How to be sure to measure all the ammonia in the original samples by infrared spectroscopy / Comment s'assurer de mesurer toute l'ammoniac présente dans un échantillon par spectroscopie infrarouge

Abstract

Infrared (IR) spectroscopy is used more and more to quantify different substances. Quantitative analysis puts some particular challenges when working with gas samples such as being sure of a calibration, the value of pressure and temperature, the amount of analyte with good precision. While working with different gases, we have observed that ammonia, NH3(g), showed a variable signal with time. Some others observed the same phenomenon. Ammonia presents a particular challenge for quantification with a decreasing signal. We consider this phenomenon as adsorption on the inside walls of the cell; this is not surprising when one considers the polarity of the molecule and the literature based on this behaviour for this gas. A series of experiments were made and quantitative results compared very well with calculations from validated data from the public database HITRAN