Paper Spray Ionization Mass Spectrometry Research Articles

Reagent-Pencil and Paper Spray Mass Spectrometry: A Convenient Combination for Selective Analyses in Complex Matrixes

The recent developments on fieldable miniature mass spectrometers require efforts to produce easy-to-use and portable alternative tools to assist in point-of-care analysis. In this paper, the reagent-pencil (RP) technology, which has been used for solvent-free deposition of reagents in paper-based microfluidics, was combined with paper spray ionization mass spectrometry (PS-MS). In this approach, named RP-PS-MS, the PS triangular piece of paper was written with the reagent pencil, consisting of mixtures of graphite and bentonite (used as a support) and a reactive compound, and allowed to react with a given analyte from a sample matrix selectively. We conducted typical applications as proof-of-principles to verify the methodology's general usefulness in detecting small organic molecules in distinct samples. Hence, various aldehydes (2-furaldehyde, valeraldehyde, and benzaldehyde) in spiked cachaça samples (an alcoholic drink produced from fermentation/distillation of sugarcane juice) were promptly detected using a reagent pencil doped with 4-aminophenol (the reactive compound). Similarly, we recognized typical ginsenosides and triacylglycerols (TAGs) in ginseng aqueous infusions and soybean oil samples, respectively, using lithium chloride as the reactive compound. The results indicate that the reagent-pencil methodology is compatible with PS-MS and provides an easy and fast way to detect target analytes in complex samples. The advantage over the usual solution-based deposition of reagents lies in the lack of preparation or carrying different specific solutions for special applications, which can simplify operation, especially in point-of-care analysis with fieldable mass spectrometers.

Phytochemical Characterization of Dillenia indica L. Bark by Paper Spray Ionization-Mass Spectrometry and Evaluation of Its Antioxidant Potential Against t-BHP-Induced Oxidative Stress in RAW 264.7 Cells.

The antioxidant effects of the ethyl acetate fraction of Dillenia indica bark (DIBEt) and the underlying mechanisms were investigated in tert-butyl hydroperoxide (t-BHP)-stimulated oxidative stress in RAW 264.7 cells. Paper spray ionization-mass spectroscopy with positive-ion mode tentatively revealed 27 secondary metabolites in D. indica bark extract; predominant among them were alkaloids, phenolic acids, and flavonoids. A new triterpenoid (nutriacholic acid) was confirmed in DIBEt for the first time. DIBEt had strong free radical-scavenging capabilities and was also able to reduce t-BHP-induced cellular reactive oxygen species (ROS) generation in RAW 264.7 cells. DIBEt was found to prevent oxidative stress by boosting the levels of heme oxygenase-1 (HO-1) through the up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) via the regulation of extracellular signal-regulated kinase (ERK) phosphorylation in RAW 264.7 cells. These results support the potential of DIBEt for defense against oxidative stress-stimulated diseases.

Rapid determination and continuous monitoring of propofol in microliter whole blood sample during anesthesia by paper spray ionization-mass spectrometry.

Propofol is a widely used intravenous anesthetic agent in sedation and general anesthesia. To improve the safety and maintain the depth of anesthesia, it is important to develop a rapid, sensitive, and reliable method to monitor the concentration of propofol in blood during anesthesia continuously. Here, we present a novel strategy based on paper spray ionization-mass spectrometry (PSI-MS) to detect propofol. Samples (in 10μL) were mixed with methanol as protein precipitation solvent and 2,6-dimethylphenol as internal standard. Protein micro-precipitation was achieved with methanol by vortexing and centrifuging for 5s each, and propofol was extracted to the supernatant. PSI-MS was performed in negative ionization mode, and MS signal lasted for 1min. The analysis of a single sample was completed within 2min. The area ratios of propofol to internal standard were calculated for quantification. Limit of detection of 5.5ngmL-1 and limit of quantification of 18.2ngmL-1 were achieved for propofol in whole blood. Calibration curve was linear in the range of 0.02-10μgmL-1. The developed method was used successfully in monitoring the propofol concentration in 3 patients' whole blood during anesthesia, showing its further application in controlling and feeding-back target concentration infusion. Graphical abstract.

