Simultaneous Determination Of Adenine Research Articles

Characterization of graphite-epoxy composite electrodes for free electrochemical detection of adenine and guanine in DNA

Graphite-epoxy composites (GECs) are alternative construction materials for electro­chemical sensors. For these materials, the electron transfer rate constant of some redox reaction depends additionally on the stoichiometric relationship between the insulating and conducting phases of the composite. In this work, the influence of dif­fe­rent ratios of araldite/hardener/graphite on the electrochemical properties of GEC electrodes is evaluated for the simultaneous determination of adenine and guanine in the single chain DNA, using the square wave voltammetry technique. Six GEC electro­des were prepared with different ratios of components, and electrochemically charac­terized by cyclic voltammetry in the presence of ferri/ferrocyanide redox couple as a redox probe. GEC electrodes that showed the best electrochemical responses of redox probe were characterized by thermogravimetric analysis (TGA) and used for the simul­taneous determination of free adenine and guanine in a solution, and DNA oligonu­cle­otides. The best results were obtained for GEC electrodes containing twice higher volu­me of araldite resin with respect to the hardener. TGA analysis revealed presence of 15-26 % of resin for these GEC electrodes. The obtained results revealed potential appl­ication of these GEC electrodes as DNA sensors based on the oxidation signal of guanine.

Synthesis of ionic liquids coated nanocrystalline zeolite materials and their application in the simultaneous determination of adenine, cytosine, guanine, and thymine

In this study, ionic liquids coated nanocrystalline zeolite based inorganic-organic hybrid materials were synthesized. Nanocrystalline ZSM-5 zeolite was prepared under hydrothermal condition in the presence of propyltriethoxysilane as an additive in the synthesis composition of conventional ZSM-5. Ionic liquids (methylimidazolium chloride and 1-butyl-3-methylimidazolium chloride) were coated on the surface of nanocrystalline ZSM-5 by the post synthesis method. For comparative study, ionic liquids coated conventional ZSM-5 based inorganic-organic hybrid materials were also prepared. Ionic liquids coated nanocrystalline ZSM-5/ZSM-5 modified electrodes were constructed for the simultaneous determination of all four DNA bases such as adenine, cytosine, guanine, and thymine. Difference in the electro-catalytic activity of the modified electrode is explained with the help of textural properties, conductivity, and density functional theory. The analytical performance of the proposed method was demonstrated in the simultaneous determination of all four DNA bases in calf thymus DNA sample.

Simultaneous Determination of Adenine and Thymine in Presence of Guanine at Electrochemically Activated Glassy Carbon Electrode

Simultaneous Determination of Adenine and Thymine in Presence of Guanine at Electrochemically Activated Glassy Carbon Electrode

Potentiality of partial least-squares multivariate calibration in the spectrophotometric analysis of binary mixtures of purine bases

A partial least-squares (PLS) modeling was developed for the simultaneous spectrophotometric determination of adenine (AD) and guanine (GU). The determination of these analytes is pharmacologically necessary. Multivariate calibration is used because of spectral overlapping. The calibration set contained AD and GU in the concentration range of 1.4–20.3 and 1.5–25.7 μg cm−3, respectively. The absorption spectra were recorded from 200 to 300 nm. The predicted residual error sum-of-squares for AD and GU was 0.0500 and 0.4000 for number of principal components 3 and 2, respectively. The root mean square error of prediction for AD and GU was 0.0913 and 0.2582, respectively. The limits of detection were 0.02 and 0.03 μg cm−3 for AD and GU, respectively. The proposed method allows the simultaneous determination of AD and GU in spiked real matrixes of human urine, serum, and plasma.

