Continuous Ammonia Monitoring
Jim Schwab, ASRC, University at Albany, SUNY
With contributions from many others!
Additional Contributers
• Eric Edgerton, ARA, Cary, NC
• Minsuk Bae, Yongquan Li, Ken
Demerjian, John Spicer – ASRC
• Sara Pryor – Indiana University
• Bjarne Jensen - Danish National
Environmental Research Institute
• Jian Hou, Xianliang Zhou – University at
Albany School of Public Health
• Donna Kenski - LADCO
Continuous Methods
• Potential Routine Methods
– Chemiluminescence
• SEARCH TRN
• API Model 201E or Thermo Model 17C (1 ppb LDL)
– Ion Mobility Spectrometer
– Laser Acousto-Optical Detection
– AiRRmonia – ECN, Netherlands, Mechatronics
Instruments, b.v.
• Research Methods
– Tunable Diode Laser – TDLAS
– Wet Effusive Diffusion Denuder (WEDD)
– Wet Scrubbing Long Path Absorption Spectrometer –
WS-LOPAP
– Wet Scrubbing IC analysis (URG AIM 9000)
– MARGA – Steam Jet Collection – IC
SEARCH Continuous NH3
Method (TRN)
• 2-channel oxidized AND reduced nitrogen
chemiluminescence analyzer
• Channel 1 samples ambient air through a
sodium carbonate denuder (TN), then two
heated converters
• Channel 2 samples ambient air through
dual sodium carbonate and citric acid
denuders (TN* ), then through a single
moly converter
• NH3 operationally defined as TN-TN*
Total Reduced Nitrogen (TRN) Analyzer
Total Reactive Nitrogen after
Na2CO3 denuder
350º C Moly
Converters
650º C Pt
Converter
Total Oxidized Nitrogen after
Na2CO3 and citric acid denuders
NH3 and NH4+ during CFPP Plume Event
75
10
SO2
NH4
NH3
NHx
9
8
SO2 (ppb)
7
45
6
5
30
4
3
15
2
1
0
5/4/05 0:00
0
5/4/05 3:00
5/4/05 6:00
5/4/05 9:00
5/4/05 12:00
5/4/05 15:00
5/4/05 18:00
5/4/05 21:00
NH4+ increases; NH3 disappears; NHx conserved
NH3, NH4, NHx (ppb)
60
Method 2 - IMS
• Candidate for routine monitoring
• IMS – Ion Mobility Spectrometer (AirSentry-IMS
Ammonia Analyzer, Particle Measuring Systems,
Boulder, CO)
• Ionization based time-of-flight technique
performed at atmospheric pressure
• Instruments are targeted to a specific molecule
in a specific concentration range
• Range for this instrument: 0–300 ppb (Lab
Intercomparison); 0-100 ppb (Field Deployment)
• Cost (with OBC) ~ $26 K
Operational Details
• Requires up to 5 li/min of clean, dry
instrument air (dewpoint ≤ -40º C)
• Internal sample pump option
• Factory default “Smoothing Factor” (8)
should be increased for minute (or longer)
averaged data
• Optional “On Board Calibration” - integral
permeation oven set up (recommended)
• Nickel 63 sealed radioactive source (less
than .005 microcuries) – ionization source
IMS Field Data
NH3 - PSP - Addison, NY; March 5-11, 2006
7
6
NH3 (ppb)
5
4
3
2
1
0
-1
3/5/2006
0:00
3/5/2006
12:00
3/6/2006
0:00
3/6/2006
12:00
3/7/2006
0:00
3/7/2006
12:00
3/8/2006
0:00
3/8/2006
12:00
3/9/2006
0:00
3/9/2006 3/10/2006 3/10/2006 3/11/2006 3/11/2006 3/12/2006
12:00
0:00
12:00
0:00
12:00
0:00
NH3 - PSP - Addison, NY; May 7-13, 2006
1.6
NH3 (ppb)
1.4
1.2
1
0.8
0.6
0.4
0.2
0
5/7/2006
0:00
5/7/2006
12:00
5/8/2006
0:00
5/8/2006
12:00
5/9/2006
0:00
5/9/2006 5/10/2006 5/10/2006 5/11/2006 5/11/2006 5/12/2006 5/12/2006 5/13/2006 5/13/2006 5/14/2006
12:00
0:00
12:00
0:00
12:00
0:00
12:00
0:00
12:00
0:00
Preliminary data: do not cite or quote!
Pranalytica Nitrolux NH3
Analyzer
Note: Instrument used was one
of the first sold by Pranalytica
and company claims to have
made significant improvements
to later (i.e. current) instruments
Photoacoustic spectroscopy
CO2 laser
Low-noise microphone
In-line particle filter (40 µm)
LDL and cost depend on model
Model 1000 – LDL ~ 1 ppb;
Cost ~$24K
Model 200 – LDL ~ 0.2 ppb;
Cost ~$38K
Model 100 – LDL ~ 0.1 ppb;
Cost ~$72K
Laboratory
Intercomparison
• September 12-30, 2005 at ASRC
• Six measurement Methods – seven
instruments in all (Chemiluminescence
method not included because instrument was
not configured properly – my error)
• Heated glass manifold for uniformity of
sampling environment
• Synthetic air and calibration system
• “Ambient” sample for two extended periods
Method Characteristics
Tested during
Intercomparison
• Response to known [NH3] –
accuracy and precision of calibration
• Time Response – to step changes
and “spikes”
• Comparability during ambient
sampling
• Potential interferences
9/28: Zero, 5, 10, 20 ppb
25
[NH3] - ppb
20
15
10
5
0
6:00
8:00
10:00
IMS
12:00
Nitrolux
14:00
TDL
Preliminary data: do not cite or quote!
