Urease immobilized single-kit' for sensing of thiourea-glucose pair employing fluorescence 'Turn off - Turn on' and as an efficient sorbent for selective sample cleanup of thiourea.

Sneha Mondal, Sanchari Saha, Shailja Mishra, Rimi Sarkar, Dipika Roy, Bhabatosh Mandal

Analytica chimica acta 2021 Jan 02

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The tenfold lowering in binding energy for TU-Tyrosine in immobilized urease (Kb: 4.7 × 103) with respect to the native enzyme (Kb: 6.5 × 104) begets easy desorption of thiourea (TU) by glucose (GL) with an eventual formation of a more strong TU- GL adduct; that rejuvenates the kit-material ready for the subsequent cycle(s). The sorption-desorption heeds fluorescence turn-off and turn-on in DCM for selective sensing of TU- GL pair at their respective linear range of concentration 2.5-26.1 ppm and 2.36-11.57 ppm. The process was found to be static (KSV ≥ 2.25 × 103 L mol-1), exothermic (ΔH: -0.08 kJ mol-1), spontaneous (ΔG: -21.1 kJ mol-1) and marginally entropy gaining (ΔS: 0.07 kJ mol-1 K-1). The 'bulk material' (200 ± 20 μm) brilliantly preconcentrates TU with an enrichment factor of 106.2 after its selective extraction at near-neutral pH from a large volume sample (800 mL) of low concentration (30 ppm). A very dilute solution (0.05 mmol L-1) of GL at minimum volume (6 mL) acts as a stripping agent and provides a longer life (200 cycles with good extraction efficiency) to the material. The method was found to be efficient in the analysis of fruit juice as a real sample. Copyright © 2020 Elsevier B.V. All rights reserved.

Citation

Sneha Mondal, Sanchari Saha, Shailja Mishra, Rimi Sarkar, Dipika Roy, Bhabatosh Mandal. Urease immobilized single-kit' for sensing of thiourea-glucose pair employing fluorescence 'Turn off - Turn on' and as an efficient sorbent for selective sample cleanup of thiourea. Analytica chimica acta. 2021 Jan 02;1141:180-193