Technology Performance Characteristics
for the
On-Site Measurement
of
Chlorinated Volatile Organic Compounds
in
Groundwater
presented by
Wayne Einfeld and Gary Brown
Sandia National Laboratories
Albuquerque, New Mexico USA
Eric Koglin
United States Environmental Protection Agency
Las Vegas, Nevada USA
1
Presentation Overview
A US EPA Environmental Technology Verification
test of field-portable water monitoring instruments
is described.
Test results are presented which include the
features and performance characteristics of five
different on-site instrumental analysis methods for
the measurement of chlorinated VOCs in
groundwater at contaminated sites.
2
Presentation Outline

Overview of ETV Program and the Site
Characterization and Monitoring Technology
Center
3

Technology Overviews

Verification Test Design

Verification Test Results

Summary and Conclusions
Environmental Technology Verification
(ETV) Program
4

Established by EPA to verify the performance of innovative
environmental technologies

Accelerates acceptance and use of improved, cost-effective
technologies

Public and private partners to test technologies under EPA
sponsorship and oversight

Six Centers including the Site Characterization and Monitoring
Technologies Center (SCMT)

Site Characterization and Monitoring Technology Center has
Sandia National Laboratories and Oak Ridge National Laboratory
as verification testing partners
Site Characterization and Monitoring
Technologies Center
Our Technology Focus . . .
Verify the performance of technologies that can
be used for generating real-time data or
information to support monitoring of human and
ecosystem health, assessing real or potential
exposure to environmental contaminants and
hazards, for monitoring environmental conditions,
and characterizing (physically and chemically)
contaminated sites
5
SCMT Center Goals
6

Accelerate the use and acceptance of
innovative environmental monitoring and
characterization technologies

Rigorous, statistically-defensible testing under
actual field conditions

Provide reliable, high-quality performance
information

Leverage federal resources and expertise
What does Verification Mean?
To establish or prove the truth of the performance
of a technology under specific, predetermined
criteria or protocols and adequate data quality
assurance procedures.
7
SCMT Technology Areas

Field analytical technologies
– Field portable X-Ray fluorescence spectrometers
– Field portable gas chromatograph/mass
spectrometers
– Immunoassay kits
– Field portable gas chromatographs
– Fiber optic chemical sensors
– Alpha detectors
– Colorimetric test kits
8
SCMT Technology Areas






9
cont’d
Decision support software systems
Physical characterization (e.g., geophysical
methods, direct-push systems)
Soil, soil gas, groundwater, surface water, and
sediment sampling methods
Technologies for assessing contaminated
structures
Monitoring bioremediation and natural
attenuation
Toxicity screening methods
Technology Verification Process
Verification
Test
Planning
Field
Testing
Data Collection
and Validation
Report
Preparation
10
Final
Report &
Verification
Statement
Verification Test Plan Development
Verification Test Plan
11
Verification Testing in the Field
Verification Org.
coordinates
Vendors operate
their instruments
Testing at two
sites or
conditions
“Blind” sample
analysis
QA audits during
field tests
12
Technology Verification Report Contents

Verification Statement

Technology Description

Site and Design Description




13
Reference Laboratory Data
Validation
Verification Test Results
Field Observations and Cost
Summary
Technology Update
Verification of Field Analytical Techniques
for the Measurement VOCs in Water

Goal: Verify field analytical techniques capable of
detecting and quantifying chlorinated VOCs in water

Demonstration objectives:
– Obtain performance information using quality control and field
samples
– Compare technology results with conventional laboratory results
– Determine logistical requirements for technology use

14
Data used in this presentation is taken from from
published ETV reports (www.epa.gov/etv)
Five Technologies Were Tested
15
Why use these technologies?
16

Faster, cheaper, better site screening and
routine ground water monitoring

Quick-turnaround sampling and analysis
enables on-site decisions and dynamic
workplans

