Uric Acid In Biological Fluids Research Articles

Conventional and planar chip sensors for potentiometric assay of uric acid in biological fluids using flow injection analysis

The potentiometric response properties of several PVC-based membrane sensors using phthalocyanine complexes of cobalt(II) (CoPC) and Fe(II) (FePC) as anion carriers, towards uric acid were constructed and characterized. The sensors demonstrated fast near-Nernstian response for uric acid over the concentration ranges 9.1 × 10 −6 to 9.1 × 10 −2 and 3.1 × 10 −5 to 3.1 × 10 −2 M with detection limits 0.67 and 2.85 μg mL −1 over pH 6.5–8 for CoPC and FePC based membrane sensors plasticized with o-NPOE and 1% TDMAC, respectively. A novel solid-state planar chip urate sensor was developed, characterized according to IUPAC recommendations, easily used in a single channel wall-jet flow injection system and compared with a tubular detector. The intrinsic characteristics of the detectors in a low dispersion manifold were determined and compared with data obtained under hydrodynamic mode of operation. Validation of the assay methods with the proposed sensors by measuring the lower limit, range, accuracy, precision, repeatability and between-day-variability revealed good performance characteristics confirming applicability for continuous determination of uric acid. The sensors were used for determining urate in biological fluids at an input rate of 50 samples per hour. The results compare favorably with data obtained by the standard spectrophotometry.

A ratiometric and non-enzymatic luminescence assay for uric acid: differential quenching of lanthanide excited states by anti-oxidants

The excited states of Tb and Eu complexes of a common macrocyclic ligand are quenched preferentially by electron transfer from the urate anion, allowing the creation of a new assay to measure uric acid in biological fluids.

An Inexpensive Biosensor for Uric Acid Determination in Human Serum by Flow-Injection Analysis

An inexpensive and easy to construct miniaturized biosensor is described for the determination of uric acid in biological fluids. The amperometric biosensor was prepared by using a carbon paste electrode prepared with uricase from Arthrobacter globiforms and tetracyanoquinodimethane as electron transfer mediator. When incorporated into a flow-injection system it was enabled to perform 50 measurements/h of uric acid in the analytical range of 1–100 μmol dm−3 with a relative standard deviation of 0.20% (n=14). The system was applied to human serum samples analysis providing good data correlation with those obtained by the reference spectrophotometric method. A linear relationship AM (μmol dm−3)=1.02 (±0.05) SP (μmol dm−3) −0.12 (±0.13) was obtained evidencing the absence of significant error. The constructed biosensor was successfully used for at least four months (250 assays) with only a 13% of decrease in the enzymatic activity.

Biological microsystem for measuring uric acid in biological fluids

This paper describes a biological microsystem (bio-system) for measuring uric acid concentration in serum, plasma or urine. Its operation is based on optical absorption in a well-defined part of the visible spectrum. The bio-system is composed by two dies: one is fabricated in polystyrene and contains the microchannels and the other is fabricated in a CMOS standard process and contains the photodetector and readout electronics. The uric acid concentration is measured by using a mixture of 14 l of infinity TM uric acid reagent with 0.25 lo f sample. The achieved sensitivity is 0.33 mg/dl (±0.6% of the value in urine of a healthy person), with a 1 mm lightpath. Using an optical absorption method, a maximum peak at wavelength λ = 494 nm, is detected. This bio-system can be included in the group of low-cost disposable devices for biological fluids analysis. © 2003 Elsevier B.V. All rights reserved.

Miniaturized graphite sensors doped with metal-bathophenanthroline complexes for the selective potentiometric determination of uric acid in biological fluids.

