Determination Of Uric Acid In Urine Research Articles

Boric acid-functionalized lanthanide metal-organic framework used as a ratiometric fluorescence probe for uric acid detection

Exploring high-performance fluorescent strategies for the highly sensitive determination of uric acid (UA) is of great importance for the early diagnosis of hyperuricemia. Herein, we constructed a simple and greatly sensitive ratiometric fluorescence sensor based on boric acid-functionalized lanthanide metal-organic framework (BA-Eu-MOF) for the determination of UA in complex environments. In this strategy, BA-Eu-MOF with dual-emission was first prepared by a one-step method at room temperature. It acts as a signal tag, allowing the sensor not only to exhibit a fast fluorescence response but also to generate an inverse response signal. This can be attributed to the inner filter effect, which enables amplification of the fluorescence signal and demonstrates satisfactory photostability, sensitivity and anti-interference capability. Benefiting from the efficient dual-channel strategy, BA-Eu-MOF sensor displayed a wide linear range (0–160 mg/L) for UA with a lower detection limit (0.06 mg/L). Moreover, the sensor has been successfully applied to the determination of UA in urine with satisfactory results. Accordingly, the developed ratiometric fluorescence sensors exhibit simple, fast, low-cost and highly sensitive properties that provide a reference for the detection of UA in complex clinical systems.

Fabrication of CeO2 Nanoparticle Modified Glassy Carbon Electrode for Ultrasensitive Determination of Trace Amounts of Uric Acid in Urine

AbstractThe preparation of a glassy carbon electrode modified by CeO2 nanoparticles was described, which was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. In pH 6.0 buffer, the CeO2 nanoparticle modified electrode (CeO2 NP/GC) gave an excellent electrocatalytic activity for the oxidation of uric acid (UA). The catalytic current of UA versus its concentration had a good linear relation in the range of 2.0×10−7−5.0×10−4 mol/L, with the correlation coefficient of 0.9986 and detection limit of 1.0×10−7 mol/L. The modified electrode can be used for the determination of UA in urine, which can tolerate the interference of ascorbic acid up to 1000‐fold. The method was simple, quick and sensitive.

Automatic Determination of Uric Acid in Urine in a FIA System with a Tubular Amperometric Detector

This paper describes the use of a FIA system for the automatic determination of uric acid in urine, using a tubular amperometric detector. In this system, glassy carbon electrodes of tubular configuration were activated by successive cyclical scans from - 0.30 to 2.00 V versus Ag/AgCl reference electrode in 0.50 mol.L -1 sulphuric acid solution. Samples were diluted in supporting electrolyte before analysis and no other pre-treatment was employed. Such dilution enabled the matrix effects to be reduced and therefore improving the sensitivity provided by the activation step that allows the uric acid (UA) to be detected at lower concentration levels after dilution. Uric acid determination was performed in a single channel FIA manifold, which provided reproducibility of sample transport to the detector and enabled a sampling rate of 120 samples per hour to be achieved. The tubular configuration of the cell offered robustness to the system since it was rigidly fixed to the manifold, allowing the manifold to be generalised for routine analysis application. The results obtained with the FIA system for UA determination in urine were compared with those from the enzymatic method used in clinical analysis laboratories. No statistical difference between methods was found at the 95% confidence level. Relative deviations between both methods were within ± 4% and the proposed system showed good repeatability (about 3%, n = 10).

A biosensor based on urate oxidase–peroxidase coupled enzyme system for uric acid determination in urine

A new amperometric biosensor based on urate oxidase–peroxidase coupled enzyme system for the specific and selective determination of uric acid in urine was developed. Commercially available urate oxidase and peroxidase were immobilized with gelatin by using glutaraldehyde and fixed on a pretreated teflon membrane. The method is based on generation of H 2O 2 from urine uric acid by urate oxidase and its consuming by peroxidase and then measurement of the decreasing of dissolved oxygen concentration by the biosensor. The biosensor response depends linearly on uric acid concentration between 0.1 and 0.5 μM. In the optimization studies of the biosensor, phosphate buffer (pH 7.5; 50 mM) and 35 °C were obtained as the optimum working conditions. In addition, the most suitable enzyme activities were found as 64.9×10 −3 U cm −2 for urate oxidase and 512.7 U cm −2 for peroxidase. And also some characteristic studies of the biosensor such as reproducibility, substrate specificity and storage stability were carried out.

Immobilized enzymes: The application of immobilized urate oxidase to the chemical analysis of uric acid in biological fluids

Urate oxidase has been successfully immobilized and utilized for uric acid determination in urine and serum with a substantial reduction of sample preparation and unit assay cost of enzyme. Satisfactory reproducibility and accuracy for clinical work has been demonstrated. The immobilized enzyme displayed excellent stability both in use and in storage. The quantitative results presented attest to the versatility and accuracy of a system employing an immobilized oxidative enzyme and an oxygen detector system for routine clinical analysis of uric acid.