On-site sampling of inorganic contamination on the metal surface and analysis with capillary electrophoresis

Pipes are the primary structural elements used for transporting fluid in various industries. The most common damage mechanism is corrosion, which occurs in pipes surface of turbine. The corrosive compounds for pipes are inorganic ion (Na⁺ , Cl^- , NH₄ ⁺ , NO₃ ^- , etc.) and grinding oil. For rapid and quantitative detection of inorganic ions on site, more reliable and reproducible analytical methods are demanded. A highly efficient solid-liquid sampling collection system is introduced in this work. Papering on the sample surface, inorganic cations and anions were simultaneously collected and analyzed by capillary electrophoresis with indirect ultraviolet detection. As a result, five cations (Na⁺ , K⁺ , NH₄ ⁺ , Ca²⁺ , Mg²⁺ ) and three anions (Cl^- , NO₃ ^- , SO₄ ^2- ) were completely separated. The efficiency of the sampling and ability of capillary electrophoresis analysis were presented by the determination of trace-level (mg/m² ) contaminants. The recoveries of cations and anions on the paper from metal surface were between 86.6 and 107.2%, and the relative standard deviations were less than 12.85%.