Simultaneous Determination Of Xanthine Research Articles

Poly(para toluene sulphonic acid) and gold nanoparticles modified glassy carbon electrode for simultaneous voltammetric sensing of xanthine and hypoxanthine.

A voltammetric sensor has been developed for the individual as well as simultaneous determination of xanthine (XA) and hypoxanthine (HX) based on an electroactive-polymerised layer of para toluene sulphonic acid and gold nanoparticles composite modified glassy carbon electrode ([p(PTSA)]/AuNPs/GCE)]. Under optimized conditions, an enhancement in the oxidation currents with well-separated and well-resolved peak position and a lower shift in the peak potentials were observed. By square wave voltammetry, the simultaneous determinations of XA and HX were achieved in the linear ranges 6.00 × 10-4M to 3.00 × 10-6M and 5.00 × 10-4M to 1.00 × 10-5M with detection limits of 4.09 × 10-7M and 4.10 × 10-7M, respectively. The mechanistic aspects were unveiled from linear sweep voltammetric studies and found that the electrode processes were diffusion-controlled. Finally, the sensor was successfully employed for the simultaneous determination of spiked amount of XA and HX in synthetic urine and serum samples.

Triethylamine-controlled Cu-BTC frameworks for electrochemical sensing fish freshness

The simultaneous determination of xanthine (XA) and hypoxanthine (HXA) has been proved to be a feasible approach for the assessment of fish freshness. In this study, copper(II) nitrate and 1,3,5-benzenetricarboxylic acid (H3BTC) were used as precursors to prepare various Cu-BTC frameworks with the addition of various amounts of triethylamine at room temperature. The characterization of X-ray diffraction, Fourier-transform infrared spectroscopy and Raman spectroscopy testified that the obtained materials are Cu-BTC frameworks. However, the amount of triethylamine had significant effects on the morphology, active response area and electron transfer ability of Cu-BTC frameworks. The oxidation behavior of XA and HXA demonstrated that the prepared Cu-BTC frameworks exhibited higher sensing activity, with greatly-enhanced oxidation signals. More importantly, the amount of triethylamine obviously affected the accumulation capacity and signal enhancement ability of Cu-BTCs toward XA and HXA, as confirmed from double potential step chronocoulometry. Based on the triethylamine-tuned signal amplification strategy of Cu-BTC frameworks, a highly-sensitive and simple electrochemical sensing system was developed for the assessment of fish freshness by simultaneous detection of XA and HXA. The developed sensing method was used in practical samples, and the results were validated by high-performance liquid chromatography.

A novel electrochemical sensor based on B doped CeO2 nanocubes modified glassy carbon microspheres paste electrode for individual and simultaneous determination of xanthine and hypoxanthine

A novel electrochemical sensor based on the use of boron doped CeO2 nanocubes modified glassy carbon microspheres paste electrode (B-CeO2NCs/GCPE) was prepared and applied for selective and sensitive determination of xanthine (XA) and hypoxanthine (HXA) individually and simultaneously. The morphology, composition and structural properties of the undoped and B doped CeO2 nanocubes were characterized by X-ray diffraction, energy-dispersed X-ray spectrometry (EDS) and transmission electron microscopy (TEM). Electrochemical activities and the surface analysis of the modified electrode were investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). From the B-CeO2NCs/GCPE, well oxidation peaks and enhanced peak currents of XA and HXA were observed owing to the excellent catalytic activity of B-CeO2NCs. For individual detection, the linear responses of XA and HXA were in the concentration range of 5.42×10−8–1.31×10−5M and 3.98×10−7–6.01×10−5M with detection limits of 3.02 and 6.17nM, respectively. For simultaneous detection by synchronous change of the concentration of XA and HXA, the linear ranges were 1.98×10−7–9.45×10−6M and 3.98×10−7–1.28×10−5M with detection limits of 3.65 and 8.17nM, respectively. The practical application of the modified electrode was demonstrated by simultaneously determining the concentrations of XA and HXA in human biological fluids and in fish meat samples with satisfactory results.

Simultaneous spectrophotometric determination of xanthine, hypoxanthine and uric acid in real matrix by orthogonal signal correction-partial least squares

The simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) mixture using spectrophotometric methods is a difficult task in analytical chemistry because of the spectral interferences. Partial least squares (PLS) modeling, as a powerful multivariate statistical tool, were applied to the spectrophotometric simultaneous determination of these substances. The concentration ranges for XA, HXA and UA were 3.0–24.3, 2.7–19.0 and 3.4–25.2 μg ml−1, respectively. The experimental calibration set consisted of 21 sample solutions with a mixture design for three-component mixtures. The absorption spectra were recorded from 220 to 320 nm. After orthogonal signal correction (OSC), the unrelated information was removed and the results were proved. The root mean square error of prediction (RMSEP) for xanthine, hypoxanthine and uric acid with OSC were 0.5161, 0.2997 and 0.5739 and without OSC were 1.6087, 0.8580 and 1.4009, respectively. This process afforded the simultaneous determination of XA, HXA and UA in human urine and human serum.

Linear-sweep voltammetry and the simultaneous determination of xanthine and xanthosine at the glassy carbon electrode

Linear sweep voltammetry of xanthine and xanthosine has been studied at a sweep rate of 10mVs−1 in phosphate buffers with different pH values. Based on the linear relation of peak current versus concentration, the simultaneous determination of both the compounds was carried out.