Electrochemical oxidation of acetyl salicylic acid and its voltammetric sensing in real samples at a sensitive edge plane pyrolytic graphite electrode modified with graphene.

We present in this manuscript for the first time the electrochemical oxidation of acetyl salicylic acid and its voltammetric sensing in real samples at a sensitive edge plane pyrolitic graphite electrode (EPPGE) modified with graphene. The electrochemical response of the sensor was improved compared to edge plane pyrolytic graphite electrode and displayed an excellent analytical performance for the detection of acetyl salicylic acid .These characteristics were attributed to the high acetyl salicylic acid loading capacity on the electrode surface and the outstanding electric conductivity of graphene. A linear response was obtained over a range of acetyl salicylic acid concentrations from 10 nM to 100nM into a pH 4 buffer solution (N defined as the sample size N = 7) with a detection limit of 3 nM based on (3-s/slope). The methodology is shown to be useful for quantifying low levels of acetyl salicylic acid in a buffer solution. The protocol is also shown to be applicable for the sensing of acetyl salicylic acid in human oral fluid samples. A linear response was obtained from 30nM to 150 nM into a human oral fluid solution (N = 7) with a detection limit of 17.3nM. Cyclic Voltammetry (CV) using EPPG modify with graphene has been employed in the proposed method for the determination of ASA in drug preparations and human oral fluid

Deferiprone, a non-toxic reagent for determination of iron in samples via sequential injection analysis.

We present for the first time the use of deferiprone as a non-toxic complexing agent for the determination of iron by sequential injection analysis in pharmaceuticals and food samples. The method was based on the reaction of Fe(III) and deferiprone in phosphate buffer at pH 7.5 to give a Fe(III)-deferiprone complex, which showed a maximum absorption at 460 nm. Under the optimum conditions, the linearity range for iron determination was found over the range of 0.05-3.0 μg mL-1 with a correlation coefficient (r2) of 0.9993. The limit of detection and limit of quantitation were 0.032 μg mL-1 and 0.055 μg mL-1, respectively. The relative standard deviation (%RSD) of the method was less than 5.0% (n = 11), and the percentage recovery was found in the range of 96.0-104.0%. The proposed method was satisfactorily applied for the determination of Fe(III) in pharmaceuticals, water and food samples with a sampling rate of 60 h-1

Pharmaceutical electrochemistry: the electrochemical detection of aspirin utilising screen printed graphene electrodes as sensors platforms.

A sensitive electrochemical sensor was designed for acetyl salicylic acid detection using graphene modified Screen Printed Electrodes. The electrochemical response of the sensor with graphene was improved compared to Screen Printed Electrodes without graphene and displayed an excellent analytical performance for the detection of acetyl salicylic acid. The high acetyl salicylic acid loading capacity on the electrode surface and the outstanding electric conductivity of graphene were also discussed in this manuscript. When a range of different concentrations of acetyl salicylic acid from 0.1 to 100 μM into a pH 4 buffer solution (N defined as the sample size N = 9) were plotted against the oxidation peak a linear response was observed. The detection limit was found to be 0.09 μM based on (3-σ/slope). Screen Printed Graphene electrodes sensors methodology is shown to be useful for quantifying low levels of acetyl salicylic acid in a buffer solution as well as in biological matrixes such as human oral fluid. A linear response was obtained over a range of concentrations from 10 to 150 μM into a human oral fluid solution (N = 10) giving a detection limit of 8.7 μM

Photocatalytic studies using a very low surface area catalyst: TiO₂ over CaCO₃ from waste shell (<em>Pomacea canaliculata</em>) in paraquat degradation

1358-1364Calcination of shell waste and subsequent processing resulted in CaCO3 powder that was used as the catalyst support for TiO2/CaCO3 catalyst. The catalyst has been characterized by scanning electron microscopy, BET measurements, X-ray diffraction, UV-visible diffused reflectance spectroscopy and Fourior transform infrared spectroscopy to elucidate the catalyst&rsquo;s properties. The TiO2 over CaCO3 catalyst has been used as a photocatalyst in paraquat removal under optimized conditions of calcination temperature, TiO2 loading method, loading content of Ti component, loading content of TiO2 in the catalyst and light irradiation. The results show that all the experimental parameters significantly affect paraquat removal efficiency of the catalyst. The calcination temperature and TiO2 loading method show the most significant effect