SPME-Arrow/GC-MS结合多元统计分析研究不同批次爆珠香精组分差异

以箭型固相微萃取(SPME-Arrow)为样品萃取手段,通过优化萃取头种类、氯化钠添加量、萃取温度、平衡时间及萃取时间等条件,构建了高效鉴定爆珠香精中挥发性及半挥发性化合物的箭型固相微萃取结合气相色谱-质谱联用(SPME-Arrow/GC-MS)法。采用该方法对不同批次爆珠香精进行分析,结合主成分分析(PCA)、正交偏最小二乘-判别分析(OPLS-DA)及显著性F检验等多元统计分析手段,筛选显著性差异成分。结果表明:最佳萃取条件为优选DVB/CAR/PDMS萃取头,添加2.0 g氯化钠,在60℃下平衡50 min,萃取时间为40 min;经谱库检索结合保留指数辅助定性,共鉴定出96种挥发性、半挥发性组分,目标物峰面积的日间相对标准偏差(RSD)小于10%的色谱峰数量占总峰数量的92.7%,表明方法的重复性较好;从不同批次爆珠香精中共筛选出17个潜在差异化合物,通过显著性检验,确定10种显著性差异化合物,分别为α-蒎烯、柠檬烯、桉叶油醇、异胡薄荷醇、薄荷酮(含异构体)、新异薄荷醇、乙酸新薄荷酯、三辛酸甘油酯和二辛酸单癸酸甘油酯。该法可有效区分不同批次爆珠样品的组分差异,具有客观真实、准确可靠、可视化强等特点,能够为爆珠产品质量检验提供技术支持。

An inversely designed integrated spectrometer with reconfigurable performance and ultra-low power consumption

Despite the pressing demand for integrated spectrometers,a solution that deliver high-performance while being practically operated is still missing.Furthermore,current integrated spectrometers lack reconfigurability in their performance,which is highly desirable for dynamic working scenarios.This study presents a viable solution by demonstrating a userfriendly,reconfigurable spectrometer on silicon.At the core of this innovative spectrometer is a programmable photonic circuit capable of exhibiting diverse spectral responses,which can be significantly adjusted using on-chip phase shifters.The distinguishing feature of our spectrometer lies in its inverse design approach,facilitating effortless control and efficient manipulation of the programmable circuit.By eliminating the need for intricate configuration,our design reduces power consumption and mitigates control complexity.Additionally,our reconfigurable spectrometer offers two distinct operating conditions.In the Ultra-High-Performance mode,it is activated by multiple phase-shifters and achieves exceptional spectral resolution in the picometer scale while maintaining broad bandwidth.On the other hand,the Ease-of-Use mode further simplifies the control logic and reduces power consumption by actuating a single-phase shifter.Although this mode provides a slightly degraded spectral resolution of approximately 0.3 nm,it prioritizes ease of use and is wellsuited for applications where ultra-fine spectral reconstruction is not a primary requirement.

Optimized online filter stack spectrometer for ultrashort X-ray pulses

Currently,with the advent of high-repetition-rate laser-plasma experiments,the demand for online diagnosis for the X-ray spectrum is increasing because the laser-plasma-generated X-ray spectrum is very important for characterizing electron dynamics and applications.In this study,scintillators and silicon PIN(P-type–intrinsic-N-type semiconductor)diodes were used to construct a wideband online filter stack spectrometer.The X-ray sensor and filter arrangement was optimized using a genetic algorithm to minimize the condition number of the response matrix.Consequently,the unfolding error was significantly reduced based on numerical experiments.The detector responses were quantitatively calibrated by irradiating the scintillator and PIN diode with various nuclides and comparing the measuredγ-ray peaks.A prototype 15-channel spectrometer was developed by integrating an X-ray detector with front-and back-end electronics.The prototype spectrometer could record X-ray pulse signals at a repetition rate of 1 kHz.Furthermore,an optimized spectrometer was employed to record the real-time spectra of laser-driven bremsstrahlung sources.This optimized spectrometer offers a compact solution for spectrum diagnostics of ultrashort X-ray pulses,exhibiting improved accuracy in terms of spectrum measurements and repetition rates,and could be widely used in next-generation high-repetition-rate high-power laser facilities.

Design and implementation of the monochromator shielding for the cold neutron spectrometers XINGZHI and BOYA

An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.

