Abstract: In a near infrared absorbance measurement instrument, an attenuated internal reflectance probe comprises a quartz rod having an inexpensive low purity central core surrounded by two high purity quartz layers. Narrow band infrared light is transmitted axially through the outer layer to cause the light to undergo total internal reflection from the inner and outer surfaces of the outer layer. A near infrared light detector measures the light transmitted through the outer layer to obtain a measurement of the absorbance of the fluid in contact with the outer surface of the outer layer without any interference from suspended particles or bubbles in the fluid being measured.

Abstract: In the system for analyzing aqueous samples, the aqueous sample is deposited upon a sheet of filter paper which is held in a filter holder by clamping the peripheral edges of the filter paper between male and female threaded members of the filter holder. The filter paper with the sample is dried by a heated air stream directed perpendicularly toward the paper so that it flows around and through the paper. After the sample has been dried, it is analyzed by near infrared spectral analysis to measure the constituents of the dried sample.

Abstract: A flow cell for use in optical measuring systems particularly suited for use with liquid food products is provided. The flow cell is manufactured from a single unitary piece of synthetic resin which is transparent to light in the near infrared range. Because the flow cell is constructed from a single piece, the interior surface is continuous and the presence of undesirable cracks or crevices is avoided.