气质联用（GC／MS）法测定血浆中硝苯地平的浓度

本文建立了气相色谱－质谱联用（ＧＣ－ＭＳ）法测定人血浆中硝苯地平浓度的方法。以安定为内标，经气相色谱分离后（程度升温），质谱单离子检测（ＳＩＭ）Ｍ／Ｚ２８４。结果表明：该方法选择性好、灵敏度高，在１￣２００ｎｇ／ｍｌ浓度范围内线性较好，回收率及精密度均能符合要求。     

Determination of indeloxazine in plasma by liquid chromatography and gas chromatography-mass spectrometry

Two methods have been developed for the quantitative determination of indeloxazine, a cerebral activator, in plasma by HPLC or GC-MS. After addition of viloxazine as the internal standard, indeloxazine was extracted from alkalinized plasma. In the HPLC method, the plasma extract was treated with 5-dimethylamino-1-naphthalenesulfonyl chloride and analyzed by HPLC with fluorescence detection. In the GC-MS method, the two plasma compounds were converted to their pentafluoropropionyl derivatives for selected-ion monitoring. The limits of detection were 5 and 2 ng/mL for the HPLC and GC-MS methods, respectively. When plasma samples obtained by giving indeloxazine hydrochloride to volunteers were analyzed by the two methods, good correlation between the data was obtained (r = 0.9901).     

Analysis of polychlorinated biphenyl residues in human plasma by gas chromatography-mass spectrometry

A method for the determination of seven polychlorinated biphenyl residues in plasma by gas chromatography-mass spectrometry was developed. The analytes were isolated from human plasma by liquid-liquid extraction, followed by solid-phase extraction, and separation on an HP5 Trace column. Ionization mode was electronic impact, and selected ion storage was used for isolation and quantitation of the compounds. The method was evaluated for its analytical performances and therefore applied to monitor the prevalence of these seven polychlorinated biphenyl residues in a female population. Eighty samples were analyzed, and 82.5% presented detectable amounts of at least one residue. For the population study, results were reported on a lipid-adjusted basis. Because the proposed method is satisfying and seems to be suitable for the quantitation of PCB congeners in a general population, epidemiological studies to evaluate the widespread contamination with these environmental compounds can be proposed.     

Determination and pharmacokinetics of ascaridole in rat plasma by gas chromatography-mass spectrometry

A rapid and sensitive method for determination of ascaridole in rat plasma was developed based on gas chromatography-mass spectrometry (GC/MS). The analyte and internal standard (IS), naphthalene, were extracted from plasma with ethyl acetate and then separated by GC on a HP-5MS capillary analytical column (30 m x 0.25 mm, 0.25 microm) and determined by a quadrupole mass spectrometer detector operated under selected ion monitoring mode (SIM). Excellent linearity was found to be from 10 to 1,000 ng/mL with a lower limit of quantitation (LLOQ) of 10 ng/mL. The accuracy was between 85.3% and 114.0%, and the precision was less than 14.5% (intra- and inter-day). The method was successfully applied to investigate the pharmacokinetic study of ascaridole in rats after a single oral dose of 30, 60 and 120 mg/kg, respectively.     

Determination of chloral hydrate metabolites in human plasma by gas chromatography-mass spectrometry

Chloral hydrate (CH) is a widely used sedative. Its pharmacological and toxicological effects are directly related to its metabolism. Prior investigations of CH metabolism have been limited by the lack of analytical techniques sufficiently sensitive to identify and quantify metabolites of CH in biological fluids. In this study a gas chromatography mass spectrometry (GC/MS) method was developed and validated for determining CH and its metabolites, monochloroacetate (MCA), dichloroacetate (DCA), trichloroacetate (TCA) and total trichloroethanol (free and glucuronidated form, TCE and TCE-Glu) in human plasma. Of these, DCA and MCA are newly identified metabolites in humans. The drug, its plasma metabolites and an internal standard, 4-chlorobutyric acid (CBA), were derivatized to their methyl esters by reacting with 12% boron trifluoride-methanol complex (12% BF3-MeOH). The reaction mixture was extracted with methylene chloride and analyzed by GC/MS, using a selected ion monitoring (SIM) mode. The quantitation limits of MCA, DCA, TCA, and TCE were between 0.12 and 7.83 microM. The coefficients of variation were between 0.58 and 14.58% and the bias values ranged between -10.03 and 14.37%. The coefficients of linear regression were between 0.9970 and 0.9996.     

Simultaneous determination of nitrate and nitrite in human plasma by gas chromatography-mass spectrometry

We devised a sensitive and simple method for the simultaneous determination of nitrate and nitrite in human plasma, using extractive alkylation. These inorganic anions were alkylated with pentafluorobenzyl bromide, using tetradecyldimethylbenzylammonium chloride as the phase-transfer catalyst, with 1,3,5-tribromobenzene as an internal standard. The derivatives were analyzed by gas chromatography-mass spectrometry, using the negative-ion chemical ionization mode with isobutane as the reagent gas. Calibration curves for nitrate and nitrite were linear over the concentration range of 0.01 to 1.0 micromol/mL in plasma, and the lower limit of detection for both compounds was 0.005 micromol/mL. The accuracy and precision of this method were evaluated and coefficients of variation were lower than 10.4%. Blood nitrate and nitrite concentrations of six victims who committed suicide by inhaling automobile exhaust gas could be determined using our method.     

