Setting Standards for Pipettes
Everybody needs standards. And that obviously includes scientists. Uniform international standards help us maintain, well … standards! This point is well made in a discussion of the ISO 8655 laboratory standard for pipettes, written by Anachem’s Pipette Service Manager, Craig Bush.
Pipettes are a vital laboratory tool and their maintenance and correct usage is a sometimes under-appreciated part of good laboratory practice. Pipettes must perform perfectly at all times, not just to prevent error creeping into experiments or procedures, but also to help prevent repetitive strain injuries.
Bad pipettes and pipetting can put quite a strain on the hand of the operator, especially when you consider the thousands of individual liquid transfers many laboratory workers carry out every year. Even the ‘simplest’ of manual pipettes is a complex mechanism and modern electronic pipettes are highly sophisticated pieces of equipment with their own particular requirements to be addressed to ensure that researchers can get optimum usage.
As Anachem found out in a recent survey the vast majority of laboratories (over 90%) use a pipette with 20% use more that 10 different types of pipettes. These are a crucial part of modern laboratory life.
This calls not just for accuracy, but also for uniformity. Manufacturers must, and by and large do, publish details of the precision and error ranges of their instruments and recommended calibration procedures. However, as with any set of instructions, they can be quite hard to penetrate, especially if one is dealing with a variety of pipettes from different sources.
This is why it makes sense to have a standard set for pipettes so that everyone can ensure they are working by the same book of rules! The snappily named EN ISO 8655 does just that. It doesn’t just deal with design specifications and error ranges that potential uses need to evaluate before any purchase (or indeed use), although those obviously are vitally important.
It goes on to discuss in depth the procedures that pipette operators need to have carried out so that the pipettes can work at maximum efficiency. This is very important, as calibration is a step where things can go very wrong.
The gravimetric method is the usual way of calibrating pipettes and it requires specific environmental conditions. Although it is a lengthy procedure, involving the accurate weighing of dispensed ultra-pure water, and a calculation of the actual water transferred, it is necessary if you want your pipettes to function as they should.
As is outline in Anachem’s summary, the number of factors that should be taken into account, including evaporation rates, speed of transfer and, of course, balance calibration, does give you food for thought and the report is worth close scrutiny. However, such a vital laboratory tool does demand this degree of attention, and over 90% of scientists would have to agree.
To find out more about the Anachem pipette service please visit their website
Date added: 2013-07-10 11:01:14