液相色谱-大气压化学电离质谱法分析人参中的人参皂甙

研究了用反相高效液相色谱-大气压化学电离质谱(HPLC/APCI-MS)分析人参皂甙的方法。液相色谱采用乙腈-水流动相进行梯度洗脱,质谱采用正负离子同时扫描并结合二级质谱进行定性,用选择反应离子模式(SRM)测定检测限。实验发现虽然人参皂甙是热不稳定物质,但在大气压化学电离质谱的高温汽化过程中仍能检测到很强的负离子分子离子峰,而且随着汽化温度的升高,人参皂甙的负离子分子离子峰的强度增加。该方法对人参皂甙Rb1和Rg1的检测限分别为1.2×10-13 g和3.0×10-14 g,并检测出白参中包括丙二酰人参皂甙在内的29种人参皂甙。该法灵敏度高,重复性好,结果准确,能有效地对药材提取物中的多种人参皂甙进行检测和结构分析。     

液相色谱-大气压化学电离串联质谱法测定婴幼儿配方奶粉中的维生素D

建立了婴幼儿配方奶粉中维生素D的液相色谱-大气压化学电离串联质谱(LC-APCI-MS/MS)分析方法。样品经正己烷和甲基叔丁基醚混合溶液提取,ProElut VDC固相萃取柱净化,Kinetex C_(18)色谱柱分离,采用大气压化学电离(APCI)源、正离子扫描和多反应监测(MRM)模式对维生素D_2和维生素D_3进行检测,内标法定量。结果表明维生素D_2和维生素D_3在5~5 000μg/L范围内均具有良好的线性关系,检出限为2μg/kg,定量限为5μg/kg。在5、10和100μg/kg添加水平下,维生素D_2和维生素D_3的回收率为85.2%~105.3%,相对标准偏差为4.7%~8.1%。该方法简便准确,灵敏度高,适用于婴幼儿奶粉中维生素D的测定。     

超高效液相色谱-大气压化学电离-串联质谱法测定烘焙咖啡中丙烯酰胺

建立了烘焙咖啡中丙烯酰胺的超高效液相色谱-大气压化学电离-串联质谱（UHPLC-APCI-MS/MS）分析方法。样品经甲醇提取，HLB固相萃取（SPE）小柱净化，Brownlee validated AQ C18色谱柱分离，采用大气压化学电离（APCI）源，正离子扫描和多反应监测（MRM）模式对丙烯酰胺进行检测，内标法定量。结果表明，丙烯酰胺在0.5~100.0 μg/L范围内具有良好的线性关系，相关系数（r²）为0.999，方法检出限为5.0 μg/kg，定量限为10.0 μg/kg。在100.0、200.0和1000.0 μg/kg添加水平下，丙烯酰胺的回收率为94.6%~115.0%，相对标准偏差（RSD）值为2.8%~3.6%（n=6）。本方法采用APCI源作为离子化方式，能有效地减少咖啡基质对丙烯酰胺的基质干扰，前处理简单，灵敏度高，适用于咖啡中丙烯酰胺的日常检测。     

电喷雾飞行时间质谱与大气压化学电离质谱法分析烟叶中茄尼醇的比较

采用反相高效液相色谱(RP-HPLC-UV)和电喷雾飞行时间质谱(ESI-TOF/MS)、大气压化学电离质谱(APCI-MS),分析烟叶中的茄尼醇.使用反相G4色谱柱,以V(甲醇):V(水)=9:1为流动相,茄尼醇和烟草中的其它成分分离良好;茄尼醇在ESI正离子全范围扫描中主要形成[M-H2O H] 和[M NH4] 离子,只有微弱的[M H] 离子,同时会产生一些碎片离子;而在APCI正离子全范围扫描中主要形成[M-H2O H] 离子,检测不到[M H] 离子,碎片离子也很少;通过对茄尼醇的ESI-TOF/MS和APCI-MS的质谱分析特征比较可以发现,茄尼醇在ESI源分析中的信号强度远远小于在APCI源分析中的信号强度,说明APCI源更适于茄尼醇的定量分析.     

