Abstract: An automated system is suggested and presented for the anal. of carbohydrates. The system is based on already existing components such as microdialysis, flow injection analysis (FIA), high-performance anion exchange chromatography (HPAEC), integrated pulsed electrochemical detection (IPED), a biosensor, online desalting employing a cation exchange membrane desalting device (CEMDD), and mass spectrometry (MS). A hydrolyzate containing mono- and oligosaccharides is profiled using an in situ tunable microdialysis probe fitted with a polysulfone membrane with a cutoff of 30 kDa, in combination with HPAEC and IPED. Sensitivities using IPED and MS are equal, so it probably is well suited for an automated online triple-detection system.

Abstract: Stopped-flow and continuous-flow microdialysis sampling systems were compared, using SPS 6005 polysulfone (30 kDa exclusion) or CMA/10 polycarbonate (20 kDa exclusion) membranes. Portions (2.5 µL) of 1,4-β-D-mannanase (50 nkat/ml from A. niger) was added to 180 µL 0.25% ivory nut mannan and the solution was diluted to 4.5 mL with 50 mM citrate buffer of pH 5.3. Dialysate samples were analyzed by HPLC as previously described (Torto et al., Anal. Chim. Acta, 1995, 313, 15) on a CarboPac PA1 column with 50 mM NaOH as mobile phase and electrochemical detection. Stopped-flow microdialysis gave the least analyte depletion and therefore the best quantitation.

Abstract: A study of the extraction fraction (EF) of metal ions Cd, Cr, Cu, Ni and Pb sampled by microdialysis from a quiescent aqueous solution is presented. A concentric type of microdialysis probe equipped with either one of two polysulfone membranes supplied by different manufacturers or a polyether sulfone membrane, all with a 10 mm effective dialysis length was used for these investigations. EF for metal ions achieved after microdialysis sampling were evaluated for membranes exhibiting a cut-off molecular weight of 3, 5, 10 and 30 kDa. The EF for all metal ions showed a dependency on membrane cut-off as well as membrane material. For Cr EFs of 0.70 and 0.80 were achieved at I µL/min using a polysulfone and polyether sulfone membrane, respectively, both with a 30 kDa cut-off molecular weight. Using the polysulfone membrane, Cr showed the highest EF and Pb had the lowest at 0.1. The polyether sulfone membrane achieved an EF of 0.95 for Ni and the lowest EF value was for Cu at 0.35. In these studies it is shown that pH as well as the inclusion of an optimal concentration (0.20 M) of 8-hydroxyquinoline (8-HQ) in the perfusion liquid can enhance the EF of metal ions. Microdialysis was also used to sample for metal ions from wastewater and from whole tomatoes grown using sewage sludge manure in order to demonstrate the potential to apply it to these complicated matrices.