THE USE OF MULTIVARIATE CALIBRATION FOR CHLORINATED-HYDROCARBON DETECTION IN WATER WITH AN MTR FIBEROPTIC SENSOR

A detection system for chlorinated hydrocarbons (CHCs) in water has be en based on a mid-infrared (MIR) fibre optic physicochemical sensor, t he measurement principle being attenuated total reflection (ATR), with the IR-beam coupled into an ATR-element, an IR-transparent silver hal ide fibre. At each reflection the penetrating energy is attenuated by the IR-absorbing analytes present in the surrounding polymer matrix. T he aim of the present study was to investigate multivariate calibratio n techniques for use of this sensor system to determine CHCs in water. Partial least-squares regression was compared with standard univariat e calibration. The spectral range from 950 to 750 cm(-1) was measured for different aqueous CHC solutions with the fibre-optic set-up couple d to a Fourier-transform infrared spectrometer. Mixed standards of tet rachloroethylene, trichloroethylene and chloroform in water were measu red according to a central composite design.