Online In-Tube Solid-Phase Microextraction Coupled with Liquid Chromatography–Tandem Mass Spectrometry for Automated Analysis of Four Sulfated Steroid Metabolites in Saliva Samples

Abstract

Accurate measurement of sulfated steroid metabolite concentrations can not only enable the elucidation of the mechanisms regulating steroid metabolism, but also lead to the diagnosis of various related diseases. The present study describes a simple and sensitive method for the simultaneous determination of four sulfated steroid metabolites in saliva, pregnenolone sulfate (PREGS), dehydroepiandrosterone sulfate (DHEAS), cortisol sulfate (CRTS), and 17β-estradiol-3-sulfate (E2S), by online coupling of in-tube solid-phase microextraction (IT-SPME) and stable isotope dilution liquid chromatography–tandem mass spectrometry (LC–MS/MS). These compounds were extracted and concentrated on Supel-Q PLOT capillary tubes by IT-SPME and separated and detected within 6 min by LC–MS/MS using an InertSustain swift C18 column and negative ion mode multiple reaction monitoring systems. These operations were fully automated by an online program. Calibration curves using their stable isotope-labeled internal standards showed good linearity in the range of 0.01–2 ng mL−1 for PREGS, DHEAS, and CRTS and of 0.05–10 ng mL−1 for E2S. The limits of detection (S/N = 3) of PREGS, DHEAS, CRTS, and E2S were 0.59, 0.30, 0.80, and 3.20 pg mL−1, respectively. Moreover, intraday and interday variations were lower than 11.1% (n = 5). The recoveries of these compounds from saliva samples were in the range of 86.6–112.9%. The developed method is highly sensitive and specific and can easily measure sulfated steroid metabolite concentrations in 50 μL saliva samples.

Modern automated microextraction procedures for bioanalytical, environmental, and food analyses

“…Likewise, the use of silica-coated capillaries for automated IT-SPME has been applied, several other times to produce open-tubular extractive micro columns. Thus, Kataoka and coworkers have published methods for the analysis of urinary biomarkers [95,96], the hormone melatonin in saliva [97], five tobacco-specific nitrosamines in hair [98], and four sulfated steroid metabolites in saliva [99], with the use of GC capillaries as IT-SPME columns. Moreover, from 2016 on, to improve the selectivity of the extractive phases, Falcó and collaborators have developed several selective extractive coatings, including silicacoated capillaries modified with carbon nanotubes [100] and or/metallic nanoparticles (MNPs) [101,102] for automated IT-SPME coupled to capillary LC (cLC) or nano-LC (nLC).…”

A quantification method for trace level of oxytocin in food matrices using LC-MS/MS

“…The Limit of quantification (LOQ) was established by spiking at 0.01 mg/kg which offered the best performance in terms of identification, confirmation following the retention time (±0.1 min), and ion ratio (±30%) criteria [ (Kataoka and Nakayama, 2022)] [(Author anonymus, 2021)]. Based on the signal to noise (>10:1), the recovery and precision were observed within acceptable criteria.…”

“…Another study built a platform containing automated filtration/filter backflushing (AFFL), online SPE, and a nano LC-MS system (Moriyama and Kataoka, 2015). Online in-tube Solid-phase micro-extraction (SPME) to couple with LC-MS for measuring salivary oxytocin (Kataoka and Nakayama, 2022).…”

Solid-Phase Microextraction and Related Techniques in Bioanalysis

“…This Special Issue, entitled “Solid-Phase Microextraction and Related Techniques in Bioanalysis”, consists of 14 original, peer-reviewed papers written by research groups worldwide. The topics covered include headspace fiber SPME (HS-SPME) gas chromatography–mass spectrometry (GC-MS) [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ], HS-in-needle ME (HS-INME)-GC-MS [ 9 ], thin film SPME (TF-SPME) liquid chromatography–tandem mass spectrometry (LC-MS/MS) [ 10 ], magnetic solid-phase extraction (MSPE) LC-MS/MS [ 11 ], in-tube SPME (IT-SPME) LC-MS/MS [ 12 , 13 , 14 ] and IT-SPME LC-UV [ 15 ]. The samples analyzed include a wide range of plant-derived volatile organic compounds [ 2 , 3 , 4 , 5 , 6 , 7 ]; body odor from the skin [ 8 , 9 ]; metabolites from urine [ 10 ], plasma [ 11 ] and saliva [ 12 ] samples; biomarkers of exposure to tobacco smoke in hair [ 13 , 14 ]; and environmental estrogens in water [ 15 ].…”

“…One method of achieving this is dispersive MSPE, in which a magnetic sorbent is dispersed in a sample solution, such as plasma, the solution stirred to extract the compounds of interest, and the extracted compounds eluted from the magnetic sorbent are used in MSPE LC-MS/MS analysis of glucocorticoids, estrogens, progestogens and androgens [ 11 ]. Furthermore, an automated analysis system that couples on-line IT-SPME and LC-MS/MS was constructed using an open-tube fused silica capillary with a coated inner surface as the extraction device, enabling simultaneous selective and sensitive analysis of the metabolism of sulfated steroids in saliva samples [ 12 ].…”