Sensitive determination of deuterated and non-deuterated tryptophan, tryptamine and serotonin by combined capillary gas chromatography and negative ion chemical ionization mass spectrometry

Sensitive methods for the determination of deuterated and non-deuterated tryptophan, tryptamine and serotonin by combined capillary gas chromatography and negative ion chemical ionization mass spectrometry were developed. [3,3-2H2]-L-Tryptophan, which was used as a tracer, was synthesized for studies of their in vivo metabolism. Tryptophan was converted into its trifluoroacetylmethyl derivative after prepurification with an AG 50W-X2 cation-exchange column. Tryptamine and serotonin were extracted with 20% butanol in diethyl ether and derivatized with trifluoroacetic anhydride. These derivatives were separated and determined by selected ion monitoring. In these determinations, [2',3,3,4',5',6',7'-2H7]-D,L-tryptophan, [alpha,alpha,beta,beta-2H4]tryptamine and [alpha,alpha,beta,beta-2H4]serotonin were used as internal standards.     

Sensitive determination of deuterated and non-deuterated indole-3-acetic acid and 5-hydroxyindole-3-acetic acid by combined capillary gas chromatography-negative-ion chemical ionization mass spectrometry

Sensitive methods for the determination of deuterated and non-deuterated indole-3-acetic acid and 5-hydroxyindole-3-acetic acid by combined capillary gas chromatography-negative-ion chemical ionization mass spectrometry were developed. Indole-3-acetic and 5-hydroxyindole-3-acetic acids were converted into pentafluorobenzyl and trifluoroacetylmethyl derivatives, respectively, after pre-purification by high-performance liquid chromatography. These derivatives were separated by gas chromatography and determined by selected ion monitoring. In the determinations, indole-3-acetic-2,2,2',4',5',6',7'-d7 acid and 5-hydroxyindole-3-acetic-3,3-d2 acid were used as internal standards. The methods developed in this work were used for the determination of deuterated and non-deuterated indole-3-acetic acid and 5-hydroxyindole-3-acetic acid in human urine samples collected before and after administration of L-tryptophan-3,3-d2.     

Determination on the microscale of plasmatic lactic acid as its t-butyldimethylsilyl derivative by stable-isotope dilution using capillary gas chromatography/mass spectrometry.

A new sensitive and precise method for the determination of lactic acid in plasmatic microsamples (50 microL) has been developed. Lactic acid was directly extracted from plasma by ethyl acetate in acidic conditions, and analysed as its di-t-butyldimethylsilyl derivative by capillary gas chromatography/electron-impact mass spectrometry (GC/MS). The internal standard was a previously synthesized deuterated compound, 3-[2H]-(2R)-lactic acid. The method gives good reproductibility and precision, the overall standard deviation being better than 3%. The GC/MS assay was in good agreement with the enzymatic determination.     

Determination of 1-hydroxypyrene in human urine by high-performance liquid chromatography with fluorescence detection using a deuterated internal standard

A high-performance liquid chromatographic method has been developed for the quantification of 1-hydroxypyrene (1-OHP) in human urine using deuterated 1-hydroxypyrene ([2H9]1-OHP) as an internal standard with fluorescence detection. [2H9]1-OHP was prepared enzymatically from deuterated pyrene ([2H10]Pyr) with cytochrome P450 1A1. It eluted immediately prior to non-deuterated 1-OHP on alkylamide-type reversed-phase columns and had nearly the same fluorescence characteristics as non-deuterated 1-OHP. The detection limit was 0.1 microg/L and the calibration range was from 1 to 100 nmol/L. Urine sample treatment involved enzymatic hydrolysis followed by solid-phase extraction using Sep-Pak C18 cartridges. The proposed method was used to determine urinary 1-OHP in smokers and non-smokers.     

Microdetermination of glucose content of plasma and its isotopic enrichment using capillary gas chromatography/ammonia chemical-ionization mass spectrometry

A new sensitive and precise method for the determination of the isotopic enrichment of [6,6-D2]glucose and concentration of glucose in plasma microsamples (20 microL) has been developed. Glucose was extracted from plasma samples by anion-cation column-exchange with absolute ethanol, derivatized as 1,2:3,5-bis(butylboronate)-6-acetyl-alpha-D-glucofuranose, and analysed by capillary gas chromatography/ammonia chemical-ionization mass spectrometry. This method gives a better reproducibility and precision (variation coefficient below 1%) than methods using isobutane chemical ionization. Stable isotopes are being used increasingly to investigate energy metabolism in vivo. Recent work has involved the development of methodologies, especially mass spectrometry, to perform tracer experiments using the stable isotopes 3H, 13C, or 13N(1-4). Chemical-ionization mass spectrometry is extensively used for the analysis of isotopically labelled amino acids. In neonates and children, "true" glucose production can be measured by the continuous infusion of the stable isotopically labelled tracer 6,6-dideutero-glucose (6,6-D2-glucose), and analytical measurement is performed using gas chromatography/electron-ionization mass spectrometry (GC/EIMS). Herein, we present a new, simple and sensitive method for the determination of the isotopic enrichment of [6,6-D2]glucose and measurement of the concentration of glucose in plasma microsamples (20 microL), based on the use of capillary gas-chromatography/ammonia chemical-ionization mass spectrometry of 1,2:3,5-bis(butylboronate)-6-acetyl-alpha-D-glucofuranose.     

