a b s t r a c tThe direct carbon fuel cell (DCFC) is a promising power-generation device that has much higher efficiency (80%) and less emissions than conventional coal-fired power plants. Two commercial carbons (activated carbon and carbon black) pre-treated with HNO 3 , HCl or air plasma are tested in a DCFC. The correlation between the surface properties and electrochemical performance of the carbon fuels is explored. The HNO 3 -treated carbon fuels have the highest electrochemical reactivity in the DCFC due to the largest degree of surface oxygen functional groups. The overall effect on changing the electrochemical reactivity of carbon fuels is in the order HNO 3 > air plasma ≈ HCl. Product gas analysis indicates that complete oxidation of carbon to CO 2 can be achieved at 600-700 • C.

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Current direct analysis methods in mass spectrometry (MS) are predominantly focused on desorbing and ionizing samples in the solid phase. Some sampling difficulties are associated with liquid (solution) or gas samples. The present study has expanded direct MS analysis to solution samples by using the desorption corona beam ionization (DCBI) technique in combination with poly(dimethylsiloxane) (PDMS) substrate sampling. Typically, the PDMS substrate is dipped in water for microextraction of pesticide compounds and then is transferred to an MS ion source for desorption and ionization. This approach improves the detection limit for DCBI and allows more organic compounds in complex mixtures to be identified within seconds. The practical application of this device is demonstrated by identifying five pesticides (acephate, isoprocarb, dimethoate, dichlorvos, and dicofol) in water. The obtained detection limits of pesticides are 1 μg/L, the measured dynamic ranges are 3 orders of magnitude, the calculated correlation coefficients are between 0.939 and 0.979 at concentration levels of 5-5000 μg/L, and the repeatabilities defined as a relative standard deviation of five successive injections are in the range of 13-17%. The results indicate that the DCBI technique coupled with PDMS sampling is an excellent method for the analysis of organic pesticides in solution, and it also opens up a new avenue for direct MS studies of solution samples with general importance.

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