IMAGE. Two examples of digital pipettors.
|
Precautions
Digitial pipettors must be calibrated prior to use. This is done first at the factory but the process must be repeated any time the instrument is stripped down (taken apart) for cleaning or repair. Both strip-down and calibration are time consuming processes so it is important that care be taken not to contaminate the pipettor. The next screen shows proper operation of a digital pipettor. Be sure to follow the directions carefully.
Accuracy
The standards for accuracy vary by model, manufacturer and volume delivered. As an example, the type of 50-200 µL pipettor shown in the photograph is considered to be within specifications if it delivers 50 µL ± 0.8µL (1.6% error) or 200 µL ± 2 µL (1% error). As received from the manufacturer, the measured inaccuracy at 50 µL for one such pipettor was listed as 0.48%.
Precision
If used with a high quality tip and good and consistent technique, very good precision can be obtained. For example, the same pipettor referred to above listed imprecision at 0.11%.
What does this mean?
In the hands of a consistent operator the pipettor will deliver volumes of solution that are ±1.6% of the volume indicated on the dial and are within ±0.11% of each other
|
