Protocol for checking pipette calibrations using absorbance readings of a dye in solution?
I see what you are getting at however this would be a very WRONG way of calibrating such an instrument. If dyes varied among trials it would throw off your calibration. Also, you would need to generate some sort of standard curve to equate absorbance to weight, since true calibration of these instruments is done by weighing the volumes they dispense (1g = 1ml water). The weight of water and the weight of your dye solution will not increase the same in terms of moles/g. Also a scale is far easier to calibrate that the detector in any spectrophotometer. Calibrate pipettes by weighing the volume of water they dispense. It should be done in a chamber that inhibits evaporation and you need a precision scale. 

Here's a reliable guide for pipette calibration

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