title: Development and validation of a LC-MS/MS method for quantitative analysis of uraemic toxins p-cresol sulphate and indoxyl sulphate in saliva.
abstract: p-Cresol sulphate (pCS) and indoxyl sulphate (IS) are uraemic toxins, the concentration of which in serum correlate with the stage of renal failure. The aim of this study was to develop and validate a high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of pCS and IS in saliva. This is the first time, to our knowledge, that such a method has been developed using saliva. Unstimulated, fasting saliva was collected from healthy volunteers in the morning and pooled for validation assay. The method was validated for linearity, precision, accuracy, stability (freeze/thaw stability, stability in autosampler, short- and long-term stability, stock solution stability), dilution integrity and matrix effect. The analysed validation criteria were fulfilled. No influence of salivary flow (pCS: p=0.678; IS: p=0.238) nor type of swab in the Salivette device was detected. Finally, using the novel validated method, the saliva samples of healthy people (n=70) of various ages were analysed. We observed a tendency for an increase of concentration of toxins in saliva in the elderly. This could be a result of age-related diseases, e.g., diabetes and kidney function decline. We can conclude that the novel LC-MS/MS method can be used for the determination of pCS and IS in human saliva. The results encourage the validation of saliva as a clinical sample for monitoring toxin levels in organisms.
authors.affiliation: Bioanalysis and Drugs Analysis Department, Pharmacy Faculty, Medical University of Warsaw, 1 Banacha Street, 02-097 Warsaw, Poland. Electronic address: joanna.giebultowicz@wum.edu.pl.
authors.forename: Joanna
authors.initials: J
authors.lastname: Giebułtowicz
authors.affiliation: Bioanalysis and Drugs Analysis Department, Pharmacy Faculty, Medical University of Warsaw, 1 Banacha Street, 02-097 Warsaw, Poland.
authors.forename: Natalia
authors.initials: N
authors.lastname: Korytowska
authors.affiliation: Bioanalysis and Drugs Analysis Department, Pharmacy Faculty, Medical University of Warsaw, 1 Banacha Street, 02-097 Warsaw, Poland.
authors.forename: Bartłomiej
authors.initials: B
authors.lastname: Sankowski
authors.affiliation: Bioanalysis and Drugs Analysis Department, Pharmacy Faculty, Medical University of Warsaw, 1 Banacha Street, 02-097 Warsaw, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Wroczyński
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002853:Chromatography, Liquid / Q000379:methods*; D003408:Cresols / Q000032:analysis*; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D007200:Indican / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000737:chemistry*; D013463:Sulfuric Acid Esters / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D055815:Young Adult
chemical_list: D003408:Cresols; D013463:Sulfuric Acid Esters; C408690:4-cresol sulfate; D007200:Indican
keywords: Bioanalysis; Chronic kidney disease; Liquid chromatography coupled to mass spectrometry; Saliva; Sample preparation