Silica Gel-Immobilized 5-aminoisophthalohydrazide: A novel sorbent for solid phase extraction of Cu,Zn and Pb from natural water samples

A novel silica sorbent, silica gel-immobilized 5-aminoisophthalohydrazide (SiO₂-APH), was prepared by the condensation of 3-chloropropyl-functionalized silica gel with 5-aminoisophthalohydrazide (APH) derived from dimethyl 5-aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO₂-APH-solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L⁻¹ for Cu, 7.4 μg L⁻¹ for Zn and 3.5 μg L⁻¹ for Pb μg L⁻¹. The accuracy of the new method was assessed by analyzing of TMDA-51.4 and TMDA-70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO₂-APH-SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.