title: Quantitative determination of piritramide in human plasma and urine by off- and on-line solid-phase extraction liquid chromatography coupled to tandem mass spectrometry.
abstract: A method for the liquid chromatography/tandem mass spectrometric (LC/MS/MS) quantification of piritramide, a synthetic opioid, in plasma after conventional off-line solid-phase extraction (SPE) and in urine by on-line SPE-LC/MS/MS in positive electrospray mode was developed and validated. Applicability of the on-line approach for plasma samples was also tested. Deuterated piritramide served as internal standard. For the off-line SPE plasma method mixed cation-exchange SPE cartridges and a 150 x 2 mm C18 column with isocratic elution were used. For the on-line SPE method, a Waters Oasis HLB extraction column and the same C18 analytical column in a column-switching set-up with gradient elution were utilized. All assays were linear within a range of 0.5-100 ng/mL with a limit of detection of 0.05 ng/mL. The intra- and interday coefficients of variance ranged from 1.3 to 6.1% for plasma and 0.5 to 6.4% for urine, respectively. The extraction recovery for the off-line plasma assay was between 90.7 and 100.0%. Influence of matrix effects, and freeze/thaw and long-term stability were validated for both approaches; influence of urine pH additionally for quantification in urine.
authors.affiliation: Institute of Pharmacology and Toxicology, Department of Clinical Pharmacology, University Hospital Tübingen, 72076 Tübingen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kahlich
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Gleiter
authors.forename: Stefan
authors.initials: S
authors.lastname: Laufer
authors.forename: Bernd
authors.initials: B
authors.lastname: Kammerer
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D009862:Online Systems; D010892:Pirinitramide / Q000097:blood* / Q000652:urine*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
chemical_list: D010892:Pirinitramide