Table 3 CA20948 clonogenic survival in mean percentage ± SD after exposure to ascorbic acid or in combination with TRIS, NaI, HCl and DTPA, n = 3. Concentration in incubation medium was; [TRIS] = 16 mmol.L−1, [AA] = ascorbic acid, 3.4 mmol.L−1, [NaI] = 3.6 mmol.L−1, [HCl] = 3.6 mmol.L−1 and [DTPA] = 6.1 × 10−3 mmol.L−1