Sulphonamide-imprinted sol–gel materials as ionophores in potentiometric transduction

Abstract

This work proposes different kind of solid-contact graphite-based electrodes for the selective determination of sulphonamides (SPHs) in pharmaceuticals, biological fluids and aquaculture waters. Sulfadiazine (SDZ) and sulfamethoxazole (SMX) were selected for this purpose for being the most representative compounds of this group. The template molecules were imprinted in sol-gel (ISG) and the resulting material was used as detecting element. This was made by employing it as either a sensing layer or an ionophore of PVC-based mem-branes and subsequent potentiometric transduction, a strategy never reported before. The corresponding non-imprinted sol-gel (NISG) membranes were used as blank. The effect of plasticizer and kind/charge of ionic lipo-philic additive was also studied. The best performance in terms of slope, linearity ranges and signal reproducibility and repeatability was achieved by PVC membranes including a high dielectric constant plasticizer and 15 mg of ISG particles. The corresponding average slope was −51.4 and −52.4 mV/decade, linear responses were 9.0 × 10 −6 and 1.7 × 10 −5 M, and limits of detection were 0.74 and 1.3 μg/mL for SDZ and for SMX, respectively. Good selectivity with log Kpotb−0.3 was observed for carbonate, chloride, fluoride, hydrogenocarbonate, nitrate, nitrite, phosphate, cyanide, sulfate, borate, persulphate, citrate, tartrate, salicylate, tetracycline, ciprofloxacin, sulphamerazine, sulphatiazole, dopamine, glucose, galactose, cysteine and creatinine. The best sensors were successfully applied to the analysis of real samples with relative errors ranging from −6.8 to +3.7%.

Bio-Mimetic Sensors Based on Molecularly Imprinted Membranes

“…In particular, progressive polycondensation reactions of molecular precursors in a liquid medium allow the construction of an oxide network. The most common precursors are tetramethyl- and tetraethylorthosilicate [ 300 , 301 ]. Molecular imprinting of sol–gel thin films is advantageous over organic-polymers, because of its easy preparation, low non-specific adsorption and high association constants.…”

“…As example, Fireman-Shoresh et al demonstrated the chiral imprintability of spin coated submicron composite sol–gel films (∼700 nm) and their enantioselectivity under steady-state conditions for various enantiomers [ 302 , 303 ]. Sol-gel imprinted membranes were prepared by Almeida et al [ 301 ] that imprinted the antibiotics sulfadiazine (SDZ) and sulfamethoxazole (SMX) in sol-gel materials which were used as sensing elements included in the matrix of poly(vinyl chloride)-based membranes connected to a potentiometric transducer. SDZ is used to treat toxoplasmosis and to put off some type of meningococcal meningitis.…”

“…The analytes were recognized by means electrostatic interactions with the silica groups of the sol–gel membrane matrix. The detection limits were 0.74 μg·mL −1 and 1.3 μg·mL −1 for SDZ and SMX, respectively [ 301 ].…”

Molecularly Imprinted Membranes

“…Almeida et al [ 64 ] proposed the construction of sulfadiazine and sulfamethoxazole selective electrodes based on imprinted sol-gel (ISG) material. The ISG was employed as the electroactive material on PVC membranes selective for sulfadiazine and sulfamethoxazole, prepared by the inclusion of ISG particles into the PVC matrix.…”

Multisensory Systems Based on Perfluorosulfonic Acid Membranes Modified with Polyaniline and PEDOT for Multicomponent Analysis of Sulfacetamide Pharmaceuticals

“…Nevertheless, they are not highly selective to individual members of sulfanilamide class in real media. For the sulfanilamide determination, ionophores based on molecularly imprinted polymers (MIPs) [31][32][33] are also developed. However, there are drawbacks of MIPs, such as the difficulty of the bound analyte extraction, the difference in the constants of the repeated interaction of analyte and reactive centers, and its non-specific binding to the matrix material [34].…”