|
| Method no.: |
PV2131 |
| |
|
| Control no.: |
T-PV2131-01-04010-M |
| |
|
| Target Concentration: |
1 mg/m3 |
| |
|
| Procedure: |
Samples
are collected by drawing a known volume of air through glass sampling tubes
containing Chromosorb 106. Samples are
extracted with a solution of 99:1 carbon
disulfide:N,N-dimethyl formamide and analyzed by GC using a flame
ionization detector (GC/FID). |
| |
|
| Sampling rate: |
240 min at 0.2 L/min (48 L) |
| |
|
| Reliable quantitation limit: |
33 µg/m3 |
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|
| Status of method: |
Partially evaluated method. This method has been
subjected to established evaluation procedures of the Methods Development Team
and is presented for information and trial use. |
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|
| January 2004 |
Mary E. Eide |
Methods Development Team
Industrial Hygiene Chemistry Division
OSHA Salt Lake Technical
Center
Sandy UT 84070-6406
|
1. General Discussion
1.1 Background
1.1.1 History
Air samples
collected using Chromosorb 106 tubes were received at OSHA SLTC with requested
analysis for tetrahydrofurfuryl acrylate. This partially-validated work was performed because SLTC had no sampling
and analytical method for tetrahydrofurfuryl acrylate.
The result of
a preliminary extraction efficiency study for tetrahydrofurfuryl acrylate
extracted from dry Chromosorb 106 with carbon disulfide was 98% recovery. The test was repeated with wet Chromosorb 106
and the recovery was initially the same, but then decreased to 85% when the
samples were allowed to stand. The
source of dry Chromosorb 106 was sampling tubes as received from SKC Inc. The source of wet Chromosorb 106 was dry
Chromosorb 106 sampling tubes which had clean, humid air drawn through
them. The extraction solvent was changed
from pure carbon disulfide to 99:1 carbon disulfide:N,N-dimethylformamide and the wet Chromosorb 106 extraction
efficiency test was repeated. The
results of this test showed no decrease in recovery; therefore, the 99:1 carbon disulfide:N,N-dimethylformamide
extraction solvent was selected for use in this work. The extraction efficiency was 98.6% using the
99:1 carbon disulfide:N,N-dimethylformamide
extraction solvent.
Tetrahydrofurfuryl
acrylate was found to be well retained on Chromosorb 106, with a retention
efficiency recovery of 99.1% and the storage stability recovery of 97.5% on day
14 of ambient storage.
1.1.2 Toxic effects (This section is for information only and should not be taken as the
basis of OSHA policy.)1
Tetrahydrofurfuryl acrylate is a
contact irritant affecting the skin, eyes, and mucous membranes, and may cause
sensitization through skin contact in certain individuals. If swallowed it causes irritation of the
gastrointestinal tract, causing nausea, and vomiting.
1.1.3 Workplace exposure2
Tetrahydrofurfuryl
acrylate is used as an intermediate in the manufacture of plasticizers and
coating materials, and printing materials.
1.1.4 Physical properties and other descriptive information1
CAS number: 2399-48-6
Synonyms3: 2-propenoic acid,
(tetrahydro-2-furanyl)methyl ester; 2-propenoic acid, tetrahydrofurfuryl ester.
| solubility: |
insoluble in water, soluble in organic solvents
|
| molecular weight: |
156.18
|
| density: |
1.064 g/mL
|
| boiling point: |
87 °C
|
| flash point: |
110 °C (230 °F)(closed cup)
|
| appearance: |
clear liquid
|
| molecular formula: |
C8H12O3
|
odor:
|
musty |
| IMIS4: |
T420 |
Structural Formula:
This
method was evaluated according to the OSHA SLTC "Evaluation Guidelines for Air
Sampling Methods Utilizing Chromatographic Analysis"5. The Guidelines define analytical parameters,
specify required laboratory tests, statistical calculations and acceptance
criteria. The analyte air concentrations
throughout this method are based on the recommended sampling and analytical
parameters.
