Since you have approximately 1.5 mm between samples on average you will have to do some re-interpolation of your data. This works provided the assumption that the interpolation-scheme is reasonable for your data. That is up for you to check/verify/demonstrate/argue/show/assume. This can be done something like this:
sample_dist = your_data(:,5);
dist_interp = min(sample_dist):0.1:max(sample_dist);
if dist_interp(end) < max(sample_dist)
dist_interp(end+1) = max(sample_dist);
end
data_reinterp = interp1(sample_dist,your_data,dist_interp,'pchip');
This works provided dist varies monotonically.
HTH
