I’m not sure what you mean by this. Do you mean when measuring the “neutral”?
The best way to document this is by taking LAB measurements. Make sure to export these lab measurements using D50 illuminant (not the default illuminant A).
Generally the neutral will be +/- 1 or so in the A and -1.5 in the B. By that I mean, there will be a small amount towards blue with this ink-set as we humans perceive neutral when it’s a tiny bit blue.
But I need your measurements. (Illuminant D-50, Angle 2 or Angle 10).