Microvolume spectrophotometric and fluorometric determination of protein concentration

Methods for determining protein concentration that use progressively smaller amounts of material are continually being developed. A new way of minimizing the amount of sample used for spectroscopic analysis is providing more opportunities for greater quality control. Traditional spectrophotometric and fluorometric methods for determination of protein concentrations have long required placing samples into containment devices such as cuvettes or capillaries. A microsample retention system is changing that paradigm by using natural surface tension properties to capture and hold microvolume samples in place during measurement without traditional containment devices. The advantage of such a system is to dramatically reduce the amount of sample required (1 to 2 microl) while greatly increasing the dynamic range of protein concentrations that can be measured. Modifications to classic protein concentration determination protocols are presented to provide a microvolume alternative to traditional cuvette-based methods.