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By Michelle Misselwitz and Jack Cochran
• Eliminate time-consuming extract concentration
without sacrificing sensitivity.
• Simplified approach uses standard injection port—no
specialized equipment.
• Analyze at sub-ppb levels with faster, less labor-
intensive procedure.
Using large volume splitless injection is advantageous when trying
to analyze trace-level contaminants in clean matrices like drinking
water because greater levels of target compounds are introduced
onto the analytical column. A special injection port is generally
required for large volume injection, which has limited its application.
A concurrent solvent recondensation–large volume splitless injection
(CSR-LVSI) technique described by Magni and Porzano [1,2] offered a
more practical alternative, but involved some modification of a split/
splitless injection port.
We have used CSR-LVSI successfully with a completely unmodified
Agilent split/splitless GC inlet. The setup utilizes a pre-column (e.g.,
5 m x 0.53 mm) press-fitted to the analytical column and a starting
GC oven temperature below the boiling point of the solvent. A fast
autosampler injection with liquid band formation into a liner con-
taining glass wool is used to prevent backflash in the injection port.
Here we investigated the applicability of this approach to analyzing
pesticides and brominated flame retardants (BFRs) in drinking water
according to U.S. EPA Method 527 [3].
Table I:
Calibration standards and concentration equivalents.
Level
Prepared Standard
(pg/µL)
On-Column Amount Injected
(pg/12.5 µL)
Equivalent Concentration in
1 L Samples (ug/L)
1
2
25
0.05
2
4
50
0.1
3
10
125
0.25
4
20
250
0.5
5
40
500
1
6
80
1,000
2
Table II:
Average percent recoveries and relative standard deviations
for 1 µg/L and 0.1 µg/L laboratory fortified blank samples analyzed
using disk extraction with no extract concentration and CSR-LVSI
GC-TOFMS (n = 3).
1.0 µg/L % Recovery
0.1 µg/L % Recovery
Compounds
AVG (n = 3)
%RSD
AVG (n = 3)
%RSD
Dimethoate
73
2.4
75
9.3
Atrazine
96
1.8
84
13
Propazine
93
3.3
92
8.5
Vinclozoline
97
4.0
97
8.0
Prometryne
179
3.0
113
7.9
Bromacil
78
2.2
66
3.1
Malathion
98
2.7
85
6.5
Thiobencarb
93
3.9
70
1.9
Chlorpyrifos
92
3.1
84
1.7
Parathion
94
0.7
92
4.6
Terbufos sulfone
88
2.8
105
11
Oxychlordane
75
8.5
74
10
Esbiol
88
2.7
79
6.5
Nitrofen
91
3.0
77
5.3
Kepone
102
18
56
32
Norflurazon
91
7.2
105
10
Hexazinone
87
0.8
68
2.1
Bifenthrin
100
3.0
81
3.2
BDE-47
96
4.4
87
15
Mirex
93
4.5
76
2.3
BDE-100
93
3.8
89
11
BDE-99
93
2.9
79
33
Perylene-D12
103
1.6
98
3.3
Fenvalerate
92
0.4
59
16
BB-153
88
3.4
45
14
Esfenvalerate
89
3.7
69
20
BDE-153
88
13
54
49
Large Volume Splitless InjectionWith an Unmodified GC Inlet
Lets You Skip Sample Concentration for Pesticides and BFRs in Drinking Water