Slug-flow microextraction coupled with paper spray mass spectrometry for rapid analysis of complex samples

Analysis of trace compounds in small-volume complex samples is of importance for forensic, clinical, pharmaceutical, environmental, and life science investigation. In this study, we reported the coupling of slug-flow microextraction with paper spray mass spectrometry for rapid analysis of trace analytes in small volume of complicated biological samples such as whole blood, milk, and body fluid, etc. The method is performed by applying a disposable glass capillary for rapid extraction of a small amount of complex samples using a small amount of organic solvent; the loaded organic solvent was then spotted onto a paper triangle and dried out; subsequently, a high voltage and some spray solvent were applied onto the paper triangle for mass spectrometric analysis. By using the proposed method, high sensitivity and satisfactory precision for quantitative analysis of trace macrolide antibiotics in whole bloods and milks as well as perfluorinated compounds in individual small organisms have been successfully achieved. In addition, investigation of bioaccumulation of perfluorinated compounds in individual small organisms has been reached.     

高效液相色谱-质谱法对癍痧凉茶的化学成分鉴定及指纹图谱研究

采用高效液相色谱-飞行时间质谱(HPLC-TOF-MS)和高效液相色谱-离子阱质谱(HPLC-IT-MS)对癍痧凉茶进行化学成分分析。研究结果表明,“黄振龙”和“平安堂”两种癍痧凉茶中共含有40种主要化学成分,其中17种通过与文献对照得到鉴定,13种通过与对照品比较保留时间和质谱数据得到确证。同时采用HPLC-IT-MS建立了“黄振龙”和“平安堂”癍痧凉茶的液相色谱-质谱联用指纹图谱,并采用主成分分析对41批次的癍痧凉茶的质量稳定性和一致性进行了评价。主成分分析结果表明,“黄振龙”和“平安堂”癍痧凉茶之间的化学成分和内在质量具有显著性差异,提示配方组成及生产工艺不同,应予以区分。该分析方法快速、高效、可靠,是癍痧凉茶质量控制的有效手段。     

Paper spray mass spectrometry and PLS-DA improved by variable selection for the forensic discrimination of beers

Paper spray mass spectrometry (PS-MS) combined with partial least squares discriminant analysis (PLS-DA) was applied for the first time in a forensic context to a fast and effective differentiation of beers. Eight different brands of American standard lager beers produced by four different breweries (141 samples from 55 batches) were studied with the aim at performing a differentiation according to their market prices. The three leader brands in the Brazilian beer market, which have been subject to fraud, were modeled as the higher-price class, while the five brands most used for counterfeiting were modeled as the lower-price class. Parameters affecting the paper spray ionization were examined and optimized. The best MS signal stability and intensity was obtained while using the positive ion mode, with PS(+) mass spectra characterized by intense pairs of signals corresponding to sodium and potassium adducts of malto-oligosaccharides. Discrimination was not apparent neither by using visual inspection nor principal component analysis (PCA). However, supervised classification models provided high rates of sensitivity and specificity. A PLS-DA model using full scan mass spectra were improved by variable selection with ordered predictors selection (OPS), providing 100% of reliability rate and reducing the number of variables from 1701 to 60. This model was interpreted by detecting fifteen variables as the most significant VIP (variable importance in projection) scores, which were therefore considered diagnostic ions for this type of beer counterfeit.     

Field-induced wooden-tip electrospray ionization mass spectrometry for high-throughput analysis of herbal medicines

This study demonstrates the first application of field-induced wooden-tip electrospray ionization (ESI) mass spectrometry (MS) for high-throughput analysis of herbal medicines. By application of an opposite and sample-contactless high voltage on the MS inlet rather than wooden tips, a high-throughput analysis device is easily set up, and a relatively fast analysis speed of 6 s per sample was successfully achieved. In addition, fast polarity switching between positive and negative ion detection mode is readily accomplished, which provides more complete chemical information for quality assessment and control of herbal medicines. By using the proposed method, various active ingredients present in different herbal medicines were rapidly detected, and the obtained mass spectra were served as the samples' fingerprints for tracing the origins, establishing the authenticity, and assessing the quality consistency and stability of herbal medicines. Our experimental results demonstrated that field-induced wooden-tip ESI-MS is a desirable method for high-throughput analysis of herbal medicines, with promising prospects for rapidly differentiating the origin, determining the authenticity, and assessing the overall quality of pharmaceuticals.     

