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1-Bromopropane
Related Information: Chemical Sampling -
1-Bromopropane
|
| Method number: | PV2061 |
| |
| Matrix: | Air |
| |
| Target concentration: |
5 ppm (25.14 mg/m3) |
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| Procedure: |
Samples are collected by drawing a known volume of air through standard size (6-mm o.d.,
100/50-mg sections) coconut shell charcoal (CSC) tubes. Samples are desorbed with a
mixture of 99/1 (v/v) carbon disulfide (CS2)/dimethylformamide (DMF) and
analyzed by gas chromatography (GC) using a flame ionization detector (FID). |
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Recommended air volumes
and sampling rate: |
12 L at 0.1 L/min |
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| Reliable quantitation limit: |
0.007 ppm (0.037 mg/m3) |
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| Status of method: |
Partially Evaluated Method. This method has been subjected to established evaluation procedures, and
is presented for information and trial use. |
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| Date: March 10, 1999 | Chemist: Wayne Potter |
Organic Service Branch I
OSHA Technical Center
Salt Lake City, UT 84115-1802
1. General Discussion
1.1 Background
1.1.1 History of procedure
The OSHA Salt Lake Technical Center recently received a set of field samples that
requested analysis for 1-bromopropane. This chemical is being used as a substitute for
ozone depleting substances. This evaluation was undertaken to establish a suitable
sampling and analysis procedure for 1-bromopropane.
1.1.2 Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy.)
1-Bromopropane is moderately toxic by ingestion and intraperitoneal routes. It is also mildly toxic by inhalation.
Experimental reproductive effects and mutation data have been reported (Ref. 5.1).
Propyl bromide has a depressant action on the central nervous system and, for that reason, has been considered as a
possible anesthetic. Exposure of animals to anesthetic concentrations may result in injury to the lungs and liver.
1-Bromopropane is reported to be irritating to the skin and eyes of mice (Ref. 5.2). Rats
exposed to 1-bromopropane began to walk with a paddle-like gait after 5 weeks of
exposure, their rear lims dragging along the ground. The motor nerve conduction velocity
(MCV) became considerably slower than normal and degeneration of the peripheral
nerves was observed. Neurotoxicity was demonstrated in this study (Ref. 5.3).
1.1.3 Workplace exposure (Ref. 5.4)
1-Bromopropane is being used as an alternative solvent to chlorofluorocarbons (CFCs).
It is also being used in aerosols, solvents, adhesives, coatings and inks.
1.1.4 Physical properties and other descriptive information
(Ref. 5.1 unless otherwise indicated).
| Synonyms: | Propyl bromide |
| CAS number: | 106-94-5 |
| IMIS: | R290 |
| RTECS: | TX4110000 (Ref. 5.5) |
| Molecular weight: | 123.01 |
| Boiling point: | 70.9°C |
| Melting point: | -110°C |
| Flash point: | 22°C (72°F) (CC) (Ref. 5.6) |
| Vapor pressure: | 100 mmHg @ 18°C (Ref. 5.6) |
| Density: | 1.353 @ 20°C / 4°C |
| Properties: | Flammable or combustible liquid. |
| Solubility: | 0.25 g/100 mL water at 20°C; soluble in alcohol,
ethyl ether and carbon disulfide. (Ref. 5.2) |
| Molecular formula: | C3H7Br |
| Structural formula: | Br  |
The analyte air concentrations throughout this method are based on the recommended sampling and analytical
parameters. Air concentrations listed in ppm are referenced to 25°C and 101.3 kPa (760 mmHg).
1.2 Limit defining parameters
1.2.1 Detection limit of the overall procedure (DLOP)
The detection limit of the overall procedure is 0.13 µg per sample (0.002 ppm or 0.011
mg/m3). This is the amount of analyte spiked on the sampler that will
give a response that is significantly different from the background response of a sampler blank.
