Figure 7
TLC spectrum for a TO-14/TO-15 ambient air analysis.
11
tor to each “unknown” analyte peak area to get the reporting limit concentra-
tion of the “unknown” in the analysis (typically in ppbv). If you have diluted
the canister to get a positive pressure, however, you must apply the dilution
factor to the concentration values. This is done by multiplying the reporting
limit by the dilution factor.
VII. Cleaning the Passive Sampling Train
The cleanliness of the sampling train is critical to collecting accurately repre-
sentative samples. Practices followed for cleaning passive sampling equipment
between uses range from purging the sampling pathway with humidified
nitrogen or air for many hours to heating the pathway during a purge to dis-
assembling each component, sonicating the pieces in solvent, and oven baking
the pieces prior to re-assembly. The most suitable mode of cleaning depends
on the concentrations of analytes of interest, and contaminants, in the previ-
ous sample collected.
The particle filter must be thoroughly cleaned between uses. Disassemble the
filter, then remove the larger particles from the frit by blowing particle-free
nitrogen through the frit from the outlet surface toward the inlet surface. After
the larger particles are removed sonicate or rinse the filter parts in methanol,
then bake the parts in an oven at 130°C to remove any residual organic vapors.
The critical orifice and flow controller can be cleaned in either of two ways.
The first method is to disassemble the flow controller and clean all the metal
parts with methanol. This will remove any high boiling compounds that have
condensed onto the wetted areas of the controller. Heat the cleaned parts in an
oven at 130°C to remove residual organic vapors. Do not sonicate in solvent or
bake any of the non-metallic parts, such as O-rings; they will be damaged dur-
ing these steps. Do not rinse the vacuum gauge with methanol. The vacuum
gauge may be heated, but do not exceed 80°C; higher temperatures will dam-
age the face and the laminated safety glass lens. Heating to 80°C will not affect
the mechanical operation of the spiral bourdon tube in the vacuum gauge.
Rtx
®
-1 60m, 0.32mm ID, 1.0µm (cat.# 10157).
Sample:
200mL of 10ppbv TO-15 standard (cat.# 34436), injected into TO-Can
™
canister and humidified to 70% RH.
Concentrator:
Nutech 3550 Preconcentrator
200mL of sample concentrated at -160°C, thermally desorbed at 150°C, and cryofocused at -185°C.
Oven temp.:
30°C (hold 4 min.) to 175°C @ 9°C/min. to 220°C @ 40°C/min.
Carrier gas:
helium @ 1.2mL/min.
Det.:
Agilent 5971 MS
Scan range:
35-265amu
4 5
6
7 8
9
10 11
12
13 14 15 16 17 18 19 20 21 22 23 min.
1
3
4
5
6
7
8
9/10
11
12
13
14
15
16
17
18
19
20
21
22/23
24
25
26
27
28
29
30
31
32
33
34
35/36
37
38
39
40
41 42
43 44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
BFB
GC_EV00379
2
1. dichlorofluoromethane
2. chloromethane
3. dichlorotetrafluoroethane
4. vinyl chloride
5. 1,3-butadiene
6. bromomethane
7. chloroethane
8. bromoethene
9. acetone
10. trichlorofluoromethane
11. isopropyl alcohol
12. 1,1-dichloroethene
13. methylene chloride
14. 3-chloropropene
15. carbon disulfide
16. Freon
®
TF
17.
trans
-1,2-dichloroethene
18. 1,1-dichloroethane
19. methyl
tert
-butyl ether
20. methyl ethyl ketone
21.
cis
-1,2-dichloroethene
22. bromochloromethane (IS)
23.
n
-hexane
24. chloroform
25. tetrahydrofuran
26. 1,2-dichloroethane
27. 1,1,1-trichloroethane
28. benzene
29. carbon tetrachloride
30. cyclohexane
31. 1,4-difluorobenzene (IS)
32. 1,2-dichloropropane
33. bromodichloromethane
34. trichloroethene
35. 1,4-dioxane
36. 2,2,4-trimethylpentane
37.
n
-heptane
38.
cis
-1,3-dichloropropene
39. methyl isobutyl ketone
40.
trans
-1,3-dichloropropene
41. 1,1,2-trichloroethane
42. toluene
43. methyl butyl ketone
44. dibromochloromethane
45. 1,2-dibromoethane
46. tetrachloroethene
47. chlorobenzene-d5 (IS)
48. chlorobenzene
49. ethylbenzene
50.
m
/
p
-xylene
51. bromoform
52. styrene
53. 1,1,2,2-tetrachloroethane
54.
o
-xylene
55. 2-chlorotoluene
56. 4-ethyltoluene
57. 1,3,5-trimethylbenzene
58. 1,2,4-trimethylbenzene
59. 1,3-dichlorobenzene
60. 1,4-dichlorobenzene
61. 1,2-dichlorobenzene
62. 1,2,4-trichlorobenzene
63. hexachlorobutadiene
