# Hydrocarbons, Aromatic (1501)

​HYDROCARBONS, AROMATIC
FORMULA: Table 1
MW: Table 1
METHOD: 1501, Issue 3
CAS: Table 1
EVALUATION: Full
Group A:
benzene
toluene
Group B:
cumene
p-tert-butyltoluene
ethylbenzene
Table 1
o-xylene
"-methylstyrene
SAMPLING SAMPLER:
SOLID SORBENT TUBE (coconut shell charcoal, 100 mg/50 mg)
FLOW RATE:
Table 3
VOL-MIN: -MAX:
Table 3 Table 3
SHIPMENT:
Routine
SAMPLE STABILITY:
30 days @ 5°C
BLANKS:
10% of samples
RTECS: Table 1 Issue 1: 15 August 1990 Issue 3: 15 March 2003
PROPERTIES:
OSHA : Table 2 NIOSH: Table 2 ACGIH: Table 2 SYNONYMS: (Synonyms in Table 1)
1501
m-xylene $-methylstyrene
p-xylene styrene
MEASUREMENT TECHNIQUE:
GAS CHROMATOGRAPHY, FID
ANALYTE:
Hydrocarbons listed above
DESORPTION:
1 mL CS2 , stand 30 min with agitation
INJECTION VOLUME:
TEMPERATURE -INJECTION: -DETECTOR: -COLUMN:
1 µL (Group A: split 5:1; Group B: split 1:1)
250 °C 300 °C Group A: 40 °C (10 min) to 230°C (10 °C/min) Group B: 35°C (8 min) to 225°C (10°C/min)
CARRIER GAS:
He @ 2.6 mL/min
COLUMN:
Capillary, fused silica Group A: 30m x 0.32-mm ID; 1-µm film 100% PEG or equivalent Group B: 30m x 0.53-mm ID; 3-µm film crossbonded® 35% diphenyl 65% dimethyl polysiloxane or equivalent
CALIBRATION:
Solutions of analytes in CS 2
RANGE:
Table 4
ACCURACY RANGE STUDIED:
Table 3
BIAS:
Table 3
OVERALL PRECISION (Ö r T ):
Table 3
ACCURACY:
Table 3
ESTIMATED LOD: Table 4 PRECISION ( þ r ):
Table 4
APPLICABILITY: This method is for peak, ceiling, and TWA determinations of aromatic hydrocarbons. Interactions between analytes may reduce breakthrough volumes and affect desorption efficiencies. Naphthalene, originally validated in S292 [4], failed to meet acceptable desorption efficiency recovery and storage stability criteria at the levels evaluated in this study. However, the application of this method to naphthalene levels at or near the REL/PEL continues to meet acceptable recovery criteria. Styrene failed to meet acceptable recovery criteria at the two lowest levels evaluated in this study (highest level to meet the criteria was 181 µg/sample). INTERFERENCES: Under conditions of high humidity, the breakthrough volumes may be reduced. Other volatile organic compounds such as alcohols, ketones, ethers, and halogenated hydrocarbons are potential analytical interferences. OTHER METHODS: This method updates NMAM 1501 issued on August 15, 1994 [1] which was based upon P&CAM 127 (benzene, styrene, toluene, and xylene) [2]; S22 (p-tert-butyltoluene) [3]; S23 (cumene) [3]; S29 (ethylbenzene) [3] ; S26 ("-methylstyrene) [3]; S30 (styrene); S311 (benzene) [4]; S343 (toluene) [4]; and S318 (xylenes) [4].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ​HYD RO CAR BO NS, AR OM ATIC : MET HO D 150 1, Issue 3, dated 15 M arch 200 3 - page 2 of 7 REAGENTS:
EQUIPMENT:
1. Ca rbon disulfide*, low ben zene , chrom ato graphic quality. 2. Analytes, reagent grade. 3. Helium, prepurified and filtered. 4. Hydrogen, prepurified and filtered. 5. Air, prepurified and filtered.
