Page 9 - Application Notebook - Hand Sanitizer Analysis

No. SSI-GC-2005

■ Results and Discussion
Calibration Curves Nitrogen (N2) was chosen as the carrier gas to reduce
Since both ethanol and 2-propanol (isopropanol the cost of analysis compared to using helium. As
alcohol or IPA) can be used to prepare hand shown in Figure 1, all peaks were well resolved, and
sanitizer, calibration standards were prepared with no contaminating peaks were found in water blank
both types of alcohol. An internal standard (IS) is with IS only.
commonly used in these assays to improve accuracy.
Although acetonitrile is specified in the USP method The calibration standards were diluted to indicated
as the IS for ethanol, it elutes closer to IPA and may concentrations with 0.5% (v/v) of n-butanol in
cause column/liner deterioration with repeated deionized water. Internal standard quantification
injections. In comparison, n-butanol elutes away methods were used, and the calibration curves were
from both ethanol and IPA, and is not known to fitted to linear regression without forcing through
cause degradation to the GC systems. It is commonly zero.
used in blood alcohol content assays as an IS for
ethanol. Therefore, n-butanol was used as the IS in
this study.

uV
n-butanol (IS)
2300000
2200000
2100000 Ethanol
2000000 Isopropanol (IPA)
1900000
1800000
1700000
1600000
1500000
1400000
1300000
1200000
1100000
1000000
900000
800000
700000
1% (v/v)
600000
500000 0.9% (v/v)
400000
300000 0.7% (v/v)
200000 0.6% (v/v)
100000
0 Blank
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 min

Figure 1: Chromatograms of calibration standards and water blank with IS (n-butanol)

Area Ratio Area Ratio
1.50

1.25
Ethanol 1.25 Isopropanol (IPA)

1.00 r =0.99928 r =0.99998
2
2
1.00

0.75 0.75

0.50
0.50

0.25 0.25

0.00 0.00
0.00 0.25 0.50 0.75 Conc. Ratio 0.00 0.25 0.50 0.75 Conc. Ratio
Figure 2: Four-point calibration curves for ethanol and IPA