Synthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and Its Application in Flow Injection-inductively Coupled Plasma Mass Spectrometry Analysis of Trace Metals in Seawater

A new method involving the use of one-step Mannich reaction was developed for the synthesis of bonded silica (SHQ), and an orthogonal experimental design was used for process optimization. The 8-hydroxyquinoline (8-HQ) SHQ synthesized by the two methods was compared for metal chelation applications. The two packings were characterized by UV/Vis spectroscopy, and their binding behaviors toward copper (II) were compared by inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of 8-HQ bonded to the two silica surfaces were 542 mol/g for the new packing and 117 mol/g for the packing by classical method. The copper (II) concentrations bound to the two SHQs were 347 mol/g and 76 mol/g, respectively. The modified silica sample obtained by this method was characterized by diffuse reflectance infrared Fourier transform (DRIFT). The results showed that the new method was more convenient, and produced product with better performance. The SHQ synthesized was used for measuring trace lead in seawater, using on-line flow injection (FIA)-ICP-MS. The detection limit of this technique was 10 ng/l. The recovery of spiked Pb standard in CASS-4 seawater by the method was about 140%. The relative standard deviation (sr) of the measurement was 9.1%.