液相色谱-串联质谱法同时测定8种花草茶中77种农药残留

以QuEChERS作为样品前处理手段,采用高效液相色谱-串联质谱（HPLC-MS/MS）检测技术,建立了适用于8种花草茶中77种农药残留同时检测的方法。8种花草茶样品均采用1%（v/v）乙酸乙腈溶液和1 g乙酸铵提取,经4 g无水硫酸镁、0.50 g C18、0.50 g N-丙基乙二胺（PSA）和0.05 g石墨化炭黑（GCB）分散萃取净化,然后采用Venusil MP C18色谱柱分离,以0.1%（v/v）甲酸水溶液和乙腈为流动相梯度洗脱,在电喷雾电离（ESI）源、正负离子交替扫描模式下进行检测,基质匹配标准溶液定量。结果表明,77种农药在0.5~100.0 μ g/L范围内线性关系良好,相关系数大于0.995;77种农药的加标回收率为70.3%~110.0%,相对标准偏差为2.6%~9.8%,检出限为1.0~10.0 μ g/kg。该法灵敏度、准确度和精密度均符合相关农药残留测定的技术要求。     

Biogenic aldehyde determination by reactive paper spray ionization mass spectrometry

Ionization of aliphatic and aromatic aldehydes is improved by performing simultaneous chemical derivatization using 4-aminophenol to produce charged iminium ions during paper spray ionization. Accelerated reactions occur in the microdroplets generated during the paper spray ionization event for the tested aldehydes (formaldehyde, n-pentanaldehyde, n-nonanaldehyde, n-decanaldehyde, n-dodecanaldehyde, benzaldehyde, m-anisaldehyde, and p-hydroxybenzaldehyde). Tandem mass spectrometric analysis of the iminium ions using collision-induced dissociation demonstrated that straight chain aldehydes give a characteristic fragment at m/z 122 (shown to correspond to protonated 4-(methyleneamino)phenol), while the aromatic aldehyde iminium ions fragment to give a characteristic product ion at m/z 120. These features allow straightforward identification of linear and aromatic aldehydes. Quantitative analysis of n-nonaldehyde using a benchtop mass spectrometer demonstrated a linear response over 3 orders of magnitude from 2.5 ng to 5 μg of aldehyde loaded on the filter paper emitter. The limit of detection was determined to be 2.2 ng for this aldehyde. The method had a precision of 22%, relative standard deviation. The experiment was also implemented using a portable ion trap mass spectrometer.     

Direct analysis of herbal powders by pipette-tip electrospray ionization mass spectrometry

Conventional electrospray ionization mass spectrometry (ESI-MS) is widely used for analysis of solution samples. The development of solid-substrate ESI-MS allows direct ionization analysis of bulky solid samples. In this study, we developed pipette-tip ESI-MS, a technique that combines pipette tips with syringe and syringe pump, for direct analysis of herbal powders, another common form of samples. We demonstrated that various herbal powder samples, including herbal medicines and food samples, could be readily online extracted and analyzed using this technique. Various powder samples, such as Rhizoma coptidis, lotus plumule, great burdock achene, black pepper, Panax ginseng, roasted coffee beans, Fructus Schisandrae Chinensis and Fructus Schisandrae Sphenantherae, were analyzed using pipette-tip ESI-MS and quality mass spectra with stable and durable signals could be obtained. Both positive and negative ion modes were attempted and various compounds including amino acids, oligosaccharides, glycosides, alkaloids, organic acids, ginosensides, flavonoids and lignans could be detected. Principal component analysis (PCA) based on the acquired mass spectra allowed rapid differentiation of closely related herbal species.     

