Page 14 - Application Notebook - Hand Sanitizer Analysis

Application Fourier Transform Infrared Spectrophotometer (FTIR)

News
Determination of Ethanol Content in and
Simple Fail/Pass Judgment of Alcohol Hand
No. A637 Sanitizer by FTIR

 Introduction Table 1 Measurement Conditions
The effects of alcohol-based hand sanitizers are dependent Instrument : IRSpirit, QATR-S (Diamond)
on type of alcohol used and alcohol concentration. The Resolution : 4 cm -1
Center for Disease Control and Prevention (CDC) has Accumulation : 20
recommended sanitizers with 60 - 95% alcohol as the most Apodization function : Sqr-Triangle
effective composition of hand sanitizers.
Detector : DLATGS
Ethanol, which has bactericidal activity, is prepared at the
optimal concentration level for a range of commercially
available alcohol-based sanitizers. To measure alcohol
concentration, the distillation method or gas
chromatography (GC) is stipulated by the United States
Pharmacopeia (USP). These methods require more than 20
minutes per sample for analysis. Pretreatment, such as
dilution, is also required. In contrast, if the Fourier
transform infrared spectrophotometer (FTIR) is used, the
preparatory steps can be skipped and the ethanol content
in alcohol sanitizers can quickly be determined in
approximately one minute.
This report introduces a simple pass/fail judgment of
ethanol concentration in a commercially available ethanol Fig. 1 IRSpirit™ FTIR with QATR™-S
sanitizer using the photometric measurement function that
comes as standard in LabSolutions™ IR.
S. Iwasaki

 Experimental
Dehydrated ethanol was spiked with water to prepare the Volatile
standards at concentrations of 70 vol% and 82 vol%. The Cover
samples were measured using IRSpirit™, a Fourier transform
infrared spectrophotometer, equipped with QATR™-S
(diamond crystal), a single-reflection ATR accessory, as
shown in Fig. 1. The measurement conditions are shown in
Table 1. First, 20 to 30 µL of the sample amount was placed
onto the ATR crystal using a micropipette and, as shown in
Fig. 2, covered immediately with a volatile cover to Fig. 2 QATR-S with Volatile Cover
minimize evaporation, which could cause its concentration
to change. Fig. 3 shows the IR spectra of ethanol standards. 0.5
The figure shows that the heights of peaks from ethanol at ― 70 vol% 0.5
1086 cm and 1044 cm (green lines) and those from water Abs ― 82 vol% Abs
-1
-1
at 3340 cm and 1650 cm (blue lines) are dependent on 0.4 0.4
-1
-1
the concentration. 0.3
0.3 0.2
0.1
0.2
0.0
1100 1050 1000
cm-1
0.1

0.0
4000 3000 2000 1500 1000
cm-1
Fig. 3 IR Spectra of Ethanol Standards (70, 82 vol%)