1. Sam pler: glass tube, 7 cm long, 6-mm OD, 4mm ID, flame-sealed ends, containing two sectio ns of a ctivate d coconut s hell charcoal (front = 100 mg, back = 50 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precedes the front section and a 3mm urethane foam plug follows the back section. Tubes are comm ercially available. 2. Personal sampling pump, 0.01 to 1.0 L/min (Table 3), with flexible connecting tubing. 3. Gas chromatograph, FID, integrator, and colum ns (page 1501-1). 4. Autosampler vials, glass, 1.8 mL, with PTFElined caps. 5. Pipets, 1-mL, and pipet bulb. 6. Syringes, 10-µL, 25-µL, and 250-µL. 7. Volumetric flasks, 10-mL.
SPECIAL PRECAUTIONS: Carbon disulfide is toxic and extrem ely flam m able (flash point = -30°C), ben zene is a su spe ct ca rcinogen . Prep are s tand ards and sam ples in a we ll ventilated hoo d.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break the ends of the sampler imm ediately before sampling. Attach sampler to personal sam pling pum p with flexible tubing. 3. Sa m ple at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size as shown in Table 3. 4. Ca p the sam plers with plastic (not rub ber) cap s and pa ck sec urely for shipm ent.
SAMPLE PREPARATION: 5. Place the front and back sorbent sections of the sampler tube in separate vials. Include the glass wool plug in the vial along with the front sorb ent section . 6. Ad d 1.0 m L eluent to each vial. Attach crim p cap to each vial im m ediate ly. 7. Allow to stand at least 30 min with occasional agitation.
CALIBRATION AND QUALITY CONTRO L: 8. Calibrate daily with at least six working standards from below the LOD to 10 times the LO Q. If necess ary, add itional standa rds m ay be a dde d to exten d the calibra tion cu rve. a. Add known a m oun ts of a nalytes to carbon disulfide so lvent in 10-m L volum etric flas ks and dilute to the mark. Prepare additional standards by serial dilution in 10-mL volumetric flasks. b. Analyze together with samp les and blanks (steps 11 through 12). c. Prepare c alibration graph (pe ak area of analyte vs. µg analyte per sam ple).
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ​HYD RO CAR BO NS, AR OM ATIC : MET HO D 150 1, Issue 3, dated 15 M arch 200 3 - page 3 of 7 9. Determine desorption efficiency (DE) at least once for each batch of charcoal used for sampling in the calibra tion ran ge (s tep 8). a. Prepare three tubes at each of five levels plus three media blanks. b. Inject a known amount of DE stock solution (5 to 25 µL) directly onto front sorbent section of each charcoal tube with a microliter syringe. c. Allow the tubes to air equilibrate for several minutes, then cap the ends of each tube and allow to stand overnight. d. Deso rb (steps 5 through 7 ) and analyze together with standards and b lanks (steps 1 1 and 12). e. Prepare a graph of DE vs. µg analyte recovered. 10. An alyze a minimum of three quality control blind spikes and three analyst spikes to insure that the calibra tion gra ph and D E graph are in control.
MEASUREMENT: 11.
Set gas chromatograph according to manufacturer's recomm endations and to conditions given on page 1501-1. Inject a 1-µL sample aliquot manually using the solvent flush technique or with an autosam pler. Note: If peak area is above the linear range of the working standards, dilute with solvent, reanalyze, and app ly the app ropriate dilution facto r in the c alculations. Analyte
a b
Approximate Retention Time (min)
benzenea toluene a ethylbenzene a o-xylenea m -xylenea p-xylenea
3.52 6.13 10.65 12.92 11.33 11.04
cumene b p-tert-butyltolueneb "-methylstyrene b $-methylstyrene b styrene b
18.61 21.45 19.99 20.82 18.33
Separation achieved using a 30-m Stabilwax fused silica capillary colum. Separation achieved using a 30-m Rtx-35 fused silica capillary column.