Cell-patterned glass spray for direct drug assay using mass spectrometry

In this work, the establishment of a glass spray mass spectrometry (GS-MS) platform for direct cell-based drug assay was described. Cell co-culture, drug-induced cell apoptosis, proliferation analysis and intracellular drug absorption measurement were performed simultaneously on this specifically designed platform. Two groups of co-cultured cells (NIH-3T3/HepG2 and HepG2/MCF-7) were cultivated and they showed high viability within 3 days. The biocompatibility of the platform facilitated the subsequent bioassays, in which, cyclophosphamide (CPA) and genistein were used as the model drugs. The distinctions of cell apoptosis and proliferation between the mono-cultured and co-cultured cells were clearly observed and well explained by in situ GS-MS measurements. A satisfactory linearity of the calibration curve between the relative MS intensity and CPA concentrations was obtained using stable isotope labeling method (y = 0.16545 + 0.0985x, R² = 0.9937). The variations in the quantity of absorbed drug were detected and the results were consistent with the concentration-dependence of cell apoptosis. All the results demonstrated that direct cell-based drug assay could be performed on the stable isotope labeling assisted GS-MS platform in a facile and quantitative manner.     

Quality control method for commercially available wild Jujube leaf tea based on HPLC characteristic fingerprint analysis of flavonoid compounds

Flavonoids are the main active components of natural medicinal plants with many physiological functions. In this study, an HPLC fingerprinting method based on the distribution and relative amount of 11 bioactive flavonoids was established for the quality evaluation of commercially available wild Jujube leaf tea (JLT) from China. Separation of the crude flavonoid extract was achieved on a column filled with C₁₈ material with a high carbon content. The flavonoids in wild JLT were identified based on UV spectroscopy and accurate mass measurements by TOF‐MS. Twenty‐one batches of practical samples collected from different habitats were analyzed by using the developed HPLC method to construct the HPLC characteristic fingerprint of wild JLT. Then, combined with clustering and similarity analyses, the HPLC characteristic fingerprint was used for the authentication and quality evaluation of commercial wild JLT. Results indicated that the proposed HPLC characteristic fingerprint reflected the inherent characteristics of wild JLT collected from different regions. Authenticity identification and quality control of commercially available wild Jujube tea were achieved based on the HPLC characteristic fingerprint analysis. This new approach to bioactive component profiling provided a promising reference method for the quality evaluation of commercial wild flower and plant tea.     

Analysis of amino acids in latent fingerprint residue by capillary electrophoresis‐mass spectrometry

The analysis of the chemical composition of fingerprints is important for the development and improvement of existing fingerprint enhancement techniques. This study demonstrates the first analysis of a latent fingerprint sample, using an optimized CE‐MS method. In total 12 amino acids were detected in the fingerprint sample. MS/MS fragmentation was used to provide additional identity confirmation, for which eight of the twelve detected amino acids generated confirmatory product ions. Nine amino acids were quantified and their relative abundances were consistent with previous studies with serine and glycine being the most abundant. The successful detection of amino acids from latent fingerprints demonstrates that CE‐MS is a potential future technique for further study of such compounds in fingerprint samples.     

Quantitation of anthocyanins in elderberry fruit extracts and nutraceutical formulations with paper spray ionization mass spectrometry

The ability to rapidly identify and quantitate, over a wide range of concentrations, anthocyanins in food and therapeutic products is important to ensuring their presence at medicinally significant levels. Sensitive, yet mild, analysis conditions are required given their susceptibility to degradation and transformation. Paper spray ionization has been used to detect and quantify the levels of anthocyanin levels in extracts of fresh and dried elderberries, and elderberry stems, as well as 3 commercially available nutraceutical formulations. The component cyanidin glucosides, including cyanidin‐3‐sambubioside, cyanidin‐3‐glucoside, cyanidin‐3,5‐diglucoside, cyanidin‐3‐sambubioside‐5‐glucoside, and the aglycone cyanidin, were readily detected in a range of sources. Quantitation was achieved by establishing a calibration plot from dilutions of a stock solution of cyanidin‐3,5‐diglucoside containing malvidin‐3,5‐diglucoside as an internal standard at a fixed concentration. The same standard was used to quantify the anthocyanin content in the fruit and nutraceutical formulations. Wide 5‐fold variations in anthocyanin concentration were detected in the nutraceutical formulations from different suppliers ranging from 1050 to 5430 mg/100 g. These concentrations compared with 500 to 2370 mg/100 g measured in the dried stems and fruit, respectively.     

