title: Quantitative mass spectrometry of unconventional human biological matrices.
abstract: The development of sensitive and versatile mass spectrometric methodology has fuelled interest in the analysis of metabolites and drugs in unconventional biological specimens. Here, we discuss the analysis of eight human matrices-hair, nail, breath, saliva, tears, meibum, nasal mucus and skin excretions (including sweat)-by mass spectrometry (MS). The use of such specimens brings a number of advantages, the most important being non-invasive sampling, the limited risk of adulteration and the ability to obtain information that complements blood and urine tests. The most often studied matrices are hair, breath and saliva. This review primarily focuses on endogenous (e.g. potential biomarkers, hormones) and exogenous (e.g. drugs, environmental contaminants) small molecules. The majority of analytical methods used chromatographic separation prior to MS; however, such a hyphenated methodology greatly limits analytical throughput. On the other hand, the mass spectrometric methods that exclude chromatographic separation are fast but suffer from matrix interferences. To enable development of quantitative assays for unconventional matrices, it is desirable to standardize the protocols for the analysis of each specimen and create appropriate certified reference materials. Overcoming these challenges will make analysis of unconventional human biological matrices more common in a clinical setting.This article is part of the themed issue 'Quantitative mass spectrometry'.
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University, 1001 University Rd, Hsinchu 300, Taiwan.
authors.forename: Ewelina P
authors.identifier: http://orcid.org/0000-0002-8852-4188
authors.initials: EP
authors.lastname: Dutkiewicz
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University, 1001 University Rd, Hsinchu 300, Taiwan Institute of Molecular Science, National Chiao Tung University, 1001 University Rd, Hsinchu 300, Taiwan plurban@nctu.edu.tw.
authors.forename: Pawel L
authors.identifier: http://orcid.org/0000-0003-3471-045X
authors.initials: PL
authors.lastname: Urban
mesh_terms: D019963:Clinical Chemistry Tests / Q000379:methods*; D044707:Forensic Sciences; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D013048:Specimen Handling; D014116:Toxicology
keywords: clinical analysis; hyphenated techniques; mass spectrometry; non-invasive sampling; toxicology