A novel device for the accurate dispensing of small volumes of liquid samples

A sample dispenser with electronic control of delivered volume has been designed and evaluated. With this device, liquid samples are dispensed in the form of uniform droplets less than 4 nl in volume; total volumes as small as 40 nl can be delivered with 1.5% precision. Important features of the microdroplet formation process have been studied and the effect of sample solution concentration and viscosity have been examined. The dispenser is expected to find application in several areas, including electrothermal atomization atomic absorption spectrometry, automated titrimetry, and high-precision, low-volume solution sampling.