טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentHadar-Markovits Hodayah
SubjectDevelopment of Sensitive Spectroscopic Analytical Methods
using Electrospun Polymeric Matrices
DepartmentDepartment of Chemistry
Supervisors Professor Israel Schechter
Professor Eyal Zussman
Full Thesis textFull thesis text - English Version


Abstract

Applications of electrospun polymeric matrices in chemical analysis were investigated. Electrospun fibers, made of superabsorbent polymers with high surface area to volume ratio, were used for both sampling and analysis. They also portrayed improved sensitivity versus bulk film and rendered low limits of detection. 

Two applications of electrospun based detection methods were developed. The first is detection and sampling of ninhydrin reactive nitrogen in solid, liquid and aerosol samples. In this application, polyvinyl alcohol and polyacrylic acid were used to form electrospun fibers of diameter 0.46±0.07µm. They were impregnated with ninhydrin reagent, which was homogenously dispersed in the polymer precursor solution. The resulted limit of detection was 0.4 nmole cm-2. The method was employed on various samples and found suitable for detection of analytes in solids, liquids and aerosols.

The second application was detection and sampling of explosive compounds. Polydimethylsiloxane and poly(methyl methacrylate) were spun to form porous fibers of diameter 1.6±0.6 µm. The fibers were characterized and their infrared spectrum revealed that they were cross-linked and thermally stable.

The absorbency of organic compounds and explosives in PDMS-co-PMMA electrospun fibers was examined. Their sampling efficiency for explosives was superior to commonly used cotton swabs. 

            The explosives, adhered on the PDMS-co-PMMA matrix, were subsequently tested with 21 color reagents. Chemometric analyses were conducted on both the UV-vis spectral data and the RGB data. A neural network model was developed for classification of energetic materials. It succeeded in classifying different energetic compounds and in distinguishing them from potential interferences.