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
