A NEW METHOD FOR THE DETERMINATION OF TOXIC DYE USING FTIR SPECTROSCOPY

Abstract

A new method was developed to determine toxic dyes content in textile
and other products using Fourier Transform Infrared (FTIR) spectroscopy with
Attenuated Total Reflectance (ATR) element and KBr transmission cell. The
wavelengths used were selected using pure dyes and dye mixtures. Transmittance values
from the wavelengths regions 3500 – 2650 and 1675 – 1500 cm-1 and partial least square
(PLS) regression method were used to derive FTIR spectroscopic calibration model for
dyes containing –N=N– in their structure. The coefficient of determinations (R2) for the
models were computed by comparing the results obtained from FTIR spectroscopy
against the actual values of the dyes concentrations. R2 were 0.9321 and 0.9819 for two
samples of toxic dyes respectively. The standard errors (SE) of calibrations were 1.84
and 1.36 respectively. The calibration model was cross validated within the same set of
samples and the standard deviation (SD) of the difference for repeatability and accuracy
of the FTIR method were determined. With its speed and ease of data manipulation,
FTIR spectroscopy is a useful alternative method to wet chemical methods for rapid and
routine detection of azo dyes as toxic dyes in such products for quality control.