Determination of urinary succinylacetone by capillary gas chromatography

The average analytical recovery of succinylacetone added to urine and separated by capillary gas chromatography was 69% for solvent extraction and 72% for anion exchange separation. Treating succinylacetone with hydroxylamine hydrochloride at a pH of less than 5 caused formation of a derivative separated by capillary gas chromatography into two isomers: 3-methyl-5- isoxazole propionate and 5-methyl-3- isoxazole propionate as their trimethylsilyl derivatives (molecular weight 227). In a pH greater than or equal to 5, succinylacetone dioxime was formed and separated into 3 isomers as their trimethylsilyl derivatives (molecular weight 404). Succinylacetone dioxime was converted to 3(5)-methyl-(3)5- isoxazole propionate whenever the pH of the solution was dropped to less than 5. Mass spectra of both derivatives are shown. This study demonstrates that capillary gas chromatography is suitable for use in urinary succinylacetone determination.     

Development of capillary gas chromatographic-mass spectrometric methodology for the simultaneous determination of ibuprofen and [ar-2H4]ibuprofen in serum: demonstration of kinetic equivalence in the beagle

A capillary gas chromatographic-mass spectrometric method for the determination of ibuprofen and tetra-deuterated ibuprofen in serum is described. Ibuprofen, [ar-2H4]ibuprofen and the internal standard, [ar-2H4,3,3,3-2H3]ibuprofen, are extracted (after acidification) from serum onto a cross-linked styrene divinyl benzene resin by an automated sample processor. After elution and evaporation of the organic phase, samples are reconstituted with solvent and analyzed without derivatization by capillary gas chromatography-mass spectrometry. This methodology was used to evaluate possible kinetic isotope effects after the coadministration of an equimolar mixture of ibuprofen and the deuterium-labeled covariant in the beagle. No significant differences in absorption or elimination were observed.     

High-performance liquid chromatographic analysis of beta-carbolines in human scalp hair

A chromatographic method was studied for the quantitation of beta-carbolines in hair as potent biomarkers. Under optimal conditions, human scalp hair was enzymatically digested to release analytes effectively. The hair digests were treated with fluorescamine before serial extractions to inhibit the artifactual production of beta-carbolines during analysis and purify them selectively, followed by reversed-phase high-performance liquid chromatography with fluorometric detection. Hair samples were found to contain beta-carboline and 1-methyl-beta-carboline, which were identified by tandem mass spectrometry, but not their reduced form 1,2,3,4-tetrahydro-beta-carboline and 1-methyl-1,2,3,4-tetrahydro-beta-carboline. Both beta-carboline and 1-methyl-beta-carboline were quantified in the concentration range of 0.1-10.0 ng/ml. Their mean recoveries from hair digests were 70-72%, and the intra- and inter-assay RSD ranged between 6.0 and 10.3% in spiking experiments with standards (1.0 ng/ml). When quantitatively analyzing scalp hair collected from alcoholics, smokers, non-smokers and autistics, beta-carboline and 1-methyl-beta-carboline showed the concentrations of ng/mg levels or less which characterized different hair samples. The proposed method will be useful for detecting the in vivo concentration changes of beta-carbolines associated with alcohol abuse, smoking behavior and neuropsychiatric disorder.     

Stable isotope dilution mass spectrometry for the simultaneous determination of cortisol, cortisone, prednisolone and prednisone in plasma.

A capillary gas chromatographic-mass spectrometric method for the simultaneous determination of cortisol, cortisone, prednisolone and prednisone in human plasma is described. [1,1,19,19,19-2H5]Cortisol, [1,1,19,19,19-2H5]cortisone, [1,19,19,19-2H4]prednisolone and [1,19,19,19-2H4]prednisone were used as internal standards. Formation of the bismethylenedioxy-3-heptafluoro-n-butyryl (BMD-HFB) derivatives made possible the separation of the four corticosteroids with good gas chromatographic behaviour. The new double derivatization has been demonstrated to be of value for sensitive and selective quantification by this technique. Detection was performed by monitoring the molecular ion (M+) of the BMD-HFB derivatives for cortisone and prednisolone, the [M - 18]+ ion for cortisol, and the [M - 30]+ ion for prednisone. The method requires no complex corrections for contributions and provides good accuracy and precision.     

