Light intensity data quantifying intensity of light generated by a light source and received at a detector during a validation mode of an absorption spectrometer can be compared with a stored data set representing at least one previous measurement in a validation mode of an analytical system. The validation mode can include causing the light to pass at least once through each of a zero gas and a reference gas contained within a validation cell and including a known amount of a target analyte. The zero gas can have at least one of known and negligible first light absorbance characteristics within a range of wavelengths produced by the light source. A validation failure can be determined to have occurred if the first light intensity data and the stored data set are out of agreement by more than a predefined threshold amount. Related systems, methods, and articles of manufacture are also described.