Feasibility of energy dispersive X-ray fluorescence determination of gold in soft tissue for clinical applications

The feasibility of using EDXRF for a rapid quantitative analysis of gold in tumor tissue has been investigated. The protocol described here demonstrates that sample biopsies can be analyzed in as little as 8 hours, with minimal sample preparation. Samples were prepared by drying a 35 mu L aliquot of tissue dissolved in KOH in a standard EDXRF cup on a Prolene (R) support, producing a thin sample. Calibration curves of XRF peak intensity (cps per mA) to the gold concentration (0-50 ppm) were prepared for liver, tumor, and a mix of tissue types. A linear regression demonstrated an R-2 correlation of 0.93. Analysis of experimental samples showed that gold accumulation in tumors (5.8-41.3 ppm) was in agreement with previous studies, where samples were processed using INAA or ICP-MS. This report provides guidance for elemental analysis of gold in tissue in a shorter time span, showing potential for its use in a clinical setting.