The determination of transition metal ions in anaerobic adhesives by reverse phase high performance liquid chromatography
Mooney, Joseph P (1989) The determination of transition metal ions in anaerobic adhesives by reverse phase high performance liquid chromatography. Master of Science thesis, Dublin City University.
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By using reverse phase high performance liquid chromatography (HPLC) and chelating agents such as dithiocarbamates or 8-hydroxyquinoline it was possible to separate a range of metal ions which are of importance in the polymerisation chemistry of anaeorbic adhesives.
These metal-chelate complexes can be formed 'in-situ' or
externally. 'In-situ' complexation involves incorporating the chelating agent into the mobile phase and external formation involves mixing the appropriate metal ions with the chelating agent prior to HPLC separation.
Using sodium diethyldithiocarbamate as the chelating agent, it was possible to selectively separate metal ions such as Ni(II), Co(lII) and Fe(lll), using a C^g reverse phase system with ultraviolet detection at 254 nm. The main disadvantage of sodium diethyldithiocarbamate was that it does not have the selectivity to fully resolve Cu(II) and Fe(IIl). These are two most important metal ions in anaerobic adhesive chemistry, and it was therefore decided to investigate an alternative chelating agent.
This alternative ligand was 8-hydroxyquinoline, and using this it was possible to resolve Cu(II) and Fe(lII) as their oxinate complexes using reverse phase high performance liquid chromatography with a mobile phase of acetonitrile: 0.02 M sodium acetate buffer (pH 6.0), _3 (50:50, v/v) which was 5 x 10 M in 8-hydroxyquinoline and 0.1 M in KNO^ with ultra-violet detection at 400nm.
An extraction system was then developed which extracted the metal ions, namely Cu(II) and Fe(III), from anaerobic adhesive formulations and anaerobic adhesive raw materials. This extraction system showed that the raw materials used in the formulation contained levels of Cu(II) and Fe(III) which if not complexed by EDTA would cause premature polymerisation of adhesive. There was also Fe(III) present in the water which was throughout the analysis, so background corrections were needed to considered at every step.
The extraction method was applied to anaeorbic adhesive products 290 and 270. Detection limits for Cu(II) and Fe(III) in PEGMA-based (polyethyleneglycoldimethacrylate) anaerobic adhesive formulations were 250 |Jg/ml and 600 Mg/ml respectively and in TRI-EGMA (triethyleneglycoldimethacrylate) were 100 ng/ml and 250 pg/ml.
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