable quantitation limit:
||151 ppb (617 µg/m3)|
|Standard errors of estimate
at the target concentration:
||Samples should be stored at reduced temperature when not in
|Status of method:
||Evaluated method. This method has been subjected to the
established evaluation procedures of the Organic Methods Evaluation
|Date: June 1992
Organic Methods Evaluation Branch
OSHA Salt Lake Technical
Salt Lake City, UT 84165-0200
1. General Discussion
The OSHA Salt Lake Technical Center has in the past used NIOSH
Method 2537 for the sampling and analysis of methyl methacrylate
5.1.). The NIOSH method specified collection using a jumbo
XAD-2 tube (6-mm i.d. × 8-mm
o.d. × 11.0 cm, 400 mg/200 mg) which had to be shipped to the
laboratory at dry ice temperature. The method also specified
desorption with carbon disulfide and analysis by GC with a flame
ionization detector (FID). To eliminate the dry ice temperature
shipment requirement, coconut shell charcoal coated with
4-tert-butylcatechol (TBC) was utilized for
sampling. TBC has been previously used in OSHA methods to inhibit
the polymerization of reactive compounds. (Refs. 5.2.
1.1.2. Toxic effects (This section is for information only and
should not be taken as the basis of OSHA policy.)
The vapor of MME can irritate the nose and throat at air
concentrations of about 170 ppm. Concentrations above 2000 ppm are
intolerable. High concentrations of vapor may cause headache,
drowsiness, dizziness, difficulty in breathing, and at very high
levels, loss of consciousness. Death by pulmonary edema has
Vapor concentrations above 170 ppm will irritate the eyes and may
generate tearing. Liquid can cause considerable irritation or burns
to the eyes. Skin contact with liquid MME may produce irritation or
burns. Allergic skin sensitization can occur over time. Sensitized
persons may have a severe reaction to low doses which do not affect
unsensitized persons. Ingestion of MME irritates the mouth and
stomach; causes nausea, vomiting, dizziness and drowsiness; and may
produce liver and kidney damage. (Ref.
The International Agency for Research on Cancer reports that
there is inadequate data to support evidence for carcinogenicity of
MME in humans or animals. (Ref.
In the Code of Federal Regulations, the final rule limits in
Table Z-1-A specify a TWA of 100 ppm (410
1.1.3. Workplace exposure
In 1979, 307 million kilograms of MME were produced in the United
5.8.). MME is used in the manufacture of acrylic plastics
(Lucite and Plexiglass), latex house paints, building materials,
automobile parts, lubricating oil additives, polishes and coatings,
adhesives, sealants, dental implants, hard contact lenses, bone
cement, bone replacements (artificial hips), corneal implants, and
ultraviolet cured inks in the printing industry. (Ref.
1.1.4. Physical properties and other descriptive information (Ref.
|4.67 kPa (35 mmHg)|
|lower explosive limit:
|upper explosive limit:
||slightly soluble in water; soluble in most organic
||methylacrylic acid, methyl ester; methyl
alpha-methyl acrylate; methyl
propenoic acid, methyl ester; MME; Pegalan|
The analyte air concentrations throughout this method are based on
the recommended sampling and analytical parameters. Air concentrations
listed in ppm and ppb are referenced to 25°C and 101.3 kPa (760 mmHg).
1.2. Limit-defining parameters
1.2.1. Detection limit of the analytical procedure
The detection limit of the analytical procedure is 0.343 ng per
injection (1.0-µL injection with a 5.4:1 split).
This is the amount of analyte that will produce a peak with height
that is approximately 5 times the height of a nearby contaminant
1.2.2. Detection limit of the overall procedure
The detection limit of the overall procedure is 1.852 µg
per sample. This is the amount of analyte spiked on the sampling
device that, upon analysis, produces a peak similar in size to that
of the detection limit of the analytical procedure. This detection
limit corresponds to an air concentration of 151 ppb (617
1.2.3. Reliable quantitation limit
The reliable quantitation limit is 1.852 µg per sample.
