No. SSI-GC-2002
■ Abstract
Haloacetic acids (HAAs) are known carcinogens that
may occur as disinfection byproducts in drinking
water. Currently five HAAs are regulated under the
Stage 2 Disinfectants and Disinfection Byproducts
Rule (DBPR) and occurrence of four more HAAs is
being monitored under the Unregulated
Contaminant Rule 4 (2018-2020) 1. Whether the
targets are HAA5 or HAA9, this analysis will continue
to be performed regularly in environmental labs.
Helium is specified as the carrier gas in EPA method
552, commonly used for HAA analysis in drinking
water. Due to the increasing cost of helium, many
labs are seeking alternative and affordable carrier
gases to meet the monitoring requirements for
HAAs. Here, we demonstrate the performance of
EPA method 552.3 for the analysis of HAA9 using
Shimadzu GC-2030 with dual line micro ECD setup.
Hydrogen carrier gas is tested and shown to be a
cost-effective alternative carrier gas for this method.
■ Introduction
Haloacetic acids (HAAs) are known carcinogens that
may occur as disinfection byproducts in drinking
water. Currently five HAAs are regulated under the
Stage 2 Disinfectants and Disinfection Byproducts
Rule (DBPR) and a Maximum Contaminant Level of
60 ppb for the sum of these five compounds
(MCAA, MBAA, DCAA, TCAA, DBAA). The
occurrence of four more HAAs (BCAA, BDCAA,
CDBAA, TBAA) is being assessed under the
Unregulated Contaminant Rule 4 (2018-2020) 1. EPA
method 552.3 is approved for the monitoring of the
regulated HAAs (HAA5), the additional four HAAs
(HAA9) and dalapon1,2.
Table 1: List of HAAs included in EPA 552.32
Compound
Acronyms
HAA Group
Monochloroacetic acid
MCAA
HAA5
HAA9
Monobromoacetic acid
MBAA
Dichloroacetic acid
DCAA
Trichloroacetic acid
TCAA
Dibromoacetic acid
DBAA
Bromochloroacetic acid
BCAA
Bromodichloroacetic acid
BDCAA
Chlorodibromoacetic acid
CDBAA
Tribromoacetic acid
TBAA
Traditionally these compounds were analyzed using
helium (He) carrier gas, the cost of which has
increased tremendously over the years. Hydrogen
(H2) has a lower molecular mass than He and its
optimal linear velocity based on Van Deemter’s plot
is faster than that of He. This means no efficiency
nor speed of analysis should be lost when using H2
carrier gas instead of He. In addition, current price of
H2 gas is approximately three to six times lower than
the price of He, due to the limited availability of the
later. This makes H2 an ideal alternative carrier gas
for HAA analysis. In this application, we explored
using H2 carrier gas to determine HAA
concentrations according to EPA method 552.3.
■ Materials and Methods
ECD grade tert-butyl methyl ester (MTBE) was
purchased from Sigma (Cat. No. 1019951000).
Internal standard (IS) solution (1,2,3-
trichloropropane, Cat. No. 31648) were purchased
from Restek. Haloacetic Acid Methyl Ester Mix was
purchased from Accustandards (Cat. No. M-552.3)
and diluted to indicated concentrations in MTBE with
1ppm internal standard.
Gas Chromatography
Determination of Haloacetic Acids in
Drinking Water According to EPA Method
552.3 using Hydrogen Carrier Gas
No. GC-2002
No. SSI-GC-2002
A Shimadzu GC-2030 with dual line split/splitless
injector, dual ECD-exceed detector and dual
autosampler was used for analysis of haloacetic acids
and dalapon according to EPA method 552.3.
Haloacetic acid methyl ester mix with internal
standard was run on the GC system. The
concentration indicated in Results and Discussion
represent the original concentration of each
compound in water before extraction and
methylation (derivatization). The extraction process
results in a sample concentration 10 times that of
the original concentration in water.
Analysis conditions are outlined in Table 2 below.
LabSolutions software was used for data acquisition
and processing.
■ Results and Discussion
We had previously analyzed methylated HAA9,
dalapon and surrogate simultaneously on an
analytical column (Rtx-1701) and a confirmation
column (Rxi5Sil-MS) according to EPA 552.3 method
using Shimadzu GC-2030 with dual inlet, detector
and autosampler with He carrier gas 3. With the dual
line setup, the EPA required quantification and
confirmation of HAAs and dalapon can be
completed in one GC run. In this application, we
compared the chromatogram of HAAs and dalapon
using H2 to that using He, as well as assessed the
performance of the same instrument setup using H2
carrier gas per EPA 552.3 criteria.
