The analysis of the concentrations of (R,S)-Ket and its metabolites in clinical samples obtained from a CRPS patient on Day 3 of a 5-Day infusion of (R,S)-Ket obtained using an achiral chromatographic method, where: A. An extracted plasma sample, in which the peak corresponding to (R,S)-Ket (peak 1) has been deleted from the chromatogram; B. An extracted urine sample in which the peaks corresponding to the glucuronides of the HNKs metabolites (6a–e) have been deleted from the chromatogram; C. An extracted urine sample in which only the peaks corresponding to the glucuronides of the HNKs metabolites (6a–e) are presented. See Table 2 for the assignment of the structures for peaks 4c–f, 5c–d and 6a–e and the text for experimental details.