12.
Measure peak areas.
CALCULATIONS: 13.
14.
Determine the mass, µg (corrected for DE ) of analyte found in the samp le front (W f) and back (W b) sorbent sec tions, and in the average m edia blank front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10, report breakthrough and possible sample loss. Calculate conce ntration, C, of analyte in the air volume sam pled, V (L):
NO TE : µg/L = m g/m 3
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ​ EVALUATION OF METHOD: The desorption efficiency, at levels ranging from 5 times the LOQ to 0.1x the REL, was determined for each analyte by spiking known amounts (in CS₂) on coconut shell charcoal tubes. Both groups of analytes (A and B) were spiked together on the charcoal sorbent tubes. All analytes, with the exception of styrene and naphthalene, exhibited acceptable desorption efficiency recovery results at all five levels evaluated. Styrene failed to meet the 75% recovery criteria at the 18.1 µg and 90.6 µg levels. Naphthalene failed to meet the 75% criteria at all levels evaluated ranging from 48.8 µg to 976.0 µg .
Each analyte , at a level approximately 0.05x REL/PEL, was evaluated for its storage stability @ 5°C after 7, 14, and 30 days. All analytes, with the exception of naphthalene, had acceptable recoveries after 30 days storage.
REFERENCES:
* NIOSH [1984]. Hydrocarbons, Aromatic: Method 1501. In: Eller PM, ed. NIOSH Manual of Analytical Method s. 4th rev. ed. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH ) Publication No. 94-1 13.
* NIOSH [1977]. NIOSH Manual of Analytical Methods, 2nd. ed., V. 1, P&CAM 127, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A.
* Ibid, V. 2, S22, S23, S25, S26, S29, S30, U.S. Department of Health, Education, and Welfare, Publ.(NIOS H) 77-15 7-B (1977 ).
* Ibid, V. 3, S292, S311, S318, S343, U.S. Department of Health , Education, and Welfare, Publ. (NIOSH) 77-157-C (1977).
* NIOSH [1977]. Documentation of the NIOSH Validation Tests, S22, S23, S25, S26, S29, S30, S292, S311, S318, S343, U.S. Department of Health, Education, and Welfare; Publ. (NIOSH) 77-185.
METHOD WRITTEN BY:
Stephanie M. Pendergrass, NIOSH/DART ​HYD RO CAR BO NS, AR OM ATIC : MET HO D 150 1, Issue 3, dated 15 M arch 200 3 - page 5 of 7 TABLE 1. SYNONY MS, FORM ULA, MO LECULAR WEIGHT , PROPERTIES Empirical Formula
Molecular Weight
Boiling Point (o C)
Vapor Pressure @ 25 o C (mm Hg)
(kPa)
Density @ 20 o C (g/mL)
C6 H6
78.11
80.1
95.2
12.7
0.879
p-tert-butyltoluene CAS #98-51-1 RTECS XS8400000 1-tert-butyl-4-methylbenzene
C1 1 H1 6
148.25
192.8
0.7
0.09
0.861
cumene CAS #98-82-8 RTECS GR8575000 isopropylbenzene
C9 H1 2
120.20
152.4
4.7
0.63
0.862
ethylbenzene CAS #100-41-4 RTECS DA0700000
C8 H1 0
106.17
136.2
9.6
1.28
0.867
"-methylstyrene CAS #98-83-9 RTECS WL5075300 isopropenylbenzene (1-methylethenyl)-benzene