Less sample handling and paperwork

Reapplication of existing equipment
How might these technologies be used?
17

Field analytical support for direct push investigations

Preliminary groundwater screening at new or existing
wells

Real-time monitoring for plume migration/barrier wall
performance

Routine groundwater monitoring programs for known
compounds at relatively high contamination levels
(>10 ug/L)

Soil vapor analysis

Waste water outfall monitoring
Getting Sample to the Instrument
Equilibrium Headspace
- simple
- less sensitive
- HAPSITE, Voyager, Multi-gas
Monitor
Purge-and-Trap/Thermal
Desorption
- more complex
- more sensitive
- Scentograph Plus II, EST Model
4100
18
Equilibrium Headspace
Henry’s Law
At constant temperature:
[VOC]gas
__________
[VOC]liq
= Henry’s Constant
Henry’s Constant is compound-specific
and is determined by the solubility of the
compound in water
Less soluble > Higher headspace
concentration
More soluble > Lower headspace
concentration
19
A gas sample is withdrawn from the
headspace and analyzed by GC. The
water concentration is calculated from the
gas concentration using Henry’s Constant
Gas Phase
VOC Concentration
Liquid Phase
VOC Concentration
Dynamic Headspace (Purge-and-Trap)
Purge
Gas
Carrier
Gas
Helium
or
Nitrogen
20
Step 1
Purge VOCs from
solution and trap on
sorbent
Step 2
Heat the sorbent trap
and sweep the VOCs
off the sorbent with
the carrier gas
Gas Chromatography (GC)
21

Separates a mixture of compounds (usually organic)

Relies on differing solubilities of the analytes in an
organic compound (stationary phase) lining the
column wall

Detector at end of column allows separated
compounds to be quantified

Retention time and detector response enable
compound identification and quantification
Headspace/Gas Chromatography
22
Perkin-Elmer, Voyager
Description: Field-portable GC with multiple columns and dual ECD
and PID detectors, isothermal operation
Size, Weight: Small, 48 pounds (with accessories)
Sample handling: Completely manual
Sample throughput: 1-3 samples/hr
Data processing: pre-programmed automated methods, printed
output
Calibration: pre-deployment calibration, daily check standards
Power: Battery or AC
Cost: $24K
Accessories: Carrier gases, optional PC,
syringes, water bath
Operator training: 1-2 hours for a chemical technician
23
Perkin-Elmer, Voyager
24
Electron Capture Detector
A “standing current” is
produced in the
detector by the
interaction of a
radioactive electron
source with the carrier
gas.
When electronegative
compounds enter the
detector they “capture”
the electrons and
cause a measurable
change in the standing
current.
25
Photoionization Detector


A UV lamp is used to
irradiate a heated ionization
chamber at the end of a GC
column
The UV energy ionizes many
organic molecules through a
photoionization reaction:
R + h = R+ + e-

26
The resulting ion current is
sensed by an electrometer
and is used to quantify the
amount of material present
Electrometer
From GC
Column
Power Supply
+
–
Exhaust
Heated Ionization Chamber
UV Lamp
Sentex Systems Inc., Scentograph Plus II
Description: Field-portable, purge-and-trap GC with micro-argon
ion and/or electron capture detector, isothermal or temperature
program operation
Size, Weight: Moderate, 80 pounds
Sample handling: Completely automated
Sample Throughput: 2 samples/hour
Data processing: pre-programmed automated methods, printed
output not readily available
Calibration: Daily three-point, daily check standards
Power: Battery or AC
Cost: $35K
Accessories: Carrier gases, PC
Operator training: Moderate
27
Sentex Systems Inc., Scentograph
Plus II
28
Micro Argon Ion Detector



The detector contains a tritium
foil that is used to irradiate the
argon carrier gas
Some of the argon molecules
become excited (metastable).
The metastable argon ionize
the organics
Electrometer
Argon carrier gas
from GC column
+
–
Ar + e– = Ar*
Ar* + R = R+ + e–

