Chemical Experimentation and Analysis with Micrograms to Nanograms

Abstract

Chemical operations have been successfully performed by numerous workers with amounts of material considerably smaller than 0.1 to 10 μg in mass, while the volumes of the solutions were from 1 nl to 1 μl so that, in general, the customary concentrations were retained. This indicates that chemical reactions take place in the usual way with such minute amounts of material and give the same results as on the large scale. This confirms conclusions derived from theoretical considerations (31) that, when dealing with substances of an assumed average molecular weight of 100, reproduction of qualitative reactions can be expected with amounts of material of the order of 10^-20 g corresponding to 100 reacting molecules, and of quantitative reactions with amounts of the order of 10^-16 g corresponding to 1,000,000 reacting molecules. It is assumed that the equilibrium is sufficiently in favor of the expected effect. With these amounts of reacting material, the number of molecules present should be sufficient to statistically ensure the establishment of average conditions to permit the kinetics of reactions to follow the customary observed course for given conditions of temperature and pressure. A chemical reaction should therefore be expected to follow the same course on any small scale down to the above mentioned limits as long as the reactants are given in the same concentrations. This indicates that microchemical work is possible even with quantities considerably smaller than micrograms and nanograms of material.