NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

BROMINE and CHLORINE 6011

Formula: 1) Br 2 MW: 1)159.82 CAS: 1) 7726-95-6 RTECS: 1) EF9100000

2) Cl 2 2) 70.91 2) 7782-50-5 2) FO2100000

METHOD: 6011, Issue 3 EVALUATION: FULL

 OSHA: 1) 0.1 ppm

2) C 1 ppm

NIOSH: 1) 0.1 ppm; STEL 0.3 ppm

2) C 0.5 ppm; 15 min ceiling

Other OELs: [1-3] 

Issue 1: 15 August 1989

Issue 3: 14 July 2022 

PROPERTIES: 1) liquid; d. 3.1028 g/mL @ 20 °C; BP 58.8 °C; VP

28.2 kPa (212 mm Hg) @ 25 °C; vapor density (air=1) 5.5; 1 

ppm=6.53 mg/m3

2) gas; d 2.898 g/L at 20 °C; BP -34.0 °C; vapor density (air=1)

2.5; 1 ppm=2.90 mg/m3 @ NTP [4] 

SYNONYMS: none

SAMPLING

SAMPLER: PREFILTER + FILTER

(PTFE, 0.5-μm + silver membrane,

25-mm, 0.45-μm)

FLOW RATE: 0.3 to 1 L/min

VOL-MIN: 1) 8 L @ 0.1 ppm

2) 2 L @ 0.5 ppm

 -MAX: 1) 360 L

2) 45 L

SHIPMENT: routine, protect from light

SAMPLE

STABILITY: ≥30 days at 25 ° [5,6] 

BLANKS: 2 to 10 field blanks per set

ACCURACY [5,6] 

RANGE 

STUDIED: 1) 0.07 to 1.42 mg/m3 (72-L samples)

2) 0.35 to 6.77 mg/m3 (15-L samples)

BIAS: 1) -1.2%

2) -1.4%

OVERALL

PRECISION 1) 0.069 

2) 0.075 

ACCURACY: 1) ± 13.6%

2) ± 14.8%

MEASUREMENT

TECHNIQUE: ION CHROMATOGRAPHY,

CONDUCTIVITY

ANALYTE: bromide ion (Br-

) or chloride ion (Cl-)

EXTRACTION: 3 mL 6 mM Na2S2O3, 10 min

INJECTION 

VOLUME: 50 μL 

COLUMN: polystyrene/divinylbenzene substrate 

agglomerated with anion exchange latex 

guard and analytical columns, metal-free

precolumn, anion micromembrane 

suppressor

DETECTOR 

SETTING: 10 μS full scale

ELUENT: 0.25 mM NaHCO3/4 mM Na2CO3/0.78 mM 

p-cyanophenol, 2 mL/min

CALIBRATION: standard solutions of Br- or Cl- in deionized 

water

RANGE: 5 to 150 μg Br- per sample

2 to 50 μg Cl- per sample [5,6] 

ESTIMATED LOD: 1.6 μg Br- per sample 

0.6 μg Cl- per sample [5,6] 

PRECISION 0.045 @ 5 to 100 μg Br- per sample

0.067 @ 5.3 to 100 μg Cl- per sample [5,6] 

APPLICABILITY: The working ranges are: for Br2 0.002 to 0.1 ppm (0.015 to 0.658 mg/m3

) for a 360-L air sample; for Cl2 0.015 to 1 

ppm (0.04 to 2.9 mg/m3) for a 45-L air sample. The method has sufficient sensitivity for STEL samples. 

INTERFERENCES: Hydrogen sulfide gives a negative interference. HCl gives a positive interference up to a maximum of 15 μg per 

sample. HBr gives a positive interference as it is sampled continuously. [5,6] 

OTHER METHODS: OSHA Methods ID-101 [7] and ID-108 [8] are alternative methods.
BROMINE and CHLORINE: METHOD 6011, Issue 3, dated 14 July 2022 - Page 2 of 6 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

REAGENTS:

1. Sodium thiosulfate (Na2S2O3), reagent grade.

2. p-Cyanophenol (C7H5NO), reagent grade.