29
The resulting ion current is
sensed by an electrometer and
is used to quantify the amount
of organic material present
Tritium Foil
Exhaust
Electronic Sensor Technology Inc., Model 4100
Description: Field-portable, purge-and-trap GC with surface
acoustic wave detector
Size, Weight: Moderate, 35 pounds
Sample Handling: Partially automated
Sample Throughput: 2-3 samples/hour
Data processing: pre-programmed automated methods,
printed output
Calibration: pre-deployment 3-point calibration, periodic
check standards, internal standard
Power: Battery or AC
Cost: $25K
Accessories: Carrier gases, PC
Operator training: 1 day for experienced chemical
technician
30
Electronic Sensor Technology Inc.,
Model 4100
31
Surface Acoustic Wave Detector
A surface acoustic wave
(SAW) detector operates
much like a quartz crystal
detector. An AC voltage
at the input transducer
causes an acoustic wave
to propagate across a
crystal surface to the
output transducer.
Adding mass, such as an
analyte from the end of a
GC column, onto the
detector surface causes a
measurable change in the
properties of the acoustic
wave.
32
Inficon Inc., HAPSITE
Description: Field-portable GC-MS and Headspace Sampling
Accessory
Size, Weight: Moderate, 75 pounds
Sample Handling: Partially automated
Sample Throughput: 2-3 samples per hour
Data Processing: pre-programmed automated methods, printed
output
Calibration: pre-deployment multi-point, periodic check standard,
internal and surrogate standards, daily MS tune check
Power: Battery or AC
Cost: $75-95K
Accessories: Calibration and carrier gases, PC
Operator training: 1 day of training for an
experienced chemical technician
33
Inficon Inc., HAPSITE
34
GC-Mass Spectrometry
An electron beam ionizes
compounds exiting the GC
column
The quadrupole filter allows
ions of specific mass to pass
through the filter and strike
the ion collector.
The mass selectivity of the
filter can be continuously
scanned over a predetermined range by
changing the dc and rf
settings of the filter.
Quadrupole Mass Selective Detector
35
Innova AirTech Instruments
Type 1312 Multi-gas Monitor
Description: Field-portable, photoacoustic infrared bandpass
spectrometer
Size, Weight: Small, 30 pounds
Sample Handling: Partially automated
Sample Throughput: 1-2 samples/hr
Data Processing: Automated method, manual recording of data
necessary, no printed report
Calibration: Factory calibration, no daily check standards
Power: Battery or AC
Cost: $28-35K
Accessories: Headspace flask, stir plate, tubing
Operator training: Several hours for a field
36
technician
Innova AirTech Instruments
Type 1312 Multi-gas Monitor
37
Photoacoustic Spectroscopy
Chopped (intermittent)
bandpass-filtered
infrared radiation is
passed through a cell
containing the gases
of interest.
The target gases
absorb the radiation.
The absorption is
accompanied by a rise
and fall in temperature
(pressure) in the cell
at the chopping
frequency.
38
This pressure cycle or acoustic signal is detected by
two sensitive microphones. The intensity of the
pressure cycle is related to the target gas
concentration.
Verification Test Design Elements

Different Environmental Conditions
– Testing at two contaminated sites with groundwater wells
(Savannah River, SC and McClellan AFB, CA)
– Historical sampling data used to select GW wells

A Blend of Field and QA Samples
– Performance evaluation (PE), 42 samples per site
– Groundwater (GW), 33 samples per site
– Blank samples, 8 per site

