Stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet/inductively coupled plasma mass spectrometry for analysis of thyroxine in urine samples

Detection of thyroid hormones in urine by liquid chromatography coupled to tandem mass spectrometry

Recently, the trend of thyroid hormones (TH) consumption in the sports community has been published. It is known the capacity of the exogenously administered TH to enhance metabolism, being an attractive feature for athletes, who search for weight control and increased caloric expenditure. This paper aimed the validation of a method to measure TH and related compounds in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method was applied to urine samples collected before and after the administration of a diiodothyronine (3,5-T2) supplement. A method to detect nine TH included an enzymatic hydrolysis, liquid-liquid extraction, and solid-phase extraction. The extracts were analyzed by LC-MS/MS. Validated parameters showed good results for accuracy (85%-104%), precision (3%-16%), LOD (10-40 pg/mL, except for thyronacetic acids that was 200 pg/mL), and the combined uncertainty (2.2%-22%). Maximum concentration of 3,5-T2 in pre-administration samples was 0.71 ng/mL, and after 30 h of the last administration, concentrations returned to pre-administration values. Maximum values of ratios between the analyte and thyronine, T3, and T4 were 0.09, 0.19, and 0.12, respectively, and after 30 h of the last administration, the ratios reached back the basal values. Acidic or basic metabolites were not found in urine at least at the method LOD. A proposed method to assess TH in urine was validated, and as a proof of concept, its efficacy was demonstrated with an excretion study of 3,5-diiodothyronine. The consumption of 3,5-T2 was detected in urine measuring the analyte concentration and ratios between the analyte and thyronine, T3, and T4.

Mass spectrometry in the diagnosis of thyroid disease and in the study of thyroid hormone metabolism

The importance of thyroid hormones in the regulation of development, growth, and energy metabolism is well known. Over the last decades, mass spectrometry has been extensively used to investigate thyroid hormone metabolism and to discover and characterize new molecules involved in thyroid hormones production, such as thyrotropin-releasing hormone. In the earlier period, the quantification methods, usually based on gas chromatography-mass spectrometry, were complicated and time consuming. They were mainly focused on basic research, and were not suitable for clinical diagnostics on a routine basis. The development of the modern mass spectrometers, mainly coupled to liquid chromatography, enabled simpler sample preparation procedures, and the accurate quantification of thyroid hormones, of their precursors, and of their metabolites in biological fluids, tissues, and cells became feasible. Nowadays, molecules of physiological and pathological interest can be assayed also for diagnostic purposes on a routine basis, and mass spectrometry is slowly entering the clinical laboratory. This review takes stock of the advancements in the field of thyroid metabolism that were carried out with mass spectrometry, with special focus on the use of this technique for the quantification of molecules involved in thyroid diseases.

Determination of 3-monoiodotyrosine and 3,5-diiodotyrosine in newborn urine and dried urine spots by isotope dilution tandem mass spectrometry

Development of an analytical method for the determination of MIT and DIT in newborn urine and dried urine spots by Liquid Chromatography Isotope Dilution Tandem Mass Spectrometry capable of correcting analyte interconversion during sample preparation.

Clinical and laboratory aspects of 3,3',5'-triiodothyronine (reverse T3)

Reverse T3 (3,3',5'-triiodothyronine or rT3) is the third most abundant iodothyronine circulating in human blood and is produced by the inner ring deiodination of the pro-hormone thyroxine (T4). Unlike the more abundant and active metabolite T3, the measurement of serum rT3 is yet to find a routine clinical application. As rT3 binds weakly to the T3 thyroid nuclear hormone receptors, it is thought to represent an inactive end-product of thyroid hormone metabolism, diverting T4 away from T3 production. The analysis of serum rT3 has, up until recently, been measured by competitive radioimmunoassay, but these methods have been superseded by mass-spectrometric methods which are less susceptible to interference from other more abundant iodothyronines. Serum rT3 concentration is increased as part of the non-thyroidal illness syndrome, and by administration of common medications such as amiodarone which inhibit the metabolism of rT3. Serum rT3 concentration is also affected by genetic conditions that affect the iodothyronine deiodinases, as well as thyroid transporters and transport proteins. Analysis of rT3 can provide a useful diagnostic fingerprint for these conditions. rT3 has been shown to bind extra-nuclear iodothyronine receptors with a potential role in cell proliferation; however, the clinical relevance of these findings awaits further study.