1.2 Detection limit of the overall procedure (DLOP) and reliable quantitation limit (RQL)
The
DLOP is measured as mass per sample and expressed as equivalent air concentrations,
based on the recommended sampling parameters. Ten samplers were spiked with equally descending increments of analyte,
such that the highest sampler loading was 10.6
µg of tetrahydrofurfuryl acrylate. This is the amount spiked on a sampler that
would produce a peak at least 10 times the response for a sample blank. These spiked samplers were analyzed with the
recommended analytical parameters, and the data obtained used to calculate the
required parameters (standard error of estimate and slope) for the calculation
of the DLOP. The slope was 869 and the
SEE was 137. The RQL is considered the
lower limit for precise quantitative measurements. It is determined from the regression line
parameters obtained for the calculation of the DLOP, providing 75% to 125% of
the analyte is recovered. The DLOP and
RQL were 0.47 µg (10 µg/m3) and
1.58 µg (33 µg/m3)
respectively. The recovery at the RQL level was 95.4%.
Table 1.2
Detection Limit of the Overall Procedure for Tetrahydrofurfuryl acrylate
|
mass per sample
(µg) |
area counts
(µV-s) |
|
| 0.00 |
0 |
| 1.06 |
904 |
| 2.13 |
1797 |
| 3.19 |
2639 |
| 4.26 |
3482 |
| 5.32 |
4512 |
| 6.38 |
5453 |
| 7.45 |
6297 |
| 8.51 |
7249 |
| 9.58 |
8091 |
| 10.6 |
9478 |
|
Figure 1.2.1
Plot of the data to determine the DLOP/RQL for tetrahydrofurfuryl acrylate. (y = 869x – 89.0) |
The
RQL is considered the lower limit for precise quantitative measurements. It is determined from the regression line
parameters obtained for the calculation of the DLOP. The recovery at the RQL was 95.4%. Below is the chromatogram of the RQL level.
Figure 1.2.2
Chromatogram of the tetrahydrofurfuryl acrylate near the RQL. (Key: (1) tetrahydrofurfuryl acrylate) |
2. Sampling Procedure
All safety
practices that apply to the work area being sampled should be followed. The sampling equipment should be attached to
the worker in such a manner that it will not interfere with work performance or
safety.
2.1 Apparatus
Samples are
collected using a personal sampling pump calibrated, with the sampling device
attached, to within ± 5% of the
recommended flow rate.
Samples are
collected with 7-cm × 4-mm i.d. × 7-mm o.d. glass sampling tubes
packed with two sections (100/50 mg) of Chromosorb 106. The sections are held in place with foam
plugs with a glass wool plug at the front. For this evaluation, commercially prepared sampling tubes were purchased
from SKC, Inc. (catalogue no. 226-110 lot 2573).
2.2 Reagents
None required.
2.3 Technique
Immediately
before sampling break off the ends of the flame-sealed tube to provide an
opening approximately half the internal diameter of the tube. Wear eye protection when breaking the
tube. Use tube holders to minimize the
hazard of broken glass. All tubes should
be from the same lot.
The smaller section of the adsorbent tube
is used as a back-up and is positioned nearest the sampling pump. Attach the tube holder to the sampling pump
so that the adsorbent tube is in an approximately vertical position with the
inlet facing down during sampling. Position the sampling pump, tube holder, and tubing so they do not impede
work performance or safety.
Draw the air to be sampled directly into the inlet of the tube holder. The air being sampled is not to be passed
through any hose or tubing before entering the sampling tube.
After
sampling for the appropriate time, remove the adsorbent tube and seal it with plastic
end caps. Seal each sample end-to-end
with an OSHA-21 form as soon as possible.
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.
Record
sample air volumes (liters), sampling time (minutes), and sampling rate (L/min)
for each sample, along with any potential interferences on the OSHA-91A form.
