Formaldehyde Test Kits

Visual Kits

Range MDL Method Kit Catalog No. Refill Catalog No.
0-1 & 1-10 ppm 0.1 ppm Purpald K-4605 R-4605
0-30 & 30-300 ppm 5 ppm Purpald K-4605D R-4605D
0-60 & 60-600 ppm 10 ppm Purpald K-4605A R-4605A
0-120 & 120-1200 ppm 20 ppm Purpald K-4605B R-4605B
0-1200 & 1200-12,000 ppm 200 ppm Purpald K-4605C R-4605C



Formaldehyde, a toxic substance, is used in the following applications: metal plating baths, textile treatments, biological specimen preservatives, and disinfectants of medical equipment. Commercial formaldehyde gas is readily soluble in water.


The Purpald Method


Reference: Purpald® developed by Aldrich Chemical Co.


Purpald® is subject to fewer interferences than Schiff's reagent or chromotropic acid procedures. A purple-colored complex is formed when Purpald in alkaline solution reacts with formaldehyde. Results are expressed as ppm (mg/L) CH2O.


Shelf-life of the Purpald Reagent: five months. We recommend stocking quantities that will be used within four months.