Quantitative HPLC of pigments of irregularly coloured eggshells: application to aliquots of powdered shell from quail

Twelve quail eggshells from farmed Coturnix coturnix japonica were separately ground to fine powder and two aliquots of each (average weights 13.86 mg and 51.90 mg) were extracted with formic acid. Biliverdin (38-284 pmol/mg) and protoporphyrin (841-1666 pmol/mg) were measured by HPLC. There was good agreement between the values for the corresponding samples and with those for two entire eggshells from the same source. The preparation of a homogenate as a powder from heterogeneously pigmented eggshells has the advantage that not all of the sample needs to be initially extracted for analysis and residual material can be stored in a stable form and used for repeat measurements and for longitudinal studies.