Simultaneous determination of spirapril and spiraprilat in plasma by capillary gas chromatography-mass spectrometry

A specific, sensitive and precise method for the simultaneous determination of spirapril (CAS 94841-17-5) and spiraprilat (CAS 83602-05-5) in human plasma is described. The method involves the use of enalapril as internal standard, solid-phase extraction, derivatization and capillary gas chromatography with mass sensitive detection. The working range is from 2.5 to 500 micrograms/l for spirapril and spiraprilat, respectively. Data demonstrating the precision and accuracy of the analytical method are given. Moreover, data concerning freeze-thaw stability, long-term stability of frozen samples, short-term stability of thawed samples, and stability of the extracts in the autosampler are given.     

Stability of thiopental and pentobarbital in human plasma determined with a new easy and specific gas chromatography-mass spectrometry assay.

A gas chromatographic-mass spectrometric (GC-MS) assay for the determination of thiopental and its main metabolite pentobarbital in human plasma is presented in this study. The sample preparation consists only in the addition of the internal standard barbital and an acidic extraction with ethyl acetate. Analytical separation is accomplished on a RTX-1 15 m x 0.25 mm capillary column with a film thickness of 0.5 micron. The effluent is observed by a mass selective detector operating in the single ion monitoring mode. The limits of detection are 5 ng/ml for pentobarbital and 10 ng/ml for thiopental, the intra-day variabilities are 2.2% and 4.0% and the inter-day variabilities are 3.3% and 7.1% at concentrations of 5 micrograms/ml, respectively. Applying this assay, the stability of thiopental and pentobarbital in human plasma was tested at concentrations of 5 micrograms/ml each. Thiopental is stable in human plasma at least over 41 days stored at -20 degrees C and 5 degrees C, respectively. A decay of about 2%/day is observed under storage at ambient temperature (19-20 degrees C). Pentobarbital is stable under all storage conditions. Methanolic solutions of thiopental are stable for 83 days under storage at 5 degrees C. Aqueous solutions of thiopental-sodium are stable for at least 23 days under storage at 5 degrees C or ambient temperature.     

Analysis of phyto-oestrogens by gas chromatography-mass spectrometry

The metabolites of oestrogenic substances of plant origin, phyto-oestrogens, have been proposed as cancer-protective agents in Asian and vegetarian populations. The two principle classes of these weak oestrogens are isoflavonoids and mammalian lignans. The former is derived from soya-based foods and the latter from oilseeds, cereals and whole grains. Asian populations such as the Japanese have high plasma concentrations of the isoflavones, daidzein and genistein, whereas vegetarians excrete large quantities of the lignan enterolactone, in their urine. The concentrations of these compounds in biological samples and foods are usually determined by GC-MS, although other techniques such as HPLC and LC-MS have also been used. A simple, robust method employing isotope dilution GC-MS will be described which could be applied to the determination of phyto-oestrogens in biological samples and food matrices. Briefly, samples are hydrolysed with β-glucuronidase, the aglycones extracted and the phyto-oestrogen fraction isolated by chromatography on Sephadex LH20. This fraction is then derivatised for GC-MS by reaction with N,O-bistrimethylsilyl-triflouroacetatamide to form trimethylsilyl derivatives. Using this technique we have determined the concentrations of the lignans, enterodiol and enterolactone, and the isoflavonoids, equol, daidzein and genistein, in the serum of men from Japan (n=42). The mean levels of daidzein and genistein in these men were 82.5 ng/ml (range 1.9-577) and 158.6 ng/ml (range 5.3-852), respectively. The majority of these men (57%) produced equol concentrations of >5 ng/ml, with a mean value of 26.7 ng/ml. Mean Levels of enterodiol and enterolactone were 0.6 and 9.4 ng/ml, respectively. The levels of daidzein and genistein produced from the hydrolysis of soya bean hulls, soya bean hypocotyl, dehulled soya beans, soya flour, soya grit and soya concentrates have also been determined by this method. Soya bean hypocotyl, for example, produces 2.1 mg/g of daidzein and 1.2 mg/g genistein, whereas some concentrates yield as much as 40% isoflavones.     

Determination of fentanyl in human plasma by head-space solid-phase microextraction and gas chromatography-mass spectrometry

A head-space solid-phase microextraction (HS-SPME) method coupled to GC–MS was developed to extract fentanyl from human plasma. The protein binding was reduced by acidification and, eventually, the sample was deproteinized with trichloroacetic acid. The parameters influencing adsorption (extraction time, temperature, pH and salt addition) and desorption (desorption time and temperature) of the analyte on the fibre were investigated and validated for method development. The developed method proved to be rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Linear range was obtained from 0.1 ng/ml to 2 μg/ml. The limit of detection was 0.03 ng/ml while an inter-day precision of less than 5% (n = 15) could be achieved. The method has been applied for the determination of fentanyl in plasma samples after application of 50 μg/h Duragesic fentanyl patch.     

