The Covid-19 crisis increased the demand for Alcohol based hand sanitizers but to ensure its effectiveness it is necessary to check the alcohol content.
These solutions can be prepared from IsoPropylalcohol (IPA) or denatured ethanol (EtOH).
In order to be effective against viruses, the alcohol content in the aqueous solution is of primary importance and determines the effectiveness as a disinfectant: for example, the concentration of isopropanol must be greater than or equal to 60%.
Alcohol is known for its rapid action and rapid evaporation, however, this causes the skin to dry out. To avoid this, an emollient (such as glycerine) is added to ensure good tolerance.
Agilent offers applications to check the alcohol level by GC/FID (extract from the Agilent poster n° 5994-1923EN dated 15/04/2020).
These analyses by gas chromatography with FID are proposed on 2 columns:
- DB-624 Ultra inerte 30m x 0.32mm 0.18µm (123-1334UI) with deactived fused silica 1mx0.32mm (160-2325-1)
- DB-WAX Ultra inerte 30mx0.25mm 0.25µm (122-7032UI)
|Column||DB-624 Ultra Inert
30m x 0.32mm x 1.8μm
Deactivated fused silica, 1m x 0.32 mm
|DB-WAX Ultra Inert,
30m x 0.25mm x 0.25μm
constant flow, 6mL/min (73cm/s)
constant flow, 6 mL/min (80 cm/s)
|Oven||40°C (5min), 20°C/min to 225 °C (2.5min)
|40°C (5min), 20°C/min to 225°C (2.5min).
|Inlet||Split mode, 140°C, split ratio 40:1||Split mode, 140°C, split ratio 40:1|
Analysis of IsoPropanol (IPA)
Figure 1. GC/FID chromatograms of an IPA-based hand sanitizer using a DB-624 UI, 30 m x 0.32 mm id x 1.8 μm df (top) and DB-WAX UI, 30 m x 0.25 mm id x 0.25 μm df (bottom). Calibration curves were prepared for IPA in a 30 to 80% v/v range. R2 were 0.997 and 0.999 for DB-624 UI and DB-WAX UI, respectively.
Analysis of Ethanol (EtOH)
Figure 2. GC/FID chromatograms of an Ethanol hand sanitizer obtained from a distillery. The chromatograms were obtained using a DB-624 UI, 30 m x 0.32 mm id x 1.8 μm df (top) and DB-WAX UI, 30 m x 0.25 mm id x 0.25 μm df (bottom). Calibration curves were prepared for EtOH in a 50 to 90% v/v range. R2 were 0.995 and 0.994 for DB-624 UI and DB-WAX UI, respectively.
Fusel oils will often be present and may present themselves as unpleasant odors in the hand sanitizer. The presence of these alcohols are apparent with both, the DB-624 UI and DB-WAX UI chromatograms. DB-624 UI has the selectivity to fully resolve fusel oils if their analysis is required.