A simple and fast method to determine water content in biodiesel by electrochemical impedance spectroscopy.

In this paper, a fast, simple and new alternative method for determination of water content (moisture) in biodiesel using electrochemical impedance spectroscopy (EIS) is developed. The method is based on the sensitive variation of the charge transfer resistance (Rct) of the biodiesel medium in the presence of different quantities of water. To obtain an accurate analytical measurement, a pre-treatment based on a simple dilution by acetonitrile is employed. The two identical Pt electrodes are used in the measurement cell filled with sample solution. The experiment conditions are also optimized for the measurements. The obtained analytical linear curve between the water content and EIS impedance is the basis for the water content analysis in biodesiel fuel. The EIS method is then successfully applied to both real and certified samples, and the results confirm that the method is reliable with high sensitivity, precision and accuracy. The comparison of EIS method with the official standard method is also made through the Student test t, demonstrating that both methods are statistically consistent and similars. The validation of such an EIS method confirms that the method presented for the fist time in this paper can be succesessfully applied to determining the water content of biodiesel fuel.

Glutathione-s-transferase modified electrodes for detecting anticancer drugs.

With the fast growth of cancer research, new analytical methods are needed to measure anticancer drugs. This is usually accomplished by using sophisticated analytical instruments. Biosensors are attractive candidates for measuring anticancer drugs, but currently few biosensors can achieve this goal. In particular, it is challenging to have a general method to monitor various types of anticancer drugs with different structures. In this work, a biosensor was developed to detect anticancer drugs by modifying carbon paste electrodes with glutathione-s-transferase (GST) enzymes. GST is widely studied in the metabolism of xenobiotics and is a major contributing factor in resistance to anticancer drugs. The measurement of anticancer drugs is based on competition between 1-chloro-2,4-dinitrobenzene (CDNB) and the drugs for the GST enzyme in the electrochemical potential at 0.1V vs. Ag/AgCl by square wave voltammetry (SWV) or using a colorimetric method. The sensor shows a detection limit of 8.8µM cisplatin and exhibits relatively long life time in daily measurements.