Characterization of thin film application parameters for drug dissolution testing using a quartz crystal microbalance

Document Type


Conference Title

National Conference on Undergraduate Research (NCUR)


University of North Carolina, Asheville, NC

Conference Dates

April 7-9, 2016

Date of Presentation



A dissolution testing method has been developed using a commercial quartz crystal microbalance (QCM) system with a microfluidic flow cell to measure drug dissolution rate. Drug dissolution rate is useful because it provides critical information on drug release timing, location, and duration. All of these factors are necessary in understanding the effectiveness of a drug and such information may be used to inform future design. The QCM method is capable of measuring minute mass changes directly and rapidly thus making the QCM method less resource, sample, and time intensive than traditional drug dissolution methods. To conduct the test, first a thin film of the drug is applied to a flat quartz crystal. The crystal with drug film is installed into the QCM and a flow cell is attached. Dissolution solution is introduced via the flow cell and passes over the drug film dissolving it. The QCM system simultaneously oscillates the crystal and the change in resonant frequency of oscillation is proportional to the mass being lost into solution. The temporal change in frequency is recorded nearly continuously by the acquisition system. From this the signature dissolution curve and dissolution rate are obtained. However, in order to optimize the procedure of the QCM technique, a deeper understanding of influence of the thin drug film to the crystal is needed. In this study, we parametrically explored the ideal ranges for both surface coverage and total mass applied for this QCM and flow cell system using benzoic acid as a model drug. A threshold was found for the minimum area fraction of coverage required for operation. Using this threshold, the relation between applied mass and resonant frequency was developed and the linear sensitivity factor compared with expected for quartz crystals. Total masses that diverge from the linear regime should not be selected.

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