Accurate measurement of water in Ethanol

Aspectrics has published a new application note showing that its innovative new MultiComponent 2750 EP-NIR analyser can achieve precise measurement of water in ethanol

Aspectrics, the innovator of patented Encoded Photometric Infrared (EP-IR) spectroscopy technology, has a new application note showing that its innovative new MultiComponent 2750 EP-NIR analyser achieves precise measurement of water in ethanol, particularly when ethanol concentrations are 90% or greater.

Determining the percentage of water contained in ethanol is especially important during the purification process of ethanol when the percentage of water needs to be minimised, for ethanol to be as absolute as possible.

Designed to respond to the needs of scientists working in the process industry, this is an efficient and cost-effective solution for measuring water content in ethanol.

The innovative EP-NIR analyser was shown recently at Pittcon 2007.

The application note entitled "Measurement of Water in Ethanol- Using an Aspectics MC2750 EP-NIR for Concentrations of Ethanol Greater Than 90% v/v" explains how the Aspectrics MultiComponent 2750 EP-NIR analyser, when coupled to an external halogen NIR source and an extended range 2mm pathlength process transmission multimode fibre probe, is able to quantify the percentage volume of water in ethanol.

The findings of this analysis are detailed in the new, free-of-charge application note available to download via the website.

All spectra were collected using the Aspectrics RTSS Chemometrics software package.

Denatured corn-based ethanol samples diluted with distilled water to concentrations ranging from 0.2 to 10.0% were used.

In order to quantitate unknown samples, a multivariate Principal Component Regression (PCR) quant model was developed from the NIR spectra of all samples.

The results of the analysis demonstrated strong correlations between concentrations in the spectral range of 1.4-1.55 nm and 1.85-2.00 nm and in the C-OH region between 2.00 and 2.2 nm.

The precision of the calibration may be ascertained through the RMSEP of the validation set, which was 0.14% v/v.

At the maximum concentration for water, this value is consistent with the precision of the reference method (1.2% relative).

A majority of this deviation originates from the single 8.0% sample, which suggests a pipetting error during sample preparation.

Furthermore, the experiment highlighted that the accuracy of study is highly dependent on the precision of the reference method.

The new application further stresses the unique capabilities of the MultiComponent 2750 EP-NIR analyser, which has already demonstrated a high degree of sensitivity due to extremely low instrumental noise, long-term photometric response stability and superior scan to scan wavelength reproducibility.

Back to top