Figure 4From: Estimation of insecticide persistence, biological activity and mosquito resistance to PermaNet® 2 long-lasting insecticidal nets over three to 32 months of use in EthiopiaValidation of XRF and HPLC methods on a subset of 32 nets collected after 3-6 months of use. Error bars denote standard deviation. N = 5 readings for all points (sample of nets from each collection site in 2007).Back to article page