Kinetic approach was undertaken to investigate the combined effect of pH and dielectric constant of the solvent on the stability of thiamine HCL in anaerobic condition. In contrast to the stabilizing effect of low dielectric constant of the solvent system on ascorbic acid in prior work, the rate of degradation of thiamine was accelerated by solvent system with decreased dielectric constant at pH range of 3.6 to 7.0. The stability of thiamine HCL showed much pH dependency than ascorbic acid in propylene glycol-water and sorbltol-water system. The mechanism of decreased stability was due to the increase of nonprotonated thiamine species in low dielectric constant media. The instability of nonprotonated thiamine could be improved by employing micellar protection of nonionic surfactant. 利用動力學方法檢討pH及誘電常數對維生素乙在溶液中分解度的複合效應。發現溶媒的誘電常數降低對維生素乙之分解有加速效應。維生素乙之安定性受pH之影響比維生素丙為大。溶媒的誘電常數降低，會阻礙酸性一中protonated thiamine 之形成，造成nonprotonated thiamine 優勢之存在而加速分解。維生乙在低誘電常數溶媒中之不安定性可利用膠質點形成之保護加以安定化。
