US EPA

1105961 

Journal Article 

Comparison of dielectric constant meter with turbidity meter and focused beam reflectance measurement for metastable zone width determination 

He, GW; Hermanto, MW; Tjahjono, M; Chow, PS; Tan, RBH; Garland, M 

2012 

Yes 

Chemical Engineering Research and Design
ISSN: 0263-8762
EISSN: 1744-3563 

90 

2 

259-265 

10.1016/j.cherd.2011.07.005 

WOS:000301314000010 

This work demonstrates a detailed process analytical technology (PAT) comparison study of dielectric constant measurement with turbidity measurement and focused beam reflectance measurement (FBRM) in detecting phase transitions during crystallization of three model solutions, namely stearic acid-ethyl acetate, paracetamol-ethanol and carbamazepine-methanol. The cloud and clear points determined by the dielectric constant measurement are found to be in close agreement with those obtained from the other two well-established PAT tools. A calibration technique can be further applied on the dielectric constant to improve the accuracy of the cloud point detection. The results have shown that the dielectric constant meter can be reliably used for metastable zone width (MZW) determination. This study opens new opportunities for the use of the dielectric constant meter as a simple and inexpensive alternative PAT tool for process monitoring of solution crystallization. Crown Copyright (C) 2011 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers. All rights reserved. 

Dielectric constant; Metastable zone width; Process analytical technology; Phase transition