Date of Award

Spring 5-15-2017

Degree Type


Degree Name

PhD. Chemistry


Chemistry and Biochemistry


Nicholas H. Snow, Ph.D.

Committee Member

Wyatt R Murphy, Ph.D.

Committee Member

Stephen Kelty, Ph.D.

Committee Member

Cecilia Marzabadi, Ph.D.


In-situ FT-IR, Dissolution, Aspirin, Salicylic Acid, HPLC, Acetaminophen, Loratadine, UV/Vis


Dissolution studies provide valuable and critical drug release information (in vitro) that are important for quality control drug development. Using in-situ FT-IR spectroscopy methods has been developed for analyzing and monitoring dissolutions of pharmaceutical APIs. The accuracy of this technique was found to be ± 3% relative to HPLC and UV/Vis Spectroscopy. A dynamic analysis of the dissolution and subsequent hydrolysis of aspirin has been determined by in-situ FT-IR. This technique allows real-time analysis of the behavior of aspirin under simulated physiological conditions (pH 1.2, 4.5, 6.8) as aspirin (1205 cm-1) and salicylic acid (1388 cm-1) are detected as separate and distinct peaks in the in-situ FT-IR.

For this study, 325 mg Bayer aspirin tablet was used. The data shows dissolution of aspirin with the hydrolysis profile and the formation of salicylic acid. Comparison of the dissolution behavior of generic brands of aspirin has been performed. The formulations contain the same amount of drug substance as present in Bayer aspirin. Dissolution and hydrolysis of enteric coated aspirin tablets has been performed, and compared with the Bayer aspirin tablets. The dissolution was carried out as per the USP procedure.

This technique indicates a future potential for real-time studies of dissolution and hydrolysis of other prodrugs such as Loratadine. The in-situ FT-IR system is extremely capable of measuring low concentrations (0.03 mg/ml) and for distinguishing separate components of a multiple component systems without requiring manual sampling. Specifically, the unique fingerprint region of the in-situ FT-IR spectra provides detailed information about the release profile of the drug. One more demonstration of the in-situ FT-IR novel technique is the dissolution study of Loratadine (hydrolysis of Loratadine), a pro-drug that has a tendency to hydrolyze to an active compound desloratadine.

In addition, research on the acetaminophen dissolution observed on extra strength Tylenol and on Tylenol Arthritis has been validated by UV/Vis spectroscopy and HPLC. In this study the non-linear behavior of Beer-Lamberts’s law was observed. The hypothesis has been established that the acetaminophen forms dimer at higher concentrations. The investigation was carried out by NMR and FTIR Spectroscopy and by measuring colligative properties such as vapor pressure osmometer and freezing point depression.

In-situ FT-IR spectroscopy is a novel technique used for monitoring the dissolution testing. The fingerprint region of the in-situ FT-IR has great potential for studying dissolution kinetics as well as hydrolysis kinetics for aspirin. A separate peak for aspirin as well as salicylic acid has been observed. This technique has excellent potential for the dissolution studies of tablets without disturbing the dissolution media.