Measuring DNA Absorbance with the STS-UV Microspectrometer

Biological molecules are routinely measured using UV absorbance to obtain critical information on concentration and sample purity. With a wavelength range of 190 to 650 nm and approximately 1.5 nm optical resolution, the STS-UV microspectrometer is ideal for these measurements. The STS-UV packs tremendous performance into a compact, powerful microspectrometer to provide high quality UV absorbance data over a wide range of sample concentrations. In this application note, we demonstrate this incredible performance through absorbance measurements of DNA samples ranging from 0.15 to 150 µg/mL.

DNA measurements typically involve samples at the extremes of the concentration range with DNA suspended in solution at either very high or very low concentrations. While dilution can be done with concentrated DNA solutions, low concentration samples present more of a challenge. Without the benefit of an adjustable pathlength spectrometer or small volume sampler, the cuvette pathlength itself must be adjusted to enable measurement of a wide range of concentrations. The high dynamic range and signal to noise ratio of the STS-UV enable DNA measurements over a wide range of concentrations without the need for changing pathlength to accommodate absorbance levels ranging from 0.005 to over 1.5 absorbance units (AU).