Fluorinated ethylenepropylene copolymer as a potential capillary material in CE

Abstract

In this work, a new generation UV-transparent polymer, fluorinated ethylenepropylene copolymer (FEP) exhibiting a low degree of crystallinity, extruded in dimensions similar to the most commonly used CE capillaries of approximately 80 mum id and about 360 mum od was investigated for its use as a CE capillary. FEP is transparent down to the low-UV region, and as fluorinated polymers in general are good electrical insulators and exhibit reasonable heat conductivity, it has considerable potential as a material for electrodriven analysis in capillary or microchip formats. The FEP capillary has been characterised with regard to some important aspects for its use as a CE capillary, including its profile of EOF versus pH, as well as procedures for manipulating EOF by coating the inner capillary wall with various semipermanent and dynamic layers. The FEP capillaries were tested and compared with fused-silica capillary for the separation of inorganic and small organic ions using conditions involving direct and indirect detection in the low-UV region. Finally, advantages of the use of the FEP capillary for simultaneous detection of a mixture containing nine inorganic cations and anions using indirect photometric detection with a movable light-emitting diode (LED) detector and a novel electrolyte are demonstrated.

Dyneon THV, a fluorinated thermoplastic as a novel material for microchip capillary electrophoresis

“…3). As previously reported in other studies employing fluorinated materials, 16,17 a cathodic EOF is observed highlighting the negative charge of the Dyneon THV surface. At pH 7.4, µ EO of Dyneon THV is 28.3 ± 0.2 × 10 −5 cm 2 V −1 s −1 which is similar to the COC 24 values (26.6 ± 0.1 × 10 −5 cm 2 V −1 s −1 ) at the same pH.…”

“…15,16 For instance, the simultaneous separation of nine cations and anions on an unmodified fluorinated ethylenepropylene (FEP) capillary has been successfully obtained. 17 Sahlin et al 18 also showed that an in-house made fluorinated capillary allowed a more efficient separation of two cationic aromatic molecules than a fused silica (FS) capillary. Tsukagoshi et al 19 obtained a better resolution of isoluminol isothiocyanate (ILITC) and hydrolyzed ILITC in a polytetrafluoroethylene capillary as compared to a FS capillary which generated a higher electroosmotic flow (EOF).…”

Recent advances in the application of CE to forensic sciences: A update over years 2007–2009

“…Fluorinate ethylenepropylene copolymers have been tested in ion analysis as a new material for capillary production both with direct and indirect LED detection. Indeed, fluorinate ethylenepropylene presents relevant advantages in terms of transparency in the low‐UV‐region though maintaining a reasonable heat conductivity, making it attractive for electrodriven separations 35.…”

Inorganic species analysis by CE – An overview for 2007–2008

“…For certain applications, e.g . where hydrophilic wall interactions typical to fused‐silica capillaries are problematic, a capillary made of a fluorinated ethylenepropylene copolymer 101 may provide higher efficiencies. However, modest mechanical stability and light scattering at λ≤214 nm, resulting in the baseline noise, are obstacles to its implementation for routine use.…”

“…6 provided tenfold lower LODs and faster separations. The benefits of a movable LED detector have been amply demonstrated by the same group when optimizing the selectivity in simultaneous separation of anions and cations 101. Additionally, a range of compounds were evaluated as probes for the indirect detection of inorganic anions using LEDs as the light source, with the aim to replace the very effective but toxic chromate 122.…”