Exploratory investigations on the potential of radiofrequency glow discharge-optical emission spectrometry for the direct elemental analysis of bone

A radiofrequency glow discharge (rf-GD) coupled to optical emission spectro metry (OES) has been tested for the analysis of the elemental composition o f bones. To achieve this goal, three sample preparation strategies were inv estigated: (i) utilization of a metallic holder for samples 1 mm thick; (ii ) embedding the samples (0.5 or 1 mm thick) in a conducting resin; and (iii ) encapsulation of thin layer (8-20 mum thick) bone samples in poly(methylm ethacrylate) and final pasting over a flat support (copper and glass were s tudied as supports). From a medical point of view, this third approach can be considered as the more practical one since it requires a smaller amount of patients' bone and also this particular sample preparation follows an al ready well-established procedure for bone analysis in clinical laboratories . Optimisation of the discharge parameters, including rf delivered power, p lasma pressure, anode orifice diameter and the effect of cooling the discha rge, has been investigated for the analysis of bones for each of the three sample preparation methodologies. The spectral region from 190 to 600 nm wa s scanned and results showed that best analytical sensitivity is obtained u sing approach "iii" with samples pasted over a flat copper support. At the selected conditions of 6 Torr, 35 W of rf delivered power and 6 mm internal diameter of the anode orifice, intense emission lines for Ca, Na, Mg, P an d C were observed for the thin layer bone.