16:00
LOPAP
18:00
WEDD1
20:00
WEDD2
22:00
0:00
9/26: 40 ppb spike from zero
40
35
30
[NH3] - ppb
25
20
15
10
5
0
10:00
11:00
12:00
IMS
Nitrolux
13:00
TDL
Preliminary data: do not cite or quote!
14:00
LOPAP
15:00
WEDD1
16:00
WEDD2
17:00
9/24: Ambient Spike
18
16
14
[NH3] - ppb
12
10
8
6
4
2
0
9/24/2005
18:00
9/24/2005
19:00
9/24/2005
20:00
IMS
9/24/2005
21:00
9/24/2005
22:00
Nitrolux
TDL
Preliminary data: do not cite or quote!
9/24/2005
23:00
9/25/2005
0:00
LOPAP
9/25/2005
1:00
WEDD1
9/25/2005
2:00
9/25/2005
3:00
Sampling and response
time
• This is an important issue for
gaseous ammonia measurement – it
clearly affects methods detecting
gaseous ammonia directly and
ammonium after scrubbing.
• The TDL is the system of choice for
quick and accurate response – but it
is not a “routine” method!
Spring 2006 Measurements –
Pinnacle State Park, Addison,
NY
• NH3 measured with AirSentry IMS
• HNO3 with denuder difference
chemiluminescence method
NH3
HNO3
Mean
1.06 ppb
0.66 ppb
Standard Dev.
0.77 ppb
0.62 ppb
Median
0.87 ppb
0.48 ppb
Maximum
5.82 ppb
5.75 ppb
Est. MDL
0.3 ppb
0.2 ppb
Completeness
90.1%
85.4%
0 1 2 3 4 5 6
60
80
100
Julian Day
120
140
Nitric Acid at Pinnacle State Park, Addison, NY - 2006
0 1 2 3 4 5 6
Concentration - ppb
Ammonia at Pinnacle State Park, Addison, NY - 2006
60
80
100
Julian Day
120
140
NH3 and HNO3 - March 30 - April 1, 2006
6
6
NH3
HNO3
5
4
4
3
3
2
2
1
1
0
0
88.0
88.5
89.0
89.5
Julian Day
90.0
90.5
91.0
HNO3 - ppb
NH3 - ppb
5
NH3 and HNO3 - May 26-31, 2006
4
4
3
3
2
2
1
1
0
0
145
146
147
148
Julian Day
149
150
151
HNO3 - ppb
NH3 - ppb
NH3
HNO3
Response Time –
Memory Effect
• Note that on previous slide the
HNO3 drops below 1 ppb each night
• However, NH3 does not drop very
low between peaks
• We believe this is due – at least in
part – to changing uptake and
release of NH3 on the sample inlet,
the switching valves, and the sample
handling lines in the instrument
Candidate Methods for Monitoring –
and their Major Shortcoming(s)
(Editorial Opinions!)
• ARA TRN (chemiluminescence)
– Not ammonia specific
– Three heated converters – difference method
• AirSentry IMS (Particle Measuring)
– Response Time Problem
• Nitrolux 200 (or 100) (Pranalytica)
– Response Time (worst of all tested
instruments, but should be better in current
versions)
– Cost – Highest of “routine monitoring”
candidates (for sufficiently low LDL)
• AIRRmonia, URG AIM, MARGA – need
liquid reagents
Recommendation
• ARA TRN (chemiluminescence)
– Custom implementation of proven
analyzer
– Response time issue minimized
(eliminated?) since there is no
“handling” of ammonia
– EPRI is considering commercialization
of converter technology
Acknowledgements
• Funding from
– EPA
– NYSERDA
– NYSDEC
•
Although the research described in this article has been funded in part by
the U.S. Environmental Protection Agency, it has not been subjected to
the Agency’s required peer and policy review and therefore does not
necessary reflect the views of the Agency and no official endorsement
should be inferred should be inferred.
End of
Presentation
Nitric Acid Measurement
• Denuder difference in conjunction with NOy
• TECO 42S low-level chemiluminescence
analyzer – operates with two measurement
channels and one background (“prereactor
zero”) channel
• Both measurement channels preceded by
external heated molybdenum converters
• “Base” channel is NOy
• Second channel uses a NaCl coated denuder
as inlet – this channel measures NOy – HNO3
• Difference of channels is HNO3
Schematic of HNO3 Method
OUTSIDE
Gas lines
SS
NEMA
box
mounted
outside
(5 m agl)
INSIDE
BYPASS
PUMP
Heated
Mo
Heated
Mo
converter
converter
NaCl
coated
denuder
PFA
Teflon
Tube
Power
and
signal
wires
Mode switching
valves
Model 42S
chemiluminescence
analyzer
1-minute NH3 and WD at Yorkville
20
360
NH3
WD
315
270
225
10
180
135
5
90
45
0
8/28/06 0:00
0
8/28/06 6:00
8/28/06 12:00
8/28/06 18:00
Spikes between 90 and 180 degrees suggest nearby
NH3 sources.
WD (deg.)
NH3 (ppb)
15
Local Sources of NH3 at YRK
2.6 km
1.5 km
3.3 km
Poultry operations
within several km
line up with NH3
spikes.