The DLOP is defined as the concentration of analyte that gives a response
(YDLOP) that is significantly different (three standard deviations
(SDBR)) from the background response (YBR).
YDLOP - YBR = 3(SDBR)
The direct measurement of YBR and SDBR in chromatographic
methods is typically inconvenient, and difficult because YBR is usually extremely low.
Estimates of these parameters can be made with data obtained from the analysis of a series of samples whose responses
are in the vicinity of the background response. The regression curve obtained for a plot of instrument response
versus concentration of analyte will usually be linear. Assuming SDBR and the precision
of data about the curve are similar, the standard error of estimate (SEE) for the regression curve can be
substituted for SDBR in the above equation. The following calculations derive a formula
for the DLOP:
| SEE |
= |
√ |
|
| Σ(YOBS - YEST)2 |
|
| n - k |
|
| Yobs | = | observed response |
| Yest | = | estimated response from regression curve |
| n | = | total no. of data points |
| k | = | 2 for a linear regression curve |
|
At point YDLOP on the regression curve
| YDLOP = A(DLOP) + YBR |
A = analytical sensitivity (slope) |
therefore
Substituting 3(SEE) + YBR for YDLOP gives
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 equal descending increments of analyte,
such that the highest sampler loading was 1.1 µg/sample. This is the amount, when spiked on a sampler,
that would produce a peak approximately 10 times the background response for the sample blank. These spiked
samplers, and the sample blank were analyzed with the recommended analytical parameters, and the data
obtained used to calculate the required parameters (A and SEE) for the calculation of the DLOP. Values of
3106.2 and 137.6 were obtained for A and SEE respectively. DLOP was calculated to be 0.13 µg/sample (0.002
ppm or 0.011 mg/m3).
Table 1.2.1
Detection Limit of the Overall Procedure
|
mass per sample
(µg) |
area counts
(µV-s) |
|
0
0.181
0.271
0.362
0.452
0.543
0.633
0.724
0.814
0.905
0.995 |
0
812
1149
1509
1734
1862
2056
2263
2860
2979
3297 |
|
|
|
Figure 1.2.1. Plot of data to determine the DLOP/RQL. |
1.2.2 Reliable quantitation limit (RQL)
The reliable quantitation limit is 0.44 µg per sample (0.007 ppm or 0.037 mg/m3).
This is the amount of analyte spiked on a sampler that will give a signal that is considered the
lower limit for precise quantitative measurements.
The RQL is determined from the regression line data obtained for the calculation of the DLOP (Section 1.2.1),
providing at least 75% of the analyte is recovered. The RQL is defined as the concentration of
analyte that gives a response (YRQL) such that
YRQL - YBR = 10(SDBR)
therefore
RQL = 0.44 µg per sample (0.037 mg/m3)
The recovery at the RQL is 97.5%.
2. Sampling Procedure
2.1 Apparatus
2.1.1 Samples are collected using a personal sampling pump calibrated, with the sampling
device attached, to within ±5% of the recommended flow rate.
2.1.2 Samples are collected using solid sorbent sampling tubes containing coconut shell
charcoal (CSC). Each tube consists of two sections of charcoal separated by a urethane
foam plug. The front section contains 100 mg of charcoal and the back section, 50 mg.
The sections are held in place with glass wool plugs in a glass tube 4-mm i.d. × 70-mm
length. For this evaluation, SKC Inc. charcoal tubes (catalog number 226-01, Lot 2000)
were used.
2.2 Technique
2.2.1 Immediately before sampling, remove the caps from the sampling tubes. All tubes should be from the same lot.
2.2.2 Attach the sampling tube to the 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 front
section of the tube first.
2.2.3 Air being sampled should not pass through any hose or tubing before entering the sampling tube.
2.2.4 Attach the sampler vertically with the front section pointing downward, in the worker's
breathing zone, and positioned so it does not impede work performance or safety.
2.2.5 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.
2.2.6 Submit at least one blank sample with each set of samples. Handle the blank sampler in
the same manner as the other samples except draw no air through it.
