Two hundred thirty-eight ground samples of tobacco were scanned with a computerized near-infra-red (NIR) spectrophotometer to study the relationship of NIR spectra to the polyphenol content of the samples. A multiple linear regression model was used to select the most appropriate wavelengths for making the measurements. The equation
P = polyphenols in %
D12 = 2nd derivative parameter
i = wavelength in micrometers at which the parameter is measured.