ISO/TR 16153:2004 gives the detailed evaluation of uncertainty for volume measurements according to the Guide to the expression of uncertainty in measurements (GUM). ISO 8655-7 covers non-gravimetric methods of volume measurement. Annex A of ISO 8655-7 presents the details of a method that employs removable cells (vials) in a UV/VIS photometer. Annex B of ISO 8655-7 presents the details of a method that employs a flow cell fixed in place in a UV/VIS photometer. ISO/TR 16153:2004 covers the uncertainty of measurement of both methods.