Date of Award


Degree Name

Bachelor of Science


Paper Science and Engineering


The variability of extinction coefficient with respect to wood species is an important aspect to ultra-violet determination of lignin both in cooking liquor and in the wood itself. The precision with which the abundance of a solution can be measured, and therefore the lignin concentration is dependent upon the extinction coefficient.

The objective of this investigation was to analyze various woods for variability and possibly determine overall extinction coefficient averages for woods or groups of woods (hardwood/softwood) that will be more representative than currently used extinction coefficients.

The results contained within indicate that the extinction coefficients for lignin samples in solution are affected by pulping conditions. It is also clear that the wood species is a factor to consider when using ultra-violet determinations of lignin samples. There is a small but significant deviation in the extinction coefficients for differing wood species.