Reference Laboratory Analyses
– Splits of all samples analyzed by an off-site reference
laboratory
– US EPA Method 8260 (Purge-and-trap GC-MS)
39
Verification Test Design Elements

cont’d
Multiple VOC Compounds
PE Mix 1 - Purgeable A
Supelco Cat. No. 4-8059
Lot LA68271
Trichlorofluoromethane
1,1-Dichloroethane
Dichloromethane
1,1-Dichloroethene
Chloroform
Carbon tetrachloride
Trichloroethene
1,2-Dichloropropane
1,1,2-Trichloroethane
Tetrachloroethene
Dibromochloromethane
Chlorobenzene
1,2-Dichlorobenzene
2-Chloroethyl vinyl ether
PE Mix 2 - VOC 3
Supelco Cat. No. 4-8779
Lot LA64701
1,1-Dichloropropene
1,2-Dichloroethane
Trichloroethene
1,2-Dichloropropane
1,1,2-Trichloroethane
1,3-Dichloropropane
1,2-Dibromoethane
1,1,1,2-Tetrachloroethane
1,1,2,2-Tetrachloroethane
1,2,3-Trichloropropane
1,2-Dibromo-3-chloropropane
cis-1,3-Dichloropropene
trans-1,3-Dichloropropene
Hexachlorobutadiene
PE Mix 3 - Purgeable B
Supelco Cat. No. 4-8058
Lot LA 63978
1,2-Dichloroethane
1,1,2,2-Tetrachloroethane
cis-1,3-Dichloropropene
trans-1,3-Dichloropropene
trans-1,2-Dichloroethene
1,1,1-Trichloroethane
Benzene
Bromodichloromethane
Toluene
Ethyl benzene
Bromoform
Participating technologies were not calibrated for all these compounds
40
Verification Test Design Elements

cont’d
A Wide Concentration Range of Compounds
– PE Samples: 10 µg/L to >1000 µg/L
– GW Samples: 5 µg/L to > 1000 µg/L

Blind Replicate Samples
– Triple or quadruplicate splits of all GW and PE samples
– for determination of instrument precision
41
A Challenging Test Sample Matrix
42

65 environmental groundwater
samples from both sites

84 performance evaluation (PE)
water samples mixed and
distributed onsite

8 blank samples

~160 samples analyzed per
technology over ~ 8 days

Over 9000 individual compound
analyses!
Groundwater
PE + Blanks
Field Sample Preparation
PE Samples
 Performance Evaluation samples were
mixed in a 10-L carboy in an onsite mobile
laboratory and then dispensed into 40-mL
VOA vials
 Each of the five technologies and
reference lab were given 4 replicates from
all PE mixtures
43
GW Samples
 10 liters of groundwater was sampled into
a glass carboy from various monitoring
wells with downhole electric pumps
 Carboy contents were mixed and then
dispensed into 40-mL VOA vials at the
wellhead. Replicate samples were
distributed to all participants and the
reference laboratory
Sample Distribution
HAPSITE
PE Samples
VOYAGER

Model 4100
GW Samples
Scentograph Plus II

Multi-gas Monitor
Blank Samples
Reference Lab
Each sample delivered in
triplicate or quadruplicate
44
Definition of Terms
45
Precision
Relative standard deviation from replicate samples
Accuracy
Average percent recovery of a known test sample
or absolute percent difference from a known
Comparability
Percent difference of results relative to reference
laboratory results
Detection Limit
Method Detection Limit or Practical Quantitation Limit
Sample
Throughput
Samples per hour
False Positive
Frequency that detects are reported for blank samples
False Negative
Frequency that no-detects are reported for compounds
at or near the 5 ug/L regulatory limit
Key Instrument Performance
Parameters in this Test
46

Accuracy - percent recovery

Precision - relative standard deviation

Comparability to reference - absolute percent difference

False positive/negative - at blank and 10 ug/L conc. levels

Sample throughput - samples per hour

Versatility - number of compounds detected

Ease of use - through field observation

Operator training requirements -through field observation
ETV doesn’t compare technologies
 In a policy of fairness and
objectivity, ETV doesn’t pick
technology winners and losers
Technologies are varied and their
application is usually site- and
application-specific

