Improvement of Sensitivity and Repeatability in Analysis of Formic Acid

Introduction

In the study of artificial photosynthesis and impurity analysis of raw materials and chemical products, high-sensitivity analysis of formic acid has become an important requirement. When conducting analysis of formic acid by gas chromatography (GC), detection is typically conducted using either a thermal conductivity detector (TCD) or a combination of methanizer + FID detector. As the TCD is appropriate for relatively low-sensitivity detection, it is mainly used for analysis of high-concentration samples, while the methanizer + FID combination is used in analysis of low-concentration samples. Because the FID alone exhibits little or no response to formic acid as is, it must first be reduced to methane using a methanizer, which then permits detection by FID. A methanizer can be a useful tool, but it does have its disadvantages under certain conditions, including deactivation of the catalyst if the oxygen concentration in the sample is greater than 100 ppm, or if the sample environment is high in carbon dioxide. Furthermore, if excessive water enters the system, it can take considerable time to restore the system. These disadvantages require the use of a valve system to eliminate oxygen or carbon dioxide. On the other hand, a barrier discharge ionization detector (BID) is a detector that is capable of detecting formic acid at ppm-order concentrations, thereby permitting high-sensitivity measurement, as long as coexisting components such as oxygen can be separated by the column. In this Application News, we introduce an example of high- sensitivity analysis of formic acid included in various organic solvents using a GC-BID system.

July 18, 2014 GMT