AMMONIA IN WORKPLACE ATMOSPHERES -
|OSHA Permissible Exposure
Final Rule Limit
(ammonium chloride fume
|35 ppm [Short-Term Exposure Limit
20 mg/m3 STEL*
mg/m3 [Time Weighted Average (TWA)]*
||50 ppm TWA|
||For ammonia collection, a personal sampling
pump is used to draw a known volume of air through a glass tube
containing carbon beads impregnated with sulfuric acid (CISA).|
0.10 liter per minute
||The sample is desorbed with deionized water
and analyzed as ammonium ion using an ion chromatograph.|
|Detection Limits Qualitative:
0.60 ppm (24-L air
1.9 ppm (7.5-L air sample)
||1.5 ppm (24-L air sample)|
4.8 ppm (7.5-L
30.7 to 101.8
Date (Date Revised):
|Robert G. Adler|
||Ammonium chloride fume or ammonium
sulfamate can be sampled and analyzed using this method. A
mixed-cellulose ester filter, polystyrene cassette, and personal
sampling pump (2 L/min) are used to collect the sample. Samples are
analyzed by ion chromatography after resorption in deionized
Commercial manufacturers and products mentioned in this
method are for descriptive use only and do not constitute endorsements by
USDOL-OSHA. Similar products from other sources can be
Branch of Inorganic Methods Development
Salt Lake City, Utah
This method describes the sample collection and analysis of airborne
ammonia. Ammonium chloride fume or ammonium sulfamate can also be
analyzed using this method. Samples are taken in the breathing zone of
workplace personnel and are analyzed by ion chromatography (IC).
The previous OSHA sampling procedure for ammonia involved the use
of a midget fritted glass bubbler containing 0.1 N sulfuric acid
(H2SO4) (8.1, 8.2). Bubbler sampling is inconvenient to use.
It involves the use of a liquid which if
spilled may be irritating to the skin or
may damage sampling pumps. Also, the sample
solutions may leak during shipment.
The present method employs glass tubes containing
CISA which avoids liquid sampling media problems.
It is based on a procedure described by Bishop,
et. al. (8.3).
Two analytical procedures have previously been used by OSHA. In the
earliest procedure, ammonia was analyzed by a colorimetric method
using Nessler reagent (8.2, 8.4). This method has significant interferences.
The most recent method involved the use of
the ammonia ion specific electrode (ISE)
which does not discriminate between ammonia
and amines (8.1).
The present method provides an analytical procedure which is easily
set up and automated. Partial processing of the data is performed
while the analysis is in progress.
1.1.3. An alternate screening technique for
measuring ammonia exposures in the workplace
involves the use of detector tubes (8.5). Other methods are needed to determine
long-term ammonia concentrations since short-term
detector tubes offer only spot checks of
A known volume of air is drawn through a sampling tube containing
carbon beads impregnated with sulfuric acid (CISA). Ammonia is collected
and converted to ammonium sulfate. Samples are desorbed using a known
volume of deionized water (DI H2O) and
analyzed as ammonium ion by IC. For ammonium chloride fume or ammonium
sulfamate, samples are collected on 0.8-µm mixed-cellulose ester
filters, desorbed in DI H2O, and also analyzed
as ammonium ion by IC.
1.3 Advantages and Disadvantages
1.3.1 This method has adequate sensitivity for determining
compliance with the OSHA permissible exposure limit (PEL) for
workplace exposures to ammonia.
1.3.2 The method is simple, rapid, and easily automated.
1.3.3 Previous IC methods for ammonia have
described rapid loss of peak resolution resulting
primarily from metal-column binding. Using
equivalent equipment described in Section
6.2 eliminates eluent contact with metal surfaces,
subsequent corrosion and rapid loss of resolution
due to metals binding on the separator column.
1.3.4 Previous studies have also indicated changes in ammonium peak
characteristics with changes in pH. When using the equipment and
conditions described herein, retention times or peak shapes were not
significantly affected when the diluent concentration was from 0.0001
to 0.02 N H2SO4.
The peak characteristics were significantly different when a diluent
of 0.1 N H2SO4 was
used. (Note: due to the
H2SO4 on the
beads, a 25 mL solution volume = 0.02 N
1.3.5 Potential exposure to
H2SO4 is reduced
in comparison to previous methods for ammonia.