Analysis of a new H2 receptor antagonist, 3-amino-5-[3-[4-(1-piperidinoindanyloxy)]propylamino]-1-methyl-1 H-1,2,4-triazole, in human plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for the determination of a new H2 receptor antagonist, 3-amino-5-[3-[4-(piperidinoindanyloxy)]propylamino] -1-methyl-1H-1,2,4-triazole (I), in human plasma and urine was developed. The method employs liquid-liquid extraction of the analyte and an internal standard and chromatographic separation using an alkylphenyl-bonded HPLC column. The total time of chromatography was less than 10 min. Sensitivity was 10 ng/ml for the plasma analysis and 1 microgram/ml for the analysis of I from urine. The coefficients of variation, based on interpolated concentrations, were less than 10%. The method was used for more than 5000 samples during clinical pharmacokinetic studies.     

Determination of the enantiomers of suprofen and [2H3]suprofen in plasma by capillary gas chromatography-mass spectrometry

A method for the stereoselective assay of the (+)- and (-)-enantiomers of suprofen and [2H3]suprofen in human plasma was developed using gas chromatography-mass spectrometry-selected-ion monitoring. (+/-)-[2H7]Suprofen was used as an internal standard. The method involved diethyl ether extraction and chiral derivatization with S-(-)-1-(naphthyl)ethylamine to form diastereomeric amide. The diastereoisomers were separated on a capillary gas chromatograph-mass spectrometer. Quantitation was achieved by selected-ion monitoring of the quasi-molecular ions of the diastereoisomers. The sensitivity, specificity, accuracy and reproducibility of the method were demonstrated to be satisfactory for application to pharmacokinetic studies of suprofen enantiomers.     

Determination of the nicotine metabolite trans-3'-hydroxycotinine in urine of smokers using gas chromatography with nitrogen-selective detection or selected ion monitoring.

A gas chromatographic method for the determination of the nicotine metabolite trans-3'-hydroxycotinine is described. The method involves conversion of the metabolite to the tert.-butyldimethylsilyl derivative, chromatography on a fused-silica capillary column, and determination using nitrogen-phosphorus detection or electron ionization mass spectrometry with selected ion monitoring. A structural analogue, trans-3-hydroxy-1-methyl-5-(2-pyridyl)pyrrolidin-2-one (trans-3'-hydroxy-ortho-cotinine), was used as an internal standard. Using selected ion monitoring, good precision and accuracy were obtained for determination of trans-3'-hydroxycotinine in urine over the concentration range 10-10,000 ng/ml. There was a good correlation between concentrations determined by selected ion monitoring and by nitrogen-phosphorus detection in urine of smokers, although low concentrations determined using nitrogen-phosphorus detection tended to be somewhat higher, suggesting some interference from urinary constituents. Concentrations and 24-h excretion of trans-3'-hydroxycotinine in the urine of 22 cigarette smokers are reported and compared to concentrations and excretion of nicotine, cotinine, nicotine 1'-N-oxide, nornicotine, and cotinine N-oxide.     

Simultaneous determination of cortisol and cortisone in human plasma by stable-isotope dilution mass spectrometry.

A method for the simultaneous determination of cortisol and cortisone in human plasma was developed using capillary gas chromatography-mass spectrometry-selected ion monitoring. [2H5]Cortisol and [2H5]cortisone were used as internal standards. Cortisol and cortisone in plasma were determined from the peak-height ratios of the [M-31] fragment ions of the methoxime-trimethylsilyl derivatives of cortisol and [2H5]cortisol (m/z 605 and 610) and of cortisone and [2H5]cortisone (m/z 531 and 536). Sensitivity, specificity, precision, accuracy and reproducibility of the method were demonstrated to be satisfactory for measuring the circulating concentrations of cortisol and cortisone.     

Investigation of naphthyridines. VII. Synthesis of 10-alkylamino-1,2,3,4-tetrahydrobenzo[b]-1,6-naphthyridines

10-Alkylamino-2-methy1-1,2,3,4-tetrahydrobenzo[b]-1,6-naphthyridines were obtained by cyclization of alkylamides of N-(1-methyl-4-piperidylidene)anthranilic acids and also by reaction of 10-chloro-2-methyl-1,2,3,4-tetrahydrobenzo-[b]-1,6-naphthyridines with amine hydrochlorides.See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 263–265, February, 1976.     