The site user is best-suited to
match site needs with technology
capabilities

Side-by-side comparisons, if
required, are left to the user

47
???
Brand X
Brand Y
How the results are presented

Presentation by instrument

Performance Characteristics
False
+/Accuracy
Precision
Comparison with Reference Lab
Summarized results are
necessary (lots of data in reports!)
 Performance for TCE and PCE is
emphasized

48
Technology
Performance
Results
Perkin Elmer Voyager False +/False positive rate in 16 blanks: 19%
False negatives for SRS site (10 Samples at 10 g/L):
Compound
1,1-Dichloroethene
Dichloromethane
Chloroform
Carbon tetrachloride
1,2-Dichloropropane
Trichloroethene
1,1,2-Trichloroethane
Dibromochloromethane
Tetrachloroethene
Chlorobenzene
1,1-Dichloroethane
1,2-Dichlorobenzene
49
False Negative Rate (%)
0
0
100
0
80
0
100
90
0
0
No calibration
No calibration
Voyager Summary Precision
%RSD
Voyager
TCE
Ref Lab
TCE
Voyager
PCE
Ref Lab
PCE
Median
15
6
**
6
Minimum
7
1
9
2
Maximum
71
12
**
22
N Sample
Sets
8
16
8
11
Combined data from PE samples at both sites
** Voyager did not detect PCE in 7 of 8 sets
50
Average Voyager Recovery for Selected Compounds
TCE @ SRS
Compound and Site
TCE @ MCL
PCE @ SRS
Low Conc. (~100 ug/L)
PCE @MCL
Mid Conc. (~200 ug/L)
High Conc. (~800 ug/L)
12DCA @ SRS
High/Low Mix Conc.
12DCA @ MCL
0
50
100
150
200
250
Average Percent Recovery
51
300
350
400
Voyager Summary Accuracy
For selected target compounds
Compound
52
% Recovery
Range
Trichloroethene
92–344
1,2-Dichloroethane
34–170
1,2-Dichloropropane
34–170
1,1,2-Trichloroethane
1,2-Dichloropropane
50–116
Tetrachloroethene
1–124
Trans-1,3Dichloropropane
72–162
Scatter Plot Comparisons with
Reference Lab





53
Example scatter plots shown for both sites combined
A total of 20 TCE and 20 PCE detects by the
reference lab at all concentration ranges at both sites
Only TCE and PCE results below 500 ug/L are plotted
False negatives reported by technology are also
shown
Diagonal line in plot is the zero-bias line
Perkin Elmer Voyager vs. Lab Reference
TCE and PCE in groundwater samples at both sites
500
450
Voyager Conc. (ug/L)
400
350
300
250
TCE at SRS
TCE at MAFB
PCE at SRS
PCE at MAFB
200
150
100
50
0 False Negatives Reported
0
0
54
100
200
300
Ref Lab Conc. (ug/L)
400
500
Perkin-Elmer, Voyager
Performance Summary

