Benzoyl Peroxide (5009)
BENZOYL PEROXIDE
(C6H5CO)2O2
MW: 242.22
METHOD: 5009, Issue 2
CAS: 94-36-0
5009
RTECS: DM8575000
EVALUATION: FULL
OSHA : 5 mg/m 3 NIOSH: 5 mg/m 3 ACGIH: 5 mg/m 3
PROPERTIES:
Issue 1: 15 February 1984 Issue 2: 15 August 1994
solid; MP 103 °C; d 1.334 g/mL @ 25 °C VP not significant; autoignition temperature 80 °C
SYNONYMS: dibenzoyl peroxide, benzoyl superoxide
SAMPLING
MEASUREMENT
SAMPLER:
FILTER (0.8-µm cellulose ester membrane)
TECHNIQUE:
HPLC, UV DETECTION
FLOW RATE:
1 to 3 L/min
ANALYTE:
benzoyl peroxide
VOL-MIN: -MAX:
40 L @ 5 mg/m 3 400 L
EXTRACTION:
ethyl ether, 10 mL
INJECTION VOLUME: 20 µL
SHIPMENT:
refrigerated
PRESSURE-COLUMN: 9000 kPa (1300 psi)
SAMPLE STABILITY:
9% loss from filter after 1 week @ 25 °C
MOBILE PHASE:
70/30 methanol/water; 1.6 mL/min
DETECTOR:
UV photometer @ 254 nm
BLANKS:
2 to 10 field blanks per set COLUMN:
250 mm x 3 mm-ID stainless steel; Spherisorb ODS (spherical silica particles with 5% bonded coating of octadecyl groups) or equivalent
CALIBRATION:
benzoyl peroxide in ethyl ether
ACCURACY RANGE STUDIED:
3 to 19 mg/m 3 [1] (90-L samples)
BIAS:
- 0.52%
ˆ ): OVERALL PRECISION (S rT
RANGE:
0.2 to 1.7 mg per sample [1]
ESTIMATED LOD:
0.01 mg per sample [2]
PRECISION (Sr):
0.024 [1]
0.060 [1]
ACCURACY:
± 11.82%
APPLICABILITY: The working range is 2 to 19 mg/m 3 for a 90-L air sample.
INTERFERENCES: None identified.
OTHER METHODS: This is Method S253 [3] in a revised format. A non-specific gravimetric method and a non-specific colorimetric method appear in the criteria document [4].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 BENZOYL PEROXIDE: METHOD 5009, Issue 2, dated 15 August 1994 - Page 2 of 3 REAGENTS: 1. 2. 3. 4. 5.
EQUIPMENT:
Benzoyl peroxide, 99% pure.* Ethyl ether, purified, without stabilizer.* Methanol, distilled in glass. Water, deionized and distilled. Calibration stock solution, 10 mg/mL. Dissolve 250 mg benzoyl peroxide in ethyl ether and dilute to 25 mL. Stable at least one week at 4 °C.
See SPECIAL PRECAUTIONS.
1. Sampler: cellulose ester membrane filter, 0.8-µm pore size, 37-mm diameter, with backup pad in cassette filter holder. 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. Refrigerated, bagged ("Blue Ice," or equivalent). 4. Vials, 20-mL, PTFE-lined caps. 5. High performance liquid chromatograph, 254-nm UV detector, sample injection valve with a 20-µL external sample loop, syringe filter, integrator and column (page 5009-1). 6. Tweezers. 7. Microliter syringes, 10- and 100-µL. 8. Volumetric flasks, 10- and 25-mL, assorted sizes. 9. Pipet, 10-mL, with pipet bulb.
SPECIAL PRECAUTIONS: Benzoyl peroxide is a flammable solid and may explode when heated; it will attack some plastics, rubber, and coatings [4]. Ethyl ether is highly flammable and forms explosive peroxides on exposure to air.
SAMPLING: 1. 2.
Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 1 and 3 L/min for a total sample size of 40 to 400 L. Do not exceed 2 mg particulate loading on the filter. Ship samples in an insulated container with bagged refrigerant.
3.
SAMPLE PREPARATION: 4. 5. 6.
Immediately upon receipt at laboratory, refrigerate the samples. As soon as possible after receipt, transfer each filter to a clean vial with tweezers. Pipet 10 mL ethyl ether into each vial; screw on cap. Swirl to mix.
CALIBRATION AND QUALITY CONTROL: 7. a. b. c. 8. a. b. c. 9.
Calibrate daily with at least six working standards covering the range 0.01 to 1.7 mg per sample. Add calibration stock solution with a microliter syringe to ethyl ether in a 10-mL volumetric flask and dilute to the mark. Analyze together with samples, blanks and control samples (steps 10 through 12). Prepare calibration graph of peak area vs. mass (mg) of benzoyl peroxide per sample. Determine recovery of benzoyl peroxide from filters at least once for each lot of samplers in the calibration range (step 7). Prepare three filters at each of five levels plus media blanks. Add aliquot of calibration stock solution with a microliter syringe directly onto a media blank filter in a vial. Prepare and analyze together with working standards (steps 5, 6 and 10 through 12). Prepare a graph of recovery vs. mg benzoyl peroxide recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 BENZOYL PEROXIDE: METHOD 5009, Issue 2, dated 15 August 1994 - Page 3 of 3 calibration graph and recovery graph are in control. MEASUREMENT: 10. 11. 12.
Set high performance liquid chromatograph according to manufacturer's recommendations and to conditions given on page 5009-1. Flush sample loop thoroughly with sample (0.1 mL) and inject sample. Measure peak area.
CALCULATIONS:
13. 14.
Read mass, mg (corrected for recovery), of benzoyl peroxide found on sample filters, W (mg), and on average blank filters, B (mg), from calibration graph. Calculate concentration, C (mg/m 3), of benzoyl peroxide in the air volume sampled, V (L):
EVALUATION OF METHOD: Method S253 was issued on January 21, 1977 [3], and validated over the range 3.1 to 19.1 mg/m 3 at 26 °C and 764 mm Hg, using 90-L samples [1,5]. The collection efficiency of the filter was determined to be 1.00, since no benzoyl peroxide was detected on a backup filter mounted directly behind the front filter. Storage stability studies on the filters held in the filter cassettes indicated a 9.3% decrease in the amount of benzoyl peroxide recovered after one week. Benzoyl peroxide was stable in ethyl ether at room temperature for at least one week. Overall precision, SˆrT, was 0.060. Recovery was 0.97 in the range 0.225 to 0.900 mg per sample for 18 spiked samples.
REFERENCES: [1] NIOSH Backup Data Report, S253, for Benzoyl Peroxide, prepared under NIOSH Contract No. 210-76-0123, available as "Ten NIOSH Analytical Methods, Set 2," Order No. PB 271-464, from NTIS, Springfield, VA 22161. [2] UBTL Memorandum, UBTL Analytical Laboratory Report for Benzoyl Peroxide, Sequence #2182-J (unpublished, February 29, 1980). [3] NIOSH Manual of Analytical Methods, 2nd. ed., V. 4, S253, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). [4] Criteria for a Recommended Standard...Occupational Exposure to Benzoyl Peroxide, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-166 (1977). [5] NIOSH Research Report-Development and Validation of Methods for Sampling and Analysis of Workplace Toxic Substances, U.S. Department of Health and Human Services, Publ. (NIOSH) 80-133 (1980).
METHOD REVISED BY: R. Alan Lunsford, Ph.D., NIOSH/DPSE; S253 originally validated under NIOSH Contract 210-76-0123.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94