This is the smallest amount of analyte which can be quantitated
within the requirements of a recovery of at least 75% and a
precision (±1.96 SD) of ±25% or better. This reliable quantitation
limit corresponds to an air concentration of 151 ppb (617
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 analyte is exceptionally higher than these limits, they may not
be attainable at the routine operating parameters.
1.2.4. Instrument response to the analyte
The instrument response over a concentration range representing
0.5 to 2 times the target concentration is linear. (Section
The recovery of MME from samples used in the 15-day ambient
storage test remained above 83.4%. (Section
4.5., regression line of Figure
1.2.6. Precision (analytical procedure)
The pooled coefficient of variation obtained from replicate
determinations of analytical standards at 0.5, 1 and 2 times the
target concentration is 0.0041. (Section
1.2.7. Precision (overall procedure)
The precision at the 95% confidence level for the 15-day ambient
temperature storage test is ±11.5%. (Section
4.7.) This includes an additional ±5% for sampling error.
Six samples, liquid-spiked with MME, and a draft copy of this
procedure were given to a chemist unassociated with this evaluation.
The samples were analyzed after 7 days of storage at 2°C. No
individual sample result deviated from its theoretical value by more
than the precision reported in Section
1.3.1. The sampling device is smaller and more conveniently
sized than the large XAD-2 tube recommended by NIOSH
1.3.2. The sampler may be shipped at ambient temperatures. The
large XAD-2 tube had to be shipped at dry ice
2. Sampling Procedure
2.1.1. Samples are collected using a personal sampling pump that
can be calibrated within ±5% of the recommended flow rate with the
sampling device attached.
2.1.2. Samples are collected with 4-mm i.d. × 6-mm o.d. × 7.0 cm
glass sampling tubes packed with two sections of coconut shell
charcoal that has been coated with TBC, 10% by weight. The front
section contains 110 mg and the back section contains 55 mg of
TBC-coated coconut shell charcoal. The sections are
held in place with glass wool plugs. For this evaluation, tubes were
purchased from SKC, Inc. (catalog no. 226-73).
No sampling reagents are required.
2.3.1. Immediately before sampling, break off the ends of the
TBC-coated coconut shell charcoal tube. All tubes should be from the
2.3.2. Attach the sampling tube to the sampling pump with
flexible tubing. It is desirable to utilize sampling tube holders
which have a protective cover to shield the employee from the sharp,
jagged end of the sampling tube. Position the tube so that sampled
air passes through the 110-mg section first.
2.3.3. Air being sampled should not pass through any hose or
tubing before entering the sampling tube.
2.3.4. Attach the sampler vertically with the 110-mg section
pointing downward, in the worker's breathing zone so it does not
impede work performance or safety.
2.3.5. After sampling for the appropriate time, remove the sample
and seal the tube with plastic end caps. Wrap each sample
end-to-end with a Form OSHA-21 seal.
2.3.6. Submit at least one blank sample with each set of samples.
Handle the blank sample in the same manner as the other samples
except draw no air through it.
2.3.7. Record sample volumes (in liters of air) for each sample,
as well as any potential interferences.
2.3.8. Ship any bulk samples separate from the air samples.
2.3.9. Submit the samples to the laboratory for analysis as soon
as possible after sampling. If delay is unavoidable, store the
samples at reduced temperature.
2.4. Sampler capacity
The sampling capacity of the front section of a TBC-coated coconut
shell charcoal sampling tube was tested by sampling from a dynamically
generated test atmosphere of MME (144 ppm or 589
mg/m3). The sample was collected at 0.05
L/min and the relative humidity was 80%. The 5% breakthrough occurred
after sampling for 164 min or 8.19 L. (Section
2.5. Desorption efficiency
2.5.1. The average desorption efficiency from TBC-coated coconut
shell charcoal adsorbent is 96.1% over the range of 0.5 to 2 times
the target concentration. (Section
2.5.2. Desorbed samples remain stable for at least 25 h. (Section
2.5.3 The desorption efficiency was determined at lower
concentrations, down to 2% of the target concentration. This was
done because the desorption efficiency decreased to 76% at the RQL.
