13
1. methylene chloride 600ppm
2. chloroform
60ppm
3. benzene
2ppm
4. trichloroethylene
80ppm
5. 1,4-dioxane
380ppm
Sample Preparation:
100µL of cat.# 36007 in 5mL distilledwater, 1 gram
sodium sulfate in a 20mL headspace vial.
30m, 0.53mm ID, 3.0µmRtx
®
-G43 (cat.# 16085)
Oven temp.:
40°C (hold 20min.) to 240°C@ 35°C/min. (hold 20min.);
Inj. temp:
140°C, 1mm split sleeve (cat.# 20916);
Det. temp.:
260°C;
FID sensitivity:
1.25 x 10
-11
AFS;
Carrier gas:
helium, 3.5psi constant pressure, 35cm/sec. set@ 40°C;
Split
ratio:
2:1; ThermoQuest HS 2000HeadspaceAutosampler Vial 80°C, 60
min. shaker on.
Figure 13
TheRtx
®
-G43 column provides the resolution and detection limits needed forUSP 24
th
edition<467> revised limit
test concentrations inUSPMethod IV.
4
1
2 3
5
2 3 4 5 6 7 8
min.
Stock Solvent
Methylene Chloride
Chloroform Benzene
1,1,1-Trichlorethylene
1,4-Dioxane
Water
10.19
10.64
14.52
16.75
18.61
Water w/ Sample
8.29
9.25
11.3
13.38
15.26
DMSO
7.37
8.59
8.18
8.01
14.43
DMSOw/ Sample
7.25
7.54
8.8
8.67
7.37
Table V
Percent RSD for stock solutions inwater vs. DMSO
Comments in the September/October 1992 Pharmacopoeial Forum
3
propose the use
of dimethyl sulfoxide as the solvent for stock standard, but this has not been
approved as of the date of this publication.
In regards to this proposal, an investigationwas conducted to determine if there
were significant changes in results if dimethyl sulfoxidewas used as the diluent for
stock standard. Similar RSDs can be obtainedwhen stock solutions are diluted in
dimethyl sulfoxide as opposed to solutionsmadewithwater (
TableV
).
✶
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