Solid-phase microextraction: An appealing alternative for the determination of endogenous substances - A review

The determination of endogenous substances is of great significance for obtaining important biotic information such as biological components, metabolic pathways and disease biomarkers in different living organisms (e.g. plants, insects, animals and humans). However, due to the complex matrix and the trace concentrations of target analytes, the sample preparation procedure is an essential step before the analytes of interest are introduced into a detection instrument. Solid-phase microextraction (SPME), an emerging sample preparation technique that integrates sampling, extraction, concentration, and sample introduction into one step, has gained wide acceptance in various research fields, including in the determination of endogenous compounds. In this review, recent developments and applications of SPME for the determination of endogenous substances over the past five years are summarized. Several aspects, including the design of SPME devices (sampling configuration and coating), applications (in vitro and in vivo sampling), and coupling with emerging instruments (comprehensive two-dimensional gas chromatography (GC × GC), ambient mass spectrometry (AMS) and surface enhanced Raman scattering (SERS)) are involved. Finally, the challenges and opportunities of SPME methods in endogenous substances analysis are also discussed.

Avoiding the pitfalls when quantifying thyroid hormones and their metabolites using mass spectrometric methods: The role of quality assurance

This short review aims to assess the application of basic quality assurance (QA) principles in published thyroid hormone bioanalytical methods using mass spectrometry (MS). The use of tandem MS, in particular linked to liquid chromatography has become an essential bioanalytical tool for the thyroid hormone research community. Although basic research laboratories do not usually work within the constraints of a quality management system and regulated environment, all of the reviewed publications, to a lesser or greater extent, document the application of QA principles to the MS methods described. After a brief description of the history of MS in thyroid hormone analysis, the article reviews the application of QA to published bioanalytical methods from the perspective of selectivity, accuracy, precision, recovery, instrument calibration, matrix effects, sensitivity and sample stability. During the last decade the emphasis has shifted from developing methods for the determination of L-thyroxine (T₄) and 3,3',5-triiodo-L-thyronine (T₃), present in blood serum/plasma in the 1-100 nM concentration range, to metabolites such as 3-iodo-L-thyronamine (3-T₁AM), 3,5-diiodo-L-thyronine (3,5-T₂) and 3,3'-diiodo-L-thyronine (3,3'-T₂). These metabolites seem likely to be present in the low pM concentrations; consequently, QA parameters such as selectivity and sensitivity become more critical. The authors conclude that improvements, particularly in the areas of analyte selectivity, matrix effect measurement/documentation and analyte recovery would be beneficial.

Introduction of organic/hydro-organic matrices in inductively coupled plasma optical emission spectrometry and mass spectrometry: a tutorial review. Part II. Practical considerations

Inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS) are increasingly used to carry out analyses in organic/hydro-organic matrices. The introduction of such matrices into ICP sources is particularly challenging and can be the cause of numerous drawbacks. This tutorial review, divided in two parts, explores the rich literature related to the introduction of organic/hydro-organic matrices in ICP sources. Part I provided theoretical considerations associated with the physico-chemical properties of such matrices, in an attempt to understand the induced phenomena. Part II of this tutorial review is dedicated to more practical considerations on instrumentation, instrumental and operating parameters, as well as analytical strategies for elemental quantification in such matrices. Two important issues are addressed in this part: the first concerns the instrumentation and optimization of instrumental and operating parameters, pointing out (i) the description, benefits and drawbacks of different kinds of nebulization and desolvation devices and the impact of more specific instrumental parameters such as the injector characteristics and the material used for the cone; and, (ii) the optimization of operating parameters, for both ICP-OES and ICP-MS. Even if it is at the margin of this tutorial review, Electrothermal Vaporization and Laser Ablation will also be shortly described. The second issue is devoted to the analytical strategies for elemental quantification in such matrices, with particular insight into the isotope dilution technique, particularly used in speciation analysis by ICP-coupled separation techniques.