Comparison of H2 carrier gas to He carrier gas.
The chromatograms obtained with H2 carrier gas
were compared to those obtained with He carrier
gas. The same instrument settings including the flow
parameters (constant pressure at initial linear velocity
of 40cm/sec) were used. The chromatograms of HAA
using H2 carrier gas were nearly identical to those
using He carrier gas. The retention times of each
compound using H2 or He carrier gas were shown in
Table 3 below. The differences are minimal.
Table 2: Instrument Configuration and Analysis Conditions
GC system
Shimadzu Nexis GC-2030 with dual SPL, dual ECD-2030 exceed and dual AOC-20 Plus autosampler
Column
Rtx-1701, 30m x 0.25mm x 0.25µm (line 1)
Rxi5Sil-MS, 30m x 0.25mm x 0.25µm (line 2)
Injector Mode
Split at 1:1 ratio increase to 10 after 0.5min
Injection Volume
1.5 µL
Carrier Gas
Hydrogen
Flow mode
Constant pressure at initial linear velocity of 40cm/sec
Column Temp
35°C, 10min – 3°C/min – 65°C – 10°C/min – 85°C – 20°C/min – 205°C, 5min
Injection Port Temp
210°C
Detector Temp and Current
290°C, 2nA
Detector Gases
N2 15mL/min, with Detector Constant Flow Mode
Nexis GC-2030
No. SSI-GC-2002
Figure 1: Chromatograms of 10 ppb HAA Methyl Ester Mix analyzed with indicated carrier gas on a) analytical column (Rtx-1701) and b)
confirmation column (Rxi5Sil-MS). Peaks indicated with an asterisk do not correspond to any of target peaks.
Table 3: List of compounds analyzed and the retention times with different carrier gases.
Compounds
Peak
no.
Ret. Time (min) on Rtx-1701
Ret. Time (min) on Rxi5Sil-MS
H2 Carrier
He Carrier
H2 Carrier
He Carrier
MCAA
1
11.32
11.26
6.12
6.09
MBAA
2
16.06
16.03
10.07
10.02
Dalapon
3
16.54
16.53
12.64
12.62
DCAA
4
16.91
16.90
11.01
10.99
TCAA
5
20.24
20.24
16.57
16.56
1,2,3-Trichloropropane (internal standard)
6
21.63
21.62
17.26
17.27
BCAA (*)
7
21.93
21.93
17.01
17.00
2-Bromobutanoic acid (surrogate)
8
22.25
22.25
18.97
18.95
BDCAA (*)
9
23.79
23.79
22.07
22.07
DBAA
10
24.11
24.11
21.81
21.81
CDBAA (*)
11
25.48
25.40
24.43
24.43
TBAA (*)
12
26.71
26.71
25.85
25.86
(*) Compounds included in HAA9 group
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
26.0
27.0 min
-50000
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
500000
550000
600000
650000
700000
750000
800000
850000
900000
950000
1000000 uV
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
26.0
min
-50000
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
500000
550000
600000
650000
700000
750000
800000
850000
900000
950000
uV
10
11
12
9
8
7
6
5
4
3
2
1
*
1
2 4
3
*
5
6
7
8
10
9
11
12
*
a) HAA9, Rtx-1701 column
H2
He
H2
He
b) HAA9, Rxi5Sil-MS column
*
No. SSI-GC-2002
Method interferences: solvents
Using H2 carrier gas, MTBE blanks were analyzed at
the beginning of each sample run. As shown in
Figure 2, the results are within the acceptable criteria
for the presence of targets in the blanks listed in EPA
method 552.3, which is below 1/3 of the minimal
reporting level (1 ppb).
There are two peaks (marked with asterisks) present
in the blanks that do not coelute with any of the
analyte peaks.
Figure 2: Chromatograms of MTBE blanks and 1 ppb HAA Methyl Ester Mix on a) analytical column (Rtx-1701) and b) confirmation
column (Rxi5Sil-MS) using H2 carrier gas. Peaks indicated with an asterisk do not correspond to any of target peaks.
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
26.0
27.0
min
-30000
-20000
-10000
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
110000
120000
130000
140000
150000
160000
uV
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
min
0
25000
50000
75000
100000
125000
150000
175000
200000
225000
uV
*
10
11
12
9
8
7
5
4
2 3
a) HAA9, Rtx-1701 column
Blank
1ppb standard
*
*
*
9
10
11
12
8
5
7
6
6
1
1
2 4
3
b) HAA9, Rxi5Sil-MS column
Blank
1ppb standard
No. SSI-GC-2002
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Area Ratio
0
100
200
300
400
Conc. Ratio
0
1
2
3
4
5
6
7
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.05
0.10
0.15
0.20
0.25
0.30
Area Ratio
Calibration Curves with H2 Carrier Gas:
The HAA methyl ester mix was diluted to prepare a
six-point calibration curve with concentrations from
1 to 50 ppb in water. Internal standard calibrations
fitted quadratically with 1/A weighting without
forcing through zero were built for all targets.