3. Sodium bicarbonate (NaHCO3), reagent

grade.

4. Sodium carbonate (Na2CO3), reagent grade.

5. Sulfuric acid (H2SO4), conc., reagent grade.

6. Potassium bromide (KBr), reagent grade.

7. Potassium chloride (KCl), reagent grade.

8. Nitric acid (HNO3), conc., reagent grade.

9. Water, deionized (at least 18 MOhm-cm).

10. Extraction solution: 6 mM Na2S2O3. Dissolve

0.474 g Na2S2O3 in 500 mL deionized water.

11. Eluent: 0.25 mM NaHCO3/4 mM Na2CO3/0.78

mM p-cyanophenol. Dissolve 0.042 g

NaHCO3, 0.848 g Na2CO3 and 0.186 g pcyanophenol in 2 L filtered deionized water.

12. Suppressor regenerant, 0.025 N H2SO4.

Dilute 2.8 mL conc. H2SO4 to 4 L with

deionized water.*

13. Calibration stock solutions, 1 mg/mL (as

anion).

1. Dissolve 0.149 g KBr in 100 mL deionized

water.

2. Dissolve 0.21 g KCl in 100 mL deionized

water.

*See SPECIAL PRECAUTIONS.

EQUIPMENT:

1. Sampler: Silver membrane filter,+ 25-mm,

0.45-μm, with porous plastic support pad;

prefilter, PTFE with PTFE support, 0.5-μm, or

polyester, 0.4-μm with porous plastic support

pad; three-piece, 25-mm carbon-filled

polypropylene cassette (opaque) with 50-mm

extension (Fig. 1)

a. In the outlet piece of cassette, place

porous plastic support pad and cleaned

silver filter. Insert 50-mm extension

(cowl) securely.

b. At the inlet (top) of the extension, place

porous plastic support pad and prefilter.

Insert inlet cassette piece securely.

c. Seal each connection with shrinkable

bands or tape.

2. Personal sampling pump, 0.3 to 1 L/min, with

flexible connecting tubing.

3. Ion chromatograph with metal-free trap precolumn containing chelating resin, analytical

and guard ion-exchange columns containing

polystyrene/divinylbenzene substrate

agglomerated with anion exchange latex,

anion micromembrane suppressor,

conductivity detector and connected to a

data processing unit (page 6011-1).

4. Bottles, 30-mL, wide mouth with screw caps,

amber or opaque polyethylene.

5. Micropipettes, with disposable tips.

6. Volumetric flasks, 10- and 100-mL.

7. Repipet reagent dispensers, 0 to 10-mL.

8. Syringes, 10-mL, polyethylene, luer lock style

or equivalent.

9. Forceps.

10. Autosampler vials.

+

Silver membrane filters must be cleaned prior

to use (see APPENDIX A).

NOTE: Some lots of silver membrane filters

contain excessively high chloride 

background levels. After cleaning, 

please screen before field use.

SPECIAL PRECAUTIONS: Wear appropriate personal protective clothing, safety goggles, and gloves. All 

work should be performed with adequate ventilation. It is imperative that acid be added to water to avoid 

a violent exothermic reaction. Sulfuric acid is extremely corrosive to skin, eyes, and mucous membranes. 
BROMINE and CHLORINE: METHOD 6011, Issue 3, dated 14 July 2022 - Page 3 of 6 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

SAMPLING:

1. Calibrate each personal sampling pump with a representative sampler in line.

2. Attach sampler to personal sampling pump with flexible tubing.

3. Sample at an accurately known flow rate between 0.3 and 1 L/min for a total sample size of 8 to 360 L

for bromine or 2 to 45 L for chlorine.