False negative rate: low for TCE and PCE

Precision: <20% RSD for TCE
Undetermined for PCE

Accuracy: 90-340% TCE Recovery
1-120% PCE Recovery

Reference Lab Comparison: Biased high for TCE and
PCE
55
Scentograph Plus II False +/False positive rate in 16 blanks: 0%
False negatives for SRS site (10 Samples at 10 g/L):
Compound
1,1-Dichloroethene
Dichloromethane
Carbon tetrachloride
1,2-Dichloropropane
Trichloroethene
1,1,2-Trichloroethane
Tetrachloroethene
Chlorobenzene
2-Chloroethyl vinyl ether
Dibromochloromethane
Trichlorofluoromethane
1,1-Dichloroethane
1,2-Dichlorobenzene
56
False Negative Rate (%)
0
0
0
30
0
0
0
0
No calibration
No calibration
No calibration
No calibration
No calibration
Scentograph II Summary Precision
57
%RSD
Scentogr
TCE
Ref Lab
TCE
Scentogr
PCE
Ref Lab
PCE
Median
6
6
7
6
Minimum
0
1
3
2
Maximum
17
12
13
22
N Sample
Sets
8
16
4
11
Average Scentograph Recovery for Selected
Compounds
Low Conc. (~100 ug/L)
TCE @ SRS
Mid Conc. (~200 ug/L)
High Conc. (~800 ug/L)
Compound and Site
TCE @ MCL
High/Low Mix Conc.
PCE @ SRS
PCE @MCL
12DCA @ SRS
12DCA @ MCL
0
20
40
60
80
100
120
Average Percent Recovery
58
140
160
180
200
Scentograph Plus II Summary Accuracy
For selected target compounds
Compound
59
% Recovery
Range
Trichloroethene
76–117
1,2-Dichloroethane
103–178
1,2Dichloropropane
84–122
1,1,2Trichloroethane
85–116
Tetrachloroethene
96–115
trans-1,3Dichloropropane
83–124
Sentex Scentograph Plus II vs. Lab Reference
TCE and PCE in groundwater samples at both sites
500
450
Scentograph Conc. (ug/L)
400
350
300
250
TCE at SRS
TCE at MAFB
PCE at SRS
PCE at MAFB
200
150
100
50
4 False Negatives Reported
0
0
60
100
200
300
Ref Lab Conc. (ug/L)
400
500
Sentex Scentograph Plus II
Performance Summary

False negative rate: low for TCE and PCE

Precision: <10% RSD for TCE
<10% RSD for PCE

Accuracy: 75-115% TCE Recovery
95-115% PCE Recovery

Reference Lab Comparison: No bias for TCE and
PCE
61
EST Model 4100 II False +/False positive rate in 16 blanks: 0%
False negatives for SRS site (10 Samples at 10 g/L):
Compound
1,1-Dichloroethene
Dichloromethane
Chloroform
Carbon tetrachloride
1,2-Dichloropropane
Trichloroethene
1,1,2-Trichloroethane
Dibromochloromethane
Tetrachloroethene
Chlorobenzene
1,1-Dichloroethane
1,2-Dichlorobenzene
62
False Negative Rate (%)
100
No calibration
100
100
100
0
100
No calibration
0
0
100
100
Model 4100 Summary Precision
%RSD
Model 4100
TCE**
Ref Lab
TCE
Model 4100
PCE
Ref Lab
PCE
Median
10
6
12
6
Minimum
2
1
6
2
Maximum
28
12
22
22
N Sample
Sets
8
16
6
11
**TCE reported as a co-eluter with 1,2 dichloropropane
63
Average Model 4100 Recovery for Selected
Compounds
Low Conc. (~100 ug/L)
TCE @ SRS
Mid Conc. (~200 ug/L)
High Conc. (~800 ug/L)
Compound and Site
TCE @ MCL
High/Low Mix Conc.
PCE @ SRS
PCE @MCL
112TCA @ SRS
112TCA @ MCL
0
20
40
60
80
100
120
140
Average Percent Recovery
64
160
180
200
Model 4100 Summary Accuracy
For selected target compounds
Compound
Trichloroethene
1,2-Dichloropropane
65
% Recovery
Range
58–75
380–5038
1,2,3-Trichloropropane
49–174
1,1,2-Trichloroethane
57–118
Tetrachloroethene
34–68
trans-1,3Dichloropropene
57–145
EST Model 4100 vs. Lab Reference
TCE and PCE in groundwater samples at both sites
500
450
Model 4100 Conc. (ug/L)
400
350
300
250
TCE at SRS
TCE at MAFB
PCE at SRS
PCE at MAFB
200
150
100
50
0 False Negatives Reported
0
0
66
100
200
300
Ref Lab Conc. (ug/L)
400
500
EST Model 4100
Performance Summary

