Bial's test

Abstract: Current high-fidelity formaldehyde detection in waterbased samples requires chemical derivatization followed by ion chromatography or liquid chromatography [1-3]. These methods are labor intensive and require expensive instrumentation. Here, we propose an additional method for detecting and quantifying aqueous formaldehyde that is based on Bial’s test and simple photometric equipment. Our approach also allows for a convenient qualitative color test that is applicable to samples with high formaldehyde concentrations. The foundation of our method was developed by Bial in the form of a colorimetric test for identifying pentose sugars in the urine of patients with pentosuria [4]. Bial’s solution consist of orcinol, hydrochloric acid, and iron (III) chloride [4]. The concentrations of the components vary from study to study and some authors have substituted hydrochloric acid with ethanol [5] When heated with pentose sugars, Bial’s solution reacts to form furfurals and changes color from a light pale yellow to blue or green [6].