A membrane-based electrochemical nanobiosensor sensitive toward whole viral particles is fabricated by forming a submicrometer thick nanoporous alumina membrane over a platinum disk electrode. Antibody probe molecules are physically adsorbed onto the walls of the membrane nanochannels. The sensing signal is based on the monitoring of the electrode's Faradaic current response toward ferrocenemethanol, which is extremely sensitive to the formation of immunocomplex within the nanoporous membrane. This nanobiosensor is demonstrated for the sensing of West Nile virus protein domain III (WNV-DIII) and the inactivated West Nile viral particle, using anti-WNV-DIII immunoglobulin M (IgM) as the biorecognition probe. The detection of the viral protein and the particle are logarithmically linear up to 53 pg mL(-1) (R(2) = 0.99) and 50 viral particles per 100 mL (R(2) = 0.93) in pH 7, with extremely low detection limits of 4 pg mL(-1) and ca. 2 viral particles per 100 mL, comparable to sensitivities of polymerase chain reaction techniques. The relative standard deviation (RSD) of whole viral particle detection in whole blood serum is 6.9%. In addition, the simple nanobiosensor construction procedure, minimal sample preparation, and short detection time of 30 min are highly attractive properties and demonstrate that the detection of a wide range of proteins and viruses can be achieved.

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A GC-high-resolution isotope dilution MS (IDMS) method for the quantification of melamine in milk powder is described. The developed technique is compared to the LC-IDMS/MS technique, typically used for the determination of melamine in various matrices. The accuracy of the GC-high-resolution IDMS method was demonstrated when a small degree of equivalence was obtained in a regional comparative study involving the determination of melamine in milk powder.