Aspectrics EP-NIR Analyzer Achieves Measurement of Water in Ethanol
Product News Mar 01, 2007
Aspectrics, Inc. has introduced a new application note detailing that its new MultiComponent™ 2750 EP-NIR analyzer 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 minimized for ethanol to be as absolute as possible.
The application note entitled “Measurement of Water in Ethanol- Using an Aspectics MC2750 EP-NIR for Concentrations of Ethanol Greater Than 90% v/v” shows how the Aspectrics MultiComponent™ 2750 EP-NIR analyzer, when coupled to an external halogen NIR source and an extended range 2mm pathlength process transmission multimode fiber probe, is able to quantify the percentage volume of water in ethanol.
All spectra were collected using 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 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 capabilities of the MultiComponent™ 2750 EP-NIR analyzer, which has already demonstrated a degree of sensitivity due to extremely low instrumental noise, long-term photometric response stability and superior scan to scan wavelength reproducibility.