2022
A preliminary study of hydrocodone and hydromorphone to oxycodone ratios for distinguishing impurities from independent opioid use
Choucair I, Villalba C, Vera M, Cassella-Mclane G, Durant T, El-Khoury J. A preliminary study of hydrocodone and hydromorphone to oxycodone ratios for distinguishing impurities from independent opioid use. Clinical Biochemistry 2022, 112: 6-10. PMID: 36535386, DOI: 10.1016/j.clinbiochem.2022.12.009.Peer-Reviewed Original ResearchMeSH KeywordsAnalgesics, OpioidChromatography, LiquidHumansHydrocodoneHydromorphoneOpioid-Related DisordersOxycodoneOxymorphoneTandem Mass SpectrometryConceptsConcentrations of hydrocodoneMean ratioOxycodone pillsPrescription complianceOpioid useUDT resultsMedication recordsOxycodoneAdditional opiatesPatientsHydromorphoneLarger sample sizeAbstractTextHydrocodoneDrug abuseLiquid chromatography-tandem mass spectrometryDrug testingChromatography-tandem mass spectrometryLC-MS/MSFurther validationPreliminary studySample sizeOpiatesSensitive methodPills
2020
Urinary cannabinoid mass spectrometry profiles differentiate dronabinol from cannabis use
Koch CD, Xu L, Curtis SA, Roberts JD, Bunch DR, El-Khoury JM. Urinary cannabinoid mass spectrometry profiles differentiate dronabinol from cannabis use. Clinica Chimica Acta 2020, 510: 515-521. PMID: 32795544, DOI: 10.1016/j.cca.2020.08.014.Peer-Reviewed Original ResearchMeSH KeywordsCannabinoidsCannabisChromatography, LiquidDronabinolHumansProspective StudiesSubstance Abuse DetectionTandem Mass SpectrometryConceptsCannabis useUrine samplesLoss of appetiteMinor cannabinoidsRapid LC-MS/MSDronabinol groupDronabinol therapyDronabinol useSevere nauseaPain managementPositive subjectsNormal controlsTherapeutic potentialProspective sampleClinical urine samplesCancer chemotherapySpecific populationsCannabisCannabinoidsMetabolite concentrationsDronabinolLC-MS/MSNegative controlDetection of cannabisCannabidiolInvestigating Interference with Lamotrigine Quantification by Liquid Chromatography–Tandem Mass Spectrometry
Hultgren C, Rogers K, Bunch DR, El-Khoury JM. Investigating Interference with Lamotrigine Quantification by Liquid Chromatography–Tandem Mass Spectrometry. The Journal Of Applied Laboratory Medicine 2020, 5: 609-611. PMID: 32445366, DOI: 10.1093/jalm/jfaa007.Peer-Reviewed Original Research
2019
Unusual Drug Test Results for a Patient on Buprenorphine and Naloxone
Gall B, El-Khoury JM. Unusual Drug Test Results for a Patient on Buprenorphine and Naloxone. Clinical Chemistry 2019, 65: 1332-1333. PMID: 31570415, DOI: 10.1373/clinchem.2019.309484.Peer-Reviewed Original Research
2016
High-throughput measurement of 25-hydroxyvitamin D by LC–MS/MS with separation of the C3-epimer interference for pediatric populations
Yang Y, Rogers K, Wardle R, El-Khoury JM. High-throughput measurement of 25-hydroxyvitamin D by LC–MS/MS with separation of the C3-epimer interference for pediatric populations. Clinica Chimica Acta 2016, 454: 102-106. PMID: 26772722, DOI: 10.1016/j.cca.2016.01.004.Peer-Reviewed Original Research
2014
Measurement of GFR for children and an LC–MS/MS method for nonradioactive iothalamate
El-Khoury JM, Gabler J, Wang S. Measurement of GFR for children and an LC–MS/MS method for nonradioactive iothalamate. Clinical Biochemistry 2014, 47: 749-750. PMID: 24858210, DOI: 10.1016/j.clinbiochem.2014.05.042.Peer-Reviewed Original Research
2013
Do deuterium labeled internal standards correct for matrix effects in LC-MS/MS assays? A case study using plasma free metanephrine and normetanephrine
Bunch DR, El-Khoury JM, Gabler J, Wang S. Do deuterium labeled internal standards correct for matrix effects in LC-MS/MS assays? A case study using plasma free metanephrine and normetanephrine. Clinica Chimica Acta 2013, 429: 4-5. PMID: 24269502, DOI: 10.1016/j.cca.2013.11.013.Peer-Reviewed Original ResearchArtifactsChromatography, LiquidDeuteriumMetanephrineNormetanephrineReference StandardsTandem Mass Spectrometry
2012
Does Paricalcitol (Zemplar®) interfere with 1,25-dihydroxyvitamin D measurement by liquid chromatography–tandem mass spectrometry assays?
