1961 年 81 巻 7 号 p. 985-994
Examinations were made on the nature of adsorption by filter paper, which is considered to be one of the reasons for variation of Rf values in partition paper chromatography, and following facts were found:
1) Examinations were made on the adsorption mechanism of a filter paper and, with considerations on adsorption, the formula representing the Rf value was established (equation (7) in the text). In a solvent system with large λs (adsorption equilibrium constant between fiber and stationary phase), result of paper chromatography would not be parallel to the counter-current distribution method unless this equation (7) is adopted. In order to prove this fact, the value of Rfu1 (Rf value in which the partition ratio will be 1/2⋅k when adsorption is taken into consideration of equation (10) in the text) was calculated and compared with the value of Rfu0 (equation (9) in the text), showing that the former is almost constant.
2) It was shown that the phenomena of tailing, double spots, and strained shape of the spot could be explained on the basis of adsorption mechanism.
3) The degree to which adsorption plays a part in partition mechanism was considered to be correlated to Vs (volume of stationary phase contained in unit weight of the filter paper) and λs, from equation (7), and equation (11) was derived from it to obtain the relationship between these two values, showing the limit at which adsorption can be neglected. From the relationship between these two within this limit, upper limit of λs of each Rf value was calculated (Table IV). It was theoretically clarified that λs≤0.05 must be satisfied in order that adsorption could be neglected throughout all Rf values and that adsorption cannot be neglected in Toyo Roshi No. 51 if λs>0.5. It was experimentally proved that Vs≅0.5 is the lower limit of Vs.
4) Measurement of λ (adsorption equilibrium constant between fiber and developing solution in adsorption-type paper chromatography) by the use of various solvents showed that adsorption on the filter paper cannot be neglected when using a solvent system with water as the stationary phase in substances sparingly soluble in water or those having strong affinity to fiber even if soluble in water. On the other hand, use of formamide or ethylene glycol as the stationary phase in such cases was found to decrease adsorptivity markedly. These facts seem to prove that the equation for calculation of Rfu values established without regard to adsorption, as shown in Part I of this series, was not a mistake.