柱前衍生-液相色谱-串联质谱法测定葡萄和樱桃中单氰胺残留

建立了丹磺酰氯（DNS）柱前衍生-液相色谱-串联质谱（LC-MS/MS）测定葡萄和樱桃中单氰胺的方法。样品经破壁机匀浆,乙酸乙酯超声提取,无水硫酸钠除水,提取液经减压浓缩,在碱性条件下与丹磺酰氯进行衍生反应。色谱柱为岛津Shim-pack XR-ODS色谱柱（75 mm×2.0 mm,1.6 μm）,流动相为甲醇和含0.05%（体积分数）甲酸的2 mmol/L醋酸铵水溶液,梯度洗脱,采用电喷雾离子源正离子多反应监测模式进行质谱检测。单氰胺在0.01~1.0 mg/L范围内,峰面积与质量浓度之间线性关系良好,相关系数不小于0.9990。在0.01、0.05和1.0 mg/kg的添加水平下,葡萄和樱桃中单氰胺的平均回收率为75%~81%,精密度为6.5%~9.8%,定量限为0.01 mg/kg。该方法简便、快速、可靠,可用于批量检测葡萄和樱桃中单氰胺残留。     

Determining Hydrogen Cyanamide in Fruit by Derivatization with 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate and HPLC with Fluorescence Detection

Hydrogen cyanamide is a plant-growth regulator used on fruit crops, and has a high toxicity. In this study, a simple and sensitive method for detecting hydrogen cyanamide in fruit was developed. In the proposed method, cyanamide was extracted with water from homogenized fruit samples (grape, kiwi, and peach). The extract was purified through twice liquid–liquid extraction. Then, the purified extract was derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Finally, the cyanamide derivative was analyzed using HPLC with fluorescence detection. This method was validated at 2, 0.2, and 0.01 mg kg⁻¹ cyanamide. The recovery rates were between 87.1 and 96.6 %, and the intraday and interday reproducibilities were within 1.8 and 2.2 %, respectively. The limits of detection and quantification were 2.4 and 8 μg kg⁻¹ cyanamide, respectively. This method was applied to explore the residue degradation of cyanamide in the field. The results show that the half-life of cyanamide residues on grapes was <2.0 days. Compared with the previous methods, this simple method is sensitive and can be applied for detecting cyanamide in a wide range of fruits.

     

Direct quantitative determination of cyanamide by stable isotope dilution gas chromatography-mass spectrometry

Cyanamide is a multifunctional agrochemical used, for example, as a pesticide, herbicide, and fertilizer. Recent research has revealed that cyanamide is a natural product biosynthesized in a leguminous plant, hairy vetch (Vicia villosa). In the present study, gas chromatography-mass spectrometry (GC-MS) equipped with a capillary column for amines was used for direct quantitative determination of cyanamide. Quantitative signals for ((14)N(2))cyanamide, ((15)N(2))cyanamide (internal standard for stable isotope dilution method), and m-(trifluoromethyl)benzonitrile (internal standard for correcting errors in GC-MS analysis) were recorded as peak areas on mass chromatograms at m/z 42 (A(42)), 44 (A(44)), and 171 (A(IS)), respectively. Total cyanamide content, ((14)N(2))cyanamide plus ((15)N(2))cyanamide, was determined as a function of (A(42)+A(44))/A(IS). Contents of ((14)N(2))cyanamide and ((15)N(2))cyanamide were then calculated by multiplying the total cyanamide content by A(42)/(A(42)+A(44)) and A(44)/(A(42)+A(44)), respectively. The limit of detection for the total cyanamide content by the GC-MS analysis was around 1ng. The molar ratio of ((14)N(2))cyanamide to ((15)N(2))cyanamide in the injected sample was equal to the observed A(42)/A(44) value in the range from 0.1 to 5. It was, therefore, possible to use the stable isotope dilution method to quantify the natural cyanamide content in samples; i.e., the natural cyanamide content was derived by subtracting the A(42)/A(44) ratio of the internal standard from the A(42)/A(44) ratio of sample spiked with internal standard, and then multiplying the resulting difference by the amount of added ((15)N(2))cyanamide (SID-GC-MS method). This method successfully gave a reasonable value for the natural cyanamide content in hairy vetch, concurring with the value obtained by a conventional method in which cyanamide was derivatized to a photometrically active compound 4-cyanimido-1,2-naphthoquinone and analyzed with reversed-phase HPLC (CNQ-HPLC method). The determination range of cyanamide in the SID-GC-MS method was almost the same as that in the CNQ-HPLC method; however, the SID-GC-MS method was much simpler than the CNQ-HPLC method.     