4. Seal ends of sample with plugs. Pack securely for shipping.

NOTE: Silver halides are photosensitive. Protect from light during sampling, transfer, and desorption.

SAMPLE PREPARATION: 

5. Under very dim or red light, open cassette and transfer the silver filter with forceps to amber bottle.

Add 3 mL 6 mM Na2S2O3 and cap.

NOTE: Prefilter may be analyzed for particulate halides or discarded.

6. Allow samples to stand a minimum of 10 min with occasional swirling. Samples may remain in the

desorbing solution for up to 24 hours.

NOTE: Once desorbed, samples are no longer photosensitive.

7. Uncap the sample bottles and add 7 mL deionized water for a total solution volume of 10 mL.

8. Pour sample into 10-mL plastic syringe for manual injection or into autosampler vials.

CALIBRATION AND QUALITY CONTROL: 

9. Calibrate daily with at least six working standards covering the range of 0.2 to 15 μg bromide and/or

0.05 to 5 μg chloride per mL of sample.

a. Add known aliquots of calibration stock solution to deionized water in 10-mL volumetric flasks and

dilute to the mark with deionized water.

b. Prepare fresh working standards biweekly.

c. Analyze working standards together with samples and blanks (steps 11 through 13)

d. Prepare a calibration graph (peak height vs. μg of anion per sample)

10. Analyze three quality control spikes, three analyst spikes and media blanks to ensure that calibration

graph is in control.

MEASUREMENT:

11. Set ion chromatograph according to manufacturer’s instructions and to conditions given on page

6011-1.

NOTE: Excessive amounts of Ag+ and Ag(S2O3)2

3- deteriorate column performance. Use a metal-free

pre-column prior to the chromatographic columns and recondition the column every 100 to 150

analyses (See APPENDIX B).

12. Inject 50-μL sample aliquot manually or with autosampler. For manual operation, inject 2 to 3 mL of

sample from syringe to ensure complete rinse of the sample loop.

13. Measure peak height. If sample peak height exceeds linear calibration range, dilute with deionized

water, reanalyze, and apply the appropriate dilution factor in the calculations.

CALCULATIONS:

14. From the calibration graph, determine the mass of Br- or Cl- in each sample, W (μg), and in the average

blank, B (μg).

15. Calculate the concentration, C (mg/m3

), of Br2 or Cl2 in the air volume sampled, V (L):
BROMINE and CHLORINE: METHOD 6011, Issue 3, dated 14 July 2022 - Page 4 of 6 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

NOTE: μg/L = mg/m3

EVALUATION OF METHOD:

The method was evaluated by sampling generated atmospheres of Br2 and Cl2 at both high (80%) and low 

(20%) relative humidities [5,6]. Samples were taken at four concentration levels ranging from 0.007 to 1.42 

mg/m3 for Br2 and 0.354 to 6.77 mg/m3 for Cl2. Samples were analyzed using a Dionex 4000i Ion 

Chromatograph with conductivity detector and AutoRegen accessory (Dionex Corp., Sunnyvale, California), 

a WISP 710B autosampler (Waters Division of Millipore, Milford, Massachusetts), and interfaced with a 

Hewlett - Packard 3357 Laboratory Data System (Hewlett - Packard, Avondale, Pennsylvania). Dionex MFC1, HPIC-AG4A, HPIC-AS4A columns and AMMS anion micromembrane suppressor were used. Overall 

recovery for Br2 was 98.8% with total overall precision, of 6.8%. Overall recovery for Cl2 was 98.6% with a 

total overall precision, of 6.7%. Samples for Cl2 were stable at least 30 days at 25 °C (103 ± 4% recovery) 

and up to 60 days at 5 °C (101 ± 3% recovery). The Br2 samples were stable up to 60 days at 25 °C (99.2 ± 

10.1% recovery).

