Isotachophoresis copolymers

The separation unit of the capillary isotachophoresis instrument used is shown in Fig. 13.1. A 0.85mm id capillary tube made of fluorinated ethylene propylene copolymer was used in the pre-separation (first) stage and a capillary tube of 0.30mm id made of the same material served for the separation in the second stage. Both tubes were provided with conductivity detection cells [18] and an ac conductivity mode of detection [15] was used for making the separations visible. 

Radioisotope detection of P, 14C, and Tc was reported by Kaniansky et al. (7,8) for isotachophoresis. In their work, isotachophoretic separations were performed using fluorinated ethylene-propylene copolymer capillary tubing (300 pm internal diameter) and either a Geiger-Mueller tube or a plastic scintillator/photomultiplier tube combination to detect emitted fi particles. One of their reported detection schemes involved passing the radiolabeled sample components directly through a plastic scintillator. Detector efficiency for 14C-labeled molecules was reported to be 13-15%, and a minimum detection limit of 0.44 nCi was reported for a 212 nL cell volume. 

Separations of copolymers by isotachophoresis will lack this molecular weight dependence, which considerably simplifies their interpretation. 

DBTHS, disodium 5,13-his(dodecyloxymethyl-4,7.11,14-tetraoxa-l,17-heptadecanedisulfonate ITP, isotachophoresis m-HEC, methyl-hydroxyethylcellulose PVP, polyvinylpirrolidone PSDVB, polystyrene-divinylbenzene copolymer SB-P-CD, sulfobutylether-p-cyclodextrin CAR-PDMS, carboxen-polyfdimefhylsiloxane) ESI-IT-MS, electrospray ionization ion trap-mass spectrometry CHES, 2-(V-cyclohexylamino)-ethanesulphonic acid CAPS, 3-(cyclohexylamino)-l-propanesttlfonic acid PHWE, pressurized hot water extraction ICP-MS, inductively coupled plasma-mass spectrometry SPME, solid-phase microextraction SPE, solid-phase extraction. 

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