Square wave anodic stripping voltammetric determination of Pb2+ using acetylene black paste electrode based on the inducing adsorption ability of I-

In the study, we developed a simple, rapid and sensitive method for the determination of tiopronin (TP) in human plasma, which was based on derivatization with p-bromophenacyl bromide (p-BPB) followed by liquid-liquid extraction and reverse-phase HPLC-UV detection. For the first time, the p-BPB was introduced into the derivatization of TP. The thiol group of TP was trapped with p-BPB to form a TP-p-BPB adduct, which can be very suitable for UV detection. From acidified plasma samples, the derivatized TP was extracted with 5 mL dichloromethane. Effective chromatographic separation was achieved using a C18 column (DIAMONSIL 150 mm × 4 mm i.d., 5 μm) based on an acetonitrile-water-trifluoroacetic acid (40:59.88:0.12, v/v/v) elution at a flow-rate of 1 mL/min. The IS and the derivatized TP were detected at 263 nm. No endogenous substances were found to interfere. The limit of quantification for derivatized TP (TP-p-BPB) in plasma was 40 ng/mL. The calibration curve for the derivatized TP showed linearity in the range 0.04-4 μg/mL with a regression coefficient corresponding to 0.9991 and the coefficient of the variation of the points of the calibration curve being lower than 10%. Extraction recoveries of the derivatized TP in plasma were greater than 72%. The method was suitably validated and successfully applied to determination of TP in human plasma samples.     

Analysis of common fatty acid glycerides by gas chromatography

A method is described for the determination of 25 common fatty acid mono-, di-, and triglycerides and their components and mixtures by packed-column gas chromatography after isolation and derivatization. The method is applied to two commercial materials, a polypropylene resin and a hand lotion. The glycerides along with glycerol and free fatty acids are first separated from the host by refluxing with 2-propanol containing an internal standard. The extract is derivatized and the compounds are identified and measured by gas chromatography. The chromatograms show sharp peaks, unique retention times and reproducibility in the range of 2–5%. Several positional isomers of the fatty acid glycerides were tested but found not to be resolved under the conditions used. Optical isomers and cis-trans isomers of unsaturated acids were not tested.     

Sample Preparation for Determination of Neomycin in Swine Tissues by Liquid Chromatography-Fluorescence Detection

A liquid chromatography method was developed for the determination of neomycin in swine tissues. Sample clean-up was especially focused on in this research. After neomycin was extracted from tissue with 10% trichloroacetic acid (w/v) solution, several clean-up procedures using MCX, CBA, WCX, and C18 solid-phase extraction (SPE) columns were compared for the purification effects and recoveries. The best result was obtained using MCX SPE column. The purified extract was derivatized with 9-fluorenylmethyl chloroformate and then separated on a C18 column and detected by a fluorescence detector. The spiked recoveries at 0.2–10 mg/kg ranged from 80.8–95.3% with coefficient of variations less than 12.1%.     

硅烷化衍生-气相色谱-质谱联用法测定橙汁粉中维生素C

橙汁粉样品用N,N-二甲基甲酰胺提取,并离心分离,所得上清液中抗坏血酸与六甲基二硅氨烷和三甲基氯硅烷进行衍生反应,产物用正庚烷萃取。萃取液加入棕榈酸甲酯作为内标,供气相色谱-质谱分析。在气相色谱分离中用HP-5MS毛细管柱(30 m×250μm,0.25μm)为固定相,在质谱测定中采用全扫描模式。硅烷化抗坏血酸标准与内标峰面积的比值与硅烷化抗坏血酸的质量在1.0～5.0 mg范围内呈线性关系。方法用于橙汁粉样品中维生素C的测定,橙汁粉中维生素C的平均质量分数(n=6)为0.195 4%,回收率在92.3%～98.5%之间。     

2-(2-Phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA) and its application for determination of amines by high performance liquid chromatography with fluorescence detection and identification with mass spectroscopy/atmospheric pressure chemical ionization

