Variation in ambient temperature as a source of error in absorbance measurements made with single-beam spectrophotometers

Abstract

Small changes (±2 °C) in ambient temperature were found to affect the zero absorbance calibration of two dissimilar single-beam spectrophotometers of modular construction. The temperature-sensitive modules of each instrument were located and their thermal responses measured. When all modules were operated at ambient temperature (23–27 °C) and monochromator drift was corrected, the thermal drifts were sufficiently large to cause a significant error in applications in which it is not the normal practice to re-calibrate zero absorbance after each measurement, e.g., atomic-absorption and continuous automated spectrophotometry.