title: Measurement of serotonin in platelet depleted plasma by liquid chromatography tandem mass spectrometry.
abstract: 5-Hydroxytryptamine (5-HT) in human platelet depleted plasma (PDP) is a biomarker in functional gastrointestinal disorders (FGID), with levels reflecting acute changes in circulating 5-HT concentration. PDP 5-HT is currently measured by reversed phase high performance liquid chromatography (HPLC) fluorimetric detection. We have developed a simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method that is two times more rapid than the current HPLC methodology. Our method employs a simple protein precipitation requiring no further downstream sample preparation. 10 microL of extract was injected directly onto a SecurityGuard SCX cation exchange column followed by isocratic elution onto an Onyx Monolithic C18 analytical column and methanolic gradient elution. Eluant was connected directly to a Quattro Premier XE tandem mass spectrometer operating in ES+ mode. We detected multiple reaction monitoring transitions m/z 160>114.9 and m/z 164.1>118.9 for 5-HT and d(4)-5-HT, respectively. 5-HT and d(4)-5-HT co-eluted at 2.79 min and cycle time between injections was 6 min. Mean recovery was 98%, limit of detection 1.5 nmol/L, lower limit of quantification 5 nmol/L, linearity to 1000 nmol/L (r(2)=0.999), imprecision <10% and bias <13.4%. 5-HT eluted with no ion suppression. No interference was found with l-tryptophan or 5-hydroxyindoleacetic acid (5-HIAA). This assay was compared to a previously published HPLC method. Passing-Bablok regression analysis showed LC-MS/MS=0.91 (HPLC)-0.83, r(2)=0.97, n=80. Bland Altman analysis showed general agreement, with a mean bias of 3.3 nmol/L. We have developed a simple and robust assay for PDP 5-HT that will increase throughput for clinical trials.
authors.affiliation: Department of Clinical Biochemistry, South Manchester University Hospital Trust, Manchester, M23 9LT, United Kingdom. phillip.monaghan@nhs.net
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Monaghan
authors.forename: Heather A
authors.initials: HA
authors.lastname: Brown
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Houghton
authors.forename: Brian G
authors.initials: BG
authors.lastname: Keevil
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods*; D005767:Gastrointestinal Diseases / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D012701:Serotonin / Q000097:blood / Q000737:chemistry* / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D012701:Serotonin