耐压多样品微量衍生反应装置在气相色谱-质谱联用法分析极性杂环胺中的应用

设计并制作了耐压多样品微量衍生反应装置。在该装置中采用N-(叔丁基二甲基硅烷基)-N-甲基三氟乙酰胺(MTBSTFA,含1%叔丁基二甲基氯硅烷)硅烷化试剂高温衍生极性杂环胺,衍生产物可以直接在气相色谱-质谱联用仪上分析。使用该装置,既可以在比试剂沸点高的温度下实现衍生反应,也可以实现多个微量样品的同时衍生。着重考察了衍生化过程中反应瓶的顶空体积、试剂蒸发面积、温度、时间等实验条件的影响。结果表明,在90 ℃衍生时,与普通衍生装置相比,使用耐压衍生装置可以有效地减小挥发损失,显著增大衍生产量;在150 ℃衍生时,由于试剂挥发损失严重导致普通衍生装置无法使用,而采用耐压衍生装置却可以实现定量衍生,但通过加温加压方式来加快衍生反应速率的效果并不十分明显。     

Gas chromatographic analysis of bifunctional amines after derivatization with methyldichlorophosphine and sulfur

Summary A derivatization procedure for the gas chromatographic analysis of bifunctional amines likeβ-adrenergic blocking drugs is described. The method consists of a two-step reaction with methyldichlorophosphine and sulfur in presence of triethylamine to form cyclic methylphosphonothioic derivatives. The properties of these compounds are discussed and the application of the method to the quantitation of ephedrine in human body fluids is presented. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Comparison of several solid-phase extraction sorbents for continuous determination of amines in water by gas chromatography-mass spectrometry

A semiautomatic method has been proposed for the determination of different types of amines in water samples including anilines, chloroanilines, N-nitrosamines and aliphatic amines. The analytes were retained on a solid-phase extraction sorbent column and after elution, 1 μL of the extract was analysed by gas chromatography coupled with electron impact ionization mass spectrometry. A systematic overview is given of the advantages and disadvantages of several sorbents (LiChrolut EN, Oasis HLB, RP-C₁₈, graphitized carbon black, fullerenes and nanotubes) in the retention of amine compounds and based on sensitivity, selectivity and reliability. The retention efficiency for the studied amines was higher (ca. 100%) with LiChrolut EN and Oasis HLB than it was with RP-C₁₈ and fullerenes (53 and 62%, respectively, on average). Detection limits of 0.5-16 ng L⁻¹ for the 27 amines studied were obtained when using a sorbent column containing 75 mg of LiChrolut EN for 100 mL of sample, the RSD being lower than 6.5%. The method was applied with good accuracy and precision in the determination of amines in various types of water including river, pond, tap, well, drinking, swimming pool and waste.     

Derivatization of aromatic amines with bromine for improved gas chromatographic determination

Summary For improved determination of aromatic amines by gas chromatography and detection with an electron capture detector (GC-ECD) a derivatization method based on the bromination of the aromatic ring in an acetic acid medium was developed. In general, all free ortho and para-positions relative to the amino group undergo electrophilic substitution. Separation of at least 30 compounds in a single chromatographic run in 30 min is possible. With this method, 56 aromatic amines were studied and only in 6 cases were no derivatives obtained. Quantitation limits determined from calibration data are 1.2–40 μg L⁻¹ for a 100 mL sample and an injection volume of 1 μL. Previous experiments suggest that both sample and injection volume may be increased to lower the quantitation limit.     

Determination of biogenic amines in wines by pre-column derivatization and high-performance liquid chromatography coupled to mass spectrometry

A new HPLC method for determining biogenic amines in wines is developed. This method is based on pre-column amine derivatization, further separation of derivatives and on-line hyphenation of HPLC to atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Biogenic amines have been derivatized with 1,2-naphthoquinone-4-sulfonate at 65 °C and pH 9.2 for 5 min. The separation of derivatives has been accomplished in a C₁₈ analytical column using an elution gradient based on increasing the percentage of methanol. Derivatives have been ionized in positive mode and detected by selected ion monitoring. The operating conditions of the APCI-MS system (voltages, temperatures and gases) have been thoroughly optimized to obtain the maximum sensitivity for all analytes. In the selected conditions, APCI-MS spectra display little fragmentation and good signal-to-noise ratio. Depending on the amine characteristics, the main spectral peaks are due to mono- and di-derivative products. Figures of merit of the method have been established under the selected conditions using red wine samples. Recoveries ranging from 94% to 106% have been obtained which prove excellent accuracy of the method in the determination of histamine, putrescine, cadaverine, tryptamine, phenylethylamine, tyramine and serotonin in red wines. The proposed method has been applied to the analysis of commercial wines from different Spanish regions.     