The calibration curves and the coefficients of
determination (r2 Values) are shown in Figure 3 and
Table 4. All r2 values were higher than 0.995.
Table 4: Coefficient of determination (r2) of the calibration
curves.
Compounds
r2 Values
Rtx-1701
Rxi5Sil-MS
MCAA
1.000
0.998
MBAA
0.999
0.998
DCAA
0.998
0.998
TCAA
0.998
0.998
DBAA
0.999
0.998
BCAA
0.998
0.998
BDCAA
0.999
0.999
CDBAA
0.999
0.999
TBAA
0.999
0.999
Dalapon
0.998
0.997
a) Rtx-1701
b) Rxi5Sil-MS
Figure 3: Six-point calibration curves for HAA5 on a) analytical column (Rtx-1701) and b) confirmation column (Rxi5Sil-MS) using H2
carrier gas.
0
100
200
300
400
Conc. Ratio
0.000
0.025
0.050
0.075
0.100
0.125
0.150
0.175
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Area Ratio
0
100
200
300
400
Conc. Ratio
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Area Ratio
0
100
200
300
400
Conc. Ratio
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
Area Ratio
MCAA
MBAA
DCAA
TCAA
DBAA
BDCAA
TBAA
Dalapon
CDBAA
BCAA
DCAA
MBAA
MCAA
TCAA
DBAA
BCAA
CDBAA
Dalapon
BDCAA
TBAA
No. SSI-GC-2002
The method requires demonstration of calibration
accuracy. Specifically, the analyte concentrations
should be within ±30% of the expected values,
except for lowest calibration level, where ±50% is
acceptable. In other words, the measured
concentrations should be within 70 - 130% of
expected values (or with 50 - 150% for the lowest
calibration level). In Table 5, the percentage of
measured concentrations over expected values
(percent recovery) are summarized. Based on the
results shown, it can be concluded that all results
were well within EPA’s acceptable range and
difference were < ±25% for the lowest calibration
level and < ±10% for all other levels.
Repeatability
The 1 ppb standard was injected three times and the
percent RSD was calculated. As shown in Table 6
below, all are under 2% RSD, greatly exceeding the
EPA requirement of less than 20% RSD. The percent
recovery required for MDL is ±50% of the expected
value. As shown in Table 6, the mean % recovery for
all compounds ranged from 76.84 to 93.80, within
25% of the expected value of 1 ppb.
Table 5: Calibration accuracy results (based on percent recoveries) at each calibration level.
Expected
conc.
1ppb
2.5ppb
5ppb
10ppb
25ppb
50ppb
Line1
Line2
Line1
Line2
Line1
Line2
Line1
Line2
Line1
Line2
Line1
Line2
MCAA
94.5
84.1
103.1
107.5
102.3
107.7
101.2
102.5
98.1
95.5
100.5
101.4
MBAA
84.8
80.1
107.3
107.8
106.6
109.1
102.2
103.1
96.0
94.9
101.3
101.7
DCAA
83.8
78.7
107.6
109.0
107.6
108.9
102.4
103.4
95.6
94.7
101.4
101.7
TCAA
82.1
79.6
107.8
108.8
108.1
108.8
102.6
102.9
95.6
95.1
101.2
101.4
DBAA
84.0
79.4
107.6
108.9
106.9
109.0
101.7
102.6
96.4
95.3
100.9
101.3
BCAA
80.3
78.5
105.7
109.0
107.8
109.2
103.3
103.3
95.8
94.8
101.1
101.6
BDCAA
88.9
84.9
105.9
107.7
105.1
106.3
100.8
101.2
97.5
96.8
100.6
100.8
CDBAA
89.2
87.0
105.4
107.0
105.3
104.9
100.7
101.2
97.6
97.2
100.6
100.7
TBAA
84.8
83.5
107.0
108.0
107.2
106.7
101.7
101.5
96.4
96.5
100.9
100.9
Dalapon
86.3
78.2
108.3
109.4
107.2
109.1
102.0
103.5
95.7
94.5
101.3
101.9
Table 6: Repeatability (%RSD, n=3) and mean % recovery of 1 ppb (MDL concentration) standard.
