ProcedureB -Confirmation
Once a residual solvent is identified and found to be above the percent daily
exposure limit, Procedure B is performed to confirm analyte identity. A G16
capillary column is used here as a confirmation column, because it yields an
alternate selectivity compared to aG43 column.The same standard and system
suitability preparations are used in Procedures A and B. The system suitability
requirements differ here in that theClass 1 standard solutionmust have a ben-
zene response greater than 5 and the resolution of acetonitrile and
cis
-
dichloroethene must not be less than 1 in the Class 2 Mixture A solution, a
change from the original version. If the analyte identified inProcedureA again
matches the retention timeandexceeds thepeak responseof the referencemate-
rials (with the same exception to1,1,1-trichloroethane), the analystmust quan-
tify the analyte usingProcedureC. Figures 7 through 9 illustrate the analysis of
Class 1, Class 2Mixture A, and Class 2Mixture B residual solvent mixes on a
Stabilwax® column.Again, the system suitability requirementswere easilymet.
ProcedureC–Quantification
Once a residual solvent has been identified and verified, ProcedureC is used to
quantify the analyte by analyzing the sample against compound-specific refer-
encematerials. Individual standards arepreparedbydiluting theanalyte in solu-
tion to a concentration of 1/20 of the concentration limit given under concen-
tration limit Table 1 or 2 of themethod. Following the procedure and instru-
ment conditions ineitherProcedureAorB (whicheverprovides themostdefin-
itive results), a quantifiable result is produced. For water-insoluble articles, the
same procedure is followed, except dimethylformamide or dimethylsulfoxide is
used as thediluent.
Figure7
USP residual solventClass1 standard solutiononaStabilwax®
column (G16).
GC_PH00951
Column:
Stabilwax
®
, 30m, 0.32mm ID, 0.25µm
(cat.# 10624)
Sample:
USP StockMixtureUSP<467>Residual
Solvents Class 1Mix (cat.# 36279) in
20mL headspace vial (cat.# 24685),
water diluent
Inj.:
headspace injection (split ratio 1:5),
2mm splitless liner IP deactivated
(cat.# 20712)
Inj. temp.:
140°C
Carrier gas:
helium, constant flow
Flow rate:
2.15mL/min., 35.2cm/sec.
Oven temp.:
50°C for 20min. to 165°C@ 6°C/min.
(hold for 20min.)
Det.:
FID@ 250°C
Headspace Conditions
Instrument:
Overbrook Scientific
HT200H
Syringe temp.:
100°C
Sample temp.:
80°C
Sample equil. time.: 45min.
Injection vol.:
1.0mL
Injection speed:
setting 8
Injection dwell:
5 sec.
S/N
1. 1,1-dichloroethene
>5
2. 1,1,1-trichloroethane
>5
3. carbon tetrachloride
>5
4. benzene
>5
5. 1,2-dichloroethane
>5
•
6
•
Interested indual
columnanalysis?
Reviewour technical poster on
dual columnanalysisof residual
solvents.
Stabilwax®Columns (fusedsilica)
(Crossbond
®
Carbowax
®
polyethylene glycol)
ID df (µm)
temp. limits
length cat.#
0.32mm 0.25
40 to 250°C
30-Meter 10624
0.53mm 0.25
40 to 250°C
30-Meter 10625
AchievingUSP<467>Compliance
(continued frompage5)
SYSTEMSUITABILITYCRITERIAMET
Customstandards
Visit usonlineat
CapillaryColumn—ProcedureB
Rtx®-1301 (G43)Columns (fusedsilica)
(Crossbond
®
6% cyanopropylphenyl/94% dimethyl polysiloxane)
ID df (µm)
temp. limits
length cat.#
0.32mm 1.80 -20 to 240°C 30-Meter 16092
0.53mm 3.00 -20 to 240°C 30-Meter 16085
CapillaryColumn—ProcedureA