An improved analytical method for determination of heterocyclic amines in chicken legs

Summary Several extraction, separation and detection methods for heterocyclic amines (HAs) in chicken legs were evaluated by liquid chromatography. Results showed that the most appropriate extraction method includes the removal of macrosubstances by centrifugation and subsequent purification using a PRS (propylsulfonic acid silica gel) and a C₁₈ cartridge, and the recovery obtained ranged between 51 and 89 %. For HPLC separation, a binary solvent system consisting of acetonitrile and 0.05 M ammonium acetate solution (pH 3.6) with gradient elution with flow rate of 1.0 mL min⁻¹ and detection at 258 nm was used to resolve 16 HAs. With fluorescence nine HAs could be detected by employing a programmable wavelength, and the sensitivity was 100–400 times higher than that by UV detection. The detection limits for UV and fluorescence detection were 0.02≈0.5 ng and 0.05≈3 pg respectively, with a signal-to-noise ratio 3. The presence of HAs in fried chicken legs was also determined.     

Determination of less polar heterocyclic amines in meat extracts: fast sample preparation method using solid-phase microextraction prior to high-performance liquid chromatography-fluorescence quantification

A procedure for the determination of less polar heterocyclic amines in meat extracts using solid phase microextraction (SPME) coupled to high-performance liquid chromatography (HPLC) with fluorescence detection is presented. Analytes were first extracted from the samples using methanol/NaOH by an ultrasound-assisted method, and then concentrated on a Carbowax-templated resin (CW-TPR) SPME fiber. The extraction conditions such as extractant mixture composition, extraction time and extractions number, were optimized and the need of an extract freezing step previous to SPME is discussed. The detection limits under optimal conditions are in the range of 0.28-1.1 ng g⁻¹. The method was applied to the determination of less polar heterocyclic amines in four commercial meat extracts. Recovery values obtained are higher than 60% for the majority of amines.     

Determination of biogenic amines in food samples using derivatization followed by liquid chromatography/mass spectrometry

A liquid chromatography (LC)/mass spectrometry method was developed for the determination of selected biogenic amines in various fish and other food samples. It is based on a precolumn derivatization of the amines with succinimidylferrocenyl propionate under formation of the respective amides and their reversed-phase liquid-chromatographic separation with subsequent electrospray ionization mass-spectrometric detection. Deuterated putescine, cadaverine, and histamine are added prior to the derivatization as internal standards that are coeluted, thus allowing excellent reproducibility of the analysis to be achieved. Depending on the analyte, the limits of detection were between 1.2 and 19.0 mg/kg, covering between 2 and 3 decades of linearity. The limit of detection and the linear range for histamine are suitable for the surveillance of the only defined European threshold for biogenic amines in fish samples. Compared with the established ortho-phthalaldehyde (OPA)/LC/fluorescence method, the newly developed method allows an unambiguous identification of the biogenic amines by their mass spectra in addition to only retention times, a fivefold acceleration of the separation, and independency from the sample matrix owing to the isotope-labeled internal standards. Various fish, calamari, and salami samples were successfully analyzed with the new method and validated with an independent OPA/LC/fluorescence method.     

Derivatization of amines with chloroformate esters for gas chromatographic analysis

Summary The gas chromatographic analysis of amines after conversion to electron capture sensitive carbamates in two-phase systems has been studied. Hydrophilic compounds, for instance methylamine, are reacted with 2,2,2-trichloro-tert. butyl chloroformate. Quantitation below 10^–7 M can be made by thermionic or electron capture detection. A hydrophobic amine, namely N,N-dimethyl-n-octylamine, was derivatized with 2,4,6-tribromophenyl chloroformate with addition of iodide ion to the aqueous phase. The favorable effect of iodide ion as well as the choice of pH and chloroformate ester is discussed.Presented at the 14th International Symposium on Chromatography London, September, 1982     

药物中水合肼残留量的气相色谱分析

建立了用气相色谱-氮磷检测器(GC-NPD)测定药物中水合肼的新方法。其萃取和衍生采用同一种试剂-丙酮,一步完成,可简单快速地定量检测药物中水合肼的残留量,其检出限为41.0μg/kg;相对标准偏差小于4.1%;回收率在101.5%~107.8%。已用于药物中水合肼的残留量分析。     

Assessment of metastable atom bombardment (MAB) ionization mass spectrometry for the fast determination of heterocyclic aromatic amines in cooked meat