False negative rate: low for TCE and PCE

Precision: <10% RSD for TCE
<20% RSD for PCE

Accuracy: 60-75% TCE Recovery
35-70% PCE Recovery

Reference Lab Comparison: Biased low for TCE
and PCE
67
Inficon HAPSITE False +/False positive rate in 16 blanks: 25%
False negatives for SRS site (10 Samples at 10 g/L):
Compound
1,1-Dichloroethene
Dichloromethane
1,1-Dichloroethane
Chloroform
Carbon tetrachloride
1,2-Dichloropropane
Trichloroethene
1,1,2-Trichloroethane
Dibromochloromethane
Tetrachloroethene
Chlorobenzene
1,2-Dichlorobenzene
68
False Negative Rate (%)
0
0
0
0
10
0
0
40
20
40
10
No calibration
HAPSITE Summary Precision
%RSD
HAPSITE
TCE
Ref Lab
TCE
HAPSITE
PCE
Ref Lab
PCE
Median
14
6
15
6
Minimum
7
1
6
2
Maximum
18
12
22
22
N Sample
Sets
8
16
6
11
69
Average HAPSITE Recovery for Selected Compounds
Low Conc. (~100 ug/L)
TCE @ SRS
Mid Conc. (~200 ug/L)
Compound and Site
TCE @ MCL
High Conc. (~800 ug/L)
High/Low Mix Conc.
PCE @ SRS
PCE @MCL
12DCA @ SRS
12DCA @ MCL
0
20
40
60
80
100
120
140
Average Percent Recovery
70
160
180
200
HAPSITE Summary Accuracy
For selected target compounds
Compound
71
% Recovery
Range
Trichloroethene
80–114
1,2-Dichloroethane
91–103
1,1,2-Trichloroethane
79–120
1,2-Dichloropropane
79–113
Tetrachloroethene
67–93
trans-1,3Dichloropropane
85–101
Inficon HAPSITE vs. Lab Reference
TCE and PCE in groundwater samples at both sites
500
450
HAPSITE Conc. (ug/L)
400
350
300
250
TCE at SRS
TCE at MAFB
PCE at SRS
PCE at MAFB
200
150
100
50
2 False Negatives Reported
0
0
72
100
200
300
Ref Lab Conc. (ug/L)
400
500
Inficon HAPSITE
Performance Summary

False negative rate: low for TCE, high for PCE

Precision: <15% RSD for TCE
<15% RSD for PCE

Accuracy: 80-115% TCE Recovery
70-95% PCE Recovery

Reference Lab Comparison: No bias for TCE
and PCE
73
Innova Multi-gas Monitor False +/False positive rate in 16 blanks: 13%
False negatives for SRS site:
(6 samples at 10 g/L, TCE and PCE only)
Compound
Trichloroethene
Tetrachloroethene
74
False Negative Rate (%)
0
50
Multi-gas Monitor Summary Precision
75
%RSD
Multi-gas
TCE
Ref Lab
TCE
Multi-gas
PCE
Ref Lab
PCE
Median
16
6
13
6
Minimum
4
1
5
2
Maximum
22
12
46
22
N Sample
Sets
13
16
13
11
Average Multi-gas Monitor Recovery
for TCE and PCE
Low 1 (~50 ug/L)
Low 2 (~100 ug/L)
TCE @ SRS
Mid 1 (~200 ug/L)
Compound and Site
Mid 2 (~250 ug/L)
High 1 (~400 ug/L)
High 2 (~700 ug/L)
TCE @ MCL
VHigh (~1250 ug/L)
PCE @ SRS
PCE @ MCL
0
20
40
60
80
100
120
140
160
Average Percent Recovery
76
180
200
Multi-gas Monitor Summary Accuracy
For TCE and PCE
77
Compound
% Recovery
Range
Tetrachloroethene
52–107
Trichloroethene
52–111
Innova Multi-gas Monitor vs. Lab Reference
TCE and PCE in groundwater samples at both sites
500
450
Multi-gas Monitor Conc. (ug/L)
400
350
300
250
TCE at SRS
TCE at MAFB
PCE at SRS
PCE at MAFB
200
150
100
50
3 False Negatives Reported
0
0
78
100
200
300
Ref Lab Conc. (ug/L)
400
500
Innova Multi-gas Monitor
Performance Summary