2.2.7 Record the sample volume (in liters of air) for each sample, along with any potential interferences.
2.2.8 Ship any bulk samples in separate containers from the air samples.
2.2.9 Submit the samples to the laboratory for analysis as soon as possible after sampling. If delay is unavoidable, store the samples in a refrigerator.
2.3 Desorption efficiency
The desorption efficiency of 1-bromopropane was determined by liquid-spiking
the charcoal tubes with the analyte at 0.1 to 2 times the target concentration. The loadings on the tubes were 30.17,
150.8, 301.6 and 603.2 µg of 1-bromopropane. These samples were stored overnight at ambient
temperature and then desorbed and analyzed by GC-FID. The average desorption efficiency over
the studied range was 97.7%.
Table 2.3.1
Desorption Efficiency of 1-Bromopropane From CSC
|
| Tube # |
% Recovered |
|
0.1 ×
30.16µg |
0.5 ×
150.8µg |
1.0 ×
301.6µg |
2.0 ×
603.2µg |
|
1
2
3
4
5
6
 |
104.0
103.9
100.8
98.0
95.6
100.5
100.5 |
97.1
95.0
94.6
94.6
96.8
97.9
96.0 |
100.0
97.8
99.3
99.8
99.0
98.0
99.0 |
94.9
93.9
97.9
95.4
94.5
93.8
95.1 |
| overall |
97.7 |
| SD |
±2.19 |
|
2.4 Retention efficiency
The sampling tubes were spiked with 603.2 µg (50.3 mg/m3 based on a 12 L air sample)
1-bromopropane, allowed to equilibrate overnight at room temperature, and then 12 L humid air (80%
RH at 25°C) was drawn through them at 0.1 L/min. The sampling tubes were opened and the front section and the
back section were each put in separate vials. The samples were desorbed and analyzed by GC-FID. The
retention efficiency averaged 99.5%.
Table 2.4
Retention Efficiency of 1-Bromopropane
|
| Tube # |
Front Section |
Back Section |
Total |
|
1
2
3
4
5
6 |
82.0
82.0
84.0
80.5
82.3
82.0 |
16.5
18.0
16.0
19.7
17.5
16.2 |
98.5
100.0
100.0
100.2
99.8
98.2 |
|
|
|
99.5 |
|
2.5 Sample storage
The adsorbing sections of twenty-four sampling tubes were each spiked with 301.6 µg (5.0 ppm
or 25.1 mg/m3 based on a 12 L air sample) of 1-bromopropane. They were
sealed and stored at room temperature. The next day 12 L of humid air (80% RH at 25°C) was drawn through each
tube at 0.1 L/min. Half of the tubes were stored in a drawer at ambient temperature and the other half were stored
in a refrigerator at 0°C. After 7 days of storage six samples from the tubes stored under refrigeration and six
samples from ambient storage were analyzed. The remaining samples were analyzed after 15 days of storage. The
average recovery of the ambient and refrigerated storage samples was 97.7%.
Table 2.5
Storage Test for 1-Bromopropane
|
Ambient Storage
|
 |
Refrigerator Storage
|
| Time (days) |
% Recovered |
Time (days) |
% Recovered |
|
7
7
7
7
7
7
15
15
15
15
15
15
|
102.9
98.4
99.6
95.7
97.1
96.4
95.9
92.5
94.1
95.9
94.5
93.6
96.4 |
7
7
7
7
7
7
15
15
15
15
15
15
|
98.0
99.0
99.8
99.0
100.5
100.0
99.5
98.3
99.0
98.5
98.3
97.9
99.0 |
|
2.6 Recommended air volume and sampling rate.
Based on the data collected in this evaluation, 12 L air samples should be collected at a sampling rate of 0.1 L/min.
