
%0 Journal Article
%A Murphy, Ricardo 
%A Ortega, Joseph K.E. 
%T <emph type="2">Research Note</emph>: Calibration of micropipettes for pressure-probe studies
%J Functional Plant Biology
%D 1999/01/29
%V 25
%N 8
%P 947-951
%K 
%R https://doi.org/10.1071/PP98084
%U https://www.publish.csiro.au/paper/PP98084 
%X In order to determine cell water-relation parameters with the pressure probe, the ratio of inner to outer pipette diameters (&#945; = Di/Do) must be estimated. Four different methods for estimating a were compared. I: measurement of the volume of oil expelled from a pipette and the corresponding movement of an oil/water meniscus within the pipette; II: measurement of Di and Do on fractured pipettes; III: measurement of Di and Do on intact pipettes; IV: measurement of Di and Do on capillary tubing. Methods I and II gave mean values for &#945; (&#177; SE) that were in excellent agreement &#91;0.587 &#177; 0.004 (n = 12), and 0.593 &#177; 0.003 (n = 14), respectively&#93;. Method III gave variable results for Do &#60; 80&#181;m; for Do &#62; 80 &#181;m a mean value &#945; = 0.624 &#177;0.007 (n = 4) was obtained. Method IV gave a mean value &#945; = 0.544 &#177; 0.001 (n = 5). It is suggested that any method for calibrating micropipettes should be checked against an independent method (e.g. Method I) that allows the determination of &#945; for Do &#60; 100 &#181;m. In the present study, Method II gave the best combination of accuracy and convenience. 