A seven-crystal spectrometer for high-energy resolution X-ray spectroscopy at Shanghai Synchrotron Radiation Facility

A Johann-type X-ray spectrometer was successfully developed at the hard X-ray branch(in-vacuum undulator with a 24-mm periodic length)of the energy material beamline(E-line)at the Shanghai Synchrotron Radiation Facility(SSRF).This spectrometer was utilized to implement X-ray emission spectroscopy(XES),high-energy resolution fluorescence-detected X-ray absorption spectroscopy(HERFD-XAS),and resonant inelastic X-ray scattering.Seven spherically bent crystals were positioned on the respective vertical 500-mm-diameter Rowland circles,adopting an area detector to increase the solid angle to 1.75%of 4πsr,facilitating the study of low-concentrate systems under complex reaction conditions.Operated under the atmosphere pressure,the spectrometer covers the energy region from 3.5 to 18 keV,with the Bragg angle ranging from 73°to 86°during vertical scanning.It offers a promised energy resolution of sub-eV(XES)and super-eV(HERFD-XAS).Generally,these comprehensive core-level spectroscopy methods based on hard X-rays at the E-line with an extremely high photon flux can meet the crucial requirements of a green energy strategy.Moreover,they provide substantial support for scientific advances in fundamental research.

Mid-infrared Optical Frequency Comb-based Fourier Transform Spectrometer for Broadband Molecular Spectroscopy

Optical frequency combbased Fourier transform spectroscopy has the features of broad spectral bandwidth,high sensitivity,andmultiplexed trace gas detection,which has valuable application potential in the fields of precision spectroscopy and trace gas detection.Here,we report the development of a mid-infrared Fourier transform spectrometer based on an optical frequency comb combined with a Herriott-type multipass cell.Using this instrument,the broadband absorption spectra of several important molecules,including methane,acetylene,water molecules and nitrous oxide,are measured by near real-time data acquisition in the 2800-3500 cm^(-1)spectral region.The achieved minimum detectable absorption of the instrument is 4.4×10^(-8)cm^(-1)·Hz^(-1/2)per spectral element.Broadband spectra of H_(2)0 are fited using the Voigt profile multispectral fitting technique and the consistency of the concentration inversion is 1%.Our system also enables precise spectroscopic measurements,and it allows the determination of the spectral line positions and upper state constants of N_(2)O in the(0002)-(1000)band,with results in good agreement with those reported by Toth[Appl.Opt.30,5289(1991)].

Artificial neural network-based method for discriminating Compton scattering events in high-purity germaniumγ-ray spectrometer

To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resulting in an extremely low detection limit and improving the measurement accuracy.However,the complex and expensive hardware required does not facilitate the application or promotion of this method.Thus,a method is proposed in this study to discriminate the digital waveform of pulse signals output using an HPGe detector,whereby Compton scattering background is suppressed and a low minimum detectable activity(MDA)is achieved without using an expensive and complex anticoincidence detector and device.The electric-field-strength and energy-deposition distributions of the detector are simulated to determine the relationship between pulse shape and energy-deposition location,as well as the characteristics of energy-deposition distributions for fulland partial-energy deposition events.This relationship is used to develop a pulse-shape-discrimination algorithm based on an artificial neural network for pulse-feature identification.To accurately determine the relationship between the deposited energy of gamma(γ)rays in the detector and the deposition location,we extract four shape parameters from the pulse signals output by the detector.Machine learning is used to input the four shape parameters into the detector.Subsequently,the pulse signals are identified and classified to discriminate between partial-and full-energy deposition events.Some partial-energy deposition events are removed to suppress Compton scattering.The proposed method effectively decreases the MDA of an HPGeγ-energy dispersive spectrometer.Test results show that the Compton suppression factors for energy spectra obtained from measurements on ^(152)Eu,^(137)Cs,and ^(60)Co radioactive sources are 1.13(344 keV),1.11(662 keV),and 1.08(1332 keV),respectively,and that the corresponding MDAs are 1.4%,5.3%,and 21.6%lower,respectively.

An empirical method for joint inversion of wave and wind parameters based on SAR and wave spectrometer data