2.7 Interferences (sampling)
2.7.1 It is not known if any compounds will severely interfere with the collection of 1-bromopropane on coconut shell charcoal tubes. In general, the presence of other
contaminants in the air will reduce the capacity of the sampling tube to collect 1-bromopropane.
2.7.2 Suspected interferences should be reported to the laboratory with submitted samples.
2.8 Safety precautions (sampling)
2.8.1 Attach the sampling equipment to the worker in such a manner that it will not interfere with
work performance or safety.
2.8.2 Follow all safety practices of the Chemical Hygiene Plan that apply to the work area being sampled.
2.8.3 Wear eye protection at all times while in the work areas.
3. Analytical Procedure
3.1 Apparatus
3.1.1 A gas chromatograph equipped with a flame ionization detector. A Hewlett Packard model
5890 was used in this study.
3.1.2 A GC column capable of separating the analyte from any interferences. The column used
in this study was a 60-meter Rtx-volatiles fused silica capillary column with a 1.5-µm film
thickness and 0.32-mm i.d.
3.1.3 An electronic integrator or some suitable method of measuring peak areas. A Hewlett
Packard model 3396A and the Waters Millennium Data System was used in this study.
3.1.4 Four milliliter vials with Teflon-lined caps.
3.1.5 A 10-µL syringe or other convenient size for sample injection.
3.1.6 Pipets for dispensing the desorbing solution. A 2-mL Labindustries dispenser was used in this study.
3.1.7 Volumetric flasks - 10-mL and other convenient sizes for preparing standards.
3.1.8 A balance for weighing 1-bromopropane in standard preparation. A Ohaus Galaxy 160D was used in this evaluation.
3.2 Reagents
3.2.1 GC grade nitrogen, hydrogen and air.
3.2.2 1-Bromopropane (CAS 106-94-5). 1-Bromopropane, 99%, was obtained from Aldrich Chemical Company, Lot 08414LS.
3.2.3 Carbon disulfide (CAS 75-15-0). Carbon Disulfide, 99.99%, was obtained from EM Science, Lot 970338.
3.2.4 N,N-Dimethyl formamide (CAS 68-12-2). N,N-Dimethyl formamide, 99.5%, was obtained from Fisher Chemical, Lot 933764.
3.2.5 ρ-Cymene (CAS 99-87-6). ρ-Cymene, 99%, was obtained from Aldrich Chemical Company, Lot 11703TR.
3.2.6 The desorbing solvent consists of 99/1 (v/v) carbon disulfide/N,N-dimethyl formamide containing ρ-cymene internal standard at a concentration of 0.25 µL/mL.
3.3 Standard preparation
3.3.1 At least two separate stock standards are prepared by weighing a quantity of 1-bromopropane
and diluting with desorbing solution. The concentration of these stock standards was approximately 30.16 mg/mL.
3.3.2 Dilutions of these stock standards were prepared to bracket the samples. The range of
the standards used in this study was from 30.16 to 603.2 µg/mL.
3.4 Sample preparation
3.4.1 Sample tubes are opened and the front section and back section of each tube are placed
in separate 2-mL vials. Discard glass wool and foam plugs.
3.4.2 Each section is desorbed with 1 mL of desorbing solution.
3.4.3 The vials are sealed immediately and allowed to desorb for one hour on a mechanical rotator or
the vials are shaken vigorously by hand several times during the desorption time.
3.5 Analysis
3.5.1 Gas chromatograph conditions.
Injection size:
| 1 µL
|
Flow rates (mL/min)
|
| Nitrogen (make-up): | 30 |
| Hydrogen (carrier): | 2 |
| Hydrogen (detector): | 40 |
Air:
| 420
|
Temperatures (°C)
|
| Injector: | 200 |
| Detector: | 275 |
| Column: | 45 °C for 4 min, 10°/min to 200 °C, hold for 8 min at 200 °C. |
| Chromatogram: | 
Figure 3.5.1 Chromatogram at the target concentration. |
3.5.2 Peak areas are measured by an integrator or other suitable means.
3.6 Interferences (analytical)
3.6.1 Any compound that produces an FID 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 desorbed.
Generally, chromatographic conditions can be altered to separate an interference from the analyte. Using the
analytical conditions in this method, 2-bromopropane does not interfere.