In this updated version of NIOSH 6011, Issue 3, the Chlorine and Bromine methods, found separately in the 

NMAM 4th edition, were combined. No new evaluation data are reported in this issue; however, the 

maximum sample volumes were recalculated using original data from the previous issue. 

REFERENCES:

[1] ACGIH [2021]. TLVs and BEIs based on the documentation of the Threshold Limit Values for chemical

substances and physical agents and Biological Exposure Indices. Cincinnati, Ohio: American

Conference of Governmental Industrial Hygienists, www.acgih.org.

[2] Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area

[2020]. List of MAK and BAT values 2020; Report 56. DFG: Deutsche Forschungsgemeinschaft,

https://series.publisso.de/sites/default/files/documents/series/mak/lmbv/Vol2020/Iss2/Doc002/mb

wl_2020_eng.pdf.

[3] Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) [no date].

GESTIS international limit values, http://limitvalue.ifa.dguv.de.

[4] CRC Press [2020]. John R. Rumble, ed. CRC Handbook of Chemistry and Physics, 101st Edition

(Internet Version 2020). Boca Raton, FL: CRC Press/Taylor & Francis.

[5] Cassinelli ME [1991]. Development of solid sorbent monitoring method for Chlorine and Bromine in

air with determination by Ion chromatography. App Occ Env Hyg 6:215-226.

[6] Cassinelli ME, Farwick DM [2021]. Backup data report for NIOSH Method 6011: Bromine and Chlorine.

[Website link here]

[7] OSHA [1991]. Chlorine in Workplace Atmospheres, OSHA Method ID-101. Salt Lake City, Utah: U.S.

Department of Labor, Occupational Safety and Health Administration.

[8] OSHA [1990]. Bromine in Workplace Atmospheres, OSHA Method ID-108. Salt Lake City, Utah: U.S.

Department of Labor, Occupational Safety and Health Administration.
BROMINE and CHLORINE: METHOD 6011, Issue 3, dated 14 July 2022 - Page 5 of 6 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

METHOD WRITTEN BY:

Mary Ellen Cassinelli, NIOSH

METHOD UPDATED BY:

Dawn Farwick, NIOSH/HELD

Disclaimer: Mention of any company or product does not constitute endorsement by the National 

Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. In addition, 

citations to websites external to NIOSH do not constitute NIOSH endorsement of the sponsoring 

organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of 

these websites. All web addresses referenced in this document were accessible as of the publication date.

APPENDIX A: CLEANING PROCEDURE FOR SILVER MEMBRANE FILTERS

1. Place each filter in a 30-mL, wide-mouth bottle, and add 3 mL 6 mM Na2S2O3.

2. Allow to stand for a minimum of 10 min with occasional swirling.

3. Discard solution and rinse thoroughly with deionized water. Allow the filters to stand in last rinse for a

few minutes.

4. Remove filters from bottles and dry between layers of absorbent laboratory towels.

5. Store cleaned filters between paper disks in manufacturer’s container. Filters are stable for a least 8

months.

NOTE: Some lots of silver membrane filters contain extremely high chloride background levels. If 

excessively high, this cleaning procedure will not remove all the chloride, even if repeated several 

times. Screening is necessary for each lot before being used for this method. Screening may be 

done by analyzing the cleaned filters starting with Step 5 of this method, or by analyzing by XRD.

Background levels should be ND to obtain optimal precision and accuracy. 

APPENDIX B: COLUMN RECONDITIONING PROCEDURE

In the following order, pump through the analytical columns at 2 mL/min:

a. 30 mL deionized water to rinse;

b. 60 mL 1 M HNO3 to remove contaminants;

c. 30 mL 0.1 M Na2CO3 to remove the NO3

-

;

d. Eluent to equilibrate.

Reconditioning is recommended after 100 to 150 analyses.
BROMINE and CHLORINE: METHOD 6011, Issue 3, dated 14 July 2022 - Page 6 of 6 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

Figure 1. Silver Filter Sampler