An investigation of metastable atom bombardment (MAB) ionization mass spectrometry for the fast characterization of mutagenic/carcinogenic heterocyclic aromatic amines (HAAs) formed during heating processes of meats is presented. The aim of our study was to use the selective ionization of MAB to develop a detection method for HAAs in non-purified meat extracts, thus avoiding purification and concentration steps and reducing analysis time. Sample introduction into the MAB ion source was achieved by pyrolysis, allowing the direct and fast insertion of complex food extracts into the mass spectrometer. Analysis conditions were optimized on standard HAAs by using different ionization gases for the MAB process. Metastable nitrogen was selected as the best MAB gas for the analysis of HAAs. Ionization selectivity is shown by the detection of heterocyclic amines in non-purified chicken meat extracts spiked with HAAs. A quantitative approach is also presented by using pyrograms as chromatograms for quantification purposes. HAAs determination using Py-MAB-ToF was finally performed on cooked chicken breast extracts and compared to an LC-APCI-MS/MS method. Although Py-MAB-ToF sensitivity remains to be improved in the present state of development of our prototype device, only 2 h from the cooking were required to obtain quantitative results in good agreement with HAAs concentrations measured by LC-MS/MS in 36 h. Figure Experimental set-up for pyrolysis-MAB-ToF mass spectrometry experiments.     

顶空衍生固相微萃取-气相色谱质谱法测定聚碳酸酯树脂中的环境雌激素

建立了固相微萃取-气相色谱质谱联用测定聚碳酸酯树脂中环境雌激素4-枯基苯酚和双酚A的分析方法。优化了固相微萃取纤维、萃取温度和时间、解吸时间、搅拌速度、pH等萃取条件及衍生化温度和时间、衍生化方式等衍生化条件，并对样品浸泡时间、浸泡温度等进行了研究。方法的线性范围为0．05μg/L～1mg／L，4-枯基苯酚和双酚A的检出限分别为50ng／L和0．5ng／L，相对标准偏差（RSD，n=5）分别为5．2％和1．6％，平均回收率（n=3）在90．50％～107．3％之间，该方法简单、快速、灵敏。     

Application of ethyl chloroformate derivatization for gas chromatography-mass spectrometry based metabonomic profiling

A new combined gas chromatography and mass spectrometry (GC-MS) method has been developed suitable for the urine sample treatment in aqueous phase with ethyl chloroformate (ECF) derivatization agents. The method has been extensively optimized and validated over a broad range of different compounds and urine samples. Analysis of test metabolite derivatives, containing spiked standards, or rat urine exhibited acceptable linearity, satisfactory intra-batch precision (repeatability) and stability, relative standard deviations (R.S.D.) less than 10 and 15% within 48 h, respectively. The quantification limits were 150-300 pg on column for most metabolites. Recovery of several representative compounds, at different concentrations, ranged from 70 to 120%, with R.S.D. better than 10% for rat urine. We were able to generally eliminate potentially confounding variables such as medium complexity, different urea concentrations, and/or derivatization procedure variability. Metabonomic profiling of 1,2-dimethylhydrazine (DMH)-induced precancerous colon rat urine using GC-MS with ECF derivatization was performed to evaluate the proposed method. The analytical variation of the method was smaller than the biological variation in the rat urine samples, proving the suitability of the method to analyze differences in the metabonome of a living system with perturbed metabolic network. Thus, the proposed GC-MS analytical method is reliable to analyze a large variety of metabolites and can be used to investigate human pathology including disease onset, progression, and mortality.     

Derivatization followed by gas chromatography-mass spectrometry for quantification of ethyl carbamate in alcoholic beverages

A sensitive and rapid analytical methodology based on derivatization followed by gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative determination of the toxic contaminant ethyl carbamate (EC, urethane, C(2)H(5)OCONH(2)) in alcoholic samples. EC was extracted using liquid-liquid extraction technique, and then silylated with bis-(trimethylsilyl)trifluoroacetamide, analysed finally by GC-MS. The isopropyl carbamate was used as the internal standard for quantitative analysis of EC in alcoholic samples. In this work, the sample extraction and derivatization reaction conditions were investigated, and the optimal extraction conditions obtained were: pH 9 and solvent of ethyl acetate, and the derivatization conditions were: derivatization reaction temperature of 80°C and time duration of 30 min. With the optimal conditions, the method validations were also studied. In the validation studies, EC exhibited good linearity with a regression coefficient of 0.9999. The limit of detection and limit of quantification were 0.30 and 5.0 μg/kg, respectively. The precision was less than 8.4%. Finally, the proposed technique was successfully applied to the analysis of EC in 35 kinds of alcoholic samples. The experimental results have demonstrated that the proposed technique is a fast, reliable and low-cost method for determination of EC in alcoholic samples.     