3.6.2 When necessary, the identity or purity of an analyte peak may be confirmed by a GC-mass
spectrometer or by another analytical procedure.
Figure 3.6.2 Mass spectra of 1-bromopropane
3.7 Calculations
3.7.1 The calibration curve was made from at least four standards at different concentrations bracketing the samples.
3.7.2 The values for the samples are obtained from the calibration curve.
3.7.3 To calculate the concentration of analyte in the air sample the following formulas are used:
(µg/mL) (desorption volume)
(desorption efficiency) |
= mass of analyte in sample |
(mass of analyte in sample)
molecular weight |
= number of moles of analyte |
| (number of moles of analyte) |
(molar volume at 25°C & 760mm Hg) |
= |
(volume the analyte will occupy at 25°C & 760mm Hg) |
(volume analyte occupies) (106) *
(air volume) |
= ppm |
* All units must cancel.
3.7.4 The above equations can be consolidated to the following formula.
(µg/mL) (DV) (24.46) (106) (g) (mg)
(Liters)(DE) (MW)(1000mg)(1000µg) |
= ppm |
| µg/mL | = Concentration of analyte in sample or standard |
| 24.46 | = Molar volume (liters/mole) at 25°C and 760mm Hg |
| MW | = Molecular weight (µg/mole) |
| DV | = Desorption volume |
| Liters | = Liters of air sample |
| DE | = Desorption efficiency |
3.7.5 To calculate the mg/m3 of analyte in the sample:
(µg/mL) (DV) (mg) (1000 L)
(Liters) (DE) (1000 µg) (m3) |
= mg/m3 |
where:
| µg/mL | = Concentration of analyte in sample or standard |
| DV | = Desorption volume |
| Liters | = Liters of air volume |
| DE | = Desorption efficiency |
3.7.6 This calculation is done for each section of the sampling tube and the results added together after a blank correction is performed, if necessary.
3.8 Safety precautions
3.8.1 Adhere to the rules set down in your Chemical Hygiene Plan (which is mandated by the OSHA laboratory standard).
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 in the laboratory areas.
4. Recommendations for Further Study
Collection studies should be performed with controlled test atmospheres.
5. References
5.1 Lewis, Richard J. Sr., "Sax's Dangerous Properties of Industrial Materials", Eighth Edition, Van Nostrand Reinhold Co., New York, 1992, Vol. 2, p. 561.
5.2 Clayton, G.D. and F.E. Clayton, "Patty's Industrial Hygiene and Toxicology", Fourth Edition, John Wiley Sons, New York, 1994, Vol. 2E, pp. 4154-55.
5.3 Yu, X., G. Ichihara, J. Kitoh, Z. Xie, E. Shibata, M. Kamijima, N. Asaeda and Y. Takeuchi: Preliminary Report on the Neurotoxicity of 1-Bromopropane, an Alternative Solvent for Chlorofluorocarbons. Journal of Occupational Health. 1998, Vol. 40, pp. 234-235.
5.4 Protection of Stratosoheric Ozone; Listing of Substitutes for Ozone-Depleting Substances. Fed. Regist. 1999, Vol. 64 (Number 32), pp. 8043-8048.
5.5 Sweet, D., "Registry of Toxic Effects of Chemical Substances", 1985-86 ed., U.S. Department of Health and Human Services, Public Health Service, Center for Disease Control, NIOSH, 1987, Vol. 4, Index Number TX4110000, p.3754.
5.6 OSHA Computerized Information System Database, Material Safety Data Sheets (CCOHS Trade Names) Database; 1-Bromopropane; Revision Date: 02/08/99; OSHA SLTC, Salt Lake City, UT 84115-1802.
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