Synthetic aperture radar(SAR)and wave spectrometers,crucial in microwave remote sensing,play an essential role in monitoring sea surface wind and wave conditions.However,they face inherent limitations in observing sea surface phenomena.SAR systems,for instance,are hindered by an azimuth cut-off phenomenon in sea surface wind field observation.Wave spectrometers,while unaffected by the azimuth cutoff phenomenon,struggle with low azimuth resolution,impacting the capture of detailed wave and wind field data.This study utilizes SAR and surface wave investigation and monitoring(SWIM)data to initially extract key feature parameters,which are then prioritized using the extreme gradient boosting(XGBoost)algorithm.The research further addresses feature collinearity through a combined analysis of feature importance and correlation,leading to the development of an inversion model for wave and wind parameters based on XGBoost.A comparative analysis of this model with ERA5 reanalysis and buoy data for of significant wave height,mean wave period,wind direction,and wind speed reveals root mean square errors of 0.212 m,0.525 s,27.446°,and 1.092 m/s,compared to 0.314 m,0.888 s,27.698°,and 1.315 m/s from buoy data,respectively.These results demonstrate the model’s effective retrieval of wave and wind parameters.Finally,the model,incorporating altimeter and scatterometer data,is evaluated against SAR/SWIM single and dual payload inversion methods across different wind speeds.This comparison highlights the model’s superior inversion accuracy over other methods.

霉变烟叶的GC-MS和FTIR分析及鉴别

采用GC-MS和FTIR分析,结合PCA、PLS等多元分析方法,对霉变烟叶进行评价鉴别。GC-MS分析筛选得到2-乙基己醇等9个烟叶霉变标记物。通过4-羟基丁酸内酯等9个关键化合物构建的线性判别方程,可以实现烟叶霉变准确识别,初始验证准确率100%和留一交叉验证准确率为98.7%。FTIR研究表明,烟叶霉变过程中消耗了烟叶大量的碳水化合物、蛋白质和脂质等。GC-MS和FTIR,分别结合PCA和PLS-DA能实现霉变烟叶的有效判别。

上海白玉兰花香和鲜花精油挥发性成分的GC-MS分析研究

为了比较上海白玉兰花香和白玉兰鲜花精油的成分差异,采用顶空气质联用技术(HS-GC-MS)或气相色谱-质谱联用技术(GC-MS)进行挥发性成分的分析。结果表明,从白玉兰花香和白玉兰鲜花精油中共鉴定出44种成分,相同成分10种;白玉兰花香中共检测出26种成分,相对含量占其总量的96.29%,其主要成分为桉叶油醇(26.73%)、桧烯(23.29%)、β-蒎烯(18.77%)、β-月桂烯(12.22%)和α-蒎烯(6.83%);白玉兰鲜花精油中共检测出28种化学成分,相对含量占其总量的79.46%,主要成分包括苯乙醇(35.48%)、桉叶油醇(10.09%)、α-松油醇(9.12%)、柳杉二醇(5.69%)和4-松油醇(5.52%)。白玉兰花香和白玉兰鲜花精油成分在类别及相对含量上均有所差异,这为白玉兰资源的合理开发利用提供了理论依据。

基于HS-SPME-GC-MS和感官评价分析不同时期木枣的挥发性物质

为了解不同时期木枣的香气成分及其差异,该研究采用顶空固相微萃取结合气相色谱-质谱(headspace solid-phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)对幼果期(S1)、膨大期(S2)、绿熟期(S3)、白熟期(S4)、半红期(S5)和全红期(S6)的木枣进行挥发性物质检测和风味感官评价,借助热图聚类分析和主成分分析,进而用正交偏最小二乘法判别分析建立模型,筛选差异挥发性物质。结果表明:不同时期木枣共检测出121种挥发性物质,主要包括醛类、醇类、酯类和烷烃类物质等;筛选出主要的差异挥发性物质有14种,有己酸乙酯、月桂酸甲酯、癸酸甲酯、壬醛、己酸、乙基己醇等;木枣的气味由青香转为果香,味道由涩味转甜,颜色由绿色转白又变红。此外,酸涩味与醛类、青香与醇类、脂香和甜味与酯类和酸类呈正相关。该文为木枣风味品质评价、食品加工利用提供理论支撑。

HS-SPME-GC-MS与Heracles NEO超快速气相电子鼻分析不同新鲜度大米挥发性物质

基于目前大米新鲜度检测方法存在的准确率低、操作难度大、检测年限短等问题,该研究选用目前啤酒企业常用大米品种——空育131为研究对象,通过人为加速大米陈化,采用顶空固相微萃取(HS-SPME)结合气相色谱-质谱联用(GC-MS)与Heracles NEO超快速气相电子鼻技术进行挥发性组分鉴定,并采用主成分分析(PCA)、层次聚类分析(HCA)和正交偏最小二乘-判别分析(OPLS-DA)进行多元统计分析。结果表明,采用HS-SPME-GC-MS从不同新鲜度大米样品中均检出30种挥发性化合物,包括烷烃、醇类、醛类、酮类等化合物。采用Heracles NEO超快速气相电子鼻均检出21种挥发性化合物,气味描述显示大米气味主要集中在草本味和果香味。PCA和OPLS-DA结果显示,不同样品之间相对独立,根据P<0.05且变量重要性投影(VIP)值>1,GC-MS筛选出2,3-庚二酮、辛醛等共10个差异性风味化合物,Heracles NEO超快速气相电子鼻筛选出乙烯基吡嗪、1-戊烯-3-醇等共7个差异性风味化合物。综上,GC-MS和Heracles NEO超快速气相电子鼻均可较好地分析不同新鲜度大米的气味特征并进行快速而准确的鉴别区分。

