An assessment of the radial diffusion method for the measurement of pepsin in gastric secretion and its comparison with the haemoglobin substrate colorimetric method.

The radial diffusion method of pepsin assay has been compared with a modified Anson-Mirsky colorimetric method. Though claimed to measure accurately over a wide range, we found that the assay range of the radial diffusion method was only 10 to 100 mg/l; even with these narrow limits, it was inaccurate. In contrast, the colorimetric method was much more rapid, sensitive and could accurately measure a wide range of 0.5 to 500 mg/l. The colorimetric technique is therefore the superior method.