Analysing avian eggshell pigments with Raman spectroscopy

Abstract

Avian eggshells are variable in appearance, including coloration. Here, we demonstrate that Raman spectroscopy can provide accurate diagnostic information about major eggshell constituents, including the pigments biliverdin and protoporphyrin IX. Eggshells pigmented with biliverdin showed a series of pigment-diagnostic Raman peaks under 785 nm excitation. Eggshells pigmented with protoporphyrin IX showed strong emission under 1064 nm and 785 nm excitation, whereas resonance Raman spectra (351 nm excitation) showed a set of protoporphyrin IX informative peaks characteristic of protoporphyrin IX. As representative examples, we identified biliverdin in the olive green eggshells of elegant crested tinamous (Eudromia elegans) and in the blue eggshells of extinct upland moa (Megalapteryx didinus). This study encourages the wider use of Raman spectroscopy in pigment and coloration research and highlights the value of this technique for non-destructive analyses of museum eggshell specimens.

Avian mitochondrial genomes retrieved from museum eggshell

“…through analysis of colour and shape; Beruldsen, Chapman & Macleod, ). These analyses can be achieved using various techniques including light and electron microscopy (Buss & Keiss, ; Oskam et al, ), computed tomography (Riley, Sturrock, Mooney, & Luck, ), reflectance spectrophotometry (Aviles, Soler, & Perez‐Contreras, ), Raman spectroscopy (Thomas et al, ) and mass spectrometry (Stewart, Allen, Jones, Penkman, & Collins, ).…”

“…| 1053 GREALY Et AL. Oskam et al, 2011), computed tomography (Riley, Sturrock, Mooney, & Luck, 2014), reflectance spectrophotometry (Aviles, Soler, & Perez-Contreras, 2006), Raman spectroscopy (Thomas et al, 2015) and mass spectrometry (Stewart, Allen, Jones, Penkman, & Collins, 2013).…”

Pigmentation of White, Brown, and Green Chicken Eggshells Analyzed by Reflectance, Transmittance, and Fluorescence Spectroscopy

“…observed reflectance and absorbance by the eggshell, and the transmittance through the shell . Vibrational spectroscopy has been applied as IR technique to analyze the properties of eggshell layers, or as Raman technique to identify avian eggshell pigments …”

“…The avian eggshell is a complex biomineral that combines mechanical stiffness, bio-functionality, and aesthetic appearance. The chicken eggshell mainly consists of calcite crystallites ( � 95 % w/w) with a small contribution of apatite ( � 1% w/w), [1] a pervading organic matrix (1-3.5 % w/w of the palisade layer), [2] pigments as colorants (0.15-1200 nmol/g), [3][4][5][6][7][8] and, according to own results, more than 10 % (v/v) void cavities with about 0.4 % (w/w) of adsorbed water. The architecture of the shell has mainly been investigated with imaging methods (scanning electron microscopy, [9] transmission electron microscopy, [2] optical microscopy, [10] and X-Ray [11] ).…”

“…[41] Vibrational spectroscopy has been applied as IR technique to analyze the properties of eggshell layers, [42,43] or as Raman technique to identify avian eggshell pigments. [5] In this paper, we disconnect the inner mebranes from the calcareous main parts of white, brown, light green and dark green chicken eggshells. According to the graphical TOC, we apply diffuse reflectance, diffuse transmittance and fluorescence spectroscopy for the in-shell analysis of the optical concentrations and axial concentration profiles of PPIX, BV, and proteins in the multiple scattering shell.…”