title: A computer-controlled system for generation of chemical vapours in in vitro dermal uptake studies.
abstract: OBJECTIVE
  Recent work in our laboratory suggests that dermal absorption and desorption of volatile chemicals may be assessed in vitro by thermogravimetric analysis (TGA), i.e. by passing chemical vapour over a piece of skin while recording the weight increase at constant temperature and humidity. This paper describes a high-precision automated vapour-generating system for use with the TGA equipment.
  
  
  RESULTS
  The system consists of computer-controlled magnetic valves and mass flow meters that split and redirect a flow of pure, dry air through different stainless-steel gas wash bottles thermostated to 25.00+/-0.05 degrees C. Each wash bottle is filled with a neat volatile chemical and designed so that the air leaving reaches 100% saturation within seconds, as shown with cyclohexanone. The air leaving the wash bottles are combined and directed via stainless-steel liners to the skin piece in the TGA chamber. The liners are heated to 30 degrees C to prevent condensation of water or chemical. Special computer software was developed to allow automatic runs with different wash bottles (chemicals) and air flows over several days. A number of measurements were made to characterize the stability and reproducibility of the vapour-generating system.
  
  
  CONCLUSIONS
  We have developed a computer-controlled vapour-generating system for use in measurements of dermal absorption of chemicals by thermal gravimetry. The system has high stability and reproducibility and produces little noise.
authors.affiliation: Work Environment Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. matias.rauma@ki.se
authors.forename: Matias
authors.initials: M
authors.lastname: Rauma
authors.forename: Gunnar
authors.initials: G
authors.lastname: Johanson
mesh_terms: D000279:Administration, Cutaneous; D004360:Drug Therapy, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D005740:Gases / Q000008:administration & dosage / Q000737:chemistry* / Q000493:pharmacokinetics*; D006801:Humans; D012869:Skin Absorption / Q000502:physiology*; D013818:Thermogravimetry / Q000295:instrumentation* / Q000379:methods
chemical_list: D005740:Gases