Hydrophilic interaction liquid chromatography and accurate mass measurement for quantification and confirmation of morphine, codeine and their glucuronide conjugates in human urine

A hydrophilic interaction liquid chromatography–time-of-flight mass spectrometry (HILIC–TOFMS) method for the quantification and confirmation of morphine (M), codeine (C), morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G) and codeine-6-glucuronide (C6G) is presented. The method was validated in terms of specificity, selectivity, extraction recovery, accuracy, repeatability, linearity and matrix effect. After a straightforward sample preparation by solid phase extraction (SPE) the compounds were analyzed directly without the need for hydrolysis, solvent transfer, evaporation or reconstitution. The HILIC technique provided good chromatographic separation which was critical for isomers M3G and M6G. The analytes were detected after electrospray ionization (ESI) in positive mode with mass accuracies below 2 mDa using a 5-mDa window. A measurement range of 50–5000 ng/ml was applied for calibration using deuterated analogs as internal standards. The precision of the method was 5.7% and 10.2% (RSD) within and between days, respectively. The applicability of the method was demonstrated with authentic urine samples known to contain codeine and/or morphine and their intact glucuronide conjugates. Identification of the analytes was based on in-source collision induced dissociation (ISCID), applying three diagnostic ions with accurate mass.