Submit
the samples to the laboratory for analysis as soon as possible after
sampling. If delay is unavoidable, store
the samples at refrigerator temperature. Ship any bulk samples separate from the air samples.
2.4 Extraction efficiency
The extraction efficiency was determined by spiking Chromosorb 106 tubes with tetrahydrofurfuryl
acrylate at 0.1 to 2 times the target concentration. These samples were stored overnight at
ambient temperature and then extracted with 1 mL of the extracting solvent for
30 minutes with shaking, and analyzed. The mean extraction efficiency over the studied range was 98.6%. The wet extraction efficiency was
determined
at the target concentration by liquid spiking the analyte onto Chromosorb 106
tubes which had 48-L humid air (absolute humidity of 15.9 mg/L of water, about
80% relative humidity at 22.2 °C) drawn through them immediately before
spiking. The mean recovery for the wet
samples was 98.6%.
Table 2.4
Extraction Efficiency (%) of Tetrahydrofurfuryl Acrylate
|
level
|
sample number
|
x Target
concn |
µg per
Sample |
1 |
2 |
3 |
4 |
5 |
6 |
mean |
|
|
0.1 |
5.3 |
98.8 |
97.1 |
97.2 |
97.3 |
99.9 |
99.6 |
98.3 |
|
0.5 |
26.6 |
98.5 |
98.7 |
99.3 |
99.0 |
99.9 |
99.7 |
99.2 |
|
1.0 |
53.2 |
98.5 |
98.2 |
98.4 |
98.3 |
98.9 |
98.8 |
98.5 |
|
1.5 |
79.8 |
98.9 |
97.8 |
99.2 |
98.4 |
98.7 |
98.9 |
98.7 |
|
2.0 |
106 |
98.4 |
98.1 |
97.9 |
98.9 |
98.7 |
99.6 |
98.5 |
| |
|
|
|
|
|
|
|
|
|
1.0 (wet) |
53.2 |
98.8 |
98.4 |
98.1 |
98.9 |
99.9 |
98.2 |
98.6 |
|
2.5 Retention efficiency
Six
Chromosorb 106 tubes had their front sections spiked with 106 µg (2.21 mg/m3)
of tetrahydrofurfuryl acrylate and allowed to equilibrate for 6 h. The tubes had
48-L humid air (absolute humidity of 15.9 mg/L of water, about 80% relative
humidity at 22.2 °C) pulled through them at 0.2 L/min. The samples were extracted and analyzed. The mean recovery was
99.1%. There was no analyte found on the back-up
section of any of the tubes.
Table 2.5
Retention Efficiency (%) of Tetrahydrofurfuryl Acrylate
|
sample number
|
| section |
1 |
2 |
3 |
4 |
5 |
6 |
mean |
|
| front |
99.4 |
100.2 |
98.7 |
99.3 |
99.3 |
98.3 |
99.1 |
| rear |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
| total |
99.4 |
100.2 |
98.7 |
99.3 |
99.3 |
98.3 |
99.7 |
|
2.6 Sample storage
Fifteen Chromosorb 106 tubes were each spiked with 53 µg (1.1 mg/m3) of tetrahydrofurufryl
acrylate and were allowed to equilibrate for 6 h, then 48-L of air, with an
absolute humidity of 15.7 milligrams of water per liter of air (about 80%
relative humidity at 22.2 °C), was
drawn through them at 0.2 L/min. Three
samples were analyzed immediately. The remaining
samples were sealed and six were stored
at room temperature (23 °C), while the other six were stored at refrigerated
temperature (4 °C). On day 7 three samples from each group were
analyzed, and the remaining three from each group was analyzed on day 14. The amounts recovered, indicate good storage
stability for the time period studied, with an average recovery on day 14 of
97.5% for ambient storage and 98.1% for refrigerated storage.
