Microscale on-line production and determination of malic acid using flow injection analysis, immobilized fumrase and malate dehydrogenase with chemiluminescence detection

A novel polyacrylacylaminourea chelating fiber is synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber) and used for the preconcentration and separation of trace In(III), Bi(III), Cr(III), V(V) and Ti(IV) ions from solution samples. The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 10.0mlmin-1 at pH 3, and can also be desorbed with 10ml of 2M HCl+2% thiourea from the fiber column with recoveries of 97-99%. The chelating fiber is reused for eight times, the recoveries of these ions are still over 92%, and 100-1000 times of excess of Fe(III), Al(III), Ca(II), Mg(II), Ni (II), Mn(II), Cu(II), Zn(II), and Cd(II) cause no interference in the determination of these ions by inductively-coupled plasma atomic emission spectrometry. The capacities of the fiber for the analytes are in the 0.23-1.17mmolg-1 range. The results show the relative standard deviation for the determination of 50.0ngml-1 In(III) and Bi(III), 5.0ngml-1 Cr(III), V(V) and Ti(IV) are in the 0.5-3.2% range. The recoveries of a standard added in real solution samples are between 96 and 100%, and the concentration of each ion in mineral sample detected by the method is in good agreement with the certified value