Liquid/air partition coefficients of the trimethylbenzenes

Liquid/air partition coefficients (lambda) of the three isomers of trimethylbenzene (1,2,3-,1,2,4-, and 1,3,5-TMB) were determined in vitro using automated head space gas chromatography. The liquids used were water (physiological saline), fresh human blood, and olive oil. The lambda water/air were 1.23 (95% confidence interval 1.11-1.35) for 1,3,5-TMB, 1.61 (1.47-1.75) for 1,2,4-TMB, and 2.73 (2.54-2.92) for 1,2,3-TMB. Corresponding lambda blood/air were 43.0 (40.8-45.2), 59.1 (56.9-61.3), and 66.5 (63.7-69.3). As expected, the TMBs have a high affinity for olive oil, the lambda oil/air being 9,880 (9,620-10,140), 10,200 (9,900-10,400), and 10,900 (10,500-11,300), respectively. It is notable that all partition coefficients increase in the order 1,3,5-TMB < 1,2,4-TMB < 1,2,3-TMB.