柱前衍生化-毛细管气相色谱法分离2,5-己二醇对映体

建立柱前衍生化-毛细管气相色谱法分离2,5-己二醇对映体的方法。用S-（-）-α-苯乙基异氰酸酯与外消旋2,5-己二醇反应,生成相应的衍生物在气相色谱上得到基线分离,同时考察载气流速和程序升温对拆分的影响。建立了一个测定2,5-己二醇对映体过量值的分析方法。     

Automated headspace solid‐phase microextraction and on‐fiber derivatization for the determination of clenbuterol in meat products by gas chromatography coupled to mass spectrometry

A method was developed for the determination of clenbuterol in meat using stable‐isotope‐dilution gas chromatography with mass spectrometry coupled with solid‐phase microextraction and on‐fiber derivatization. The samples were first homogenized with hydrochloric acid followed by protein deposition. After headspace solid‐phase microextraction and on‐fiber derivatization, the content of clenbuterol was measured with the aid of stable‐isotope dilution. The condition of solid‐phase microextraction was optimized by central composite design. The relative standard deviations, limit of detection, and recoveries for clenbuterol were 4.2–9.2%, 0.48 μg/kg, and 96–104%, respectively. The proposed method was satisfactory for analysis of real samples as compared with the Chinese standard method.     

Evaluation of fast gas chromatography and gas chromatography-mass spectrometry in the analysis of lipids

Fast and conventional gas chromatography (GC) techniques were applied to nine different lipidic matrices (butter, lard, tallow, and peanut, corn, sunflower, soya, olive, menhaden oils). Simultaneous methylic transesterification was performed on all samples prior to GC analysis. Several practical aspects concerning high speed analysis were investigated, such as the great increase in linear velocity, the use of fast temperature ramps, column sample capacity and detection systems. Analytical results showed certain losses in resolution, balanced by a consistent reduction in analysis time. The actual time savings were variable (60-70 min) as they were dependent on the complexity of the sample while the speed enhancement factor was equal to 10.5. Peak identification was achieved by means of different information sources, such as fast GC-mass spectrometry (MS), linear retention indices and comprehensive two-dimensional (2D) gas chromatography group patterns. The method developed was shown to be applicable in routine applications on complex natural samples.     

Determination of biogenic amines in fresh and processed meat by suppressed ion chromatography-mass spectrometry using a cation-exchange column

A new method for simultaneous determination of underivatized biogenic amines based on the separation by cation-exchange chromatography and suppressed conductivity coupled with mass spectrometry detection has been developed. The method has been applied to the analysis of cadaverine, putrescine, histamine, agmatine, phenethylamine and spermidine in processed meat products. The amines were extracted from muscle tissue with methanesulfonic acid without any additional derivative step or sample clean-up. Biogenic amines were separated by the IonPac CS17 column, a cation-exchange column used with gradient elution, and detection was done by suppressed conductivity and mass spectrometry. Tyramine was simultaneously analysed by using a spectrophotometer (275 nm) before the suppressed conductivity detection. Linearity of response was obtained in the range 0.25-25 microg mL(-1). The detection limits ranged from 23 microg L(-1) for putrescine to 155 microg L(-1) for spermidine (suppressed conductivity) and from 9 microg L(-1) for agmatine to 34 microg L(-1) for spermidine (MS). Average recoveries from meat samples ranged from 85 to 97% and coefficients of variation ranged from 4.5 to 9.7%. The analysis of biogenic amines in fresh and processed meats (dry-cured, cooked and fermented products) can be used as a quality marker of raw material and for studying the relationship between their changes and the fermentation process involved in dry sausage ripening.     

High performance liquid chromatography —Electrospray tandem mass spectrometry (HPLC-ESI-MS-MS) for the analysis of heterocyclic aromatic amines (HAA)

Summary Sensitive and selective detection of the sixteen most abundant heterocyclic aromatic amines (HAA) has been achieved by application of high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS-MS) in combination with selected reaction monitoring (SRM). Detection limits between 0.1 and 50 ng mL^–1 were established by use of HAA model solutions.     

Analysis of heterocyclic aromatic amines in foods by gas chromatography-mass spectrometry as their tert.-butyldimethylsilyl derivatives

A derivatization method for the analysis of 12 heterocyclic aromatic amines (HAs) in food, by gas chromatography-electron impact mass spectrometry, was developed. The amines are derivatized in a one-step reaction with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. The derivatives are characterized by easy-to-interpret mass spectra due to the prominent ion [M-57]+ by loss of a tert.-butyldimethylsilyl group, allowing quantification in the selected-ion monitoring mode at the picogram level. The effect of temperature, time, and reagents on the formation of the derivatives was monitored in detail. Quality parameters were evaluated in the optimum working conditions. This derivatization method is not applicable to the pyridoimidazoles Glu-P-1 and Glu-P-2 and to the beta-carboline harman due to incompletely derivatization. The instability of the imidazolquinoline and imidazoquinoxaline derivatives, requiring their injection on the same working day, is a further drawback. This simple, rapid and accurate derivatization procedure is suitable for routine analysis, as illustrated by the analysis of some common foods.