Comments regarding D.H. Marchand and J.W. Dolan, Priming Injections, LC GC Europe, 12(#9), 542 (1999)
Expectedly, the phenomenon that proteins can stick to columns was more pronounced with older columns. There is an interesting account on this in R. Huber and K.Zech, Determination of Drugs and their Metabolites . . . ., in R.W. Frei and K. Zech, eds., J. of Chromatogr. Library, 39A, 108 (1988).
We have seen a somewhat different, but related effect. Proteins can adhere strongly to frits in columns. Even though many human serum/plasma samples were injected on restricted access columns without immediate problems (there were always some long-range flow restrictions), some patients´ samples plugged the frit immediatly after injection. [Such serum/plasma samples also plugged micro-filters (0.45 µm) after one drop got through.] In cases where there was only an increased flow reduction toward the end of a session it had often disappeared on standing over night, but only for the first 5 minutes after flow was restarted. The proteins, or whatever, had apparently changed positions, but were pushed back into obstruction by the mobile phase flow. Whether such an adherence changes quantitation of proteins could not be ascertained as they were not the subject of the analysis and were present in too high amounts for quantitation.
Right now we see some unexplained variation in protein peak intensities with UV and fluorescence detection, which could be due to partial extreme peak broadening (part of the proteins sneak through)or changes in absorbance/fluorescence. We will report on this when we know more.