Table 2.6
Storage Test for Tetrahydrofurfuryl Acrylate
|
| time (days) |
ambient storage recovery (%) |
refrigerated storage recovery (%) |
|
| 0 |
99.1 |
98.3 |
98.5 |
|
|
|
| 7 |
97.9 |
98.4 |
98.7 |
98.9 |
98.2 |
97.7 |
| 14 |
97.2 |
98.1 |
97.1 |
98.0 |
98.4 |
97.9 |
|
2.7 Recommended air volume and sampling rate
Based on
the data collected in this evaluation, 48-L air samples should be collected at
a sampling rate of 0.2 L/min for 240 minutes.
2.8 Interferences (sampling)
There are
no known compounds which will severely interfere with the collection of tetrahydrofurfuryl
acrylate.
Suspected
interferences should be reported to the laboratory with submitted samples.
3. Analytical procedure
Adhere
to the rules set down in your Chemical Hygiene Plan. Avoid skin contact and inhalation of all
chemicals and review all appropriate MSDSs.
3.1 Apparatus
3.1.1 A gas
chromatograph equipped with a FID detector. An Agilent 6890 Gas Chromatograph equipped with a
FID and a 7683 Injector was used in this evaluation.
3.1.2
A GC
column capable of separating tetrahydrofurfuryl acrylate from the extraction
solvent, internal standard, and any potential interferences. A 60-m × 0.32-mm i.d. DB-1 (1.0- µm df) capillary column was used in this
evaluation.
3.1.3
An
electronic integrator or some other suitable means of measuring peak
areas. A Waters Millennium32 Data System was used
in this evaluation.
3.1.4
Glass
vials with poly(tetrafluoroethylene)-lined caps. For this evaluation 2-mL vials were used.
3.1.5
A dispenser capable of delivering 1.0 mL of
extracting solvent to prepare standards and samples. If a dispenser is not available, a 1.0-mL
volumetric pipet may be used.
3.1.6
Volumetric flasks – 10-mL and other convenient
sizes for preparing standards.
3.1.7
Calibrated 10-µL or 20-µL
syringe for preparing standards.
3.1.8
A mechanical shaker. An Eberbach mechanical shaker was used in
this evaluation.
3.2 Reagents
3.2.1 Tetrahydrofurfuryl acrylate, Reagent grade. Aldrich 99% (lot 04106CO) was used in this
evaluation.
3.2.2
Carbon disulfide, Reagent grade. Omni-Solv® 99.99% (lot 43279343) was used in this evaluation.
3.2.3 p-Cymene,
Reagent grade. Aldrich 99% (lot 11703TR)
was used in this evaluation.
3.2.4 N,N-Dimethylformamide, anhydrous Reagent grade.
Aldrich 99.8% (lot 04643LA) was used in this evaluation.
3.2.5
The extraction solvent was 99:1 carbon
disulfide: DMF with 0.25 µL/mL p-cymene internal standard.
3.3 Standard preparation
3.3.1
Prepare working analytical standards by
injecting microliter amounts of terahydrofurfuryl acrylate into volumetric
flasks containing the extraction solvent. An analytical standard at a concentration of 106 µg/mL is equivalent to 2.2 mg/m3 based on a 48-liter air volume.
3.3.2
Bracket sample concentrations with working
standard concentrations. If sample
concentrations are higher than the concentration range of prepared standards,
either analyze higher standards, or dilute the sample. The higher standards should be at least as
high in concentration as the highest sample. Diluted samples should be prepared with extracting solvent to obtain a
concentration within the existing standard range. Dilutions of stock standards are prepared
using the extraction solvent for the concentration range of 1 to 213 µg/mL.
3.4 Sample preparation
3.4.1
Remove
the plastic end caps from the sample tubes and carefully transfer the adsorbent
sections to separate 2-mL vials. Discard
the glass tube, urethane foam plug and glass wool plug.
3.4.2
Add 1.0 mL of desorbing solvent to each vial using the same dispenser as used for
preparation of standards.
3.4.3
Immediately seal the vials with
poly(tetrafluoroethylene)-lined caps.