The desorption efficiency did not decrease over the concentration
range studied. (Section
2.5.4. Desorption efficiencies should be confirmed periodically
because differences may occur due to variations in sampler lots,
desorption solvent, and operator technique.
2.6. Recommended air volume and sampling rate
2.6.1. For TWA samples, the recommended air volume is 3 L
collected at 0.05 L/min (1-h samples).
2.6.2. For short-term samples, the recommended air volume is 0.75
L collected at 0.05 L/min (15-min samples).
2.6.3. When short-term samples are required, the reliable
quantitation limit becomes larger. For example, the reliable
quantitation limit is 0.60 ppm (2.47
mg/m3) when 0.75 L of air is collected.
2.7. Interferences (sampling)
2.7.1. It is not known if any compounds will severely interfere
with the collection of MME on TBC-coated coconut shell
charcoal. In general, the presence of other contaminant vapors in
the air will reduce the capacity of TBC-coated coconut
shell charcoal to collect MME.
2.8. Safety precautions (sampling)
2.7.2. Suspected interferences should be reported to the
laboratory with submitted samples.
2.8.1. The sampling equipment should be attached to the worker
in such a manner that it will not interfere with work performance or
2.8.2. All safety practices that apply to the work area being
sampled should be followed.
2.8.3. Protective eyewear should be worn when breaking the ends
of the glass sampling tubes.
3. Analytical Procedure
3.1.1. A GC equipped with a flame ionization detector (FID). A
Hewlett-Packard 5890 Gas Chromatograph equipped with a
7673A Autosampler and an FID was used in this evaluation.
3.1.2. A GC column capable of separating MME and the internal
standard from the desorbing solvent and any potential interferences.
A 60-m × 0.32-mm i.d. SPB™-1
(4.0-µm film thickness) capillary column
(Supelco, Inc.) was used in this evaluation.
3.1.3. An electronic integrator or some other suitable means of
measuring detector response. A Waters 860 Networking Computer System
was used in this evaluation.
3.1.4. Two-milliliter glass vials with
3.1.5. A dispenser capable of delivering 1.0 mL of desorbing
solution is used to prepare standards and samples. If a dispenser is
not available, a 1.0-mL volumetric pipet may be used.
3.2.1. Methyl methacrylate (MME). Reagent grade or better should
be used. The BAKER grade used in this evaluation was purchased from
JT Baker Chemical Co. (Phillipsburg, NJ).
3.2.2. Toluene. Reagent grade or better should be used. The
Burdick & Jackson B&J Brand™ High Purity Solvent used in
this evaluation was purchased from Baxter Healthcare Corp.
3.2.3. Desorbing solution. The desorbing solution is prepared by
adding 20 µL of an appropriate internal standard to 1 L of
toluene. Benzene (reagent grade) was used in this evaluation as the
internal standard and was purchased from EM Science (Gibbstown, NJ).
3.3. Standard preparation
3.3.1. Prepare concentrated stock standards of MME in toluene.
Prepare working analytical standards by injecting microliter amounts
of concentrated stock standards into 2-mL vials
containing 1 mL of desorbing solution delivered from the same
dispenser used to desorb samples. For example, to prepare a target
level standard, inject 10 µL of a stock solution containing
123.5 mg/mL of MME in toluene into 1 mL of desorbing solution.
3.3.2. Prepare a sufficient number of analytical standards to
generate a calibration curve. Ensure that the amount of MME found in
the samples is bracketed by the standards. Prepare additional
standards if necessary.
3.4. Sample preparation
3.4.1. Remove the plastic caps from the sample tube and
carefully transfer each section of the adsorbent to separate
2-mL vials. Discard the glass tube and glass wool
3.4.2. Add 1.0 mL of desorbing solution to each vial and
immediately seal the vials with
3.4.3. Shake the vials vigorously several times during the next
30 min to ensure complete desorption.
