Page:NIOSH Manual of Analytical Methods - 6016.pdf/1

 AMMONIA by IC NH3

MW: 17.03

CAS: 7664-41-7

METHOD: 6016, Issue 1

6016 RTECS: BO0875000

EVALUATION: FULL

OSHA : 50 ppm NIOSH: 25 ppm; STEL 35 ppm; Group III Pesticide ACGIH: 25 ppm; STEL 35 ppm (1 ppm = 0.697 mg/m3 @ NTP)

PROPERTIES:

Issue 1: 15 May 1996

gas; MP -77.7 C; BP -33.4 C; VP 888 kPa (8.76 atm) @ 21.1 C; vapor density 0.6 (air = 1); explosive range 16 to 25% v/v in air

SYNONYMS: none SAMPLING SAMPLER:

MEASUREMENT

SOLID SORBENT TUBE (sulfuric acid-treated silica gel) a 0.8-µm MCE prefilter may be used to remove particulate interferences.

FLOW RATE:

0.1 to 0.5 L/min

VOL-MIN: -MAX:

0.1 L @ 50 ppm 96 L @ 50 ppm [1]

SHIPMENT:

routine

SAMPLE STABILITY:

at least 35 days @ 5 C [2]

BLANKS:

2 to 10 field blanks per set

TECHNIQUE:

ION CHROMATOGRAPHY, CONDUCTIVITY DETECTION

ANALYTE:

ammonium ion (NH4+)

EXTRACTION:

10 mL deionized water

INJECTION VOLUME:

50 µL

ELUENT:

48 mM HCl/4 mM DAP-HCl/4 mM L-histidine-HCl; 1 mL/min alternate: 12 mM HCl/0.25 mM DAP-HCl/ 0.25 mM L-histidine-HCl; 1 mL/min

COLUMNS:

HPIC-CS3 cation separator; HPIC-CG3 cation guard; CMMS-1 cation micromembrane suppressor

CONDUCTIVITY SETTING:

30 µS full scale

ACCURACY RANGE STUDIED:

17 to 68 mg/m [1] (30-L samples)

BIAS:

2.4% [1]

OVERALL PRECISION ( ACCURACY:

CALIBRATION:

standard solutions of NH4+ in deionized water

RANGE:

4 to 100 µg per sample [3]

3

rT): 0.071 [1]

ESTIMATED LOD: 2 µg per sample [3] PRECISION ( r):

0.038 [2]

± 14.5%

APPLICABILITY: The working range is 24 to 98 ppm (17 to 68 mg/m3) for a 30-L sample. This method is applicable to STEL measurements when sampled at 0.2 L/min. INTERFERENCES:Ethanolamines (monoethanolamine, isopropanolamine, and propanolamine) have retention times similar to NH4.+ The use of the alternate (weak) eluent will aid in separating these peaks.

OTHER METHODS: This method combines the sampling procedure of methods S347 [4] and 6015 with an ion chromatographic analytical procedure similar to Method 6701 [5] and OSHA Method ID-188 [3].

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 5/15/96