Separation and identification of monoglucuronides of vitamin D metabolites in urine by derivatization-assisted LC/ESI-MS/MS using a new Cookson-type reagent.

A liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method was developed using a new Cookson-type reagent, 4-[4-(1-pipelidinyl)phenyl]-1,2,4-triazoline-3,5-dione (PIPTAD), to analyze the monoglucuronides (Gs) of vitamin D metabolites in human urine. The G of 23S,25-dihydroxyvitamin D [23,25(OH)D] was previously found as a major metabolite of vitamin D in the urine, but its conjugation position remained undetermined. Determination of the position was an important research issue to clarify the whole picture of the excretion of surplus 25-hydroxyvitamin D [25(OH)D, the circulating form of vitamin D] in humans.

An LC/MS/MS method for quantifying testosterone and dehydroepiandrosterone sulfate in four different serum samples during a single run.

Simultaneous measurements of the circulating testosterone (TS) and dehydroepiandrosterone sulfate (DHEAS) are deemed to be helpful for the assessment of men's health. Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) is the most reliable methodology for this purpose; however, it has room for improvement in analysis throughput. In this study, a quadruplicate of the Girard reagents was used to develop an LC/ESI-MS/MS method capable of quantifying TS and DHEAS in four different serum samples in a single run.

A method for determination of aldosterone concentrations of six adrenal venous serum samples during a single LC/ESI-MS/MS run using a sextet of Girard reagents.

The accurate quantification of aldosterone (ALD) in adrenal tributary venous serum/plasma collected by a super-selective adrenal venous sampling (ssAVS) technique has become a definitive procedure to identify the forms (laterality) of primary aldosteronism (PA) and the location of the affected segment(s), and to subsequently make the treatment decision. In this study, a stable isotope-dilution LC/ESI-MS/MS-based method was developed and validated for the determination of the ALD concentrations of the six ssAVS serum samples during a single run. A sextet of Girard reagents was used to convert ALD to the derivatives having different masses for each sample.

Derivatization-based sample-multiplexing for enhancing throughput in liquid chromatography/tandem mass spectrometry quantification of metabolites: an overview.

The quantification of metabolites in various samples, including body fluids, tissues, cells, and foodstuffs, contributes to our understanding of their biological activities and roles in the body, diagnosis for many diseases, drug and biomarker discovery, and many aspects of human health. Liquid chromatography (LC)/tandem mass spectrometry (MS/MS) is the most powerful and reliable methodology for the quantification of metabolites due to its high specificity and sensitivity, and broad coverage of various compounds. Derivatization often makes the quantification power of LC/MS/MS stronger due to the desirable LC behavior and enhanced MS/MS detectability of the derivatized metabolites.

Derivatization-based quadruplex LC/ESI-MS/MS method for high throughput quantification of serum dehydroepiandrosterone sulfate.

The quantification of the circulating dehydroepiandrosterone sulfate (DHEAS) might be of diagnostic help for several diseases. For the DHEAS quantification, LC/ESI-MS/MS has the advantage of a high specificity compared with immunoassay, whereas LC/ESI-MS/MS has room to improve the analysis throughput. One of the promising solutions to enhance the analysis throughput is sample-multiplexing in the same injection, which can reduce the total LC/ESI-MS/MS run time.

3-Epi-25-hydroxyvitamin D is a poor substrate for SULT2A1: Analysis of its 3-sulfate in cord plasma and recombinant human SULT2A1 incubate.

A variety of metabolites derived from 25-hydroxyvitamin D [25(OH)D], including its 3-epimer [Epi-25(OH)D] and 3-O-sulfate [25(OH)D-3S], is found in human plasma/serum. We hypothesized that the 3-O-sulfate of Epi-25(OH)D [Epi-25(OH)D-3S] might be present in plasma/serum. Clarifying this point could improve our understanding of the metabolism of vitamin D.

Enhancing LC/ESI-MS/MS Throughput for Plasma Bile Acid Assay by Derivatization-based Sample-Multiplexing.

Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) enables the accurate and precise quantification of various analytes at very low concentrations, but it has room for improvement in analysis throughput. Multiplexing of samples in the same injection could be a promising procedure for enhancing the analysis throughput. This could be achieved by derivatization of the multiple samples with multiple isotopologous reagents.

Sample-multiplexing by derivatization using multiple analogous reagents for enhancing throughput in LC/ESI-MS/MS assay of steroids: Plasma 17α-hydroxyprogesterone as an example.

The measurements of steroids in biological fluids are of importance for the diagnosis and treatment of many diseases. Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) has a high specificity and accuracy for the steroid analysis, whereas it has a lower analysis throughput, which could become a big issue in clinical practice. One of the promising solutions to this issue is the multiplexing of samples in the same injection.

Quantitative MALDI-MS/MS assay for serum cortisol through charged derivatization.

Cortisol (CRT), the main glucocorticoid in humans, plays a crucial role in many physiological processes, therefore, the measurement of its serum level is of great clinical significance. Matrix-assisted laser desorption/ionization-tandem mass spectrometry (MALDI-MS/MS) might be an effective approach for the quantification of CRT in serum due to its attractive properties, i.e.