A New Strategy for the Analysis of Steroid Hormones in Industrial Wastewaters by Paper Spray Ionization Mass Spectrometry.

A new approach using paper spray ionization mass spectrometry (PSI-MS) for the analysis of steroid hormones in wastewater samples has been demonstrated. Triangular papers containing paraffin barriers as microfluidic channels were used to direct the sample solution to the paper tip, preventing the sample from spreading over the corners of the paper. The method was used to analyze the hormones levonorgestrel and algestone acetophenide in industrial wastewaters. Analytical curves presented a correlation coefficient (R2) above 0.99. Limits of quantification were below 2.3 ppm and limits of detection below 0.7 ppm. Values of precision (coefficient of variation) and accuracy (relative error) were less than 15% for all analyses. Recovery results ranged from 82% to 102%. Levonorgestrel was also analyzed by high-performance liquid chromatography coupled to mass spectrometry in order to compare the analytical performance with PSI-MS. No statistically significant differences were found between both methods. This study demonstrates the usefulness of PSI-MS for rapid analysis of hormones in industrial wastewater samples and also indicates its potential to be employed as a simple and reliable analytical method in environmental sciences.

Mass Spectrometry Techniques in Emerging Pathogens Studies: COVID-19 Perspectives.

As corona virus disease 2019 (COVID-19) is a rapidly growing public health crisis across the world, our knowledge of meaningful diagnostic tests and treatment for severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) is still evolving. This novel coronavirus disease COVID-19 can be diagnosed using RT-PCR, but inadequate access to reagents, equipment, and a nonspecific target has slowed disease detection and management. Precision medicine, individualized patient care, requires suitable diagnostics approaches to tackle the challenging aspects of viral outbreaks where many tests are needed in a rapid and deployable approach. Mass spectrometry (MS)-based technologies such as proteomics, glycomics, lipidomics, and metabolomics have been applied in disease outbreaks for identification of infectious disease agents such as virus and bacteria and the molecular phenomena associated with pathogenesis. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) is widely used in clinical diagnostics in the United States and Europe for bacterial pathogen identification. Paper spray ionization mass spectrometry (PSI-MS), a rapid ambient MS technique, has recently open a new opportunity for future clinical investigation to diagnose pathogens. Ultra-high-pressure liquid chromatography coupled high-resolution mass spectrometry (UHPLC–HRMS)-based metabolomics and lipidomics have been employed in large-scale biomedical research to discriminate infectious pathogens and uncover biomarkers associated with pathogenesis. PCR-MS has emerged as a new technology with the capability to directly identify known pathogens from the clinical specimens and the potential to identify genetic evidence of undiscovered pathogens. Moreover, miniaturized MS offers possible applications with relatively fast, highly sensitive, and potentially portable ways to analyze for viral compounds. However, beneficial aspects of these rapidly growing MS technologies in pandemics like COVID-19 outbreaks has been limited. Hence, this perspective gives a brief of the existing knowledge, current challenges, and opportunities for MS-based techniques as a promising avenue in studying emerging pathogen outbreaks such as COVID-19.

Lab-on-Membrane Platform Coupled with Paper Spray Ionization for Analysis of Prostate-Specific Antigen in Clinical Settings.

The analysis of protein antigens as biomarkers in clinical samples is particularly helpful for the early diagnosis of diseases. However, this is difficult to accomplish owing to the presence of the antigens in trace amounts as well as the complexity of the matrixes in clinical samples. In this study, a lab-on-membrane platform that can be combined with paper spray ionization mass spectrometry was developed for the in situ high-throughput sensitive detection of the prostate-specific antigen (PSA). The sensitivity of the proposed platform was enhanced via two strategies: (1) the synthesis of a biotin-streptavidin scaffold caused an increase in the capturing efficiency of PSA by a factor of 5 and (2) the immobilization of a large number of mass tag molecules on the gold nanoparticles allowed for the amplification of the mass spectrometry signals. The limit of detection was approximately 3.0 pg mL-1. The selectivity to PSA was guaranteed by using an antibody-aptamer pairing sandwich immunoassay, and PSA detection was unaffected even when other protein antigens (carcinoembryonic antigen and carbohydrate antigen 125) were present. The modified membranes maintained their performance for at least 30 days when stored at 4 °C. Finally, analysis of human serum samples confirmed that the PSA concentration as determined using the proposed platform was consistent with that determined with a conventional chemiluminescent immunoassay. Thus, this PSA analyzing platform is suitable for prostate cancer diagnosis in clinical settings.