A simple, sensitive, and mild method for the determination of amino compounds based on a condensation reaction with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl) as the dehydrant with fluorescence detection has been developed. Amines were derivatized to their acidamides with labeling reagent 2-(2-phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA). Studies on derivatization conditions indicated that the coupling reaction proceeded rapidly and smoothly in the presence of a base catalyst in acetonitrile to give the corresponding sensitively fluorescent derivatives with an excitation maximum at λ_ex 260 nm and an emission maximum at λ_em 380 nm. The labeled derivatives exhibited high stability and were enough to be efficiently analyzed by high-performance liquid chromatography. Identification of derivatives was carried out by online post-column mass spectrometry (LC/APCI-MS/MS) and showed an intense protonated molecular ion corresponding m/z [MH]⁺ under APCI in positive-ion mode. At the same time, the fluorescence properties of derivatives in various solvents or at different temperature were investigated. The method, in conjunction with a gradient elution, offered a baseline resolution of the common amine derivatives on a reversed-phase Eclipse XDB-C₈ column. LC separation for the derivatized amines showed good reproducibility with acetonitrile-water as mobile phase. Detection limits calculated from 0.78 pmol injection, at a signal-to-noise ratio of 3, were 3.1-18.2 fmol. The mean intra- and inter-assay precision for all amine levels were <3.85% and 2.11%, respectively. Excellent linear responses were observed with coefficients of >0.9996. The established method for the determination of aliphatic amines from real wastewater and biological samples was satisfactory.     

Selective enrichment of aminothiols using polysorbate 20-capped gold nanoparticles followed by capillary electrophoresis with laser-induced fluorescence

In this article, we report a simple method for selective enrichment of aminothiols using Tween 20-capped gold nanoparticles (AuNPs) prior to capillary electrophoresis coupled with laser-induced fluorescence (CE-LIF). Compared to citrate-capped AuNPs, Tween 20-capped AuNPs exhibit the ability to disperse in a highly saline solution and selectively extract aminothiols through the formation of Au–S bonds. After extraction and centrifugation, 1 mM thioglycollic acid (TGA) was utilized to remove aminothiols that attached to the NP surfaces. After a solution of 8.0 mL aminothiols were extracted using 2× AuNPs (200 μL), the extracted aminothiols derivatized with o-phthalaldehyde at pH 12.0 were detected by CE-LIF. As a result, the limits of detection at a signal-to-noise ratio of 3 for homocysteine (HCys), glutathione (GSH), and γ-glutamycysteine (Glu-cys) are 4013.2, 79.8, and 382.8 pM, respectively. The use of this probe provided approximately 11-, 282-, and 21-fold sensitivity improvements for HCys, GSH, and Glu-cys, respectively. A practical analysis of HCys, GSH, and Glu-cys in human urine sample has been accomplished by this present method.     

A new cleanup method of dioxins in sediment using large volume injection gas chromatography online coupled with liquid chromatography

A new cleanup method was developed and validated for the determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in sediment. The sample extract was first treated with sulfuric acid and then cleaned up by a large volume injection gas chromatography online coupled with liquid chromatography (LVI-GC-LC) system. PCDD/Fs in the extract were separated by a GC column (DB-5), selected cut, cool trapped and transferred to a LC column (alumina). The fraction of PCDD/Fs eluted from the alumina column was collected and concentrated for the instrumental analysis. Under the optimized conditions, LVI-GC-LC method achieved the recoveries of 57–102% for 2,3,7,8-substituted PCDD/Fs, which met the requirements of US Environmental Protection Agency (EPA) Method 1613 and were better than those obtained using the conventional multistep column cleanup method. Meanwhile, compared with the conventional method, the limit of detection (LOD) values of 2,3,7,8-substituted PCDD/Fs cleaned up by LVI-GC-LC method were decreased due to the high-efficiency removal of interferents. These results suggested that the LVI-GC-LC cleanup method was a promising alternative to the multistep cleanup procedure for the determination of dioxins in environmental samples.     