Identification of conjugation positions of urinary glucuronidated vitamin D metabolites by LC/ESI-MS/MS after conversion to MS/MS-fragmentable derivatives.

A liquid chromatography/electrospray ionization-tandem mass spectrometry-based method was developed for the identification of the conjugation positions of the monoglucuronides of 25-hydroxyvitamin D [25(OH)D ] and 24,25-dihydroxyvitamin D [24,25(OH) D ] in human urine. The method employed derivatization with 4-(4-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione to convert the glucuronides into fragmentable derivatives, which provided useful product ions for identifying the conjugation positions during the MS/MS. The derivatization also enhanced the assay sensitivity and specificity for urine sample analysis.

Changes in Polyamine Content in Rice Bran due to Fermentation with Aspergillus oryzae Analyzed by LC/ESI-MS/MS Combined with Derivatization.

Many studies have demonstrated that the dietary supplementation of polyamines, especially spermidine (SPD), prevents age-related diseases. Rice bran is rich in polyamines and their amounts could be increased by fermentation with Aspergillus oryzae (A. oryzae).

A Method for Quantification of Tetrahydroglucocorticoid Glucuronides in Human Urine by LC/MS/MS with Isotope-coded Derivatization.

The determination of urinary tetrahydroglucocorticoid (THGC) glucuronides might prove helpful in the diagnosis, pathophysiological analysis and assessment of the therapeutic efficacy of the diseases caused by abnormal cortisol secretion. We developed and validated a method for the determination of the THGC glucuronides in human urine using liquid chromatography/electrospray ionization (ESI)-tandem mass spectrometry not requiring enzymatic hydrolysis. The method employed a derivatization using an ESI-enhancing reagent for carboxylic acids, 1-[(4-dimethylaminophenyl)carbonyl]piperazine (DAPPZ), and its isotopologue, H-DAPPZ.

A method for determination of aldosterone in adrenal tributary venous serum by derivatization using Girard P reagent isotopologues followed by LC/ESI-MS/MS.

The quantification of aldosterone (ALD) in adrenal tributary venous blood serum/plasma combined with the super-selective adrenal venous sampling (ssAVS) technique is recognized as a definitive procedure for differentiation of the forms of primary aldosteronism (PA), identification of the affected segment(s) and operating decision-making. In this study, an enhanced throughput and sensitive method was developed and validated for the quantification of ALD in ssAVS serum samples by liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) combined with derivatization using the Girard P reagent (GP) isotopologues (H- and H-GP). The right and left adrenal serum samples were separately pretreated and derivatized with either isotopologue.

Chemical Synthesis of Rare Natural Bile Acids: 11α-Hydroxy Derivatives of Lithocholic and Chenodeoxycholic Acids.

A method for the preparation of 11α-hydroxy derivatives of lithocholic and chenodeoxycholic acids, recently discovered to be natural bile acids, is described. The principal reactions involved were (1) elimination of the 12α-mesyloxy group of the methyl esters of 3α-acetate-12α-mesylate and 3α,7α-diacetate-12α-mesylate derivatives of deoxycholic acid and cholic acid with potassium acetate/hexamethylphosphoramide; (2) simultaneous reduction/hydrolysis of the resulting △ -3α-acetoxy and △ -3α,7α-diacetoxy methyl esters with lithium aluminum hydride; (3) stereoselective 11α-hydroxylation of the △ -3α,24-diol and △ -3α,7α,24-triol intermediates with B H /tetrahydrofuran (THF); and (4) selective oxidation at C-24 of the resulting 3α,11α,24-triol and 3α,7α,11α,24-tetrol to the corresponding C-24 carboxylic acids with NaClO catalyzed by 2,2,6,6-tetramethylpiperidine 1-oxyl free radical (TEMPO) and NaClO. In summary, 3α,11α-dihydroxy-5β-cholan-24-oic acid and 3α,7α,11α-trihydroxy-5β-cholan-24-oic acid have been synthesized and their nuclear magnetic resonance (NMR) spectra characterized.

Improved sensitivity of serum/plasma 1α,25-dihydroxyvitamin D quantification by DAPTAD derivatization.

Background: Although immunoassays have several limitations such as the cross-reactivities of antibodies, such techniques are widely used for serum/plasma 1,25(OH)D quantification. An accurate method is required for the determination of the 1,25(OH)D status.

Methods: We designed a serum/plasma 1,25(OH)D quantification method using LC-MS/MS.

Unconjugated bile acids in rat brain: Analytical method based on LC/ESI-MS/MS with chemical derivatization and estimation of their origin by comparison to serum levels.

Although some studies have revealed the implication of bile acids (BAs) and neurological diseases, the levels and origin of the BAs in the brain are not fully understood. In this study, we first developed and validated a sensitive and specific method for the determination of three unconjugated BAs [cholic acid (CA), chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA)] in the rat brain by liquid chromatography/electrospray ionization-tandem mass spectrometry combined with chemical derivatization. The measured brain concentrations (mean±standard deviation, n=10) of normal rats were 58.

