The objective of this research is to develop a low-cost infrared absorption spectroscope based on linear variable filter technology for the automated detection of concentrated gases and vapors, and the semiautomated detection of liquids. This instrument represents an alternative to electronic-nose devices based on cross-selective gas sensor arrays. Instead, the proposed instrument uses the concept of computational "pseudosensors," whereby spectral lines in an analytical instrument are clustered into groups and used as independent variables. We characterize the system on a database of chemical mixtures, and evaluate it on two real-world applications in the foodstuffs domain: oil adulteration and transfatty acid detection. Our results show that the proposed system is a viable low-resolution, low-cost analytical technique for niche applications.