Rapid and simultaneous determination of curcuminoids and gingerols in food products containing turmeric and ginger using paper spray mass spectrometry

Turmeric and ginger are extensively employed as functional ingredients due to their high content of curcuminoids and gingerols, considered the key bioactive compounds found in these roots. In this study, we present an innovative and fast method for the assay of curcuminoids and gingerols in different foods containing the two spices, with the aim of monitoring the quality of products from a nutraceutical perspective. The proposed approach is based on paper spray tandem mass spectrometry coupled with the use of a labeled internal standard, which has permitted to achieve the best results in terms of specificity and accuracy. All the calculated analytical parameters were satisfactory; accuracy values are around 100% for all spiked samples and the precision data result lower than 15%. The protocol was applied to several real samples, and to demonstrate its robustness and reliability, the results were compared to those arising from the common liquid chromatographic method.     

On the intersection of electrochemistry and mass spectrometry

The application of nanopipettes, developed first as a tool for electrochemistry and electrophysiology, as tools for mass spectrometry is considered. Recent examples of advances in electrospray ionization and sampling for mass spectrometry with nanopipettes is discussed. These examples show a scientific intersection that is ripe for further development.     

Multiresidue GC-MS/MS pesticide analysis for evaluation of tea and herbal infusion safety

ABSTRACT

A fast, simple, low-cost and high-throughput multiresidue pesticide analysis method was developed and validated for 300 pesticides in herbal and fruit infusion samples based on modified QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure combined with gas chromatography coupled with tandem mass spectrometry method (GC-MS/MS). The objectives were to develop low cost GC-MS/MS method, validate the method in accordance to SANTE/11,813/2017 guidance document and application in routine. The results obtained using different GC and MS/MS parameters were evaluated in order to develop quick, robust, accurate and effective multiresidue method. Total analysis time was 28 min with 0.6 µL injection volume. For accurate quantification, matrix-matched calibration (MMC) curves (in range of 10 µg/kg – 250 µg/kg) were applied to compensate matrix effect. The limits of quantification (LOQ) were ranged between 0.06 µg/kg and 135 µg/kg, and for the majority of the pesticides the LOQ were below the regulatory maximum residue limits. Most recoveries at 10 µg/kg and 100 µg/kg were in the range 70%–120% indicating satisfactory accuracy. The validated method was applied to commercial herbal and fruit infusion products detecting chlorpyriphos, DEET, tebuconazole, terbuthylazine, piperonyl butoxide, biphenyl, pendimethalin, pirimiphos-methyl and p,p’-DDE in more than 100 samples from 1,466 so risk assessment on human health was calculated specially for those pesticides.     

超高效液相色谱-串联质谱法对癍痧凉茶中18种活性成分的定量分析

建立了超高效液相色谱-串联质谱(UHPLC-MS/MS)测定癍痧凉茶中18种活性成分的定量分析方法。癍痧凉茶样品经甲醇萃取后,采用RRHD SB-C18(100 mm×3.0 mm,1.8μm)超高效液相色谱柱进行分离,以0.5%甲酸水溶液-乙腈为流动相进行梯度洗脱。18种活性成分的定量分析采用三重四极杆串联质谱以负离子检测模式多重反应离子监测进行。实验结果表明,所建立的方法线性良好,18种目标化合物的线性相关系数(r)不小于0.996 4;分析方法的灵敏度高,检出限和定量下限分别为0.001~0.08μg/m L和0.002~0.27μg/m L;同时具备精密度高、准确度好、稳定性理想等优点。建立的分析方法用于测定11批"黄振龙"癍痧凉茶和8批"平安堂"凉茶。结果表明,"黄振龙"和"平安堂"样品中18种活性成分的浓度分别为0.7~149.8μg/m L和0.9~110.3μg/m L。采用主成分分析(PCA)对这19批次癍痧凉茶样品进行来源追踪,并对其质量的稳定性和一致性进行了评价。PCA得分图可将两个厂家的癍痧凉茶明显区分开,提示两种凉茶的配方组成及生产工艺不同,所建立的分析方法可有效用于癍痧凉茶的质量评价与控制。     

Direct drug analysis from oral fluid using medical swab touch spray mass spectrometry

Fourteen common drugs of abuse were identified in spiked oral fluid (ng mL⁻¹ levels), analyzed directly from medical swabs using touch spray mass spectrometry (TS-MS), exemplifying a rapid test for drug detection. Multiple stages of mass analysis (MS² and MS³) provided identification and detection limits sought by international forensic and toxicological societies, Δ⁹-THC and buprenorphine excluded. The measurements were made using a medical swab as both the sampling probe and means of ionization. The adaptation of medical swabs for TS-MS analysis allows non-invasive and direct sampling of neat oral fluid. Data acquisition was rapid, seconds per drug, and MS³ ensured reliable identification of illicit drugs. The reported data were acquired to investigate (i) ionization of common drugs from commercial swabs, (ii) ion intensity over spray duration, and (iii) dynamic range, all as initial steps in development of a quantitative method. The approach outlined is intended for point-of-care drug testing using oral fluid in clinical applications as well as in situ settings, viz. in forensic applications. The proof-of-concept results presented will require extension to other controlled substances and refinement in analytical procedures to meet clinical/legal requirements.     

Vibrating tip spray ionization mass spectrometry for direct sample analysis

In this work, a vibrating tip spray ionization source was developed for direct mass spectrometric analysis of raw samples under voltage‐free condition. A solid tip was mounted on a vibrator, and the solid tip was placed on the front of MS inlet. Liquid, viscous, and bulk solid samples could be directly loaded on the tip‐end surface, and then a drop of solvent at microliter level was subsequently loaded on the tip for dissolution and extraction of analytes, and a vibrator was then started to atomize and ionize the analytes under ambient condition. We demonstrated vibrating tip spray mass spectrometry in various applications, including food safety, pharmaceutical analysis, and forensic science. Furthermore, in situ analysis of biological tissues and in vivo analysis of living plants were conveniently performed, due to voltage‐free. Different vibration frequencies and solvent compositions were investigated. The analytical performances, including sensitivity, reproducibility, and linear range, were investigated. The ionization process and mechanism were also discussed in this work.     

Observation of dimethylaminoethyl methacrylate–myoglobin binding reaction using laser spray mass spectrometry

Covalent bonds are often created by a reaction between chemicals and protein before causing various adverse effects in a cell. Dimethylaminoethyl methacrylate (DMAEMA), which has moderate toxicity, causes skin inflammation and throat irritation. For this study, we investigated a reaction mechanism between myoglobin and (DMAEMA) using a new analytical tool developed at our laboratory: laser spray mass spectrometry technique. It was found that initially DMAEMA was added to the amino group of protein by the Michael addition mechanism; the added DMAEMA was hydrolyzed to methacrylic acid using an autocatalytic system. The results of this study indicate the feasibility of the laser spray technique in analyses of reaction dynamics. Copyright © 2012 John Wiley & Sons, Ltd.     

QuEChERS-超高效液相色谱-串联质谱法快速测定凉茶中非法添加的12种化学药物

建立了凉茶中马来酸氯苯那敏、吡罗昔康、α-细辛脑等12种非法添加的化学药物的QuEChERS结合超高效液相色谱-串联质谱(UPLC-MS/MS)的检测方法。样品经乙腈提取,应用QuEChERS技术净化,经0.22 μm微孔滤膜过滤后进行UPLC-MS/MS测定,以乙腈-0.1%(v/v)乙酸水溶液为流动相梯度洗脱,在XBridge BEH C₁₈柱(100 mm×2.1 mm, 3.5 μm)上实现12种化学药物的基线分离。该方法采用多反应监测(MRM)正离子模式扫描,标准曲线外标法定量。12种待测物在各自的质量浓度范围内线性关系良好,相关系数均大于0.997,检出限为0.1~2.1 μg/L,定量限为0.4~8.0 μg/L。在3个不同添加水平下的平均回收率为62.7%~95.2%, RSD为1.3%~10.8%。应用该方法对市面上销售的74批次凉茶进行了筛查测定,部分样品的测定结果为阳性。该方法操作简单,净化效果好,灵敏度高,适用于凉茶中12种非法添加的化学药物的快速分析。     

Review of molecular modification techniques for improved detection of biomolecules by mass spectrometry

After a soft ionizing method was established, MS (mass spectrometry) has become a more common tool in biochemistry because soft ionization made it possible to detect large molecules such as proteins. Many kinds of applications were established to further utilize MS for the identification or quantitation of biomolecules. In this review, we introduce recent applications with special focus on chemical modification techniques and chemical probes developed for the MS determination of biomolecules.