Fig. 2. Effects of temperature and concentration on the density of levo (L)–bupivacaine. Depicted are all measurements at least in triplicate per concentration at 5°, 20°, 30°, and 37°C and polynomial curve fits ( P and R 2given in table 2 ). L-bupivacaine, 5 and 2.5 mg/ml as commercially available solutions, 3.75 mg/ml (NaCl) diluted from 5 mg/ml with isotonic saline, 3.75 mg/ml (aq) diluted from 5 mg/ml with distilled water. Horizontal line = cerebrospinal fluid (CSF) (n = 7) at 37°C; gray bar = 3-SD range.