What are the common methods of pipette calibration?
1. Gravimetric: requires a controlled environment, a high precision balance, a skilled pipette technician and the use of statistics. Principle: given a certain mass of water with a known specific gravity, its volume can then be calculated. The gravimetric method of calibration entails weighing deonized (i.e. distilled) water on a balance and converting from a mass unit to a volumetric unit by utilizing the Z-factor. (Z-factor converts from a mass unit to a volumetric unit and includes calculations for air buoyancy, temperature, humidity, barometric pressure and the cubic expansion coefficient). 2.Colorimetric or Photometric involves the analysis of volumes of diluted dye in a cell of a known path length. If a beam of monochromatic light passes through homogeneous solutions of equal path-lengths, the absorbance measured is proportional to the dye concentration. Principle: An unknown volume of dye can be pipetted into a known volume of diluent, the resulting dye concentration can be meas