Compounds
Rtx-1701
Rxi5Sil-MS
Mean % recovery
%RSD
Mean % recovery
%RSD
MCAA
93.80
0.67
84.62
1.19
MBAA
83.54
1.34
78.69
1.58
DCAA
82.63
1.24
77.14
1.80
TCAA
81.13
1.15
78.82
0.95
DBAA
83.23
0.86
78.40
1.42
BCAA
80.20
1.72
77.17
1.65
BDCAA
88.32
0.59
84.15
0.81
CDBAA
88.51
0.64
86.32
0.81
TBAA
84.14
0.83
82.82
0.77
Dalapon
86.92
0.70
76.84
1.62
No. SSI-GC-2002
Cost savings by switching to hydrogen carrier gas
Based on the current market prices for He and H2,
cost of analysis, when switching from He to H2 as
carrier gas, will decrease approximately between 3
and 6 times, depending on the gas grade used. One
concern about switching carrier gas is the safety of
using H2 gas, as it is flammable. To address this
concern, the Nexis GC-2030 offers an integrated H2
sensor to detect the presence of H2 in the GC oven.
If H2 concentration inside oven is above 0.4%, an
error message will appear, and the GC will
automatically vent and shut down its heat control. At
2% the system will completely shut off to allow H2
to dissipate before reaching the explosion threshold
of 4%. In addition, GC-2030 features an automatic
carrier gas leak check function that allows users to
run a H2 leak test at their desired frequency.
■ Conclusion
Hydrogen carrier gas was used successfully to
analyze HAA9 compounds according to EPA method
552.3 on Nexis GC-2030 with dual line split/splitless
injectors and ECDs. The results obtained met and
exceeded EPA’s quality assurance requirements for
HAA9 and dalapon, proving that H2 is a suitable
alternative carrier gas to He.
Based on the current market prices for both gases,
cost of analysis, when switching from He to H2
carrier gas, will decrease approximately 6 times when
using Research Grade (99.9999%) gas or 3 times
when using Ultra High Purity (99.999%).
Additionally, laboratories will avoid potential
restrictions in He purchasing that are being more
frequently implemented by gas suppliers. Moreover,
H2 can be easily generated by gas generators,
eliminating of the need for gas tanks altogether.
Safety concerns regarding the use of H2 can easily be
minimized with the safety features of Nexis GC-
2030.
■ References
1.
EPA method 552.3, Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-liquid
Microextraction, Derivatization, and Gas Chromatography with Electron Capture Detection, EPA 815-B-
03-002 (2003)
2.
EPA the Fourth Unregulated Contaminant Monitoring Rule (UCMR4) Fact Sheet for Assessment
Monitoring – Haloacetic Acid (HAA) (2016)
3.
Determination of Haloacetic Acids (HAA5 and HAA9) in Drinking Water According to EPA Method 552.3,
Shimadzu Application News GC-009 (2020)
H2 Sensor
No. SSI-GC-2002
■ Consumables
Part Number
Description
Unit
Instrument
221-76650-01
Septa, Green, Premium Low Bleed
Pk of 25
GC-2030
Restek 23322
Topaz Liner, Single Taper with Wool
Pk of 5
221-81162-01
ClickTek Ferrule 0.4mm
Pk of 6
221-77155-41
ClickTek Column Connector
each
221-34618-00
Syringe, 10µL, fixed needle
each
AOC-20i/s
220-97331-31
Sample Vials, 1.5mL Amber Glass with Caps & Septa
Pk of 100
220-97331-47
Sample Vials, 1.5mL Amber Glass with Caps & Septa
Pk of 1000
220-97331-63
200µL Glass Silanized Inserts for 1.5mL Vials
Pk of 100
220-97331-23
Wash Vials, 4mL Amber Glass with Caps & Septa
Pk of 100
For Research Use Only. Not for use in diagnostic procedure.
This publication may contain references to products that are not available in your country. Please contact us to check the availability of
these products in your country.
The content of this publication shall not be reproduced, altered or sold for any commercial purpose without the written approval of
Shimadzu. Shimadzu disclaims any proprietary interest in trademarks and trade names used in this publication other than its own.
See http://www.shimadzu.com/about/trademarks/index.html for details.
The information contained herein is provided to you "as is" without warranty of any kind including without limitation warranties as to its
accuracy or completeness. Shimadzu does not assume any responsibility or liability for any damage, whether direct or indirect, relating to
the use of this publication. This publication is based upon the information available to Shimadzu on or before the date of publication, and
subject
First Edition: March 2020
© Shimadzu Corporation, 2020
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