反相高效液相色谱-离子阱质谱法测定鸡肉中的氯霉素

采用反相高效液相色谱 离子阱质谱法测定鸡肉中的氯霉素残留。鸡肉样品用乙腈进行提取 ,V(甲醇 )∶V( 0 .0 1mol L乙酸铵水溶液 ) =40∶60为流动相 ,采用ZorbaxEclipeseXDBC18柱进行分离 ,通过离子阱质谱 ,以选择离子反应进行检测。该方法的线性范围为 1～ 1 0 0 0 μg L ,样品的检出限为 0 .1 μg L。     

高效液相色谱/大气压化学电离质谱分析新型复合抗氧剂

 应用高效液相色谱 /大气压化学电离质谱技术 ,其中包括直接进样技术、同时正负离子扫描方式、可编程的源内碰撞诱导解离 (CID)技术 ,以及红外光谱分析技术 ,对一种用于润滑油的新型复合抗氧剂进行了分离分析 ,并对其中的有效组分进行了定性鉴定。该方法简便、快速、可靠。     

高效液相色谱-电喷雾离子阱质谱法测定红葡萄酒中酚类物质

建立了高效液相色谱-质谱联用(HPLC-MS)技术检测葡萄酒中酚类物质的方法,并评价其定量分析的准确性、线性、重复性和检出限,结果显示:16种酚类物质除芦丁和白藜芦醇糖苷外,平均加标回收率大于78%;相关系数R2>0.999,线性关系良好;保留时间和峰面积在日内(n=10)与日间(n=6)重复性的相对标准偏差(RSD)均分别低于2.0%和5.0%;检出限为0.05~1.0 mg/L。利用该方法对6个红葡萄酒中16种酚类物质进行了定性定量分析,其相对标准偏差(CV%)均小于5.0%,说明本方法简便、准确、灵敏、重现性好,可用于葡萄酒产品质量监控。     

超高效液相色谱-大气压化学电离-三重四极杆质谱法同时测定保健食品中14种性激素类药物

建立了超高效液相色谱-大气压化学电离-三重四极杆质谱（UPLC-APCI-MS/MS）测定保健食品中14种性激素类药物的方法。样品用乙腈提取2次，再用HLB固相萃取柱净化处理。采用Hypersil Gold C18色谱柱（100 mm×2.1 mm，1.9 μm）分离，以乙腈-10 mmol/L乙酸铵溶液为流动相进行梯度洗脱，采用APCI-三重四极杆质谱检测，外标法定量。结果表明，14种性激素类药物在各自范围内线性关系良好，相关系数（r）≥0.996，检出限为0.0990~2.09 μg/kg，定量限为0.495~5.23 μg/kg；在低、中、高3个水平下的平均加标回收率为65.8%~118.8%，精密度为0.6%~8.7%（n=6）。该方法前处理简单，灵敏度高，回收率良好，适用于保健食品中性激素类非法添加物的定量测定。     

高效液相色谱-大气压化学电离-串联质谱法同时测定动物源食品中复硝酚钠的3种组分

复硝酚钠(SNP)是一种生长调节剂,在我国动物源食品检测中被列为禁用药物。由于复硝酚钠痕量分析方法不成熟,至今尚无标准检测方法,因此建立复硝酚钠中3种组分(5-硝基愈创木酚钠、对硝基酚钠和邻硝基酚钠)同时检测的方法对我国动物源食品中复硝酚钠残留水平的控制、检测标准的制定和政府相应管理措施的实行采取具有一定的理论和现实意义并兼具创新性。研究建立了高效液相色谱-大气压化学电离-串联质谱(HPLC-APCI-MS/MS)对猪肉、鸡肉、鱼肉和肝脏中复硝酚钠3种组分残留量的检测方法。样品采用氢氧化钠溶液提取,用盐酸调节pH值为酸性后,加氯化钠使溶液饱和,再用乙腈溶液反萃两次后,合并上清液并加入饱和氯化钠溶液,再经正己烷液液萃取除脂后吸出中间乙腈层,浓缩并定容后,以甲醇-水溶液作为流动相进行梯度洗脱,采用CORTECT C₁₈色谱柱分离,大气压化学电离,在多反应监测(MRM)负离子模式下测定,外标法定量分析。5-硝基愈创木酚钠、对硝基酚钠和邻硝基酚钠分别在0.5~10、1.0~20和2.5~50 μg/L范围内线性良好,定量限分别为1.0、2.0和5.0 μg/kg,在定量限、2倍定量限和10倍定量限加标水平上的回收率分别为81.5%~98.4%、81.5%~102%和81.4%~95.1%,相对标准偏差分别为1.51%~5.98%、1.10%~8.85%和0.91%~8.61%(n=6),均符合要求,能够满足动物源食品中复硝酚钠残留量的检测要求。     

液相色谱-电喷雾离子阱串联质谱分析烟草水提取物中的尼古丁

用液相色谱-电喷雾线性离子阱串联/质谱(LC-ESI-ITMS/MS)在正离子模式下对烟草水提取物中的尼古丁进行了分析:定性分析了尼古丁MS/MS图谱中碎片的可能结构;用尼古丁标准溶液对质谱检测条件进行优化后,在SRM扫描模式下对尼古丁进行定量分析。最低检出限(LOD)可达0.21μg/L;回收率为99%-105%。测试3个不同浓度样品得到的RSD为0.64%-0.72%。实验选用高效的短色谱柱达到了快速定量的目的,适用于对大量样品的分析。     