1.3.6. The analysis is specific for the ammonium ion
1.3.7 After sample preparation (and acidification with additional
H2SO4), ammonia can also be determined by the
ISE analytical technique (8.1) or a calorimetric procedure (8.2).
1.3.8 One disadvantage is that ammonium salts present in the air as
dust would constitute a positive interference; however, particulate
will be captured in the glass wool plug preceding the acid-treated
beads. A polystyrene cassette containing a mixed-cellulose ester
filter can also be used as a prefilter to collect any particulate.
1.3.9 Another disadvantage is the positive
interference from monoethanolamine, isopropanolamine,
or propanolamine. If present, these compounds
will produce peaks in the vicinity of the
ammonium ion when using this method. Mobile
phase ion chromatography (8.6) can be used for confirmation of ammonia
if these compounds are present.
1.4 CAS No. and Physical Properties (8.7, 8.8)
|Density, gas (air = 1)
||11.3 × 103 kPa|
||16-25% (by volume in air)|
Hot water (100°C)
89.9 g/100 cc
7.4 g/100 cc
|Lower limit of perception
||Approximately 20 ppm|
|Ammonium chloride CAS No.
|Ammonium sulfamate CAS No.
1.5 Prevalence and Use
Ammonia is a widely used chemical, being
involved in the manufacture of fertilizers,
nitric acid, explosives, and synthetic fibers.
It is also used in refrigeration (8.8). Occupations with the potential for exposure
to ammonia include the following (8.7):
Coal tar workers
Compressed gas workers
Organic chemical synthesizers
Rocket fuel makers
Soda ash makers
1.6 Toxicology (8.7, 8.9, 8.10)
||Information contained within this section is a
synopsis of present knowledge of the physiological effects of
ammonia and is not intended to be used as a basis for OSHA
Ammonia forms a strong alkaline solution in water, and the high
solubility and strong alkalinity make it especially irritating to the
upper respiratory system. Exposure to ammonia can occur not only from
the vapor but also from the liquid and from concentrated aqueous
solutions. Depending upon the exposure, symptoms can range from mild
upper respiratory irritation to inflammatory processes of the entire
respiratory tract with complications of pulmonary edema and
bronchopneumonia. Symptoms may also include hoarseness and tightness in
the throat. The odor threshold for ammonia varies among the reports
received; 50 ppm is known to produce a strong odor. Brief exposure to
100 ppm increases nasal air flow resistance, possibly from vascular
congestion, edema and increased mucus secretion. Mild irritation of the
eyes, nose and throat is produced by 50 ppm but not by 25 ppm.
Acclimation appears to develop to 50 ppm within one week, and to 100 ppm
within 2 to 3 weeks of repeated exposure. Volunteers exposed to 500 ppm
for 30 minutes experienced hyperventilation and an increase in
respiratory rate. Exposure to 1,000 ppm produced immediate coughing.
Exposures to 700 to 1,700 ppm can be incapacitating due to extreme
lacrimation and coughing. The eyes, skin and respiratory tract may be
severely inflamed. Massive accidental exposure can be quickly fatal;
autopsies of individuals who have died from exposure have indicated
severe damage at every level of the respiratory system, including edema
and hemorrhage. Skin burns from exposure to liquid ammonia can also
occur. Ammonia is irritating to the eyes; failure to irrigate the eyes
with a considerable amount of water following heavy exposure may lead to
- Range, Detection Limit and Sensitivity (8.11)
2.1 This method was validated over the concentration range of 30.7 to
101.8 ppm. Air volumes of about 21 L and flow rates of about 0.1 L/min
were used. The average sampling time was 210 min.
2.2 The qualitative detection limit was 0.2 µg/mL or 10.0 µg (as
NH3) when using a 50-mL solution volume. This
corresponds to 0.60 ppm NH3 for a 24-L air
volume. The quantitative detection limit was 0.50 µg/mL or 25 µg (as
NH3) when using a 50-mL solution volume. This
corresponds to 1.5 ppm NH3 for a 24-L air
volume. A 50-µL sample loop and a 30 microsiemens detector setting were
used for both IC detection limit determinations.
