AA remaining in synthetic RTLF following a 4 h incubation with three separate dung cake (DC) samples at 50 and 100 μg/ml (grey bars) The impact of co-incubation with the transition metal chelator DTPA (200 μM) is illustrated by the white bars. Pre (0 hr) and post (4 hr) AA concentrations in the particle-free controls are illustrated in the black filled bars. The losses observed with 50 μg/ml doses of fresh diesel and gasoline PM0.1–2.5, as well as ROFA are also illustrated. Data represent the mean (SD) of 3 separate experiments: 'a' – indicates that AA concentrations after the 4 h incubation were significantly lower (P < 0.05) than the 4 h particle free control values; 'b' illustrates that the losses observed at 100 μg/ml are significantly greater than those seen at the lower 50 μg/ml concentration. The '*' illustrates a significant loss of AA in the particle free control over the 4 h incubation period.