Isotope-coded derivatization based LC/ESI-MS/MS methods using a pair of novel reagents for quantification of hydroxycinnamic acids and hydroxybenzoic acids in fermented brown rice product.

Hydroxycinnamic acids (HCAs) and hydroxybenzoic acids (HBAs) are antioxidant phytochemicals found in rice and effective for the prevention of human diseases including cancer. FBRA, which is a functional food manufactured by fermenting brown rice and rice bran with Aspergillus oryzae, has been demonstrated to have chemopreventive effects against carcinogenesis in various organs. In this study, we developed methods for the relative and absolute quantification of ferulic acid, sinapic acid, caffeic acid, protocatechuic acid and syringic acid in the FBRA and raw material (RM; unfermented brown rice and rice bran) samples by LC/ESI-MS/MS combined with derivatization using a newly developed reagent, N-(2-aminoethyl)-4-(diethylamino)benzamide (ADB) and its deuterium-coded analog, d-ADB.

Enhancing analysis throughput, sensitivity and specificity in LC/ESI-MS/MS assay of plasma 25-hydroxyvitamin D by derivatization with triplex 4-(4-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione (DAPTAD) isotopologues.

The plasma/serum concentration of 25-hydroxyvitamin D [25(OH)D] is a diagnostic index for vitamin D deficiency/insufficiency, which is associated with a wide range of diseases, such as rickets, cancer and diabetes. We have reported that the derivatization with 4-(4-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione (DAPTAD) works well in the liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) assay of the serum/plasma 25(OH)D for enhancing the sensitivity and the separation from a potent interfering metabolite, 3-epi-25-hydroxyvitamin D [3-epi-25(OH)D]. However, enhancing the analysis throughput remains an issue in the LC/ESI-MS/MS assay of 25(OH)D.

A Method for Simultaneous Determination of 25-Hydroxyvitamin D3 and Its 3-Sulfate in Newborn Plasma by LC/ESI-MS/MS after Derivatization with a Proton-Affinitive Cookson-Type Reagent.

A method for the simultaneous determination of 25-hydroxyvitamin D3 [25(OH)D3] and its 3-sulfate [25(OH)D3S] in newborn plasma, which is expected to be helpful in the assessment of the vitamin D status, using stable isotope-dilution liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) has been developed and validated. The plasma was pretreated based on the deproteinization and solid-phase extraction, then subjected to derivatization with 4-(4-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione (DAPTAD). The derivatization enabled the accurate quantification of 25(OH)D3 without interference from 3-epi-25(OH)D3 and also facilitated the simultaneous determination of the two metabolites by LC/positive ESI-MS/MS.

Development and validation of the simultaneous measurement of four vitamin D metabolites in serum by LC-MS/MS for clinical laboratory applications.

The quantification of serum 25-hydroxyvitamin D [25(OH)D] as an indicator of vitamin D status is currently primarily conducted by immunoassays, yet LC-MS/MS would allow more accurate determination. Furthermore, LC-MS/MS would allow simultaneous measurement of multiple analytes. The aim of this study was to develop and validate an LC-MS/MS method to simultaneously measure four vitamin D metabolites (25(OH)D, 3-epi-25(OH)D, 25(OH)D, and 24,25(OH)D) in serum for clinical laboratory applications.

Isotope-coded ESI-enhancing derivatization reagents for differential analysis, quantification and profiling of metabolites in biological samples by LC/MS: A review.

The analysis of the qualitative and quantitative changes of metabolites in body fluids and tissues yields valuable information for the diagnosis, pathological analysis and treatment of many diseases. Recently, liquid chromatography/electrospray ionization-(tandem) mass spectrometry [LC/ESI-MS(/MS)] has been widely used for these purposes due to the high separation capability of LC, broad coverage of ESI for various compounds and high specificity of MS(/MS). However, there are still two major problems to be solved regarding the biological sample analysis; lack of sensitivity and limited availability of stable isotope-labeled analogues (internal standards, ISs) for most metabolites.

Methods for determination of fingernail steroids by LC/MS/MS and differences in their contents between right and left hands.

Fingernail clipping is expected to be a specimen for steroid testing, because it has several advantages over blood; i.e., noninvasive collection, ease of storage, portability and handling, and possibility for an assessment of the steroid status over a relatively long and retrospective time window.

[Assessment of Vitamin D Metabolism by LC-MS/MS].

Vitamin D is pro-hormone that has important roles in calcium metabolism in the intestine, kidneys, and bone. Many studies have indicated that vitamin D deficiency causes not only rickets and osteomalacia, but also increases the risk of various diseases such as cancer and autoimmune disease. Of the many vitamin D metabolites, 25-hydroxyvitamin D[25OH-D], 1α,25-dihydroxyvitamin D[1,25(OH)2-D], and 24,25-dihydroxyvitamin D [24,25 (OH) 2-D] are important for assessing vitamin D metabolism.