A system arranged to determine the volume of a sample solution delivered to a cell by a liquid delivery device to aid in testing the liquid delivery device, the system comprising: a cell having a cell entry port arranged to receive the sample solution from the liquid delivery device into the cell, a substantially constant cross sectional area and a known horizontal optical pathlength and arranged to contain the liquid therein; wherein the system is characterized by the combination of: a horizontal beam spectrophotometer arranged to transmit a horizontal optical beam through contents in the cell and to output information indicative of light absorbance by the contents, wherein the contents of the cell includes a diluent, wherein the diluent includes a first chromophore; a vertical beam spectrophotometer arranged to transmit a vertical optical beam through the contents in the cell and to output information indicative of light absorbance by the contents, wherein the contents in the cell includes the sample solution and the diluent, wherein the sample solution includes a second chromophore; and a computer program arranged to calculate the volume of the sample solution dispensed by the liquid delivery device into the cell based on the substantially constant cross sectional area, the known horizontal optical pathlength, the light absorbance information from the horizontal beam spectrophotometer and the light absorbance information from the vertical beam spectrophotometer. a cell having a cell entry port arranged to receive the sample solution from the liquid delivery device into the cell, a substantially constant cross sectional area and a known horizontal optical pathlength and arranged to contain the liquid therein; wherein the system is characterized by the combination of: a horizontal beam spectrophotometer arranged to transmit a horizontal optical beam through contents in the cell and to output information indicative of light absorbance by the contents, wherein the contents of the cell includes a diluent, wherein the diluent includes a first chromophore; a vertical beam spectrophotometer arranged to transmit a vertical optical beam through the contents in the cell and to output information indicative of light absorbance by the contents, wherein the contents in the cell includes the sample solution and the diluent, wherein the sample solution includes a second chromophore; and a computer program arranged to calculate the volume of the sample solution dispensed by the liquid delivery device into the cell based on the substantially constant cross sectional area, the known horizontal optical pathlength, the light absorbance information from the horizontal beam spectrophotometer and the light absorbance information from the vertical beam spectrophotometer. a horizontal beam spectrophotometer arranged to transmit a horizontal optical beam through contents in the cell and to output information indicative of light absorbance by the contents, wherein the contents of the cell includes a diluent, wherein the diluent includes a first chromophore; a vertical beam spectrophotometer arranged to transmit a vertical optical beam through the contents in the cell and to output information indicative of light absorbance by the contents, wherein the contents in the cell includes the sample solution and the diluent, wherein the sample solution includes a second chromophore; and a computer program arranged to calculate the volume of the sample solution dispensed by the liquid delivery device into the cell based on the substantially constant cross sectional area, the known horizontal optical pathlength, the light absorbance information from the horizontal beam spectrophotometer and the light absorbance information from the vertical beam spectrophotometer.