2.3 The sensitivity of the analytical method,
when using the instrumentation specified
in Section 6.2, was calculated from the slope of a linear
working range curve (1 to 10 µg/mL ammonium
ion). The sensitivity was 12,380 area counts
per 1 µg/mL ammonium ion (a Dionex AutoIon
400 data reduction system was used). Data
manipulation was also performed using a Hewlett-Packard
3357 Laboratory Automation System. The sensitivity
for this system was 361,000 area counts per
1 µg/mL ammonium ion (1 area count = 0.25
microvolt-second for the Hewlett-Packard
- Method Performance (8.11)
Test results are based on samples collected from an in-house dynamic
generation system at flow rates of approximately 0.1 L/min and sampling
times of 180 to 240 min. Exceptions are noted below.
3.1 The pooled coefficient of variation
(CVT) for samples taken in the range of 30.7
to 101.8 ppm was 0.050. The method exhibited slight negative bias
(-0.009). overall error was within acceptable limits at ±10.9%.
3.2 The collection efficiency at about 2 times the PEL was 100%.
3.3 Breakthrough tests were performed at a concentration of 258 ppm,
50% RH, and 25°C. Breakthrough of ammonia into backup sections of
sorbent was undetectable. Samples were collected for 335 min.
3.4 Samples can be stored at ambient (20 to 25°C) laboratory
conditions for at least 29 days. The mean recovery of samples analyzed
after 29 days was within 5% of the mean recovery of samples analyzed
after 1 day of storage. Samples were stored in an office desk.
3.5 Sampling tubes stored 11 months before use gave satisfactory
results during validation experiments.
4.1 When other compounds are known or suspected to be present in the
air, such information should be transmitted with the sample.
4.2 Any compound having the same retention
time as the ammonium ion, is an interference.
The following compounds were noted as potential
interferences with ammonium ion when using
the equipment and conditions stated in Section
Methyl- and dimethylamine, mono- and diethanolamine, iso- and
4.2.1 Methylamine and ammonium are not separated
well in a 1:1 mixture (Figure 1a and 1b). Dimethylamine and ammonium in a 1:1 mixture
show better resolution (Figure 1c).
- 1) Both mixtures displayed diminished
peak areas for the ammonium ion; however}
ammonium peak heights were similar to the
10 µg/mL standard shown in Figure 1a. If an interference of this type is present,
peak heights can be used for calculations
instead of peak areas.
- 2) An alternate eluent (0.012 M HCl)
offered sufficient resolution between ammonia
and methyl- or dimethylamine (Figure 1d and 1e). This eluent can be used for confirmation
4.2.2 A peak in the same vicinity as ammonia
was noted when a dilute monoethanolamine
(MEA) solution was analyzed (see Figure 1f). The detector response for MEA is about
one-half that seen for ammonia at a concentration
of approximately 10 µg/mL (Figure 1a and 1f). Separation of ammonium and MEA was not
noted when a 1:1 mixture (10 µg/mL for each)
was analyzed when using either the recommended
or the alternate eluent.
||The MEA used for this study contained trace
contaminants as shown by peaks 1 and 3 in
Figure 1f. These peaks probably represent trace amounts
of sodium and potassium ions, respectively.)|
4.2.3 Diethanolamine (DEA) also produces a response; however, this
response is only noticeable at very large concentrations. A
concentration of 10 µg/mL DEA did not produce a measurable peak.
4.2.4 Propanolamine and isopropanolamine elute at approximately the
same time and with a similar response as MEA.
4.2.5 If necessary, the presence of ammonia,
methyl- or dimethylamine, MEA, isopropanolamine
or propanolamine can be confirmed using mobile
phase ion chromatography (8.6).
4.3 Contaminant cations, such as Na+ and
K+, do not interfere when using the conditions
and instrumentation specified. When using
the conditions described in Section 6, peak retention times of individual 10 µg/mL
solutions of various analytes were:
||Retention Time (min)|
||The listing above is for information only. The
majority of these analytes will most likely not be present when
sampling for ammonia. Retention times may vary
4.4 Interferences may be minimized by changing the eluent, eluent
concentration or pump flow rate.
4.5 Complete separation and quantitation
of low molecular weight alkyl amines as well
as the alcoholic amines can be achieved using
mobile phase ion chromatography (8.6) or alternate sampling and analytical methods
4.6 Alternate ISE or calorimetric methods
can also be used (8.1, 8.2); however, interferences are a significant
problem for both methods.
