Preparation of stable standards of biological tissues for laser ablation analysis

A novel method for preparation of durable standards of biological samples for quantitative analysis by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has been developed. Rat brain tissue samples were ground and then spiked by aqueous solutions containing controlled amounts of trace metals of interest. The spiked rat brain samples were then encapsulated in a sol–gel matrix produced by tetraethyl orthosilicate (TEOS). The spiked standards were prepared by addition of 0–50 μg g−1 of eight elements (Li, Co, Cr, Cu, Fe, Mn, Pb and Zn) to the biological samples. The correlation coefficients of the calibration curves for all elements tested were better than 0.97. Carbon-13, found in all biological samples, was used as an internal standard to correct for variations in the amount of material ablated and carried to the ICP-MS plasma torch, a common problem in LA-ICP-MS analysis. The results of analysis of the standards showed very good repeatability and homogeneity as well as long room temperature shelf life.

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► A novel method, for preparing sol-gel based standards for laser-ablation analysis.
► The method is suitable for biological matrices, like rat brain tissue.
► Homogenuous distribution of elements in the standard has been demonstrated.
► Carbon-13 serves as a built-in internal standard.
► Long shelf life of standards at room temperature.