An apparatus and method are provided for determining boundaries between fractions in a fractionated sample. The method includes the steps of providing the fractionated sample in a receptacle, the receptacle having a transparent window, positioning the receptacle in a known position relative to datum means, capturing an image of the receptacle and datum means, and processing the image to determine the position of boundaries between the fractions in the sample relative to the datum means. An apparatus and method for extracting a selected fraction of a fractionated sample are also disclosed.