Quantification of 6-gingerol, metabolomic analysis by paper spray mass spectrometry and determination of antioxidant activity of ginger rhizomes (Zingiber officinale)

Ginger is a plant whose rhizome has a high therapeutic potential in combating various diseases due to the action of several of its constituents. The 6-gingerol, phenolic compounds and carotenoids, act on macrophage modulation, antiplatelet aggregation and immunosuppressive activity. This work aimed to determine the total antioxidant capacity as well as to evaluate the use of paper spray mass spectrometry to obtain fingerprints of ginger samples of conventional and organic cultivation. The results demonstrated that organic farming samples showed higher levels of fiber and total protein, as well as 6-gingerol. One must still give preference to organic Ginger intake since it presented significant levels of 6-gingerol, fiber and protein. Several chemical classes such as sugars, fatty acids, phenylpropanoids and flavonoids were identified in organic and conventional ginger through paper spray ionization mass spectrometry. This analysis proved to be a very efficient and fast technique for obtaining fingerprints of ginger, allowing the identification of 19 compounds in the positive mode and 28 in the negative mode.

Restrict access material for paper spray ionization mass spectrometry: A versatile tool for catecholamines and antidepressants determination in plasma samples

In the present study, a fast, accurate and reliable mass spectrometry methodology without any sample pretreatment step and low solvent consumption for catecholamines and antidepressants determination in plasma samples is reported. An internal surface reversed-phase restrict access material was synthesized onto a paper surface and applied to the extraction of dopamine, epinephrine, diazepam, nortriptyline, and fluoxetine from human plasma following direct desorption by paper spray mass spectrometry (PSI-MS). The developed methodology showed to be accurate, precise and linear in a concentration range from the limit of quantification to 1000 ng mL−1. The limits of quantification for all analytes ranged from 1.4 to 5.3 ng mL−1. According to the results, the developed methodology could be a powerful tool for drug levels monitoring in clinical or urgent care.

Paper Spray Ionization Mass Spectrometry as a Potential Tool for Early Diagnosis of Cervical Cancer.

Squamous intraepithelial lesion is an abnormal growth of epithelial cells on the surface of the cervix that may lead to cervical cancer. Analytical protocols for the determination of squamous intraepithelial lesions are in high demand, since cervical cancer is the fourth most diagnosed cancer among women in the world. Here, paper spray ionization mass spectrometry (PSI-MS) is used to distinguish between healthy (negative for intraepithelial lesion or malignancy) and diseased (high-grade squamous intraepithelial lesion) blood plasmas. A total of 86 blood samples of different women (49 healthy samples, 37 diseased samples) were collected, and the plasmas were prepared. Then, 10 μL of each plasma sample was deposited onto triangular papers for PSI-MS analysis. No additional step of sample preparation was necessary. The interval-successive projection algorithm linear discriminant analysis (iSPA-LDA) was applied to the PSI mass spectra, showing six ions (mostly phospholipids) that were predictive of healthy and diseased plasmas. Values of 77% accuracy, 86% sensitivity, 80% positive predictive value (PPV), and 75% negative predictive value (NPV) were achieved. This study provides evidence that PSI-MS may potentially be used as a fast and simple analytical technique for the early diagnosis of cervical cancer.

Directly transferring pepper constituents to triangular papers for pungency determination by paper spray ionization mass spectrometry.

