Inductively Coupled Plasma Mass Spectrometry (ICP-MS) determination of platinum and arsenic in tumors. Mice were perfused for 1 h with cisplatin (CP/37; CP/43) or cisplatin + NaAsO2 (CPA/37; CPA/43) at 37 or 43°C respectively. Tumors from untreated (UT) and treated mice were harvested at 0 and 24 h after treatment. Tumors were homogenized and samples of the homogenate were analyzed for protein concentration by BCA or digested in nitric acid for ICP-MS analysis for platinum and arsenic. Data are presented as means ± SEM of ≥3 tumors each from different mice. Statistical analysis was performed using wilcoxon rank sum test. P < 0.05, N ≥ 3: # = lower than 0 h partner, ‡ = higher than CP/37 at 0 h and CP/43 at 0 h, ¶ = higher than CPA/43°C at 0 h.