3.5.1. Analytical conditions
||initial temp at 120°C, increase temp at 5°C/min
to 150°C, hold for 5 min|
|column gas flow:
||1.35 mL/min (hydrogen)|
||1.5 mL/min (hydrogen)|
||1.0 µL (5.4:1 split)|
||60 m × 0.32-mm i.d. capillary
SPB™-1 (4.0-µm film
||9.8 min (MME)
9.3 min (benzene)
3.5.2. An internal standard (ISTD) calibration method is used. A
calibration curve can be constructed by plotting micrograms of
analyte per milliliter versus ISTD-corrected response
of standard injections. Bracket the samples with freshly prepared
analytical standards over a range of concentrations.
3.6. Interferences (analytical)
3.6.1. Any compound that produces an FID response and has a
similar retention time as the analyte or internal standard is a
potential interference. If any potential interferences were
reported, they should be considered before samples are desorbed.
Generally, chromatographic conditions can be altered to separate an
interference from the analyte.
3.6.2. Retention time on a single column is not considered proof
of chemical identity. Analysis by an alternate GC column or
confirmation by mass spectrometry are additional means of
The amount of analyte per milliliter is obtained from the
appropriate calibration curve in terms of micrograms per milliliter
uncorrected for desorption efficiency. The back (55-mg)
section is analyzed primarily to determine the extent of sample
saturation during sampling. If any analyte is found on the back
section, it is added to the amount on the front section. This total
amount is then corrected by subtracting the total amount (if any)
found on the blank. The air concentration is calculated using the
|where A =
||micrograms of analyte per milliliter|
||liters of air sampled|
|where 24.46 =
||molar volume (liters) at 101.3 kPa (760 mmHg) and
3.8. Safety precautions (analytical)
3.8.1. Restrict the use of all chemicals to a fume hood.
3.8.2. Avoid skin contact and inhalation of all chemicals.
3.8.3. Wear safety glasses, gloves and a lab coat at all times
while working with chemicals.
4. Backup Data
4.1. Detection limit of the analytical procedure
|The injection size recommended in the analytical procedure
(1-µL, 5.4:1 split) was used to determine
the detection limit of the analytical procedure. The detection
limit of the analytical procedure is 0.343 ng
on-column. This was the amount of analyte that gave
a peak with a height about 5 times the height of a nearby
contaminant peak. This detection limit was determined by
analysis of a standard containing 1.852 µg/mL of MME.
Figure 4.1. Detection limit of the analytical
4.2. Detection limit of the overall procedure
|The detection limit of the overall procedure is 1.852
µg per sample (151 ppb or 617
µg/m3). The injection size
listed in the analytical procedure (1.0 µL, 5.4:1 split)
was used to determine the detection limit of the overall
procedure. Six vials containing 110 mg of
TBC-coated coconut shell charcoal were
liquid-spiked with 1.852 µg of MME. The
samples were stored at ambient temperature and were desorbed
about 8 h after being spiked.
Detection Limit of the
Procedure for MME
4.3. Reliable quantitation limit data
|The reliable quantitation limit is 1.852 µg per
sample (151 ppb or 617 µg/m3).
The injection size listed in the analytical procedure (1.0
µL, 5.4:1 split) was used to determine the reliable
quantitation limit. Six vials containing 110 mg of
TBC-coated coconut shell charcoal were
liquid-spiked with a toluene solution containing
MME. Because the recovery of the analyte from the spiked samples
was greater than 75% and had a precision of ±25% or better, the
detection limit of the overall procedure and reliable
quantitation limit are the same.
Reliable Quantitation Limit for
(Based on samples and data of Table 4.2.)
4.4. Instrument response to the analyte
The instrument response to MME over the range of 0.5 to 2 times the
target concentration is linear with a slope of 819 (in
ISTD-corrected area counts per microgram per milliliter).