A method named imprint paper spray ionization mass spectrometry (imprint-PSI-MS) has been developed and employed for the determination of pungency of peppers. A pepper fruit was cut into a triangular shape, deposited onto a triangular paper, and compressed by a homemade press tool aiming to imprint and transfer the pepper constituents onto the paper surface. Subsequently, the triangular paper was submitted to conventional PSI-MS analysis. Twelve peppers were analyzed, ranging from highly pungent to lowly pungent taste. Pepper pungency values from the Scoville scale (in Scoville heat units, SHU) were compared with the ion intensities of the capsaicin and dihydrocapsaicin compounds obtained from the imprint-PSI-MS analysis, and a correlation coefficient of 0.97 was achieved. In addition, the ion intensities of a sugar compound were monitored in all peppers, and the results were compared with the Scoville scale. Low sugar ion intensities were detected in pungent peppers, while high ion intensities were achieved in low-pungent peppers, suggesting that the pepper pungency may be determined by inversely relating pungency to sugar contents. This work demonstrates the utility of the imprint-PSI-MS method to perform rapid qualitative analyses of peppers and estimate the pungency by monitoring the pepper metabolites. Graphical abstract.

Integrating SERS and PSI-MS with Dual Purpose Plasmonic Paper Substrates for On-Site Illicit Drug Confirmation.

Forensic laboratory backlogs are replete with suspected drug samples. Shifting analysis toward the point of seizure would save significant time and public funds. Moreover, a two-tiered identification strategy for controlled substance testing that relies on two independent, discerning methods could entirely circumvent the need for forensic laboratory testing. To this end, we coupled Raman spectroscopy and paper spray ionization mass spectrometry (PSI-MS) on a single instrumental platform. Both methods are capable of ambient analysis with fieldable instruments, yet Raman is often limited to bulk analysis. Critical to this work is the development of a gold nanoparticle (AuNP)-embedded paper swab to extend the capability of Raman spectroscopy to trace evidence via surface-enhanced Raman scattering (SERS). Plasmonic papers are characterized with respect to SERS signals and compatibility with PSI-MS analysis. Proof-of-principle is established with the identification of five representative drugs, and detection limits on the scale of 1-100 ng are achieved for both PSI-MS and SERS. The integrated SERS-PSI-MS system achieved 99.8% accurate chemical identification in a blind study consisting of 500 samples. Additionally, we demonstrate facile discrimination of several JWH-018 isomers via SERS even when MS and MS2 spectra are indistinguishable. Successful coupling of SERS and PSI-MS to enable on-site chemical analysis by two independent methods can potentially lead to a desirable paradigm shift in the handling of drug evidence.

Protein precipitation coupled to paper spray with a tube for one-step analysis of blood.

Accurate measurement of trace compounds in blood samples is important in clinical diagnosis and life science. Ambient ionization mass spectrometry, however, suffers from the matrix effect when dealing with complex samples such as blood. Therefore, it is important to reduce the matrix effects in blood samples. A low-cost and disposable Teflon tube was used as a platform to precipitate the protein in blood. The analytes are extracted into organic solvent, and the precipitated protein can be adsorbed by the chromatography paper inserted. Therefore, the Teflon tube after precipitation can be directly subjected to paper spray ionization mass spectrometry, achieving one-step analysis of blood. High sensitivity and satisfactory stability were achieved for pharmaceuticals, acids, and endogenic metabolites in blood. The absolute signal intensities of characteristic product ions of the tested analytes were 8-20 times higher after protein precipitation than those obtained using paper spray. Detection limits and quantitative performance were evaluated for three drugs: carbamazepine, metformin, and tioconazole. In addition, the limits of detection and quantitation were improved 9-14- and 8-12-fold, respectively. Protein precipitation coupled to paper spray with a tube and then to mass spectrometry was successfully achieved and applied in the one-step analysis of trace compounds in blood samples. The experimental results showed that this method was sensitive, stable, convenient, and economic for the direct analysis of blood.

Distinguishing legal and illegal cigarettes by applying paper spray mass spectrometry and chemometric tools.

Smoking is responsible for one in five deaths around the world. Thus, governments have been trying to reduce the number of active smokers by increasing taxes on products. This scenario creates a new problem by raising the consumption of illegally traded cigarettes, which are often seized and analyzed by police forces. Legal and illegal cigarette samples were extracted and analyzed using paper spray ionization mass spectrometry (PS-MS). The mass spectrometer was set to operate in full-scan positive ion mode to yield representative chemical profiles of each sample. The results were used to build a chemometric model using partial least squares discriminant analysis (PLS-DA) to discriminate between both sets of samples, i.e. legal and illegal. The PS-MS procedure was fast, simple and efficient, yielding high-quality and reproducible mass spectra with a very good signal-to-noise ratio. Even though all samples displayed visually indistinguishable mass spectra, the PS-MS data handled by the PLS-DA approach furnished a model that reached sample classification with rates of 100% and 80% for the training and validation sets, respectively. A novel methodology was successfully developed associating the PS-MS technique with chemometric analysis to differentiate between legal and illegal cigarettes. The PS-MS technique proved to be adequate for obtaining fingerprints of such types of samples despite high complexity, and a PLS-DA model was successfully constructed achieving 82.1% accuracy.