C9 H1 0
118.18
165.4
2.5
0.33
0.909
$-methylstyrene CAS #873-66-5 RTECS DA8400500
C9 H1 0
118.18
175.0
0.911
toluene CAS #108-88-3 RTECS XS5250000 methylbenzene
C7 H8
92.14
110.6
28.4
3.79
0.867
C8 H1 0 (ortho) (meta) (para)
106.17 144.4 139.1 138.4
6.7 8.4 8.8
0.89 1.12 1.18
0.880 0.864 0.861
C8 H8
104.15
145.2
6.1
0.81
0.906
Name/Synonyms benzene CAS #71-43-2 RTECS CY1400000
xylenec CAS #1330-20-7 RTECS ZE2100000 dimethylbenzene (p-xylene) styrene CAS #100-42-5 RTECS WL3675000 vinylbenzene
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ​HYD RO CAR BO NS, AR OM ATIC : MET HO D 150 1, Issue 3, dated 15 M arch 200 3 - page 6 of 7
TABLE 2. PERMISSIBLE EXPOSURE LIMITS, PPM NIOSH
ACGIH mg/m3 per ppm
OSHA TWA
TWA
C
1
0.1a
1
10
10
50 (skin)
50 (skin)
ethylbenzene
100
100
125
100
125
4.34
"-methylstyrene
100
50
100
50
100
4.83
$-methylstyrene
100
50
100
50
100
4.83
toluene
200
100
150
50 (skin)
o-xylene
100
100c
150
100
150
4.34
m-xylene
100
100
100
150
4.34
p-xylene
100
100
100
150
4.34
styrene
100
50
50
100 (skin)
4.26
Substance benzene p-tert-butyltoluene cumene
STEL
TLV
STEL
10b
3.19
1
6.06
50 (skin)
4.91
20
100
3.77
a
Potential carcinogen Suspect carcinogen c Group I Pesticide
b
a
TABLE 3. SAMPLING FLOWRATE , VOLUME, CAPACITY, RANGE, OVERALL BIAS AND PRECISION
Substance benzene
Sampling Flowrate Volumeb (L) (L/min) MIN MAX
5
30
Breakthrough Volume @ Concentration (L) (mg/m3 ) >45
149
Range at VOL-MIN (mg/m3 )
Bias (%)
42 - 165
Overall Precision (ÖrT )
Accuracy (±%)
-0.4
0.059
11.4
c
p-tert-butyltoluene
1
29
44
112
29 - 119
-10.3
0.071
20.7
cumene
1
30
>45
480
120 - 480
5.6
0.059
15.2
-7.6
c
17.1
c
ethylbenzene
1
24
35
917
222 - 884
0.089
"-methylstyrene
1
30
>45
940
236 - 943
-7.6
0.061
16.9
$-methylstyrene
1
30
>45
940
236 - 943
-7.6
0.061
16.9
toluene
1
8
12
2294
548 - 2190
1.6
0.052
10.9
xylene (o-,m-,p-)
2
23
35
870
218 - 870
-1.2
0.060
12.2
styrene
<1.00
1
14
21
1710
426 - 1710
-7.9
0.058c
16.7
a b
c
Minimum recommended flow is 0.01 L/min. VM in = minimum sample volume @ OSHA TWA; VM a x = maximum sample volume @ OSHA TWA Corrected value, calculated from data in Reference 5.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ​HYD RO CAR BO NS, AR OM ATIC : MET HO D 150 1, Issue 3, dated 15 M arch 200 3 - page 7 of 7
TABLE 4. MEASUREMENT RANGE AND PRECISION a Measurement Substance
a
LOD (µg/sample)
Range (mg)
Precision ( Ö r)
benzene
0.5
0.004-0.35
0.013
p-tert-butyltoluene
1.1
0.013-1.09
0.017a
cumene
0.6
0.039-3.46
0.017
ethylbenzene
0.5
0.045-8.67
0.015
"-methylstyrene
0.6
0.036-3.57
0.014
$-methylstyrene
0.6
0.036-0.728
0.014
toluene
0.7
0.024-4.51
0.022
o-xylene
0.8
0.044-10.4
0.014
m-xylene
0.8
0.043-0.864
0.013
p-xylene
0.7
0.043-0.861
0.015
styrene
0.4
0.181-8.49
0.014
Corrected va lue, ca lculated from data in [5].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition