Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) is regarded as a novel molecular imaging approach that integrates DESI source with conventional mass spectrometry to provide spatial information and molecular composition on the sample’s surface. In this review, the principle of DESI-MSI was elucidated, including its desorption process and ionization mechanism. Through the applications in biological tissues and organs, the advantages of DESI-MSI technology were demonstrated in exploring the tissue functional roles and disease mechanisms, including brain, liver, kidney, and lung. Building on these findings, we review DESI-MSI’s unique capability to map both exogenous and endogenous biomolecules, thereby providing insights into spatial distribution of exogenous organisms and endogenous metabolic of transformation pathways and pharmacokinetics. Finally, the recent applications of DESI-MSI in biomedicine, environmental monitoring, and food safety are also reviewed. With the continuous improvement of instruments and analysis methods, DESI-MSI is expected to bring meaningful changes across a growing number of fields, opening up exciting opportunities to support innovative technologies and applied research.

Understanding the dynamic evolution of volatile organic compounds (VOCs) in crushed garlic is important for controlling sensory quality during processing and storage. Herein, a quasi-real-time analytical platform based on acoustic levitation (AL) coupled with GC-MS and chemometric analysis was developed for monitoring VOCs changes during the color transition of crushed garlic. The gas-liquid interface of acoustically levitated droplets enabled efficient contactless enrichment of VOCs, improving detection sensitivity and minimizing contamination. During a six-day color transition, 94 VOCs were identified, among which 24 flavor-active compounds were classified into nine aroma categories. Chemometric analyses (PCA and OPLS-DA) clearly differentiated four color stages based on VOC profiles and aroma categories. Generalized additive models (GAMs) revealed nonlinear temporal changes in representative VOCs. Integrated analysis of OPLS-DA variable importance on projection results, GAMs indicated that diallyl trisulfide was strongly associated with garlic discoloration and could serve as a potential marker compound for color-related flavor evolution. Finally, sensory evaluation revealed significant differences in aroma attributes across color stages (p < 0.05), with green and cooling notes peaking early and sulfur, burnt, fruity, and dairy notes increasing at later stages, consistent with VOC profiles. This study demonstrates the capability of AL-GC-MS for quasi-real-time VOC monitoring and provides new insights into the relationship between color development and flavor evolution in crushed garlic.

Vacuum ultraviolet photoionization (VUV-PI), as a soft ionization technique, is characterized by few fragment ions, high sensitivity, and rapid analysis, making it suitable for the complex sample detection. Due to cost-effectiveness, compact structure, and low maintenance requirements, VUV lamps are the primary light source choice for vacuum ultraviolet photoionization mass spectrometry (VUV-PI-MS). This article reviews the advancements and applications of VUV-PI-MS, focusing on novel photoionization sources based on VUV lamps. The ionization mechanisms of VUV-PI are first explicated, and the working mechanisms and structures of VUV lamps are then introduced. Key advancements include the development of novel VUV lamps to increase photon flux, the fabrication of innovative optical windows to extend VUV lamps lifetime, the design of ionization region to enhance ion transmission efficiency and the addition of dopants to assist photoionization for an expanded analysis range. The advantages and disadvantages of four different photoionization source technologies are compared. Representative examples of VUV-PI-MS applications are reviewed in life sciences, environmental monitoring, food safety, and public security. Finally, the future development of VUV-PI source in enhancing photon flux and long-term stability are envisioned, aiming to provide valuable insights for researchers in the field of mass spectrometry.

Development of combined mass spectrometry ionization sources has enabled expansion of the application and scope of mass spectrometry. A novel hybrid ionization system combining vacuum ultraviolet (VUV) and atmospheric pressure chemical ionization (APCI) was constructed. Gaseous samples were self-aspirated into an ionization zone through a capillary by negative pressure, generated by high-speed airflow based on the Venturi effect. Compared with APCI mode alone, the signal-to-noise ratio (S/N) in APCI/VUV mode was increased by about 276-times. To increase the ionization efficiency further, correlated experimental conditions were optimized. Four types of volatile organic compounds (VOCs) were tested to evaluate the performance of the APCI/VUV ion source. Excellent linearity and limit of detection were achieved for compounds in mixed solutions. Quantitative analyses of four VOCs (toluene, cyclohexanone, styrene and ethylbenzene) using APCI/VUV-MS were done, and the relative standard deviations (RSDs) were 1.57%, 6.30%, 4.49% and 8.21%, respectively, indicating that the APCI/VUV ionization source had excellent reproducibility. Our results demonstrated that the developed method was promising for analyzing VOCs as well as being rapid, simple, and easy to operate. An atmospheric pressure chemical ionization/photoionization combined ionization source was built through the Venturi effect for introducing samples to detect volatile organic compounds.

Various nucleic acid molecular machines have emerged in recent years. However, when the nucleic acid tracks are fully depleted, these walkers are highly susceptible to premature release or stalling in regions where the tracks are locally exhausted. In this work, a molecular walking machine with a cleat domain preventing dissociation from the track was explored for ultrasensitive detection of miRNA. It has been verified that the cleat design can enhance the signal amplification efficiency of molecular walking machines for electrochemical miRNA-141 detection. Notably, the single-step electrochemical biosensing platform utilizing the cleat -equipped molecular walking machine (CMWM) is exceptionally straightforward and rapid, concluding the reaction within 90 min and achieving a remarkable low detection limit of 0.26 fM. The proposed molecular walking machine with this specific cleat structure was utilized for the identification of miRNA-141 in cellular lysates, exhibiting remarkable selectivity and consistent reproducibility, showcasing its effective utility in bioanalysis. Therefore, the cleat walker developed in this study introduces an innovative method for constructing a miRNA electrochemical biosensing platform, offering new perspectives for its application in biomolecule detection and clinical disease diagnosis.

Matrix deposition plays a critical role in image quality of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). To improve the ionization efficiency and overcome the limitation of traditional matrix deposition methods in the face of difficult-to-sublimate or difficult-to-dissolve matrix, covalent organic frameworks (COFs) named COF-DhaTab was successfully synthesized and firstly used as matrix film. It was fabricated by imprinting of sieved COF-DhaTab powder on the surface of a double-sided adhesive tape. Outstanding reproducibility and uniformity of COF-DhaTab film were demonstrated by relative standard deviation (RSD) within 8.37% and 7.71% from dot-to-dot and plate-to-plate, respectively. With the introduction of double-sided adhesive tape, water contact angle (WCA) of COF-DhaTab film increased from 55 degrees to 141 degrees, resulting in significant suppression of analyte diffusion. Moreover, the intensity of potassium perfluorooctanic sulfonate (PFOS, C8F17SO3-, m/z 498.93) was 9.3 x 105, more than six hundred times higher than that using DHB matrix. This enhancement was attributed to the rough surface and multiple branches of the synthesized COFDhaTab. To verify the ability of COF-DhaTab film as substrate, the spatial distribution of PFOS in zebrafish, rat liver and kidney tissues was explored. Superior imaging capability was displayed with high-spatial resolution and reliable location distribution. These results not only demonstrate the outstanding ability of COF-DhaTab as matrix for MALDI-MS and MALDI-MSI, but also provide a facile approach for fabrication of novel matrix films for MALDI-MSI.

A twice-walk strategy based on a three-dimensional (3D) cleat-equipped DNA walking machine with a high signal amplification efficiency was investigated for ultrasensitive detection of miRNA.

为凸显桂叶油的感官特征并降低其中黄樟素的质量分数,以水蒸气蒸馏法获得了桂叶油,利用自主设计研发的制备级全自动二维柱色谱分离系统对桂叶油进行了精细化加工,结合感官评价定位了风格特征突出的桂叶油特色风味组群,利用GC-MS分析了特色风味组群中的挥发性成分及黄樟素的质量分数.结果表明:①水蒸气蒸馏法获得的桂叶油得率为0.9%.②二维柱色谱技术有效分离了桂叶油中感官表现不良的组群,获得了感官特征突出、感官品质提升的桂叶油特色风味组群产品,组群C1维持了桂叶油显著的辛香特征,同时甜香和甜味得以提升;组群C2的甜香提升明显且能够降低参比卷烟的收敛感.③组群C1中共检出31种挥发性成分,其中,8种成分具有辛香特征,16种成分具有甜香特征,丁香酚的质量分数高达720.92μg/g;组群C2中检测出14种挥发性成分,其中,7种成分具有甜香特征.④与分离前桂叶油相比,特色风味组群C1和C2中黄樟素的质量分数分别降低了99.7%和98.7%.该研究可为烟用天然香料的精细化加工提供技术参考.

Accurate and sensitive measurements of free fatty acids (FFAs) in biological samples are valuable for diagnosing and prognosing diseases. In this study, an in-source microdroplet derivation strategy combined with highresolution mass spectrometry was developed to analyze FFAs in lipid extracts of biological samples directly. FFAs were rapidly derivated with 2-picolylamine (PA) in the microdroplet which is derived by electrospray. With the proposed method, twelve typical FFAs were determined reliably with high sensitivity and acceptable linearities (R2 & GE; 0.94). The LODs and LOQs for the twelve FFAs were 9-76 pg mL-1 and 30-253 pg mL-1, respectively. The developed method was applied to analyze the alteration of FFAs in liver and kidney samples of rats induced by perfluorooctane sulfonate (PFOS) exposure. The good results demonstrate that the established analysis technique is dependable and has promising applications in detecting FFAs associated with complex biological samples.

为探讨配标溶剂对双区大气压化学电离-质谱(DRAPCI)源内溶剂效应造成的影响,以环境烟气(ETS)标志物3-乙烯基吡啶(3-EP)为研究对象,以环己烷、甲醇、丙酮和乙腈为配标溶剂,考察3-EP在不同溶剂背景下离子化效率的差异,探讨造成差异的原因,并比较不同配标溶剂下方法的分析性能.结果表明:①配标溶剂的选择会影响3-EP的离子化效率,从而限制方法的检出限和定量限,通过营造不同的溶剂氛围发现3-EP的离子化效率差异可能是质子竞争和中性分子团簇包埋共同作用的结果.在此基础上,确定环己烷为配标溶剂并建立ETS中3-EP分析的DRAPCI-MS方法,该方法检出限(0.38 ng/L)和定量限(1.15 ng/L)低,在低浓度范围区域线性良好(R2=0.9964).②对ETS中3-EP变化的动态监测显示选择合适配标溶剂建立的方法可延长动态检测时间范围,更好地呈现环境烟气动态变化的特征,表明采用常压质谱法进行定量分析时必须考虑溶剂效应可能造成的干扰,应优化配标溶剂的组成和用量.

为了解干燥工序对卷烟风格的影响,开展了 5种典型烟叶模块经回潮后不同干燥方式及加工强度工艺试验,并对样品风格特征进行了感官评价和分析.结果表明:①干燥加工处理均引起生青气减少,除部分低强度干燥外均引起焦香增加、果香降低;云南、福建烟叶模块清香和巴西烟叶模块酸味、苦味有所减少;河南、贵州烟叶模块干草香、坚果香有所增加.②松散回潮与真空+松散回潮处理样品甜香、清香、焦香、坚果香、果香、树脂香、枯焦气有显著性差异;滚筒干燥和气流干燥样品坚果香、木质气、焦香、木香有显著性差异.③滚筒干燥脱水量与生青气、清香、果香、甜香负相关,与枯焦气、焦香正相关;气流干燥脱水量对风格的影响与滚筒干燥基本类似,并与干草香、甜味负相关.

为使读者了解敞开式离子化质谱(AIMS)技术及其在烟草化学中的应用,综述了基于电喷雾、等离子体和激光电离技术的AIMS的研究进展,对其中具有代表性和应用较广泛的AIMS技术进行了详细介绍,归纳了近十年来AIMS技术在烟草化学中的应用情况,并对其在烟草化学中的未来发展方向进行了总结和展望.

The excessive flavorings in food are a growing public health concern, particularly in foods for infants and children. A rapid and simple method for simultaneous detection of multiple flavorings in food is urgently needed. In this work, a method with direct analysis in real time-mass spectrometry has been developed and applied to the simultaneous determination of four flavorings, including maltol, ethyl maltol, vanillin, and ethyl vanillin. The ionization efficiency of flavor compounds in the quantitatively-dip-it probe mode was compared with that in the quick strip mode, which revealed that a solvent-assisted ionization mechanism might be involved in the ionization process. The developed method showed good linearity (R-2 > 0.99) in the range from 5 to 1000 mu g L-1, sensitivity (LODs < 3.3 mu g L-1), recoveries (84.8%-96.9%), satisfactory repeatability (RSD < 14.3%, n = 5), and high-throughout (12 infant formula samples completed in 15 min). The LOQs (0.55-1.1 mg kg(-1)) for the infant formula sample were much lower than the regulatory limits. The developed method provided an alternative way to monitor the excessive addition of flavorings.

为了解烟用天然香料中有机酸和无机阴离子的分布特征,采用超声辅助萃取-离子色谱方法定量考察了202种烟用天然香料中的乙酸、乳酸、苹果酸、富马酸、柠檬酸、Cl-、NO2-、SO42-和PO43-,并采用单因素方差分析和主成分分析法分析相关数据.结果表明:①不同种类天然香料中有机酸和无机阴离子的浓度差异较大.浓缩物、提取物和浸膏中有机酸和无机阴离子的浓度均值高于精油和净油,酊剂和树脂中有机酸和无机阴离子的浓度均值居中;枣类天然香料中富马酸和梅子类天然香料中柠檬酸的浓度均值显著高于其他类天然香料.②不同产品类型和原料种类的天然香料中有机酸和无机阴离子分布特征明显,这对于天然香料的品质评价和调香时天然香料的选用具有重要参考价值.

A derivatization-direct mass spectrometry for determination of formaldehyde, acetaldehyde and acrolein in aerosols from electronic cigarette was developed. O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) was chosen as derivatization reagent. The determination results were verified by a recommended method. The results showed that this method had high sensitivity with limits of detection <= 0.028 mu mol/L, good precision with a relative standard deviation <= 5.3%, favorable linearity with R(2)0.9966, and spiked recoveries from 93% to 101%. The relative errors of determination results of two methods were less than 9.8%. A toxicology assay indicated that these aldehydes have important contributions to the toxicity of aerosols.

In this paper, graphitic carbon-nitride (g-C3N4) nanosheets agglomerated poly (styrene-divinylbenzene) (PSDVB) anion-exchange stationary phase was prepared and applied in ion chromatography. The mono-dispersity, diameters, porosity and surface characteristics of g-C3N4 nanosheets agglomerated PS-DVB microspheres were measured by scanning electron microscope and nitrogen adsorption-desorption measurements. The quaternized g-C3N4 nanosheets agglomerated PS-DVB anion-exchange stationary phase was characterized by Fourier Transform Infrared Spectroscopy, Elemental Analysis, Breakthrough Curve and Mechanical Intensity Test. The chromatographic properties of self-fabricated anion-exchange column packed with septuple quaternized g-C3N4 nanosheets agglomerated PS-DVB microspheres were investigated by separating six conventional anions and four monovalent organic acids. According to the results, g-C3N4 nanosheets were successfully agglomerated onto the surface of PS-DVB microspheres; g-C3N4 nanosheets agglomerated PS-DVB showed good reactivity due to the presence of terminal amino groups; baseline separation of six conventional anions and four monovalent organic acids were obtained on this column. Finally, the self-fabricated column was successfully applied to the determination of mercaptoacetic acid in water reducer.

为阐明基质对烟碱感官作用的影响,系统评价了不同质量分数的烟碱在水溶液、亲水性气溶胶(丙二醇)和亲油性气溶胶(三乙酸甘油酯)等不同介质中的感官作用特征,测定了各介质中烟碱的风味觉察阈值,并分别利用pH值和核磁共振谱(NMR)计算了不同质量分数烟碱水溶液和烟碱气溶胶冷凝物中的游离烟碱比例(αfbn).进而,考察了各类介质中乳酸和薄荷醇对烟碱感官作用特征、风味觉察阈值以及αfbn的影响;对比了相同质量分数的烟碱在不同气溶胶介质中感官作用的差异,并利用顶空固相微萃取-气质联用技术(SPME-GC/MS)研究了溶剂极性对烟碱气相分布的影响.结果表明:①在所采用的评价方式下,烟碱水溶液主要表现为口腔刺激,烟碱气溶胶具有喉部顶撞感(劲头)并带来鼻腔和喉部的刺激性;②烟碱在水溶液、丙二醇气溶胶和三乙酸甘油酯气溶胶中的风味觉察阈值分别为0.072、0.296和0.197 mg/g;③在不同介质中,乳酸均通过显著降低αfbn而降低烟碱刺激性并提升其觉察阈值,薄荷醇也能产生类似作用但对αfbn没有影响;不同极性的气溶胶介质则可能通过改变烟碱气相分布情况影响其感官作用特征和风味觉察阈值.

电气设备状态监测与故障诊断技术是提高电气系统运行安全高效的关键.结合烟草行业从意大利G.D公司进口的GDX2型包装机组为例,对卷烟包装机的电气设备状态监测与故障诊断技术现状进行分析研究,结合具体设备的电控组成,客观认识未来电气设备状态监测与故障诊断技术的发展,目的 在于保证烟草行业包装设备运行的安全性和性能有效性.

电气设备状态监测与故障诊断技术作为保证电气设备运行正常的关键,结合其重要性剖析,对故障诊断技术具体应用进行详细研究,目的在于更有效地保证电气设备运行正常,提高电气设备的运行效率.电气设备状态监测与故障诊断技术的应用,直接影响电气系统运行情况.

The transfer rates to particulate phase of mainstream cigarette smoke and olfactory thresholds of 15 endogenous acidic aroma components in cigarette smoke were studied. The ratio of transfer rate to olfactory threshold of each component was defined as its to characterize the difference in contributions of aroma components to sensory characteristic of cigarette smoke. The results showed that:1) The transfer rate of acetic acid was the highest (36.61%), and those of the other 14 acidic aroma components ranged from 9.67% to 17.15%. 2) The flavoring contribution of isovaleric acid was the highest (169.76), and those of 3-methylvaleric acid, valeric acid, and butyric acid were in the range of 14.25-52.13, and those of acetic acid, 2-methylbutyric acid, 2-methylvaleric acid, hexanoic acid, 3-phenylpropionic acid were from 1.59 to 4.55, and those of the other components were less than 1.00. 3) The flavoring contribution integrated transfer ratio and olfactory threshold of aroma components and could comprehensively and authentically reflect the differences of flavoring components in influencing the sensory characteristics of cigarette smoke, which could be used to guide cigarette flavoring.