Identification and Confirmation of Fentanyls on Paper using Portable Surface Enhanced Raman Spectroscopy and Paper Spray Ionization Mass Spectrometry

Fentanyl and its analogues play a major role in the current opioid epidemic. In particular, these highly potent opioids have become a health hazard due to their use as additives in street drugs. Consequently, rapid on-site procedures for the analysis of this class of seized drugs are needed, especially considering the reported backlog of drug samples, which must undergo identification and confirmation tests to validate the presence of an illicit substance. Paper based devices are cheap sampling and analysis vehicles that have been shown capable of allowing rapid identification and confirmation of drugs of abuse. Modifying paper substrates by imprinting nanoparticles enables surface enhanced Raman spectroscopy (SERS) as well as a second analysis from the same substrate, namely paper spray ionization mass spectrometry. While such a procedure has been described for laboratory use, these illicit drug samples are typically collected in the field and this is where testing should be done. We combine paper SERS and paper spray MS on field-portable and commercial off-the-shelf (COTS) devices for the rapid and low-cost identification and confirmation of fentanyl and its analogues, enabling in situ analysis at the point of seizure of suspect samples. The commercial nature of both instruments moves this technology from the academic realm to a setting where the criminal justice system can realistically utilize it. The capabilities of this single-substrate dual-analyzer technique are further examined by sampling a variety of surfaces of forensic interest.

Supramolecular microextraction combined with paper spray ionization mass spectrometry for sensitive determination of tricyclic antidepressants in urine

This work describes a novel methodology to analyze four tricyclic antidepressants (amitriptyline, doxepin, imipramine and, nortriptyline) in urine samples by combining supramolecular microextraction and paper spray ionization mass spectrometry (PS-MS). The proposed method uses a supramolecular solvent in which reverse micelles of 1-decanol are dispersed in tetrahydrofuran (THF)/water. The extraction of the tricyclic antidepressants at pH 9.0 requires a sample volume of 10.0 mL, short extraction time (1.0 min of extraction and 5 min of centrifugation), low amounts of organic solvent (50 μL of 1-decanol and 200 μL of THF), and provides high preconcentration factors: 96.9 to amitriptyline, 93.6 to doxepin, 71.3 to imipramine, and 146.9 to nortriptyline. The quantification by PS-MS is fast and straightforward because chromatographic separation is not required and all analytes were determined simultaneously. The limits of detection (LOD), quantification (LOQ), and the precision (RSD, %) of the developed method ranged between 5.2 and 8.6 μg L−1, 17.4–28.7 μg L−1 and 1.3–12.9%, respectively. Urine samples of five individuals (three males and two females) were used for accuracy evaluation. The accuracy obtained in these spiked urine samples at μg L−1 levels varied from 95.3 to 112.0%. The method also provided clean mass spectra with a high signal-to-noise ratio, which demonstrates the analytical appeal combination of supramolecular microextraction with determination by paper spray mass spectrometry.

Agarose hydrogel-enhanced paper spray ionization mass spectrometry for metabolite detection in raw urine.

Rapid analysis of metabolites in biofluids is of great importance for disease diagnosis or new-born disease screening. Herein, we introduce an agarose hydrogel conditioning method to enhance the performance of paper spray ionization mass spectrometry. With facile and fast hydrogel conditioning, the signal intensity of therapeutic drugs spiked in urine was 5 to 15 fold higher than that in direct paper spray ionization mass spectrometry analysis. Consequently, the sensitivity of metabolites in urine was improved via hydrogel conditioning, resulting in 9 to 15 fold decrease in the possibility of detection (POD) levels. These results show that agarose hydrogel conditioning coupled with paper spray ionization mass spectrometry could serve as a facile ionization method for ambient mass spectrometry, which might be useful in fast screening of metabolites and therapeutic drugs in raw biofluids.

