In a distributed scenario it is possible to find systems consisting of independent parties that collaboratively execute a business process, but cannot disclose a subset of the data used in this process to each other. Such systems can be modelled using the PE-BPMN notation: a privacy-enhanced extension of the BPMN process modeling notation. Given a PE-BPMN model, we address the problem of verifying that the content of certain data objects is not leaked to unauthorized parties. To this end, we formalise the semantics of PE-BPMN collaboration diagrams via a translation into process algebraic specifications. This formalisation enables us to apply model checking to detect unintended data leakages in a PE-BPMN model. We specifically consider data leakages in the context of secret sharing technology. The approach has been implemented on top of the mCRL2 toolset, and integrated into the Pleak toolset supporting privacy analysis of business processes. The proposal has been evaluated using real scenarios.