RESPIROMETER FOR SMALL SAMPLES WITH AUTOMATIC REGISTRATION

The respiration chamber containing the sample is a small glass test tu be with a closure of KOH solution. During registration the gas volume is kept constant by adjusting the pressure through a feedback mechanis m: a microscope projects the picture of the meniscus of KOH onto a pho todiode connected to a pen recorder with a vertically moving pen. A le velling bulb with water mounted on the pen transmits the pressure adju stments to the KOH solution through a water filled tubing. The accurac y is +/-0.1 mm water column (1 Pa) and the minimum air volume is 10 nl , so that an oxygen consumption down to 1 pl can be seen. (C) 1997 Els evier Science B.V.