AL4021 Correlation with Other Methods

The AL4021 formaldehyde monitor replaces the conventionally employed Hantzsch method carried out by wet chemistry (e.g. flask method) in combination with colorimetric detection of DDL. A comparison of HCHO concentrations of the very same samples measured by both, the AL4021 and the flask method, reveals a very good correlation of 1. Data was provided by courtesy of the Institut für Holzforschung IHD, Dresden, Germany. 

A verification of the linearity and data quality for gas measurements in the lower ppb range requires an exact and stable gas generator like the model KinTek 491M from Kin-Tek Laboratories Inc. The next figure shows a correlation of diluted gas samples generated with a 491M and the concentration measured by an AL4021.

The AL4021 was tested indipendently by two institutions for correllation to the DNPH method. The plot below shows data for a huge range of concentrations from below 50 μg/m3 to ~1.4mg/m3. The data was produced by IMAT/UVE and the California Department of Public Health.