Levels of 5-hydroxytryptophol in cerebrospinal fluid from alcoholics determined by gas chromatography-mass spectrometry

A quantitative gas chromatographic-mass spectometric method using a deuterated analogue as internal standard was developed for the analysis of 5-hydroxytryptophol in cerebrospinal fluid. The analytical procedure involves the addition of the internal standard and 5-hydroxyindole to the cerebrospinal fluid followed by extraction into chloroform and derivatization with pentafluoropropionic anhydride. 5-Hydroxytryptophol levels in the CSF of male alcoholics and a control group were examined. During ethanol intoxication the mean level, 10.4 ± 4.4 pmoles/ml, was significantly (P < 0.001) higher than in the controls, 3.31 ± 0.94 pmoles/ml. The following morning the mean had decreased (P < 0.01) to 4.46 ± 1.81 pmoles/ml. The level after 8 days was 4.70 ± 2.47 pmoles/ml, which is lower than during intoxication (P <0.01). The levels found during the recovery from ethanol intoxication was not statistically different from the levels in the control group. These results indicate that serotonin metabolism in the central nervous system is affected by ethanol consumption.     

Solid-phase microextraction of human plasma samples for determination of sufentanil by gas chromatography-mass spectrometry

A solid-phase microextraction (SPME) method has been developed for the quantitative analysis of sufentanil from human plasma by gas chromatography-mass spectrometry (GC-MS). The immersion SPME sampling technique was optimized for the extraction of sufentanil from plasma. The influence of the pH and the ionic strength of the sample on the extraction of the analytes by the SPME fiber were investigated. Sufentanil and fentanyl (internal standard) were extracted from plasma with a 65-microm polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber for 30 minutes using salting out agents in basic conditions. The calibration curve was linear over a concentration range of 6-50 ng/mL. Intraday and interday relative standard deviations were 3.6% and 10.6%, respectively. The limit of quantification was 6 ng/mL for a plasma volume of 1 mL. With regard to selectivity, simplicity, and low cost, the SPME method described should be useful for a rapid extraction of sufentanil from human plasma.     

Simultaneous determination of mecamylamine, nicotine, and cotinine in plasma by gas chromatography-mass spectrometry

The nicotine receptor antagonist mecamylamine has been shown to increase the efficacy of transdermal nicotine as a pharmacotherapy for tobacco addiction. A product for simultaneous transdermal administration of nicotine and mecamylamine is undergoing clinical trials. In order to carry out pharmacokinetic studies, quantitation of low nanogram per milliliter levels of mecamylamine and nicotine was required. This paper describes a method for simultaneous determination of mecamylamine, nicotine, and the nicotine metabolite, cotinine, in human plasma using gas chromatography-mass spectrometry (GC-MS). Limits of quantitation for mecamylamine, nicotine and cotinine are 2, 1 and 2 ng/ml, respectively.     

Determination of levamisole in urine by gas chromatography-mass spectrometry

The United States Public Health Service Substance Abuse and Mental Health Services Administration is alerting medical professionals that a substantial percentage of cocaine imported into the United States is adulterated with levamisole, a veterinary pharmaceutical that can cause blood cell disorders such as severe neutropenia and agranulocytosis. Levamisole HCl is the active ingredient in a number of veterinary drugs approved to treat worm infestations in animals. Levamisole HCl was also the active ingredient in a human drug for oral administration approved on June 18, 1990, as adjuvant treatment in combination with fluorouracil after surgical resection in patients with Duke's stage C colon cancer. This drug was withdrawn from the U.S. market around 2000, and it has not been marketed in the U.S. since then. The objective of this study was to develop a method to determine the amount of levamisole in urine samples. The procedure will be provided to state health laboratories as needed to be used in the evaluation of patients that have developed neutropenia or agranulocytosis in the setting of recent cocaine use. A gas chromatography-mass spectrometry method was validated and tested at two different laboratories, and the method limit of detection for levamisole is 1 ng/mL in urine when using a 5-mL sample. Confirmation of the stereoisomer of levamisole was done by high-performance liquid chromatography using a chiral column.     

Rapid and sensitive liquid chromatography-mass spectrometry method for determination of ropinirole in human plasma

A rapid and robust liquid chromatography–mass spectrometry (LC–MS/MS) method was developed for non-ergoline dopamine D₂-receptor agonist, ropinirole in human plasma using Es-citalopram oxalate as an internal standard. The method involves solid phase extraction from plasma, reversed-phase simple isocratic chromatographic conditions and mass spectrometric detection that enables a detection limit at picogram levels. The proposed method was validated with linear range of 20–1200 pg/ml. The extraction recoveries for ropinirole and internal standard were 90.45 and 65.42%, respectively. The R.S.D.% of intra-day and inter-day assay was lower than 15%. For its sensitivity and reliability, the proposed method is particularly suitable for pharmacokinetic studies.