Formation of the mixed-ligand complexes of lead(II), cadmium(II), and zinc(II) sorbed on the surface of silicas with chemically immobilized N-propyl-N′-allylthiourea and mercaptopropyl groups

Complexing properties of polyhexamethyleneguanidine chemically grafted to a silica surface

“…The metal (М) coordination sphere in SiO 2 ]-L 1 -M n+ type complexes, which are formed on the modi fied silica surface, is often unsaturated with respect to the surface grafted ligands (L 1 ) due to their decreased mobility [17][18][19]. Thus, by reactions of these com plexes with solutions of reagents that can act as addi tional ligands, it is possible to obtain different ligand complexes SiO 2 ]-L 1 -M n+ -L 2 , some of which can be luminescent or colored.…”

Lead Assays with Smartphone Detection Using a Monolithic Rod with 4-(2-Pyridylazo) Resorcinol

“…Pretreatment may be associated with the colorimetric determination of lead using PAR. Some sorbents such as AV-17 [ 17 , 18 , 19 ], polyurethane foam (PUF) [ 20 ], Amberlite XAD-1180 [ 21 ], Amberlite XAD-7 [ 22 ], modified silica [ 23 ], imprinted polymer nanoparticles [ 24 ], modified nano-alumina [ 6 ], nanomagnetic materials [ 3 , 5 ], TrisKem Pb resin [ 25 ], NOBIAS chelate PA-1 [ 26 ], Amberlite IR-120 [ 27 ], PB-resin [ 28 ], and nonwoven polypropylene [ 29 ] have been employed. Some of those were used to sorb lead with elution, for the next step of forming color with PAR for a colorimetric assay [ 22 , 25 , 26 , 27 , 28 ].…”

“…In some previous works, lead that formed anionic complexes before being sorbed on AV-17 could then form a color complex when treated with a PAR solution [ 17 , 18 , 19 ]. The silica was treated with mixed ligands for the sorption of lead before forming a color product with PAR [ 23 ]. In both the latter cases, detection with diffuse reflectance spectrometry was employed.…”