Cocktail assay approach

Andersson K, Hamalamen M, Malmqvist M (1999) Identification and optimization of regeneration conditions for affinity-based biosensor assays. A multivariate cocktail approach. Anal Chem 71 2475-2481... 

Despite much effort there is still no meaningful magnesium ISE. The current approach utilizes the divalent ISE (10,35-39). In principle, the magnesium may be found from the difference in samples assayed respectively with the divalent ISE and the calcium (only) ISE (10). However, serious errors can arise with ready-to-use cocktails, e.g. Orion 92-32-02 contains appreciable amounts of di-octylphenyl phosphonate (Table 3.1). Selectivity values for /c g,ca deviate considerably from unity, not only for PVC-Orion 92-32 electrodes, but also for PVC ISEs based on pure di-decylphosphate/decan-l-ol (39). 

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