No abstract

Access to high-quality and safe food is a basic need in our community and, consequently, the European Union has defined maximum residue levels (MRLs) for a number of antibacterial compounds. However, despite the obvious demand for quantitative multi-residue detection methods that can be carried out on a routine basis, there is currently a lack in the development of such systems. In particular, an automated multianalyte detection instrument is needed that is capable of quantifying several antibiotics simultaneously within minutes. The newly developed hapten microarrays are designed for the parallel analysis of 13 different antibiotics in milk within six minutes by applying an indirect competitive chemiluminescence microarray immunoassay (CL-MIA). To allow multiple analyses, a regenerable microarray chip was developed based on epoxy-activated PEG chip surfaces, onto which microspotted antibiotic derivatives like sulfonamides, beta-lactams, aminoglycosides, fluorquinolones and polyketides are coupled directly without further use of linking agents. Using the chip reader platform MCR 3, this antigen solid phase is stable for at least 50 consecutive analyses.

Hypochlorite and chlorite exchange resins are evaluated as co-oxidants or oxidants, respectively, for the oxidation of alcohols to the corresponding aldehydes, ketones or carboxylic acids. Polymer-bound hypochlorite can act as a co-oxidant in TEMPOmediated oxidations of alcohols. The formation of aldehydes only works under weakly acidic conditions. However, the cheap hypochlorite exchange resin is less efficient as co-oxidant compared to the use of ionically immobilised bisacetoxybromate(I) anions. In contrast, the chlorite exchange resin is a highly potent co-oxidant for the preparation of carboxylic acids from the corresponding primary alcohols in the presence of TEMPO. It is demonstrated that in this case also the resin acts as a polymer-bound co-oxidant for both oxidation steps. Yields are commonly excellent as is also demonstrated for examples taken from natural product synthesis which include acid labile glycosides. In most cases, work-up of this heavy metal-free oxidation is kept to a minimum. It often includes filtration followed by removal of the solvent.