The other poorly performing and/or PEG-lacking compounds make up a broadly dispersed cluster (cluster 3). There appears to be a moderate negative correlation between component terminal carbon, or one within a furan ring, implies that greater APR shielding (and therefore enhanced stability) would be achieved by a branched compound with short aliphatic chains, a a high degree of complexity and a broad distribution in space of a large number of heteroatoms. This is further supported by the lower impact on decreasing the SASA of APRs of compounds with a high alkyl chain content: phospholipids, Span 85 (three oleates) and glycerols all had little impact on the SASA of the APRs of HSA.