Thursday, September 17, 2020
Binders play a key role in the preparation of SPME devices and their performance. Fluorinated polymers have been widely used as binders in a large variety of practical applications, due to their exceptional thermal and chemical properties, good adhesion, superior chemical resistance, impact resistance, corrosion resistance, abrasion resistance, heat resistance, and good flexibility. When poly tetrafluoroethylene (TeflonTM) was used for GC and LC applications, superior results were obtained compared to commercial coatings using standard binders for extraction of both volatile/semivolatile organic compounds for GC and drugs of abuse from biofluids for LC: Gionfriddo, Emanuela; Boyaci, Ezel; Pawliszyn, Janusz (2017), “New Generation of Solid-Phase Microextraction Coatings for Complementary Separation Approaches: A Step toward Comprehensive Metabolomics and Multiresidue Analyses in Complex Matrices” Anal. Chem. 89, 4046−4054, (DOI: 10.1021/acs.analchem.6b04690). However, the use of this material as a binder has limitations; for instance, poly tetrafluoroethylene is only soluble in fluorinated solvents, which are highly toxic, volatile, and leads to ozone depletion.
Poly vinylidene difluoride (PVDF), another fluorinated polymer, has been around for many years and like other fluorinated binders, has been used extensively for many applications. When compared to TeflonTM, PVDF as a binder is similar in structure except that it affords a higher amount of -CH bonds, a property that makes it superior as a binder for SPME applications. PVDF is thermally stable, chemically inert, and stable at 0-12 pH, whereas crosslinked PVDF is stable from 0-14 pH, soluble in solvents such as dimethyl sulfoxide, dimethylformamide, and N-methyl pyrrolidone, as well as fluorinated solvents, while stable in general sample preparation solvents, making it a suitable binder for SPME applications.
Singh, Varoon; Ghosh, Chiranjit; Kaur, Avneet; Pawliszyn, Janusz (2020): “Polyvinylidene Difluoride: A Universal Binder for Preparation of Solid Phase Microextraction Devices”. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.12959885.v1