基于HS-SPME-GC-MS解析核桃雄花挥发性成分

检测分析核桃雄花的香气组分种类、相对体积分数,探明核桃雄花的呈香成分及香气特征。以鲜核桃雄花为材料,采用顶空固相微萃取串联气质技术(HS-SPME-GC-MS)对核桃雄花中挥发性成分进行鉴定和定量分析。结果从核桃雄花中共鉴定出22种挥发性成分,其中胡桃醌、二甲硫醚2种化合物占总体积分数的62.18%±2.93%、醇类占19.03%±1.91%、烯烃类占10.32%±1.84%、醛类、酮类及酯类化合物占比较低;核桃雄花香气主要由芳樟醇、反松香芹醇、2-甲基丙醛、2-甲基丁醛、3-甲基丁醛、壬醛、十六烷酸乙酯及烯烃类所贡献;主成分分析将22种挥发性化合物归为2类。综合显示:贵州产区核桃雄花香气主要由醇类、醛类和烯烃类成分所构成,种类最为丰富的烯烃类化合物贡献了突出的水果类气味。

基于P&T-GC-MS技术的甲醇试剂中苯系物本底研究

苯系物是衡量水质的重要指标之一,是水环境监测优先管控的主要污染物。生活饮用水,尤其水源地水中通常并不希望检出苯系物,这些水体中苯系物的含量一般不高,浓度在方法检出限附近。因此分析过程所用试剂,尤其是标样配制必不可少的甲醇中是否存在苯系物杂质,存在情况如何,对水中低浓度苯系物的准确测定非常关键。吹扫捕集-气相色谱-质谱联用法(P&T-GC-MS)具有较好的分离度和灵敏度,且进样量少、干扰小,是水中痕量苯系物检测的优选方法。本研究基于P&T-GC-MS法,开展甲醇试剂的苯系物本底研究,探索实验室常用甲醇试剂中的苯系物杂质对定量结果的影响程度和影响规律,为环境监测相关工作和研究提供数据支持。

浅谈GC1级蒸汽管道监督检验

GC1级蒸汽管道(高温、高压)的监督检验,文中从材料、设计、制造与安装、检验与试验具体分析监督检验过程中需要重点关注的地方。

基于HS-GC-MS的黄精霉变前后VOCs变化规律和关键差异成分研究

目的:以黄精为研究对象,通过研究不同霉变程度下挥发性有机化合物(VOCs)的变化和关键差异成分,筛选黄精霉变的特征标志物,为黄精霉变的快速识别和中药霉变的早期预警提供科学依据。方法:在高温高湿条件下,通过人工促霉处理结合传统性状鉴定法,制备不同霉变程度的黄精样品。采用顶空-气相色谱-质谱联用(HS-GC-MS)技术分析黄精样品中的主要VOCs。运用偏最小二乘判别分析(PLS-DA)和主成分分析(PCA)探讨黄精霉变前后VOCs的变化规律和关键差异。结果:从未霉变、轻微霉变、严重霉变的黄精中分别鉴定出35、33、34种成分,包括醛、醇、酮、酯、酸、烃、胺、醚及其他类成分。PLS-DA分析结果显示,不同霉变程度黄精样品之间VOCs存在显著差异,成功筛选出9个差异性成分:2-甲基丁醛、三甲胺、异戊醛、冰醋酸、正己醛、2,3-丁二醇、正戊醛、2,6-二甲基吡嗪、丙酮醛。其中,霉变后异戊醛和2,3-丁二醇含量降低,正己醛含量增加;三甲胺仅在严重霉变样品中出现;而2,6-二甲基吡嗪则仅存在于未霉变的黄精样品中。PCA分析进一步显示,正戊醛、2-甲基丁醛、正己醛、三甲胺、丙酮醛是霉变黄精的特征标志物。结论:本研究筛选出的关键差异成分可作为黄精霉变的标记物,为黄精及中药霉变的监测和质量控制提供有效手段。

Separation of Ions from Volatile Organic Compounds Using High-Field Asymmetric Waveform Ion Mobility Spectrometry-Mass Spectrometer

