A simple dilute-and-shoot procedure for the determination of platinum in human pleural effusions using HR-CS GF-AAS

High-resolution continuum source AAS is an emerging technique for the determination of trace elements in clinical analysis. We aimed to develop a method for the direct determination of platinum (Pt) in pleural effusions that could deepen the understanding of the dynamics of intrapleural Pt concentration during cytostatic therapy.

Samples were collected by thoracic drainage from five patients with lung cancer undergoing platinum based chemotherapy. A simple dilute-and-shoot method for Pt determination in the pleural effusions was developed. Ashing of the sample in an oxygen flow in a graphite tube allowed for direct analysis without prior mineralization. The trueness of the method was verified using an independent technique (ICP-MS). As platinum derivatives are only active in its free form (not bound to proteins), Pt in samples was further divided into free and protein-bound forms by means of ultrafiltration.

Using the proposed method, Pt contents (free and total) were determined in samples collected at different times after the intravenous application of the Pt derivative. The concentration of total Pt reached values of up to 5,000 μg/L and different patterns of its dynamics in intrapleural fluid were observed.

The developed method enables the fast and simple determination of Pt in biological fluids. It may be applied on a large scale to improve the understanding of Pt dynamics during cytostatic therapy, and also to determine the optimal timing of both thoracic drainage and administration of systemic chemotherapy.