False negative rate: low for TCE, high for PCE

Precision: <20% RSD for TCE
<15% RSD for PCE

Accuracy: 50-110% TCE Recovery
50-110% PCE Recovery

Reference Lab Comparison: No bias for TCE
and PCE
79
Perkin-Elmer, Voyager
Advantages
80

Lightweight and small

Sensitive and selective for a variety of VOCs

Three columns and dual detectors (PID/ECD) can
help in the identification of unknown compounds

Detects most VOCs, including halogenated and nonhalogenated aliphatic and aromatic hydrocarbons

Instrument is easy to operate
Perkin-Elmer, Voyager
Limitations





81
EC detector requires radioactive permit/license
Isothermal column only -- co-elution of analytes
possible in complex samples
Somewhat cumbersome manual sample handling and
injection is required
Equilibrium headspace method limits sensitivity for
some VOC compounds
Equilibrium headspace method used in this test
needed further development and negatively
influenced the results
Sentex Systems Inc., Scentograph Plus II
Advantages

Purge-and-trap system with MAID offers high
sensitivity -- sub-ppb detection for most VOCs

Isothermal or temperature programmable
operation

Dual detector option can give versatility:
– microargon ionization (MAID)
– electron capture detector (ECD)

Virtually no sample handling required

System could be fully automated to run
unattended
82
Sentex Systems Inc., Scentograph Plus II
Limitations
83

Maximum operating temperature of 179 o C

MAID and ECD detectors contain tritium and may
require a state permit/license

At the time of the test, control and analysis software
was dated and in need of an upgrade

Only moderately portable -- two bulky packages plus
accessories
Electronic Sensor Technology Inc.,
Model 4100
Advantages
84

Compact portable package

Purge-and-trap feature enables improved detection
levels over equilibrium headspace methods

Minimal sample handling requirements

Universal (mass sensitive) SAW detector

Wide detector dynamic range (greater than 104)

Fast throughput (less than 30-second
chromatographic total elution time)
Electronic Sensor Technology Inc.
Model 4100
Limitations
85

With fast analysis times, co-elution of compounds is
possible

Data analysis for complex samples is not fully
automated and requires considerable operator
intervention

Operator experience in chromatography desirable for
complex samples
Inficon, HAPSITE
Advantages
86

Headspace accessory enables automatic GC injection

Unknown compound identification with on-board
mass spectral libraries

Highly versatile for unknown identification

Moderately portable (3 pieces including PC) in light of
the analytical power of the instrument
Inficon, HAPSITE
Limitations
87

Considerable sample handling is required

Isothermal operation only

Compound sensitivity is limited by equilibrium
headspace considerations

Instrument is relatively expensive

Maintenance costs can be high (getter pump)
Innova AirTech Instruments
Type 1312 Multi-gas Monitor
Advantages
88

Detection limits for TCE and PCE in water are in the
low ppb range

Large dynamic range (6 orders of magnitude)

Small cell volume reduces volumes of samples and
calibration gas

Instrument is easy to use

Calibrations are stable over many months
Innova AirTech Instruments
Type 1312 Multi-gas Monitor
Limitations
89

Some sample handling is required

The headspace flask accessory needs further
development

Instrument must be factory calibrated for the
compounds of interest

Compound sensitivity is limited by equilibrium
headspace considerations

The presence of unknowns can cause
erroneous results
For more information...
ETV Site Characterization and Monitoring Technologies
information is at the US EPA web site
www.epa.gov/etv
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