or absorption cartridge, which contains either physical or chemical absorbing agents that capture HCHO or any air pollutants for a given time (e.g, 1.00 hr), and analyze by GC or HPLC at EPA acredited lab. Some needs calibration some do not. For sophiscated analysis one can seek for specific cartrige kits from Sigma-Aldrich and/or Agilent Company:
http://www.sigmaaldrich.com/technical-documents/articles/reporter-eu/lpdnph-air-monitoring.html
For easy and quick test, one can order a paper strip from Amazon.com to compare the color change - similar as one tests for blood suger:
http://www.homeaircheck.com/our-products?gclid=CMrKzrrAs7ECFUMCQAodkxEADg