A combination of high-field asymmetric waveform ion mobility spectrometry （FAIMS） with mass spectrometer （MS） was analyzed. FAIMS separates ions from the volatile organic compounds in the gas-phase as an ion-filter for MS. The sample ions were created at ambient pressure by ion source, which was equipped with a 10.6 eV UV discharge lamp （A=116.5 nm）. The drift tube of FAIMS is composed of two parallel planar electrodes and the dimension is 10 mm×8 mm×0.5 mm. FAIMS was investigated when driven by the high-filed rectangular asymmetric waveform with the peak-to-peak voltage of 1.36 kV at the frequency of 1 MHz and the duty cycle of 30%. The acetone, the butanone, and their mixture were adopted to characterize the FAIMS-MS. The mass spectra obtained from MS illustrate that there are ion-molecular reactions between the ions and the sample neutral molecular. And the proton transfer behavior in the mixture of the acetone and the butanone is also observed. With the compensation voltage tuned from -30 V to 10 V with a step size of 0.1 V, the ion pre-separation before MS is realized.

基于UPLC-Q-TOF MS及GC-MS技术分析脑血栓专利方全成分

本研究采用超高效液相色谱-四极杆飞行时间质谱(UPLC-Q-TOF MS)法和气相色谱-质谱(GC-MS)法分析脑血栓专利方的化学成分。对于非挥发性成分,采用Waters BEH C18色谱柱(100 mm×2.1 mm,1.7μm),以0.1%甲酸水溶液-乙腈为流动相进行梯度洗脱,电喷雾离子源正、负离子模式采集数据;对于挥发性成分,采用DB-5MS毛细管柱(30 m×0.25 mm,0.25μm)在程序升温下分离,EI离子源电离,质量扫描范围m/z 50~550。根据精确质荷比、二级质谱信息、NIST标准谱库检索及相关文献鉴定脑血栓专利方成分,并对化合物进行来源归属。结果表明,在脑血栓专利方中共鉴定出61种非挥发性成分以及29种挥发性成分,其中包括14种黄酮类、13种萜类、9种苷类、5种有机酸类、17种烃类、3种醇类、1种醛类、1种酯类、3种酚类、2种萜烯类以及12种其他类型的化合物。本研究可为揭示脑血栓专利方的药效物质基础提供数据支持。

Fourier Spectrometer based on Wide-range and Phase-locked Michelson Interferometer with Femtosecond Laser Excitation

A wide-range and phase-locked Michelson interferometer technique is described. This technique combined with femtosecond laser is used to measure the spectrum of the rare-earth ion Nd：YVO4, which presents very high signal to noise ratio of interferometric intensity output and higher spectral resolution than traditional grating spectrophotometer.

基于GC-IMS和GC-MS技术结合化学计量法分析干燥方式对香椿挥发性成分的影响

为研究干燥方式对香椿挥发性风味物质的影响,利用气相色谱-离子迁移谱技术(gaschromatography-ion mobility spectrometry,GC-IMS)和气相色谱-质谱联用技术(gas chromatography-mass spectrometry,GC-MS)、相对香气活性值(relative odor activity value,ROAV)对真空冷冻干燥、热泵干燥、热风干燥、微波真空干燥的香椿样品进行挥发性成分分析,并进一步结合化学计量方法主成分分析(principal component analysis,PCA)和偏最小二乘判别分析(partial least squares-discriminant analysis,PLS-DA),探究样品间挥发性成分的差异性。结果表明,通过GC-IMS检测到78个峰,鉴定出59种化合物。通过GC-MS鉴定出94种挥发性化合物,主要挥发性成分是硫化物、烯烃类和醛类。经过干燥后总挥发性化合物的含量显著降低。通过ROAV法确定了(E,Z)-二-1-丙烯基二硫化物、2-巯基-3,4-二甲基-2,3-二氢噻吩、正己醛、2-己烯醛、丁香酚等为香椿样品中关键香气化合物。PCA和PLS-DA结果表明,不同干燥方式的样品与新鲜样品有明显的分离,彼此之间也有明显的区别。鲜样和真空冷冻干燥样品为一组,其他3个干燥香椿样品为一组。根据变量投影重要性(variable importance in projection,VIP)得分共筛选出10种(VIP>1)标志挥发性化合物。干燥方式对香椿风味特性影响显著,真空冷冻干燥组与鲜样最为接近,考虑实际应用热泵干燥为香椿最适宜的脱水方式。本研究为热加工过程中风味品质控制提供一定的理论参考。