Fig. 1

Percent original remaining for 10 μg mL^− 1, 20 μg mL^− 1, 30 μg mL^− 1, 40 μg mL^− 1 and 50 μg mL^− 1 remifentanil reconstituted with water, 0.9% saline, 20% saline and sodium bicarbonate solution and left in isolation over 24 h. Data expressed as mean ± SEM, n = 3. *P < 0.01 vs. water, 0.9% saline and 20% saline; ^#P < 0.04 vs. water; ^{^}P < 0.05 vs. 20% saline; **P < 0.05 vs. 0.9% saline and 20% saline