El-Khoury JM, Bicer F, Bunch DR, Yuan C, Wang S. Does Paricalcitol (Zemplar®) interfere with 1,25-dihydroxyvitamin D measurement by liquid chromatography–tandem mass spectrometry assays? Clinica Chimica Acta 2012, 415: 230-232. PMID: 23142648, DOI: 10.1016/j.cca.2012.10.050.Peer-Reviewed Original ResearchHighly sensitive and selective measurement of underivatized methylmalonic acid in serum and plasma by liquid chromatography-tandem mass spectrometry
Yuan C, Gabler J, El-Khoury JM, Spatholt R, Wang S. Highly sensitive and selective measurement of underivatized methylmalonic acid in serum and plasma by liquid chromatography-tandem mass spectrometry. Analytical And Bioanalytical Chemistry 2012, 404: 133-140. PMID: 22618327, DOI: 10.1007/s00216-012-6099-z.Peer-Reviewed Original ResearchMeSH KeywordsChromatography, High Pressure LiquidFemaleHumansMaleMethylmalonic AcidPlasmaSensitivity and SpecificitySerumSolid Phase ExtractionTandem Mass SpectrometryConceptsLC-MS/MS methodSample preparationMS methodAnion exchange solid phase extractionChromatography-tandem mass spectrometry methodLiquid chromatography-tandem mass spectrometry methodNegative electrospray modeSuccinic acidOrganic acid columnStrong anion-exchange solid-phase extractionSolid-phase extractionStability of 1,25-dihydroxyvitamin D2 and 1,25-dihydroxyvitamin D3 in human serum
El-Khoury JM, Wang S. Stability of 1,25-dihydroxyvitamin D2 and 1,25-dihydroxyvitamin D3 in human serum. Clinical Biochemistry 2012, 45: 707-708. PMID: 22465273, DOI: 10.1016/j.clinbiochem.2012.03.016.Peer-Reviewed Original Research
2011
A simple and fast liquid chromatography–tandem mass spectrometry method for measurement of underivatized l-arginine, symmetric dimethylarginine, and asymmetric dimethylarginine and establishment of the reference ranges
El-Khoury JM, Bunch DR, Reineks E, Jackson R, Steinle R, Wang S. A simple and fast liquid chromatography–tandem mass spectrometry method for measurement of underivatized l-arginine, symmetric dimethylarginine, and asymmetric dimethylarginine and establishment of the reference ranges. Analytical And Bioanalytical Chemistry 2011, 402: 771-779. PMID: 22124751, DOI: 10.1007/s00216-011-5462-9.Peer-Reviewed Original ResearchMeSH KeywordsAdultArginineChromatography, High Pressure LiquidClinical Laboratory TechniquesFemaleHumansMaleMiddle AgedReference ValuesTandem Mass SpectrometryYoung AdultConceptsFast liquid chromatography–tandem mass spectrometry methodAnalytical cycle timeChromatography-tandem mass spectrometry methodLiquid chromatography-tandem mass spectrometry methodMinimum sample preparationMass spectrometry methodLiquid chromatography-tandem mass spectrometryChromatography-tandem mass spectrometryAsymmetric dimethylarginineSymmetric dimethylarginineLC-MS/MS methodMass spectrometerFormic acidSpectrometry methodMass spectrometrySilica columnProtein precipitationSample preparationInternal standardAmmonium acetateMS methodGlomerular filtration rateAnalytesNitric oxide synthaseΜM