QASoft is an automatic quantitative analysis program developed by Infrared Analysis, Inc. that enables the measurement of all infrared-active gases. The program can be operated with many types of FT-IR spectrometers and long path optical systems.

QASoft uses the spectroscopist's traditional method of comparing band areas in sample and reference spectra. With a computer doing the comparisons rather than a human operator, the analyses are faster and more accurate, and the computer can immediately subtract the measured spectrum from the sample spectrum. The data system then can proceed to the measurement of other designated compounds.

The foundation of QASoft is the database of quantitative reference spectra. See the topic DATABASE OF GAS PHASE INFRARED SPECTRA.


The analytical technique used in QASoft is called RIAS--for Region Integration and Subtraction. RIAS can succeed when other quantitative analysis methods will fail, because RIAS takes advantage of fine structure in the spectra. RIAS works when measuring narrow spectral features--spikes (Q-branches), shoulders of bands, small bundles of lines, or even individual lines. This use of sharp features allows accurate measurements on mixtures of compounds with overlapping spectra, even when there are unknown contributors to the absorption. Gases can be measured even when their spectral features are below the noise level in the spectrum. See the topic REGION INTEGRATION AND SUBTRACTION (RIAS).

QASoft is written in the GRAMS Array Basic programming language, and it operates within theThermo Galactic GRAMS software. Operations are carried out through the Infrared Analysis, Inc. workbook page, shown in the figure here. There are two main parts to QASoft: (1) the database and (2) the operating programs. The database contains spectra of 300 compounds at resolutions of 0.5 and 1.0 cm-1. These spectra permit the computation of concentrations from a sample spectrum without the need for any other calibration. In analyzing for the 300 compounds, the only chemical that the user will need to handle is his sample.

The operating programs permit manipulation of the database spectra in many ways, especially in the automatic quantitative analysis of mixtures of gases. The quantitative analysis may be carried out with two different stages of automation..

Automation Stage l is the quantitative analysis for designated compounds, chosen one at a time, with interaction between operator and computer.


Automation Stage 2 is the measurement of a list of many compounds with the operator only being required to start the run and call for a print-out of the results.

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