Some reactions of 1-methyl-(2-phenylethyl)-1,2,3,4-tetrahydropyridines with organic azides. Synthesis of 1-methyl-(2-phenylethyl)piperidylidene-2-sulfonamides

The 1,3-dipolar cycloaddition reaction of 1-methyl- and 1-(2-phenylethyl)-1,2,3,4-tetrahydropyridines 7 with organic azides 8 afforded the respective 1-substituted-piperidylidene-2-sulfon(cyan)amides 9. Nitration of the 1-(2-phenylethyl) analogue 9o yielded the 1-[2-(4-nitrophenyl)ethyl] derivative 9r which on reduction with palladium-on-charcoal and hydrazine gave the 1-[2-(4-aminophenyl)ethyl] analogue 9s.     

Rapid gas chromatographic--mass spectrometric quantitation of gamma-aminobutyric acid in biological specimens

A mass fragmentographic method for gamma-aminobutyric acid (GABA) quantitation using the heptafluorobutyryl-cyclohexyl-GABA derivative is described. Both capillary and packed column gas chromatography were used. This procedure employs 2,2[2H2]GABA as an internal standard and allows the rapid, sensitive, and specific measurement of GABA with a minimum of sample clean-up. Application of the method is demonstrated in mouse embryonic brain, body, and palate and human platelets, plasma, cerebrospinal fluid, and urine.     

2，6-二-O-乙氧乙基-3-O-三氟乙酰基-β-环糊精气相色谱手性固定相的制备及应用

将β-环糊精的2,6-位引入乙氧乙基,3-位引入三氟乙酰基,合成了新的环糊精衍生物2,6-二-O-乙氧乙基-3-O-三氟乙酰基-β-环糊精,并采用静态法涂渍毛细管气相色谱柱,考察了毛细管柱的柱性能和分离性能。结果表明,该固定相对G rob试剂、苯的二取代位置异构体氯甲苯、硝基甲苯和溴甲苯以及10种手性化合物如α-取代丙酸酯化合物、1-(2′-硝基苯基)-乙醇、α-甲基-对氯苯乙腈和丙炔醇酮乙酸酯等具有良好的分离效果。其中,对α-甲磺酰基丙酸酯对映体的拆分效果最好;对α-取代丙酸的甲酯衍生物的分离效果优于乙酯衍生物;对α-羟基取代丙酸酯的分离效果优于α-卤代丙酸酯。     

Synthesis,Crystal Structure and Fe3+Recognition of a Fluorescent Probe Based on Quinazolinone Derivative

A novel quinazolinone derivative ethyl 2-(2-methyl-4-oxo-1,2,3,4-tetrahydroquinazolin-2-yl)ace-tate(EMOTA)was synthesized and characterized by HRMS,1H NMR,13C N...     

Simultaneous determination of stable isotopically labelled L-histidine and urocanic acid in human plasma by stable isotope dilution mass spectrometry.

A capillary gas chromatographic-mass spectrometric method for the simultaneous determination of stable isotopically labelled L-histidine (L-[3,3-2H2,1',3'-15N2]histidine, L-His-[M + 4]) and urocanic acid ([3-2H,1',3'-15N2]urocanic acid, UA-[M + 3]) in human plasma was developed using DL-[2,3,3,5'-2H4,2'-13C,1',3'-15N2]histidine (DL-His-[M + 7]) and [2,3,5'-2H3,2'-13C,1',3'-15N2]urocanic acid (UA-[M + 6]) as internal standards. L-Histidine and urocanic acid were derivatized to alpha N-(trifluoroacetyl)-imN-(ethoxycarbonyl)-L-histidine n-butyl ester and imN-(ethoxycarbonyl)urocanic acid n-butyl ester. Quantification was carried out by selected ion monitoring of the molecular ions of the respective derivatives of L-His-[M + 4], DL-His-[M + 7], UA-[M + 3] and UA-[M + 6]. The sensitivity, specificity, precision and accuracy of the method were demonstrated to be satisfactory for measuring plasma concentrations of L-His-[M + 4] and UA-[M + 3] following administration of trace amounts of L-His-[M + 4] to humans.     

Simultaneous high-performance liquid chromatographic determination of antazoline phosphate and tetrahydrozoline hydrochloride in ophthalmic solution

A method for the determination of 2-[(N-phenyl)benzylaminomethyl]-2-imidazoline X H3PO4 (antazoline phosphate) and 2-(1,2,3,4-tetrahydro-1-naphthyl)-2-imidazoline X HCl (tetrahydrozoline hydrochloride) in ophthalmic solution is described. The pharmaceutical preparation is analysed directly by reversed-phase ion-pair high-performance liquid chromatography and the method is very rapid, selective and simple.