Systematic screening and characterization of glycosides in tobacco leaves by liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry using neutral loss scan and product ion scan

Glycosides in tobacco leaves are highly important aromatic precursors. It is necessary to reveal glycosides in tobacco leaves to improve tobacco planting and processing. This study describes a method for the systematic screening of glycosides in tobacco leaves by liquid chromatography with tandem mass spectrometry. Although glycosides contain numerous aglycones, the number of glycans is limited. Based on a screening table of glycans designed for neutral loss scan, glycosides with different aglycones were systematically screened out. Then, the MS² fragment spectra of scanned glycosides were further obtained using product ion scan. By comparison with the spectra in online tandem mass spectral databases, reported references, and verification by commercial standards, 64 glycosides were detected, including 39 glycosides linked with monosaccharides, 18 glycosides linked with disaccharides and 7 glycosides linked with trisaccharides. It is noteworthy that glycosides linked with trisaccharides have previously been rarely reported in tobacco. This method appears to be a useful tool for the systematic screening and characterization of glycosides in tobacco and can potentially be applied to other plants.     

Determination of polycyclic aromatic hydrocarbons in fractions in asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization

An analytical method using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization for the determination of polycyclic aromatic hydrocarbons in asphalt fractions has been developed. The 14 compounds determined, characterized by having two or more condensed aromatic rings, are expected to be present in asphalt and are considered carcinogenic and mutagenic. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all of the compounds. The limits of detection ranged from 0.5 to 346.5 μg/L and the limits of quantification ranged from 1.7 to 1550 μg/L. The method was validated against a diesel particulate extract standard reference material (NIST SRM 1975), and the obtained concentrations agreed with the certified values. The method was applied to asphalt samples after its fractionation according to ASTM D4124 and the method of Green. The concentrations of the seven polycyclic aromatic hydrocarbons quantified in the sample ranged from 0.86 mg/kg for benzo[ghi]perylene to 98.32 mg/kg for fluorene.     

Determination of polymer additives by liquid chromatography coupled with mass spectrometry. A comparison of atmospheric pressure photoionization (APPI), atmospheric pressure chemical ionization (APCI), and electrospray ionization (ESI)

A method for the determination of polymer additives like antioxidants, UV absorbers and processing stabilizers using liquid chromatography (LC) coupled with atmospheric pressure photoionization mass spectrometry (APPI-MS) is presented. Ion source parameters were optimized regarding temperatures, gas flow rates, and voltages applied. Detection limits were determined using APPI with or without dopant and were compared with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). Differences between APPI, ESI and APCI are pointed out and the effect of the dopant toluene and acetone is discussed. The optimized method yielded detection limits between 0.001 mg L⁻¹ and 0.022 mg L⁻¹ for 15 different analytes. Linear calibration plots could be obtained for all solutes over a wide concentration range showing satisfying repeatability with standard deviations of peak areas between 3.4% and 7.6%. The results indicate that the developed method can be regarded as suitable for the quantitative determination of polymer additives even at low concentration levels.     

Determination of eight nitrosamines in water at the ng L levels by liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry

In this work, we have developed a sensitive method for detection and quantification of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMor), N-nitrosomethylethylamine (NMEA), N-nitrosopirrolidine (NPyr), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPip), N-nitroso-n-dipropylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA) in drinking water. The method is based on liquid chromatography coupled to tandem mass spectrometry, using atmospheric pressure chemical ionization (APCI) in positive mode with a triple quadrupole analyzer (QqQ). The simultaneous acquisition of two MS/MS transitions in selected reaction monitoring mode (SRM) for each compound, together with the evaluation of their relative intensity, allowed the simultaneous quantification and reliable identification in water at ppt levels. Empirical formula of the product ions selected was confirmed by UHPLC-(Q)TOF MS accurate mass measurements from reference standards.Prior to LC–MS/MS QqQ analysis, a preconcentration step by off-line SPE using coconut charcoal EPA 521 cartridges (by passing 500 mL of water sample) was necessary to improve the sensitivity and to meet regulation requirements. For accurate quantification, two isotope labelled nitrosamines (NDMA-d₆ and NDPA-d₁₄) were added as surrogate internal standards to the samples.The optimized method was validated at two concentration levels (10 and 100 ng L⁻¹) in drinking water samples, obtaining satisfactory recoveries (between 90 and 120%) and precision (RSD < 20%). Limits of detection were found to be in the range of 1–8 ng L⁻¹. The described methodology has been applied to different types of water samples: chlorinated from drinking water and wastewater treatment plants (DWTP and WWTP, respectively), wastewaters subjected to ozonation and tap waters.     

Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization

Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6–191 μg/L for nitrated and 0.3–8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2‐nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected.     

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a “soft” ion source for preserving highly diagnostic molecular ion is desirable, as compared to the “hard” ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS.     

Multi-component analysis (sterols, tocopherols and triterpenic dialcohols) of the unsaponifiable fraction of vegetable oils by liquid chromatography-atmospheric pressure chemical ionization-ion trap mass spectrometry

A simple and sensitive method for the analysis of sterols, tocopherols and triterpenic dialcohols from the unsaponifiable fraction from oil samples in a single analytical run using liquid chromatography coupled to mass spectrometry was developed. With this method, the compounds could be detected directly after dissolving the unsaponifiable fraction in acetonitrile without necessity of time-consuming sample pre-treatment or derivatization. Separation of the analytes was carried out at room temperature, by using a C18 column (5 μm i.d. 3.0 mm × 250 mm) with a linear gradient of acetonitrile/water (0.01% acetic acid) at a flow rate of 1.5 mL/min. The full scan mass spectra of the investigated compounds were measured by an ion trap mass spectrometer equipped with an APCI ion source. The optimized methodology was suitable for the identification of 23 compounds belonging to different families present in olive oil and other kinds of oils, as well as for the quantification of 15 analytes (vs. their commercial standards).     

Determination of polar organic compounds in atmospheric aerosols by gas chromatography with ion trap tandem mass spectrometry

A gas chromatography with ion trap mass spectrometry method has been developed and validated for the analysis of 27 polar organic compounds in atmospheric aerosols. The target analytes were low‐molecular‐weight carboxylic acids and methoxyphenols, as relevant markers of source emissions and photochemical processes of organic aerosols. The operative parameters were optimized in order to achieve the best sensitivity and selectivity for the analysis. In comparison with the previous gas chromatography with mass spectrometry procedure based on single ion monitoring detection, the tandem mass spectrometry technique increased the analytical sensitivity by reducing detection limits for standard solutions from 1–2.6 to 0.1–0.4 ng/μL ranges (concentrations in the injected solution). In addition, it enhanced selectivity by reducing matrix interferences and chemical noise in the chromatogram. The applicability of the developed method in air quality monitoring campaigns was effectively checked by analyzing environmental samples collected in the Po Valley (Northern Italy) in different seasons. The obtained results indicate that the ion trap mass spectrometer may be an ideal alternative to high‐resolution mass spectrometers for the user‐friendly and cost‐effective determination of a wide range of molecular tracers in airborne particulate matter.     

Optimization of HPLC-APCI-MS conditions for the qualitative and quantitative determination of total solanesol in tobacco leaves

HPLC coupled online with atmospheric pressure chemical ionization MS (APCI-MS) technique was evaluated for the qualitative and quantitative determination of solanesol in extracts of tobacco leaves. The solanesol and other compounds in the extract were separated on an Alltima C(8) (4.6 mm x 250 mm) column with methanol and water (98:2 v/v) as mobile phase, with flow rate of 0.8 mL/min and UV detection wavelength of 211 nm. In the APCI(+) mode, abundant stable [M-H(2)O + H](+) ion (m/z at 613.5) was observed, with low abundance of other fragmentation ions. A comparison of APCI-MS and ESI-MS techniques showed that APCI mode is more sensitive than ESI mode, and thus better suited for solanesol analysis. When comparing UV 211 nm and APCI-MS in SIM for solanesol quantification, the former offered better precision and reproducibility, but the latter was more than 200 times sensitive in detection. The developed method has been successfully applied to the analysis and comparison of solanesol concentration in different tobacco leaf samples.     

Selective adduct formation by furan chemical ionization reagent in gas chromatography ion trap mass spectrometry

The analytical potential of furan as a chemical ionization (CI) reagent was evaluated for selectivity with nine monosubstituted naphthalene compounds. The ion-molecule reactions of furan and tetrahydrofuran (THF) were compared with those of methane, methanol and acetonitrile (prominently producing [M + H](+) ion base peaks) with naphthalene compounds in chemical ionization mass spectrometry (CI-MS). Reactions with furan predominantly show M(+) and [M + 39](+) ions. Based on this phenomenon, investigations were carried out for some of the molecular factors such as proton affinity, substituent effects and the preferred site of [C(3)H(3)](+) ion attachment that influence reactivity in furan CI. High selectivity with different substituents is observed in the formation of [M + 39](+) adduct ion, suggesting its usefulness as selective ionization reagent liquid. The selectivity and sensitivity are illustrated in the analysis of mixture of amino acids. Furthermore, the structure determination and reaction mechanism study is characterized by collision-activated dissociation experiments in CI-MS/MS and CI-MS/MS/MS.