285 / 302
Table 4. MS/MS experimental conditions for SRM.
Results and Discussion
In negative ion mode,
13
C
2
-acetic acid was used as an
internal standard. Acetic acid produced a deprotonated
molecule (
m/z
94) [
13
CH
3
13
COOH·O
2
]
-
which, under CID
conditions, produces CH
3
COO
-
(
m/z
61). Phenol forms an
analog adduct [C
6
H
5
OH·O
2
]
-
(
m/z
126), which yields a
product ion at
m/z
93, C
6
H
5
O
-
.
In positive ion mode, acetone-d
6
(
m/z
65 to
m/z
33)
was used as an internal standard. Two precursor ion –
product ion transitions were monitored,
m/z
91 to
m/z
31
and
m/z
91 to
m/z
73, respectively, in multiple reaction
monitoring (MRM) mode for the analysis of PGME.
The limit of detection (LOD) is the concentration
equivalent of 3x standard deviation of the response at the
background level (i.e., ambient air, in the absence of the
subject compound).
The calibration data for ethylacetate, MEK, PGME,
and phenol are shown in Figures 3 through 10. The
quantitative results are listed in Tables 5 through 8.
Precursor Ion
Product Ion
Tube Lens
Collision
Compound
(m/z)
(m/z)
Voltage (V)
Energy (V)
13
C
2
-acetic acid
94
61
56
11
d
6
-acetone
65
33
82
18
Ethylacetate
89
61
45
8
MEK
73
43
108
13
PGME
91
31
54
21
PGME
91
73
54
5
Phenol
126
93
35
13