4.7 Ammonium salts present as dust would interfere; however, this
material should be collected in the glass wool plug preceding the
collecting medium. A prefilter consisting of a mixed-cellulose ester
filter in a polystyrene cassette can also be used if a large amount of
particulate is present in the atmosphere. Preliminary tests comparing
sampling tubes with and without a prefilter did not indicate a
significant difference in recoveries; therefore, ammonia did not react
with the prefilter components. Tests were conducted using a dynamic test
atmosphere of 184 ppm NH3 at 50% RH and 25°C.
5.1 Equipment - Ammonia Sampling
5.1.1 Personal sampling pumps capable of sampling within ±5% of the
recommended flow rate of 0.1 L/min.
5.1.2 Carbon bead, 20/30 mesh (Kureha Chemical Industry Co., 420
Lexington Ave., Suite 1742, NY, 10170, phone no. 212-867-7040).
5.1.3 Sampling tubes which contain an adsorbing section consisting
of carbon beads treated with
H2SO4. Tubes are
commercially available, but may also be easily prepared
(Caution: Sulfuric acid can cause severe burns. Wear protective
gloves, labcoat and eyewear when using
- The commercially available tube consists of two sections; a 500-mg
carbon bead front and a 250-mg backup section (ORBO-77 Tubes, cat. no.
582-12, Supelco Inc., Bellefonte, PA or SKC cat. no. 226-29, SKC, Eighty
- Ammonia collection tubes may be prepared
according to the method of Bishop, Belkin
and Gaffney (8.3). The following is a variation of this method:
Thirty-one sampling tubes can be prepared
using 23 g of carbon beads. The beads are
placed in a beaker, rinsed five times with
0.01 N H2SO4 and then five
times with DI H2O . Sufficient concentrated
H2SO4 (1.2 g of acid
for 23 g of beads) is added so the final product, when dried, will
consist of 5% acid by weight. Enough DI H2O to
just cover the beads is also added and the con ents are mixed. The
product is dried at 110°C overnight in a drying oven. The beads are
mixed and then packed into glass tubes, 10 cm × 8 mm o.d. × 6 mm id. The
front absorbing section contains 500 mg and the backup section 250 mg of
carbon beads. Each section is held in place by glass wool plugs. The
tubes are capped with plastic end caps or are fire sealed.
5.1.4 A stopwatch and bubble tube or meter are used to calibrate
the pumps. A blank sampling tube or device is placed in-line during
flow rate calibration.
5.1.5 Various lengths of flexible tubing are used to connect the
sampling tubes to the pumps.
5.1.6 Mixed-cellulose ester filters and polystyrene
be used as prefilters if particulate
are a potential problem. See
Section 5.3 for further details.
5.2 Sampling Procedure - Ammonia
5.2.1 Calibrate the sampling pumps to the recommended flow rate of
0.1 L/min for TWA determinations or to 0.5 L/min for STEL
5.2.2 Connect the sampling tube to the pump such that air enters
the larger (500 mg) section first.
5.2.3 Place the sampling tube in the breathing zone of the
5.2.4 Sample with the pre-calibrated pump at the listed flow rate
and sampling time. The recommended sampling time is 4-h for TWA
assessments, giving a total air volume of about 24-L. For STEL
determinations, sample for 15 min.
5.2.5 Prepare one sampling tube as a blank sample. Treat this tube
the same as the samples except that no air is drawn through it.
5.2.6 Place plastic end caps on each tube after sampling. Attach an
OSHA seal around each tube to secure the end caps. Send the samples
along with a blank sample to the laboratory with the OSHA 91A
paperwork requesting ammonia analysis.
5.2.7 Bulks can also be submitted for analysis. Ship bulk samples
separately from air samples. They should be accompanied by Material
Safety Data Sheets if available. Check current shipping restrictions
and ship laboratory by the appropriate method.
5.3 Sampling for Ammonium Chloride or Ammonium
The following equipment is used:
- Mixed-cellulose ester (MCE) filters (0.8 µm pore size), cellulose
backup pads, and cassettes, 37-mm diameter (part no. MAWP
037 AO, Millipore Corp., Bedford, MA).
- Gel bands (Omega Specialty Instrument Co., Chelmsford, MA) for
- Calibrated sampling pumps - 0.1 to 2 L/min flow rate.