Amino acid, fatty acid, and carbohydrate content of Artocarpus altilis (breadfruit)

A study is conducted to determine the amino acid, fatty acid, and carbohydrate content of breadfruit using high-performance liquid chromatography (HPLC) and gas chromatography (GC). An HPLC method is used for the determination of amino acids and fatty acids in breadfruit. Representative amino acid samples are derivatized with phenylisothiocianate and the resulting phenylthiocarbamyl derivatives are separated on a reversed-phase column by gradient elution with a 0.05M ammonium acetate buffer and 0.01M ammonium acetate in acetonitrile-methanol-water (44:10:46, v/v). Representative fatty acid samples are derivatized with phenacyl bromide and the resulting fatty acid phenacyl esters are separated on a reversed-phase column by gradient elution with acetonitrile and water. Amino acid and fatty acid derivatives are detected by ultraviolet detection at 254 nm. The analysis of the carbohydrates in breadfruit employs a GC method. Carbohydrates are derivatized using trimethylchlorosilane and hexamethyldisilazane to form trimethylsilyl ethers. Compounds in the samples are separated by the temperature programming of a GC using nitrogen as the carrier gas. Percent recoveries of amino acids, fatty acids, and carbohydrates are 72.5%, 68.2%, and 81.4%, respectively. The starch content of the breadfruit is 15.52 g/100 g fresh weight.     

An LCEC method for the analysis of synthetic amino acids in fruit juices

Summary A fast and simple HPLC-method for the determination of synthetic amino acids in adulterated orange juice has been developed. The amino acid enantiomers were derivatized with a chiral reagent and the derivatives separated on a 3 m particle size C₁₈ column. An electrochemical detector operating in the oxidative mode was used for detection. The potential at which the derivatives are oxidized was determined by cyclic voltammetry.By using selective (electrochemical) detection it is possible to reduce the sample clean-up to simple centrifugation and filtration steps.     

Cyanamide: a convenient building block to synthesize 4-aryl-2-cyanoimino-3,4-dihydro-1H-pyrimidine systems via a multicomponent reaction

4-Aryl-2-cyanoimino-3,4-dihydro-1H-pyrimidine derivatives were prepared using a multicomponent reaction by reacting a mixture of arene or heteroarenecarbaldehyde, 1,3-dicarbonyl compounds, and cyanamide under acidic conditions. The novelty of this approach derives from its use of cyanamide as a building block in a four-component Biginelli-type reaction. Varying the reaction conditions led to the formation of either N-(2-imino-6-phenyl-1,3,5-oxadiazinan-4-ylidene) cyanamide or 3,4-dihydropyrimidin-2(1H)-one. The type of heterocycle skeleton synthesized depends on the nature of the acid catalyst as well as the reaction conditions employed.     

Improved method of determination of biologically important C10:0-C22:6 fatty acids as their 2-nitrophenylhydrazides by reversed-phase high-performance liquid chromatography

Fatty acids were separated by reversed-phase high-performance liquid chromatography after derivatization with 2-nitrophenylhydrazine hydrochloride in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The separation of a mixture of fourteen kinds of biologically important fatty acid hydrazides (C10:0-C22:6) was achieved within 15 min. Using margaric acid (C17:0) as internal standard, each fatty acid could be quantitated over the range of 2.5-5000 pmol per injection. Analytical recoveries ranged from 98.1 to 102.6%. The intra- and inter-assay coefficients of variation were less than 2.5 and 3.2%, respectively. For the determination of esterified fatty acids in fats and oils, the saponified mixture was directly derivatized without extraction. This method was compared gave similar fatty acid profiles to those obtained with the conventional liquid-liquid extraction method. It is simple, rapid and accurate for routine analyses of esterified fatty acids in biological materials.     

Direct enantiomeric analysis of amphetamine in plasma by simultaneous solid phase extraction and chiral derivatization

Summary An analytical approach has been developed for the one step determination of enantiomeric amphetamine composition in plasma, using on-line, pre-column solid phase derivatization with reversed phase HPLC separation. The high molecular weight protein components were excluded by the small pore structure of the polymer and washed out of the reaction column before derivatization. Spiked amphetamine in human plasma was extracted and derivatized by the polystyrene based FMOC-L-prolyl solid phase reagent. The derivatized diastereomers were separated on a conventional ODS column with an ACN/H₂O mobile phase. No kinetic resolution or racemization was observed in this solid phase derivatization. Calibration plots and reproducibility experiments were performed to demonstrate the validity of the new approach. Automation of the procedure provided a simple and reproducible method for direct chiral recognition in plasma samples.     

