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. 

Liquid measurents: Correlation between the flask sampling in combination with colorimetric detection of the HCHO concentration by the Hantzsch-method and the AL4021. measurements were made on the same diluted standard solutions. The measurements were friendly provided by the Institut für Holztechnologie Dresden (IHD), 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.

Gas measurements: Concentration of HCHO generated by a KinTek calibrator 491M and measured by an AL4021 in the gas measurement mode.

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.

Correllation between the AL4021 and the DNPH method for formaldehyde concentrations from below 50 µg/m3 to ~1.4 mg/m3.