3.4.4
Shake the vials on a shaker for 30 minutes
3.5 Analysis
3.5.1
Gas chromatographic conditions
GC conditions
|
| zone temperature: |
|
| column: |
initial 50 °C, hold 1 min, ramp at 10°/min to 170 °C, hold 7 min |
| injector: |
250 °C |
detector:
|
250 °C
|
| run time: |
20 min |
| column gas flow: |
3.2 mL/min (hydrogen) |
| septum purge: |
1.9 mL/min (hydrogen) |
| injection size: |
1.0 µL (10:1 split) |
| column: |
60-m
× 0.32-mm i.d. capillary DB-1 (df = 1.0 µm) |
| retention times: |
4.0 min carbon disulfide |
| |
7.0 min DMF |
| |
11.8 min p-cymene |
| |
13.7 min tetrahydrofurfuryl acrylate |
FID conditions
|
| hydrogen flow: |
30 mL/min |
| air flow: |
400 mL/min |
| makeup flow: |
25 mL/min (nitrogen) |
Figure 3.5.1
A chromatogram of 53.0 µg/mL tetrahydrofurfuryl
acrylate in 99:1 carbon disulfide:DMF with 0.25 µL/mL p-cymene internal standard. (Key: (1) carbon disulfide; (2)
benzene
contaminant in carbon disulfide; (3) DMF; (4) p-cymene; and (5)
tetrahydrofurfuryl acrylate) |
3.5.2 Peak areas are measured by an integrator or
other suitable means.
3.5.3
An
internal standard (ISTD) calibration method is used. A calibration curve can be constructed by plotting
ISTD-corrected response versus micrograms of analyte per sample. Bracket the samples with freshly prepared
analytical standards over the range of concentrations.
Figure 3.5.3
Calibration curve of tetrahydrofurfuryl acrylate. (y = 499x + 506) |
3.6 Interferences (analytical)
3.6.1Any
compound that produces a GC response and has a similar retention time as the
analyte is a potential interference. If
any potential interferences were reported, they should be considered before
samples are extracted. Generally,
chromatographic conditions can be altered to separate an interference from the
analyte.
3.6.2When
necessary, the identity or purity of an analyte peak may be confirmed by mass
spectrometry or by another analytical procedure. The mass spectrum in Figure 3.6 was from the
analytical standard analyzed on an Agilent 6890 with a 5973 Mass Selective
Detector.
Figure 3.6
Mass spectrum of tetrahydrofurfuryl acrylate. |
3.7 Calculations
The
amount of analyte per sampler is obtained from the appropriate calibration
curve in terms of micrograms per sample, uncorrected for extraction
efficiency. This total amount is then
corrected by subtracting the total amount (if any) found on the blank. The air concentration is calculated using the
following formula.
| where: |
CM is concentration by weight (mg/m3) |
| M is micrograms per sample |
| V is liters of air sampled |
| EE
is extraction efficiency, in decimal form |
4.
Recommendations for further study
Collection,
reproducibility, and other detection limit studies need to be performed to make
this a fully validated method.
References
1.
Material Safety Data Sheet: tetrahydrofurfuryl
acrylate, Chemwatch Victoria Australia, accessed 12/23/03.
2.
Howe-Grant, M., Kroschwitz, J., Ed, Encyclopedia
of Chemical Technology, John Wiley & Sons, New
York, 1998, Supplement, p 174.
3.
Howard, P., Neal, M., Ed., Dictionary of
Chemical Names and Synonyms, Lewis Publishers, Boca
Raton FL, 1992, p I-705.
4.
OSHA Chemical Sampling Information, www.osha.gov
(accessed 12/17/03).
5.
Burright,
D.; Chan, Y.; Eide, M.; Elskamp, C.; Hendricks, W.; Rose, M. C. Evaluation
Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis; OSHA Salt Lake Technical Center,
U.S. Department of Labor: Salt Lake City, UT, 1999.
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