Capillary zone electrophoresis of aldoses,ketoses and uronic acids derivatized with ethylp-aminobenzoate

Summary A number of mono- and oligosaccharides derivatized with ethylp-aminobenzoate have been separated as their borate complexes by capillary zone electrophoresis, using a fused silica capillary containing 175 mM borate buffer, pH 10.5, as carrier. The derivatized carbohydrates were sufficiently separated within 17 min at an applied voltage of 25 kV. On-column UV monitoring allowed detection of these derivatives at the 10 fmol level, and quantification by the relative peak area method allowed reproducible determination of the saccharides at least in the concentration range of 0.5–20 mM in reaction solutions. This method has been applied to the determination of the monosaccharide compositions of polysaccharides extracted from Flos matricariae and Radix althaeae.     

Analysis of ultratrace triorganotin compounds in aquatic organisms by using capillary electrophoresis-inductively coupled plasma mass spectrometry

A microwave-assisted extraction used to extract trace triorganotin from aquatic organisms and a sensitive analytical method for the determination of ultratrace triorganotin (namely trimethyltin, triethyltin, tripropyltin and tributyltin) with capillary electrophoresis-inductively coupled plasma mass spectrometry were firstly described in this study. The extraction method is simple, effective and can be used to extract trace triorganotin in aquatic organisms within several min. The analytical method has a much lower detection limit of 0.2-0.7 ng Sn/mL for triorganotin compounds, and can be used to determine trace triorganotin in aquatic organisms directly without any derivatization and preconcentration. Using above methods, we have successfully determined trimethyltin, triethyltin, tripropyltin and tributyltin in dried Mya arenaria Linnaeus and Corbicula fluminea within 17 min with a recovery of 93-104% and a RSD (relative standard deviation, n = 6) of 2-5%. Our results showed that dried M. arenaria Linnaeus contained an extremely high tributyltin of 5.1 μg Sn/g dried weight, indicating that it may be a good biomarker for the organotin pollution in ocean.     

柱前衍生-高效液相色谱-荧光检测法测定罐头食品中的尿素

建立了罐头食品中尿素残留检测的柱前衍生-高效液相色谱-荧光检测方法.取5.0 g样品,经20 mL 1%(v/v)乙酸溶液提取、定容,离心后取上清液过滤,吸取0.5 mL提取液用呫吨醇进行衍生,采用高效液相色谱-荧光检测器进行测定.尿素在0.1~500 mg/L内线性良好,相关系数大于0.9995.实验表明,在5种罐头食品中各添加0.001~30 g/kg尿素,其平均回收率为80.2%~109.7%,相对标准偏差(n=6)为2.05%~6.53%,检出限为0.5 mg/kg,定量限为1.0 mg/kg.利用本研究建立的方法对168个实际样品进行测定,在3个肉类罐头样品中检出尿素,含量分别为10.6、62.1和2.6 mg/kg.方法稳定、可靠、操作简单,适用于罐头食品中尿素的检测.     

Determination of capsaicinoids in peppers by microwave-assisted extraction-high-performance liquid chromatography with fluorescence detection

In this study, a simple method for the determination of free fatty acids, phytosterols, tocopherols, mono and diglycerides present in canola oil deodorizer distillate (DD) and soapstock samples was developed. Analytes were derivatized “in situ” using a mixture of hexamethyldisilazane (HMDS), pyridine and trifluoroacetic acid; separated by gas chromatography (GC) with mass spectrometry (MS) for final detection. Two drying procedures were evaluated for drying deodorizer distillate samples before derivatization: freeze drying and drying at 100 °C for 24 h. The use of high temperatures caused the degradation of tocopherols and phytosterols, while lyophilization did not affect the substances negatively. The chromatographic conditions used in this work allow for the separation and quantification of oleic, linoleic and linolenic acids, monoolein and monolinolein in both samples, and brassicasterol and α-tocopherol in deodorizer distillate samples. MS provided an accurate identification for the compounds which were at very low concentrations (>0.09%). Oleic acid was the most abundant compound in both samples. Deodorizer distillate was an important source of tocopherols which were not detected in the soapstock samples.     

手性柱前衍生高效液相色谱法拆分牙本质中天冬氨酸对映体

手性柱前衍生高效液相色谱法拆分牙本质中天冬氨酸对映体傅世江,范垂昌,张世鑫魏奉群赵婷（中国医科大学法医化学教研室沈阳１１０００１）（辽宁基础医学研究所沈阳ｌ１０００３）（辽宁省分析测试研究中心沈阳１１００１５ｊ１前言由于氨基酸消旋化理论￣［１］在考古...