Identification of the chemical form of sulfur compounds in the Japanese pink coral (Corallium elatius) skeleton using μ-XRF/XAS speciation mapping

Precious coral non‐destructive characterization by Raman and XRF spectroscopy

“…Significant is also the higher presence of sulphur in the Mediterranean corals (0.81 ± 0.14% as averaged value) with respect to Pacific samples (0.49 ± 0.14% as averaged value), whose origin (organic or inorganic) in precious coral is still debated. Indeed, some authors working on pink ( C. elatius ) and white ( Paracorallium japonicum ) corals and others working on Mediterranean red corals ( C. rubrum ), demonstrated the coexistence of both organic and inorganic sulphur compounds in the precious coral skeleton suggesting that sulfate is attached to calcium in the coral skeleton calcite. Therefore the major sulfate species (SO 4 −2 ) in coral skeleton is structurally substituted to the carbonate group (CO 3 −2 ) of calcite and the small amount of organic matrix (~1.5%) is in fact not enough to explain the measured sulphur concentration in the analyzed samples.…”

“…In terms of elemental analysis different techniques have been used so far for the analysis of Corallidae spp . samples such as inductively coupled plasma mass spectrometry (ICP‐MS), atomic absorption spectroscopy (AAS), micro‐X‐ray fluorescence (micro‐XRF) on thin cross section and X‐ray absorption near edge structure (XANES) …”

“…Indeed, different studies have shown how trace elements in corals can be used as indicators of the origin and the growing habitat [7][8][9][10][11][12] and for long-lived samples also as proxy tools to reconstruct sea water temperature [13] , pH changes [14] and nutrient availability [15] over long periods of time. [16] Indeed, since several elements, such as toxic metals, can substitute Ca in the calcitic structure of the skeleton or can be associated with particulate organic matter within skeletal pores, the analysis of trace element composition allows to monitor the metal loads in marine environment.…”

“…samples such as inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectroscopy (AAS), micro-X-ray fluorescence (micro-XRF) on thin cross section and X-ray absorption near edge structure (XANES). [7,10,12,29,30] The main requirements for an analytical method to be used for the characterization of precious corals are surely the non destructiveness, easiness of sample preparation (or no sample preparation) and, eventually, the possibility to perform the analysis in situ with portable and easily operated instruments. Considering these constraints, an ideal solution appears the combination of XRF elemental analysis for the inorganic components of the coral matrix and Raman spectroscopy for the molecular information as also demonstrated by previous works that characterized different materials combining the aforesaid techniques.…”

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

“…Ulrich et al 144 investigated dissolution-precipitation processes governing the carbonation and silicication of serpentine from the New Caledonian ophiolite, using m-XRF images performed on a cm scale to describe relationships between serpentinite and alteration products. The identication of the chemical form of sulfur compounds in Japanese pink coral was the topic of interest to Tamenori et al 146 using m-XRF spectrometry combined with so X-ray photoabsorption speciation mapping. Their work was undertaken at the Australian SR facility using a detector array called Maia, which allowed data to be collected from a 2 mm spot with very short dwell times (0.1 to 0.5 ms), facilitating the recording of a map from an entire thin section in about 5 hours.…”