Quantitative Analyses by Diffusion Column Reactions

Summary

1. 1. Experimental interpolation of slope K (diffusion (mm) vs √min) for SD columns of albumin homologous reactions resulted in the detection of concentration differences of 0.10 mg N₂/ml (0.06% protein) of antigen and 0.010 mg N₂/ml of antibody in 75% and 50% of the respective paired slope comparisons within specific antigen and antibody ranges.

2. 2. Comparison of the Kjeldahl concentrations with the same concentrations estimated from diffusion measurements for both antigen and antibody strengths in SD columns were made using results from regression of K on log of the appropriate reactant concentration. The data used were strictly selected for linearity and reproducibility. For 30 antigen derivations involving Fractions II and V homologous systems at three antibody levels, the mean deviation was 3.44%. The smallest deviation was -0.29% or 0.001 mg antigen N₂ lower for the predicted as compared to the Kjeldahl concentrations.

3. 3. Estimated homologous antibody concentrations from rigidly selected data and curves (K regressed on the logarithm of the antibody concentrations), when compared with Kjeldahl values, showed an average deviation of 2.54% for 50 antibody derivations at five antigen levels for Fractions II and V in SD columns. The over-all mean difference (sign ignored) between Kjeldahl and diffusion—estimated values—was 0.007 mg antibody N₂/ml.

4. 4. The limits of resolution for reactant concentration differences in SD column reactions at certain ranges are discussed in detail.