Gas chromatographic and mass spectrometric analysis of corrosion inhibitors used in the fertilizer industry

Abstract

Liquid fertilizers are widely manufactured, stored and shipped in metallic tanks, which can completely corrode in a few months if corrosion inhibitor is not added. Corrosion inhibitors are chemical compounds which protect metallic surface by forming a protection layer. It protects metallic surface from reaction with liquid fertilizers compounds and can save millions of dollars, since there are no need to replace or repair the tanks. The chemical composition of corrosion inhibitors depends on particular liquid fertilizer for which they are designed to protect metallic surface. Such corrosion inhibitors commonly consist of some fatty acids, amines, surfactants etc. In this work several ways to analyze corrosion inhibitors using gas chromatography - mass spectrometry were applied: (I) analysis of the samples using derivatization reaction with trifluoroacetic acid anhydride (derivatization is needed for synthesis of amides, which do not strongly interact with the stationary phase and are volatile and thermally stabile); (II) applying solid-phase micro extraction; (III) direct injection of methanol solution of the corrosion inhibitor.