The precision of the response to the analyte was determined by
multiple injections of standards. The data below is presented
graphically in Figure
Instrument Response to MME
|× target concn
Figure 4.4. Calibration curve for
4.5. Storage data
Storage samples were prepared by injecting 10 µL of a
standard solution onto the TBC-coated coconut shell
charcoal. The standard contained 123.5 mg/mL MME in toluene. Humid
air, 80% RH, was drawn through the tubes for 1 h at 0.05 L/min.
Thirty-six storage samples were prepared. Six samples
were analyzed immediately. Fifteen tubes were stored at reduced
temperature (12°C) and the other fifteen were stored in a closed
drawer at ambient temperature (about 22°C). At 2 to 4 day intervals,
three samples were selected from each of the two storage sets and
analyzed. The results are listed below and shown graphically in
Storage Test of MME
4.6. Precision (analytical method)
|The precision of the analytical procedure is defined as the
pooled coefficient of variation determined from replicate
injections of MME standards at 0.5, 1 and 2 times the target
concentration. Based on the data of Table 4.4., the coefficient
of variation (CV) for the three levels and the pooled
coefficient of variation were calculated. The pooled coefficient
of variation is 0.0041.
Precision of the Analytical Method for
(Based on the Data of Table
|× target concn
1 - in area counts
4.7. Precision (overall procedure)
The precision of the overall procedure is determined from the
storage data. The determination of the standard error of estimate
(SEE) for a regression line plotted through the graphed storage data
allows the inclusion of storage time as one of the factors affecting
overall precision. The SEE is similar to the standard deviation,
except it is a measure of dispersion of data about a regression line
instead of about a mean. It is determined with the following equation:
|total number of data points|
2 for linear
3 for quadratic regression
||observed percent recovery at a given time|
||estimated percent recovery from the regression line at the
same given time|
An additional 5% for pump error is added to the SEE by the addition
of variances. The precision at the 95% confidence level is obtained by
multiplying the SEE (with pump error included) by 1.96 (the
z-statistic from the standard normal distribution at the
95% confidence level). The 95% confidence intervals are drawn about
their respective regression line in the storage graph as shown in Figure
4.5.1. The data for Figure 4.5.1. was used to determine the SEE of
±5.85% and the precision of the overall procedure of ±11.5%.
4.8. Reproducibility data
|Six samples were prepared by injecting an aliquot of a
toluene solution containing 116.3 mg/mL MME onto the
TBC-coated coconut shell charcoal. Humid air, 80%
RH, was drawn through the tubes for 1 h at 0.05 L/min to add
water to the sampler matrix. The samples were given to a chemist
unassociated with this study. The samples were analyzed after
being stored for 7 days at 2°C in a refrigerator. Sample results
were corrected for desorption efficiency. No sample result has a
deviation greater than the precision of the overall procedure
determined in Section
4.7., which is ±11.5%.
Reproducibility Data for MME
4.9. Sampler capacity
An attempt to generate a dynamic test atmosphere was performed by
injecting pure MME from a gas-tight syringe driven by a
syringe pump at 2.11 mg/min into an air stream that was flowing at
2.45 L/min (21°C and 80% relative humidity). This should have
generated an atmosphere of 210 ppm or 861
mg/m3. The MME polymerized in the airstream
to form a solid and only a small amount of the MME vaporized. To
overcome this problem, the bottom of a U-tube was filled
with glass beads coated with r-methoxy phenol. r-Methoxy phenol is commonly used to inhibit
the polymerization of MME. By placing the end of the
polytetrafluoroethylene needle in the glass beads, most of the MME to
vaporize and resulted in an atmosphere of 589
mg/m3 or 144% of the target concentration.