Simultaneous determination of adenine and guanine in DNA based on carboxylic acid functionalized graphene

A nano-material carboxylic acid functionalized graphene (graphene − COOH) was prepared and used to construct a novel biosensor for the simultaneous detection of adenine and guanine. The direct electrooxidation behaviors of adenine and guanine on the graphene − COOH modified glassy carbon electrode were carefully investigated by cyclic voltammetry and differential pulse voltammetry. The results indicated that both adenine and guanine showed the increase of the oxidation peak currents with the negative shift of the oxidation peak potentials in contrast to that on the bare grassy carbon electrode. The electrochemical parameters of adenine and guanine on the modified electrode were calculated and a simple and reliable electroanalytical method was developed for the detection of adenine and guanine, respectively. The modified electrode exhibited good behaviors in the simultaneous detection of adenine and guanine with the peak separation as 0.334 V. The detection limit for individual determination of guanine and adenine was 5.0 × 10 −8 M and 2.5 × 10 −8 M (S/N =3), respectively. Furthermore, the measurements of thermally denatured single-stranded DNA were carried out and the value of (G + C)/(A + T) of single-stranded DNA was calculated as 0.80. The biosensor exhibited some advantages, such as simplicity, rapidity, high sensitivity, good reproducibility and long-term stability.

Simultaneous determination of adenine, guanine and thymine based on β-cyclodextrin/MWNTs modified electrode

In the electroanalytical fields, carbon nanotubes (CNTs) have been usually utilized to modify the electrodes to enhance the relevant detection sensitivity because of their unique physical and chemical properties. In this research, novel nanocomposites of β-cyclodextrin and multi-wall CNT (MWCNTs) have been prepared and deposited on the glassy carbon electrodes to form the β-CyDex/MWNT modified electrodes. These novel modified electrodes offer a new strategy for the simultaneous determination of guanine (G), adenine (A) and thymine (T). Well separated voltammetric peaks are obtained between G and A (330 mV), A and T (170 mV) present in the analyte mixture. The detection limits of A, T and G for individual analysis can be calculated to be 0.75, 6.768 and 33.67 ± 7.8% nmol L −1, respectively. The functional properties of the composite films from differential pulse voltammetry (DPV) show that the β-CyDex/MWNT nanocomposites modified electrodes are quite sensitive and could be readily applied in biosensor devices.

Simultaneous determination of adenine and guanine in ruminant bacterial pellets by ion-pair HPLC

An ion-pair reversed-phase high-performance liquid chromatography with gradient elution and UV detection was used to measure adenine (A) and guanine (G) in lyophilized bacterial pellets from ruminants using allopurinol as internal standard. The separation was performed on a Symmetry C18 column and the detection was monitored at 280 nm. Calibration curves were found to be linear in the concentration range from 5 to 50 mg/l with correlation coefficients (r2)>0.999. Mean recoveries of A and G standards added to bacterial samples were 102.2 and 98.2, respectively. The method proposed yielded sharp, well-resolved peaks within 25 min and was successfully applied for the determination of A and G in bacterial pellets.

Simultaneous determination of adenine, uridine and adenosine in cordyceps sinensis and its substitutes by LC/ESI-MS

A simple, sensitive and reproducible high performance liquid chromatography-mass spectrometry coupled with electrospray ionization method for simultaneous separation and determination of adenine, adenosine and uridine was developed. The analytical column is a 2.0 mm × 150 mm Shimadzu VP-ODS column and volume fraction of the mobile phase is 86.5% water, 12.0% methanol and 1.5% formic acid. 2-chloroadenosine was used as internal standard. Selective ion monitoring mode and selective ion monitoring ions at ratio of mass to electric charge of 136 for adenine, 268 for adenosine and 267 for uridine were chosen for quantitative analysis of the three active components. The results show that the regression equations and linear range are Y=0.062X+0.005 and 2.0 – 140.0 µg·mL−1 for adenine, Y=0.049X+0.004 and 4.0–115.0 µg · mL−1 for uridine, Y=0.154X+0.014 and 1.0–125.0 µm · mL−1 for adenosine. The limits of detection are 0.6 µg·mL−1 for adenine, 1.0 µg·mL−1 for uridine and 0.2 µg·mL−1 for adenosine. The recoveries of the three constituents are from 96.6% to 103.2%.