Many people used to use "graduated pipette tips". Do a search on Google and you'll still find suppliers. Two reasons they aren't used anymore: 1. They are accurate enough and 2.Nobody bothered. The world is now quality and traceability crazy and there are many forces in play to monitor and control risk areas (clinical, pharma manufacture etc). Pipettes are no exception. Some people use in-house colorimetric systems (the creation of these then need quality controlling - the proverbial piece of string) or commercial systems such as Artel, but these can be very expensive and are not recognised by varying quality bodies due to corrleation with the gold standard of gravimetric/weighing technique. Easiest is to use a balance (also checked) and de-ionised water, and use a simple spreadsheet with Z factor correction etc and record the results. As for leak tests; put the manufacturers tip on the tip cone and aspirate the full volume, see it is drips. I have seen quite a few pipettes in serological labs over the years delivering over 10% error, so 90Ul instead of 100ul for example. The results can be signficantly wrong especially using commerical test kits. Add to this the wrong tip, filter tips, poor techniques and the errors can increase! This last bit is what the lawyers like!!
