ANALYSIS OF NANOGRAM SPOTS OF INK BY FOURIER-TRANSFORM INFRARED MICROSCOPY AND SPECTRAL STRIPPING

Dot matrix printing inks for industrial printers consist of solvent, b inder, dye and various minor additives, We have used FTIR microspectro scopy to examine the composition of these inks from the analysis of si ngle dots of less than 1 mm diameter. Good spectra were obtained by re flection-absorption on metal surfaces and by ATR on plastic surfaces, Paper substrates have proved more troublesome, Analysis of the printed inks was performed by an iterative process of component identificatio n through library searching and spectral subtraction, Some bandshifts mere observed which complicated this process, but two or three success ive identification-subtraction cycles could often be made. A compariso n of real sample spectra with synthetic spectra produced by addition o f pure component spectra was also useful in highlighting spectral diff erences, indicating component interactions in the formulated inks.