Connect the MCE filter/cassette assembly to a calibrated sampling
pump and collect samples at a flow rate of about 2 L/min.
||If the filters are to be used as prefilters, attach
the cassette to the CISA sampling tube with a minimum amount of
tubing, and attach the free end of the CISA tube to the sampling
pump. Sample at a flow rate of 0.1 L/min if a prefilter is
Sample for at least 15 min for STEL measurements and up to 8 h for
TWA determinations. After sampling, seal and submit the samples to the
laboratory. Request analysis for ammonium sulfamate or ammonium
6.1.1 Refer to instrument and standard operating
(SOP) manuals (8.14) for proper operation.
6.1.2 Observe laboratory safety regulations and practices.
Caution: Sulfuric or hydrochloric acid can cause severe burns.
Wear protective gloves, labcoat and eyewear when using these acids.
6.2.1 Ion chromatography (Model 2010i, Dionex, Sunnyvale, CA)
equipped with a conductivity detector.
6.2.2 Automatic sampler (Model AS-1, Dionex) and sample vials (0.5
6.2.3 Data processing system (AutoIon 400 System, Dionex).
6.2.5 Cation separator column (Model HPIC-CS3, Dionex).
6.2.6 Cation guard column (Model HPIC-CG3, Dionex).
6.2.7 Cation micromembrane suppressor (Model CMMS-1 suppressor,
6.2.8 Disposable syringes (1 mL) and prefilters.
||Some prefilters are not cation- or anion-free.
Tests should be done with blank solutions first to determine
suitability for the analyte being determined).|
6.2.9 Polyethylene scintillation vials (20 mL) with polyethylene
cap liners (Part No. 58515, Kimble, Toledo, OH).
6.2.10 Miscellaneous volumetric glassware: Beakers, graduated
cylinders, beakers, and volumetric flasks (0.25 to 4 L).
6.2.11 Analytical balance (0.01 mg).
6.3 Reagents - All chemicals should be reagent
grade or better
6.3.1 Deionized water (DI H2O) with a
specific conductance of less than 10 microsiemens.
6.3.2 Hydrochloric acid (HCl) solution (1 N):
Dilute 166 mL of concentrated HCl to 2.0 L with DI
6.3.3 Strong eluent (48 mM HCl, 4 mM DAP-HCl, 4 mM L-histidine
-HCl): Weigh 0.560 g 2,3-diaminopropionic acid monohydrochloride
(DAP-HCl) and 0.840 g L-histidine monohydrochloride monohydrate and
then place in a 1-L volumetric flask. Add 48 mL of 1 N HCl. Dilute to
volume with DI H2O. Mix thoroughly. Prepare
6.3.4 Weak eluent (12 mM HCl, 0.25 mM DAP-HCl,
0.25 mM L-histidine-HCl):
||Prepare a new solution for each analysis. Aged
solutions of weak eluent tend to lose buffering capacity.
Chromatographic dips in the vicinity of the ammonium peak have
been noted using aged eluent and may lead to erroneous results.
These dips only occur with samples (which contain a small amount
of sulfuric acid) and do not occur with standards (prepared with
Dilute 252 mL of strong eluent and 36 IRL of 1 N HCl to 4.0 L with
DI H2O. Mix thoroughly.
6.3.5 Alternate eluent (12 mM HCl):
This eluent is only used if potentially resolvable
interferences are present (See Section 4.2.1 for further information). Dilute 48 mL of
1 N HCl to 4.0 L with DI H2O. Prepare a new solution for each
6.3.6 Regeneration solution [0.04 N tetramethylammonium hydroxide
(Note: The purity of the reagent must be considered when preparing the
0.04 N TMAOH solution.): Commercially prepared solutions of 25% TMAOH
can be used (25% TMAOH, cat. no. 33,163-5, Aldrich Chemical Co.,
Milwaukee, WI). Dilute 57.4 mL of 25% TMAOH to 4 L with DI
H2O. An alternative preparation is to
dissolve 29.00 g of tetramethylammonium hydroxide pentahydrate
in 4.0 L of DI H2O.
6.3.7 The eluent
used with CSRS suppressor, IonPac CS12 column, and CG12 guard column
is 20 mM methane sulfonic acid (CH3SO3H)
solution. Dilute 5.2 mL methane sulfonic acid to 2.0 L with DI
H2O (Methane sulfonic acid, cat. no. M860-6, Aldrich
Chemical Co., Milwaukee, WI).
6.3.8 Sulfuric acid solution (0.1 N): Dilute 5.6 mL of
to 2.0 L with DI H2O.
