Anovelapproachhasbeendevelopedtodeterminetheamountofresidualwaterinhumanerythrocyteatroomtemperaturebyelectronicparticlecounter.Naclsolutionsof13osmolalitieswerepreparedandtheequilibriumcellvolumesinwhichweremeasuredonebyone.Theisotonicvolume,Vo,wasobtainedundertheisotoniccondition.ThemeanRBCvolumesof5donorsateachosmolalitywerefittedaccordingtoBoylevan'tHoffrelationship,andtheosmoticallyinactivevolume,Vb,oferythrocytewasthendetermined.TheresultsshowthatVb＝50%Vo.Moreimportantly,thefinalcellvolumewithregardtothesolutionofthehighestconcentrationfoundtobekeptatabout0.5V0.Thedifferencebetweenthesetwovolumesisunconspicuous.Accordingtothepublisheddatathatnon-watervolumeofhumanerythrocyteisabout28.3%ofitsisotonicvolume,residualwaterofhumanerythrocytecanbegainedbysubtractingVdryfromVf,thatisVrw----21.7%VoThenitwasconcludedthattheresidualwaterofhumanlaysin2states,oneisboundwater,andtheotherisfreewater.