Miniaturized poly(vinyl chloride) matrix membrane sensors in an all-solid-state graphite support, responsive to urate anion, were developed. The membranes incorporate lipophilic ion-pair complexes of urate anion with ruthenium(III), iron(II), nickel(II) and copper(I) bathophenanthroline (4,7-diphenyl-1,10-phenanthroline) counter cations. The sensors demonstrate a near-Nernstian response to urate over the concentration range 1 x 10(-2)-1 x 10(-5) mol l-1 and have micromolar detection limits and good selectivity properties. The response is virtually unaffected by pH changes in the range 7-10 and the response times are 5-10 s in aqueous solutions and in human serum and urine samples. A flow injection detector incorporating an iron(II) bathophenanthroline-urate graphite sensor was used for continuous monitoring of uric acid. The minimum detectable concentration was approximately 8 micrograms ml-1 and the sample throughput was approximately 120 h-1. Direct potentiometric determination of uric acid in the static and hydrodynamic modes of operation over the range 15 micrograms ml-1-1.5 mg ml-1 showed average recoveries of 98.7 and 97.8% with RSDs of 0.6 and 0.7%, respectively. Application of the method to the determination of uric acid in human serum and urine gave results that compared favourably with those obtained by the standard spectrophotometric method.

Determination of catecholamines and uric acid in biological fluids without pretreatment, using chemically amplified biosensors

Chemically amplified biosensors based on substrate recycling using oxidase and reducing agents have been applied to the convenient detection of catecholamines and uric acid in biological fluids. These methods are based on the highly sensitive detection of trace amounts of analytes (10 −8 M level) in highly diluted (1000–10000 fold) body samples, in which the interfering species are also diluted to negligible concentration level for an amperometric measurement. The concentration of uric acid obtained by the chemically amplified uric acid sensor is in fairly good agreement with that obtained by conventional spectrophotometry.

Continuous-flow analysis for uric acid in biological fluids, with immobilized uricase in a closed-loop system.

Continuous-flow analysis for uric acid in biological fluids, with immobilized uricase in a closed-loop system.

Determination of hypoxanthine, xanthine, and uric acid in biological fluids by ion-pair high-performance liquid choromatography

Determination of hypoxanthine, xanthine, and uric acid in biological fluids by ion-pair high-performance liquid choromatography

Determination of uric acid in biological fluids by high-pressure liquid chromatography

A high-pressure liquid chromatographic assay for uric acid in biological fluids has been developed. Blood uric acid can be analyzed in as little as 20 μl of plasma. The mean and range of plasma uric acid concentrations in healthy adults determined by high-pressure liquid chromatography were similar to these obtained by enzymatic analysis. One of the advantages of the present method is that naturally occurring metabolites in biological fluids or drugs do not interfere with the analysis. Data are presented for blood and urine specimens obtained from mice fed a known uricase inhibitor, potassium oxonate. Comparisons are made between the present method and methods previously employed for uric acid determination.

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.

Micromethod for the determination of uric acid in biological fluids

A micro procedure for estimating uric acid in body fluids, based on the carbonate method, is described. Interferences are elucidated. The stoichiometry of the reaction is carefully worked out. Reliability of the method is established by comparison with two other methods, by recovery experiments, and by replicate analyses.

The determination of uric acid in biological fluids: I. A modification of the method of Bergmann and Dikstein

A simplified, generally applicable modification of Bergmann and Dikstein's method for uric acid analysis is proposed which has been verified by means of Kalckar's uricase method when applied to urine and blood plasma. Recovery of 95.1 ± 3.4% has been obtained with 5 μg uric acid/ml added to an extract of cockroach feces containing 3 μg uric acid/ml, and equally good results with the addition of 2.5 or 1.25 μg. Similar recoveries were obtained from urine and plasma.

A Comparison of Three Methods, Utilizing Different Principles, for the Determination of Uric Acid in Biological Fluids

A Comparison of Three Methods, Utilizing Different Principles, for the Determination of Uric Acid in Biological Fluids

A Comparison of Three Methods, Utilizing Different Principles, for the Determination of Uric Acid in Biological Fluids

A Comparison of Three Methods, Utilizing Different Principles, for the Determination of Uric Acid in Biological Fluids

A new method for preparing a highly purified uricase suitable for uric acid determination by ultraviolet spectrophotometry.

Abstract A much simpler, and considerably less time-consuming modification of Holmberg's method for the preparation of a highly purified, stable uricase preparation has been described. It is hoped that the introduction of this method of preparing uricase will result in more widespread use of Kalckar's specific, accurate and quick method for the determination of uric acid in biological fluids.