This was determined by sampling the air stream with a
TBC-coated coconut shell charcoal tube and analyzing the
tube. The atmosphere was much higher than the earlier attempt but was
still not at theoretically amount. Solid polymerized MME was still
found among the glass beads and this was the reason for the lower than
The sampling capacity of the front section of a
TBC-coated coconut shell charcoal sampling tube was
tested by sampling the second dynamically generated atmosphere at
0.048 L/min. A GC equipped with a gas sampling valve and an FID
detector was used to analyze the downstream effluent from the tube
periodically. The response was compared to the previously measured
upstream air flow. After the downstream concentration had exceeded 8%
of the upstream concentration, the sampling was stopped. The 5%
breakthrough air volume was determined to be the point when the
downstream concentration was 5% of the upstream concentration or 8.19
Breakthrough on the TBC-coated
Charcoal Tube for MME
4.9. Breakthrough air volume for MME.
4.10. Desorption efficiency and stability of desorbed samples
4.10.1. Desorption efficiency
|The desorption efficiency (DE) of MME was determined by
liquid-spiking 110-mg portions of
TBC-coated coconut shell charcoal with MME at
0.5, 1 and 2 times the target concentration. These samples
were stored for 6 h at ambient temperature and then desorbed
and analyzed. The average desorption efficiency over the
studied range was 96.1%.
Desorption Efficiency of
4.10.2. Stability of desorbed samples
|The stability of desorbed samples was investigated by
reanalyzing the target concentration samples 25 h after
initial analysis. The original analysis was performed and the
vials were not recapped after injection. The samples were
reanalyzed with fresh standards at the completion of the
desorption efficiency test without removing the samples from
the GC. The average recovery of the reanalysis, compared to
the average recovery of the original analysis, was 97.2%
Stability of Desorbed Samples for
after 25 h
4.10.3. Linearity of desorption
The average desorption efficiency is 96.1% for MME but the
desorption at the RQL, 0.15% of the target concentration, is 76.0%.
This can infer that the desorption efficiency is not constant as the
amount of MME on the sampler decreases. To determine the linearity
of the desorption efficiency, a series of samplers were spiked over
the range of 2 to 100% of the target concentration. The data from
these samples resulted in a line that deviates only 2% from
theoretical values. The desorption efficiency is linear throughout
5.1. "NIOSH Manual of Analytical Methods", 3rd
ed.; U.S. Department of Health and Human Services, Center for Disease
Control, National Institute of Occupational Safety and Health;
Cincinnati, OH, 1984, Method 2537, DHHS (NIOSH) Publ. No.
5.2. "OSHA Analytical Methods Manual", 2nd ed.;
U.S. Department of Labor, Occupational Safety and Health
Administration; OSHA Analytical Laboratory; Salt Lake City, UT, 1990;
Method 56; American Conference of Governmental Industrial Hygienists
(ACGIH); Cincinnati, OH, Publication No. 4542.
5.3. Burright, D.D. "OSHA Method No. 89; Divinyl
Benzene, Ethyl Vinyl Benzene, and Styrene", OSHA Salt Lake Technical
Center, unpublished, Salt Lake City, UT 84165, July 1991.
5.4. Burright, D.D. "OSHA Method No. 92; Ethyl
Acrylate and Methyl Acrylate", OSHA Salt Lake Technical Center,
unpublished, Salt Lake City, UT 84165, December 1991.
5.5. Cheminfo Database on CCINFO CD-ROM disc
91-3, Canadian Centre for Occupational Health and Safety, Hamilton,
5.6. International Agency for Research on Cancer,
"IARC Monograph on the Evaluation of the Carcinogenic Risk of
Chemicals to Humans: Some Monomers, Plastics and Synthetic Elastomers,
and Acrolein", IARC, Lyon, France, 1986, Vol. 19, pp.
5.7. "Code of Federal Regulations", Title 29,
1910.1000, Table Z-1-A. Limits for Air Contaminants, U.S.
Government Printing Office, Washington, D.C., 1990.
5.8. Nemec, J.W. and Kirch, L.S. in "Kirk-Othmer
Encyclopedia of Technology" 3rd ed.; Grayson, M. Ed.; John Wiley &
Sons, New York, 1981, Vol. 15, pp. 346-376.