Determination of isosmolar blood anticoagulant solutions by the freezing-point method.

LTHOUGH SUITABLE CONCENTRATIONS of many anticoagulants have been determined for mammalian blood, isosmolar concentrations are not generally available among vertebrates. In some instances the correct concentrations may be computed from known equations (1) or from known freezing-point depressions (ATs) at specific concentrations (2). The data are still fragmentary. In the present study, ATs covering a wide range of useful concentrations of 7 anticoagulants which are currently of importance and can work in vitro have been determined. MATERIALS AND METHODS ATs in degrees C. were determined with a Beckmann thermometer, calibrated from +1#{176} to -5#{176}, and surrounded by a crushed ice-saline mixture. AT of any solution was found by obtaining the period of constant temperature after the heat of fusion was dissipated. Each value was determined 30 times. The anticoagulants studied included potassium oxalate, lithium oxalate, sodium oxalate, ammonium potassium oxalate, sodium citrate, disodium ethylenediamine tetraacetate (Sequestrene), and dipotassium ethylenediamine tetra#{228}cetate(Versene). All solutions were prepared in molar concentrations for biologic preference. “G” values (Van’t Hoff i; isotonic coefficients) were computed The G value indicates that a given concentration of an electrolyte has a AT a certain number of times greater than that of a nonelectrolyte. If, for example, AT for turtle blood (3) is minus 0.522#{176}, and if AT for a one molal concentration of any ideal nonelectrolyte is minus 1.86#{176},