Quantification and fast-screening of malachite green in aquaculture water using paper spray ionization mass spectrometry

A rapid quantitative technique had been developed for the screening of malachite green(MG) in aquaculture water using paper spray ionization mass spectrometry(PSI-MS). To rapid extract MG, chloroform and deep eutectic solvents(DESs) were used as extraction agent and co-solvent respectively. malachite green D_5(MG-D_5) was used as an internal standard to quantitative determination MG, C_(18) chromatographic column(4. 6 mm×250 mm, 5 μm). The method showed a good linearity(R~2=0. 999) in the concentration range of 0. 1-10 μg/mL with the detection limit of 0. 03 μg/mL and the quantitative limit of 0. 1 μg/mL. The intra-and inter-day precisions were 3. 5% and 6. 2%, and the recovery ranged from 98. 9% to 106. 9%(n=7). The detection result by PSI-MS were in agreement with those by liquid chromatography-tandem mass spectrometry(LC-MS/MS), but the run time was only 1 min each sample. The method is accurate and reliable. And compared with the conventional LC-MS/MS technology, it is simple, rapid and low-cost.

PHYSICOCHEMICAL CHARACTERIZATION, ANTIOXIDANT ACTIVITY AND FINGERPRINTS OF INDUSTRIALIZED “DETOX” MIXED BEVERAGES BY PAPER SPRAY MASS SPECTROMETRY

The objective of this work was to determine the chemical composition, total phenolic compounds content, antioxidant capacity through the ABTS (2,20-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) method, as well as to evaluate the use of paper spray ionization mass spectrometry (PS-MS) to obtain fingerprints in different brands of mixed industrialized beverage based on fruits and vegetables with “detox” denomination. The carbohydrate contents ranged from 4.17% (sample D) to 12.72% (sample G). The differences may be related to the composition and proportion of the ingredients present in each formulation. The contents of total phenolic compounds varied between 26.75 mg GAE (gallic acid equivalents) g-1 (sample F) to 48.61 mg GAE g-1 (sample D). The samples A, B and C contain cabbage, spinach and parsley and presented significantly higher phenolic compounds content than the other samples. The antioxidant activity values varied between 1.76 µmol L-1 Trolox g-1 (sample B) to 18.95 µmol L-1 Trolox g-1 (sample E). The brands E, F, and G, that presented higher antioxidant potential, have ingredients pineapple, apple, cabbage, and ginger as common. The analysis of PS-MS allowed for the identification of a number of substances, including organic acids, sugars, and phenolic acids. PS-MS is a relatively simple method, fast and efficient to obtain fingerprints of mixed beverages.

Paper spray mass spectrometry for discriminating the quality of commercial gasolines

Paper spray ionization mass spectrometry is an alternative and sensitive methodology for the rapid evaluation of gasoline samples from different refining companies.

DETERMINATION OF CHEMICAL PROFILE OF Eugenia dysenterica ICE CREAM USING PS-MS AND HS-SPME/ GC-MS

The incorporation of Cerrado fruits in food products such as ice cream has many advantages because it represents a source of nutrients and bioactive compounds. Given the demand for less laborious methods to analyze food, the paper spray ionization mass spectrometry technique was applied for the first time for a rapid characterization of the chemical components found cagaita ice cream. PS-MS in positive and negative ionization modes were used. The profile of volatile compounds was determined by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry. Fingerprints obtained through PS-MS identified various classes of compounds, such as flavones, anthocyanins, sugars, organic acids, hydroxybenzoic acids, fatty acids, hydroxycinnamic acids, lignin, and phenylpropanoid. The use of both fibers enabled the extraction and identification of 18 volatile compounds in cagaita, and 16 of them were also identified in cagaita ice cream. The most common volatile compound found in both cagaita and ice cream was 3-carene monoterpene. Considering the effect of processing on cagaita constituents, 89% of the volatile compounds remained in the ice cream. Also, 78% of the fruit chemical compounds analyzed by PS-MS were found in the product. Thus, the results indicate that most of the fruit compounds remained in the ice cream after processing.