Effect of sample volume on metastable zone width and induction time

The metastable zone width (MSZW) and the induction time, measured for a large sample (say > 0.1 L) are reproducible and deterministic, while, for a small sample (say < 1 mL), these values are irreproducible and stochastic. Such behaviors of MSZW and induction time were theoretically discussed both with stochastic and deterministic models. Equations for the distribution of stochastic MSZW and induction time were derived. The average values of stochastic MSZW and induction time both decreased with an increase in sample volume, while, the deterministic MSZW and induction time remained unchanged. Such different behaviors with variation in sample volume were explained in terms of detection sensitivity of crystallization events. The average values of MSZW and induction time in the stochastic model were compared with the deterministic MSZW and induction time, respectively. Literature data reported for paracetamol aqueous solution were explained theoretically with the presented models. (c) 2012 Elsevier B.V. All rights reserved.