Evaluation of two methods of measuring the absorbing capacity of paper points

This study analyzed two methods of measuring the absorbing capacity of paper points (PP), testing the hypothesis that there is a positive correlation between the results from the percentage of increase mass (PIM) and the linear dye penetration (LDP) methods.

The initial dry weight (IDW) of each PP was recorded using a digital balance before 1-mm introduction into one of the dye solutions, 1% methylene blue (MB) or 1% rodamine B (RB), for 10s. The PP's were removed from the solution and weighed (final weight - FW). PIM was calculated from the difference between FW and IDW (n=50). The LDP was measured using a stereomicroscope and a ruler (n=50). Data was statistically analyzed using the Pearson correlation and Student's t tests.

Moderate positive correlations between LDP and PIM methods were found using methylene blue (r=0.6356) and rodamine B (r=0.7743), partially confirming the study hypothesis, and suggesting that results from these two methods should be confronted carefully.

The results of this study suggest that the most reliable method of measuring the absorbing capacity of paper points is the PIM and investigators should be aware of differences between the two research protocols when comparing results from these two methods (PIM and LDP).