Transcript Noxious Gases Ref Peaks: An Alternative to Dual Inlet Bellows

Noxious Gases Ref Peaks:
An Alternative to Dual Inlet Bellows
Paul Eby
Normal Conflo Ref Gas
Ref Gas
GC / EA
He
- Ref Gas is always flowing (0.2mL/min)
- Not okay for noxious gases
IRMS
- CO, CH3Cl, SO2
- Small quantities / expensive gases
Using the Bellows
GC / EA
REF
SAMPLE
IRMS
- Consumption is very low (0.02 to 0.002mL/min)
- Continuously flows
- Noxious gas exits with the pump exhaust
- Requires dual inlet
37Cl
Measurements
1. Precipitate chloride out as AgCl by adding AgNO3
2. Convert AgCl to CH3Cl gas by reacting with CH3I
3. Run by GC-IRMS
4. Measured as CH3Cl
Problems
Requires an extra cup to measure masses 50 and 52
Bellows needed for toxic CH3Cl (also expensive)
$
$$$
Thermo Conflo IV
Allows for 5 different reference gases, 2 at a time
Thermo Conflo IV
Ref A
Ref B
Can we leave the ref gas off until a peak is
needed?
Ref C
Does the gas need to reach a steady state
by constantly flowing?
How long does it take to reach a steady
state?
Can I test this before upgrading the IRMS?
IRMS
Thermo Conflo IV in Isodat
Extra columns added to the method using Configurator
Carbon Dioxide On/Off Test
ave = -0.03 stdev = 0.02
ave = -0.01 stdev = 0.04
Carbon Dioxide On/Off Test
0.2
0.15
d13C / permil
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
1
2
3
4
5
6
7
8
9
10
11
12
Methyl Chloride Trials
1. Upgrade the detectors
2. Add ventilation to the Conflo IV
3. Pump exhaust vented
4. Small bomb of CH3Cl
Methyl Chloride On/Off Test
ave = 0.01 stdev = 0.01
ave = -0.02 stdev = 0.02
Methyl Chloride On/Off Test
0.2
d37Cl / permil
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
1
2
3
4
5
6
7
8
9
10
11
Methyl Chloride On/Off Test
Conclusions
1. ConFlo IV can be used to limit consumption of ref gas
2. Comparing to Bellows:
Flow rate in Conflo IV
0.2mL/min
Flow rate in bellows
0.02 - 0.002mL/min?