The use of a thermogravimetric analyzer for the generation of primary analytical vapor standards of organophosphate pesticides

A thermogravimetric analyzer (TGA) was used for the generation of primary vapor standards of three organophosphate pesticides encompassing a wide range of vapor pressures. The technique combines a dynamic flow-through evaporation system with gravimetric analysis of weight loss from an analyte reservoir. Vapor reference standards may be produced in less than 1 h per compound, including purging the system between compounds. Vapor concentrations are gravimetrically monitored in real-time (1 Hz). Equilibration time was negligible, as the linear vaporization curves for the compounds were produced in real-time, and all had correlation coefficients (R2) greater than 0.99. For the current study, vapors were collected by sampling bags for transport. This sensitive (parts-per-million to parts-per-billion), fast (negligible equilibration time), robust (compounds with vapor pressures spanning five orders of magnitude), low consumption (μL), and extremely general technique may be used for the generation of countless vapors in a number of concentrations and quantities.