6.3.9 Ammonia stock standard (1,000 µg/mL ammonia): Dissolve
3.141 g of ammonium chloride in 0.1 N
H2SO4 and dilute
to the mark in a 1-L volumetric flask. Prepare every month.
6.3.10 Ammonia standard (100 µg/mL). Dilute 50 mL of the 1,000
µg/mL ammonia stock standard to 500 mL with DI
H2O. Prepare weekly.
6.3.11 Ammonia standard (10 µg/mL). Dilute 50 mL of the 100 µg/mL
ammonia stock standard to 500 mL with DI
H2O. Prepare weekly.
6.4 Working Standard Preparation
6.4.1 Ammonia working standards may be prepared weekly in the
* Already prepared in Section 6.3
6.4.2 Pipette appropriate aliquots from standard
solutions prepared in Section 6.3 into volumetric flasks of the final volumes
specified. Dilute to volume with DI H2O.
6.4.3 Pipette a 0.5- to 0.6-mL portion of each standard solution
into separate automatic sampler vials. Place a 0.5-mL filter cap into
each vial. The large exposed filter portion of the cap should face the
standard solution. Also prepare a reagent blank from the DI
H2O used for standard preparation.
6.5 Sample Preparation - CISA Samples
||For the CISA samples, always use a final solution
volume >25 mL.|
6.5.1 Carefully remove and discard the glass wool plugs from the
sample tubes, making sure that no sorbent is lost in the process.
Transfer each sorbent section into individual polyethylene
6.5.2 Add 10 mL of DI H2O to each vial,
cover vials with polyethylene lined caps and then shake vigorously for
about 30 s. Allow the solutions to settle for at least 1 h.
6.5.3 Quantitatively transfer each front section desorption
solution to individual 25- or 50-mL volumetric flasks.
6.5.4 Rinse the beads in the vial with additional portions of DI
H2O and also transfer this rinse to the
flask. Take care so the beads are not transferred to the flask.
6.5.5 Dilute to volume with DI H2O. Also
transfer each backup section resorption solution to individual 25- or
50-mL volumetric flasks and dilute to volume.
6.5.6 An alternate method of resorption and dilution is: Place the
beads into 25- or 50-mL volumetric flasks. Measure the appropriate
amount of DI H2O using a pipette or
graduated cylinder and add this to the carbon beads.
6.5.7 If the sample solutions contain
particulate, remove the particles using a prefilter and syringe. Fill
the 0.5-mL automatic sampler vials with sample solutions and push a
filtercap into each vial.
6.5.8 Load the automatic sampler with labeled
samples, standards and blanks.
6.6 Sample Preparation - Ammonium Chloride Fume or Ammonium Sulfamate
6.6.1 Open the filter cassette, carefully remove the sample filter
with forceps, and place in a scintillation vial. If the cassette
contains loose dust, carefully rinse the dust into the vial with DI
H2O. If necessary, wipe out the dust with a
clean MCE filter and place this filter in the vial. If the backup pad
appears to be discolored, it may be due to leakage of air around the
filter during sampling. In these cases, the pad should also be
prepared and analyzed. Place the backup pad in a separate vial. Also
prepare a blank backup pad.
6.6.2 Add 10 mL of DI H2O to each scintillation vial. Allow to sit
for at least 1 h with occasional agitation
of the solution and filter. Proceed with
the analysis as described in Sections 6.5.7-6.5.8 and 6.7
6.7 Analytical Procedure
6.7.1 Set up the ion chromatography in accordance
with the SOP (8.14) or instrument manuals.
Typical operating conditions for a Dionex 2010i with an automatic
sampler are listed below:
Eluent (Section 6.3.4):
approximately 7 microsiemens
2 to 3 mL/min (0.04 N TMAOH)
Sample injection loop:
approximately 550 psi
Average peak retention time:
3.7 to 3.9 min
If the alternate eluent is used, allow a longer
period of time for the ion chromatography to equilibrate (2 to 3
h). The retention time of the ammonium ion will be much longer
with the alternate eluent.
6.7.2 If an ion chromatography is not available, the sample
solutions may be acidified with
H2SO4 to 0.1 N and analyzed with an ammonia ISE
as described in Method No. ID-164 (8.1).
7.1 After the analysis is completed, peak
areas and heights can be retrieved using
a variety of methods or programs (8.14). Hard copies of chromatograms, which list
peak heights and areas, can be obtained from
a printer. An example chromatogram containing
3 µg/mL sodium, 20 µg/mL ammonium, and 10
µg/mL potassium ions is shown in Figure 2.
