A chemistry matrix for use in determining the concentration of an analyte in a biological fluid includes a glucose dehydrogenase, nicotinamide adenine dinucleotide, an alkylphenazine quaternary salt, and/or a nitrosoaniline. The chemistry matrix is used with an electrochemical biosensor to determine the concentration of an analyte after a reaction occurs within the biosensor, at which time an analysis is completed to determine the concentration. A method of determining the concentration of an analyte using the chemistry matrix of glucose dehydrogenase, nicotinamide adenine dinucleotide, an alkylphenazine quaternary salt, and/or a nitrosoaniline is another aspect that is described. The method also further features test times of five seconds or less. Methods utilizing the new chemistry matrix can readily determine an analyte such as blood glucose at concentrations of from about 20-600 mg/dL at a pH of from about 6.5 to about 8.5.