7.2 prepare a concentration-response curve by
plotting the concentration of the standards in µg/mL (or µg/sample if
the same solution volumes are used for samples and standards) versus
peak areas or peak heights. Blank correct each sample section (sample
and blank solution volumes should be the same). Add the backup section
results to the front section results for each tube.
7.3 The concentration of ammonia in each air sample is expressed in
ppm. The equation is:
ppm NH3 =
molar volume × µg/mL NH3
× solution volume (mL)
formula weight × air volume (L)
24.46 (25°C and 760 mm Hg)
Blank corrected value from Section 7.2
7.4 For ammonium chloride fume or ammonium sulfamate:
mg/m3 analyte =
µg/mL NH3 × solution
volume (mL) × GF
Blank corrected value from Curve
7.5 Report CISA results to the industrial hygienist as ppm ammonia.
Report ammonium chloride or ammonium sulfamate results as
mg/m3. Ammonium chloride or sulfamate results
are based on the analysis of the ammonium ion; other ammonium salts
present in the air during sampling may be a positive interference.
8.1 Occupational Safety and Health
Administration Analytical Laboratory: OSHA Analytical Methods
Manual (OSHA-SLCAL Method No. ID-164). Cincinnati, OH: American
Conference of Governmental Industrial Hygienists (Pub. No. ISBN:
8.2 Occupational Safety and Health
Administration Analytical Laboratory: OSHA Manual of Analytical
Methods edited by R.G. Adler (OSHA-SLCAL Method No. VI-1). Salt Lake
City, UT. 1977.
8.3 Bishop, R.W., F. Belkin and R. Gaffney:
Evaluation of a New Ammonia Sampling and Analytical Procedure. Am.
Ind. Hyg. Assoc. J. 47: 135-137 (1986).
8.4 National Institute for Occupational Safety
and Health: NIOSH Manual of Analytical Methods, 2nd ed., Vol.
1 (HEW/NIOSH Pub. No. 77-157-A). Cincinnati, OH: National Institute
for Occupational Safety and Health, 1977.
8.5 Occupational Safety and Health
Administration Analytical Laboratory: Ammonia Detector Tubes
(PE-7). Salt Lake City, UT. 1987.
8.6 Dionex Corp.: Basic Ion
Chromatography. Sunnyvale, CA: Dionex Corp., 1983.
8.7 National Institute for Occupational Safety
and Health: Criteria for a Recommended Standard . ..Occupational
Exposure to Ammonia) (HEW/NIOSH Pub. No. 74-136). Cincinnati, OH:
National Institute for Occupational Safety and Health, 1974.
8.8 Windholz, M., S. Budavari, R.F. Blumetti,
and E.S. Otterbein, ed.: The Merck Index. 10th ed. Rahway,
NJ: Merck & Co., 1983. p. 498.
8.9 Proctor, N.H. and J.P. Hughes:
Chemical Hazards of the Workplace. Philadelphia, PA: J.B.
Lippincott Company, 1978. pp. 101-102.
8.10 Frank, R.: Acute and Chronic
Respiratory Effects of Exposure to Inhaled Toxic Agents. In
Occupational Respiratory Diseases, edited by J.A. Merchant.
Washington, D.C.: U.S. Government Printing office, 1986. pp. 573-576.
8.11 Occupational Safety and Health
Administration Technical Center: Ammonia Backup Data Report
(ID-188). Salt Lake City, UT, Revised 1991.
8.12 Occupational Safety and Health
Administration Analytical Laboratory: OSHA Analytical Methods
Manual (OSHA-SLCAL Method Nos. 34, 36, 40, 41). Cincinnati, OH:
American Conference of Governmental Industrial Hygienists (ACGIH Publ.
No. ISBN: 0-936712-66-X), 1985.
8.13 Occupational Safety and Health
Administration Analytical Laboratory: Ethanolamine and
Diethanolamine (OSHA-SLCAL Stopgap Method). Salt Lake City, UT. 1987
8.14 Occupational Safety and Health
Administration Technical Center: Standard Operating Procedure-Ion
Chromatography. Salt Lake City, UT. In progress (unpublished).
All identified species are 10 µg/mL
Ion Chromatogram of Sodium, Ammonium, and Potassium