Yunyun Yang

Coupling Solid-Phase Microextraction with Ambient Mass Spectrometry Using Surface Coated Wooden-Tip Probe for Rapid Analysis of Ultra Trace Perfluorinated Compounds in Complex Samples

Coupling solid-phase microextraction (SPME) with ambient mass spectrometry using surface coated wooden-tip probe was achieved for the first time and applied in the analysis of ultra trace perfluorinated compounds (PFCs) in complex environmental and biological samples. We modified n-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride on the surface of sharp wooden tip via silanization to form a novel SPME probe, which was then used for highly selective enrichment of PFCs from complex matrices and applied as a solid substrate to induce electrospray ionization for mass spectrometric analysis. The porous structural surface together with the dual extraction mechanisms (reversed phase adsorption and ion exchange adsorption) demonstrated that the SPME probe has an outstanding enrichment capacity, enhancing sensitivity by approximately 4000-8000 folds for the detection in aqueous samples, and 100-500-fold in whole blood and milk samples. The method showed good linearity, with correlation coefficient values (r(2)) of no less than 0.9931 for eight target PFCs. The limits of detection and qualification of the eight PFCs were 0.06-0.59 and 0.21-1.98 ng/L, respectively. Quantification of real samples was achieved by isotope internal standard calibration curve method or isotope dilution method, and ultratrace levels of PFCs present in lake water, river water, whole blood, and milk samples had been successfully detected and qualified.

Surface-Coated Probe Nanoelectrospray Ionization Mass Spectrometry for Analysis of Target Compounds in Individual Small Organisms

Analysis of target compounds in individual small organisms is of significant importance for biological, environmental, medicinal, and toxicological investigation. In this study, we reported the development of a novel solid-phase microextraction (SPME) based ambient mass spectrometry (MS) method named surface-coated probe nanoelectrospray ionization (SCP-nanoESI)-MS for analysis of target compounds in individual small organisms with sizes at micrometer-to-millimeter level. SCP-nanoESI-MS analysis involves three procedures: (1) modification of adsorbent at the surface of a fine metal probe to form a specially designed surface-coated SPME probe with probe-end diameter at several-micrometer level, (2) application of the surface-coated SPME probe for enrichment of target analytes from individual small organisms, and (3) employment of a nanospray tip and some solvent to desorb the analytes and induce nanoESI for mass spectrometric analysis under ambient condition. A SCP-nanoESI-MS method for determination of the perfluorinated compounds (PFCs) in individual Daphnia magna was developed. The method showed satisfactory linearities for analysis of real Daphnia magna samples, with correlation coefficient values (R(2)) of 0.9984 and 0.9956 for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), respectively. The limits of detection were 0.02 and 0.03 ng/mL for PFOS and PFOA, respectively. By using the proposed method, the amount, bioaccumulation kinetics, and distribution of PFOS and PFOA in individual Daphnia magna were successfully investigated.

Pharmaceutical analysis by solid-substrate electrospray ionization mass spectrometry with wooden tips.

AbstractElectrospray ionization (ESI) using wooden tips as solid substrates allows direct ionization of various samples and their simple and efficient analyses by mass spectrometry (MS). In this study, wooden-tip ESI-MS was used for pharmaceutical analysis. A wide variety of active components present in pharmaceuticals with forms of tablets, capsules, granules, dry suspensions, suspensions, drops, and oral liquids, etc., were all successfully ionized directly for mass spectrometric analysis. Trace degradation products were also sensitively detected using wooden-tip ESI-MS. This strategy was extended to construct chemical fingerprints of herbal products containing complex and unknown components, and the fingerprints provided valuable information for their quality assessment and origin tracing. Our experimental data demonstrated that wooden-tip ESI-MS is a useful tool for rapid pharmaceutical analysis, with high sensitivity and wide applicability, showing promising perspectives for quality assessment and control, authentication, and origin tracing of pharmaceuticals. Figureᅟ

Coupling liquid-phase microextraction with paper spray for rapid analysis of malachite green, crystal violet and their metabolites in complex samples using mass spectrometry

Coupling liquid-phase microextraction (LPME) with paper spray mass spectrometry (PS-MS) has been successfully achieved and applied in the analysis of malachite green, crystal violet and their metabolites in complex samples. This technique involved liquid-phase microextraction for the enrichment of target analytes followed by paper spray for direct mass spectrometric analysis under ambient and open-air conditions. Extraction conditions including extraction solvent, volume, time, temperature, pH and salinity were optimized. The proposed method showed enhanced sensitivity, by approximately 100–700 fold, for the detection of target analytes in aqueous samples. The method showed good linearity, with correlation coefficient values (r2) of no less than 0.9917 for four target compounds. The limits of detection and quantification of the four target compounds were 2.2–3.1 and 6.5–13.7 ng L−1, respectively. High recovery values of 92.2–112.4% and 93.1–108.6% were obtained at different concentrations of 50 ng L−1 and 500 ng L−1, respectively. The proposed method has been applied for the analysis of four target analytes in real lake water samples, and the experimental results demonstrated that this method was rapid, convenient, economic and friendly to the environment.

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.

Rapid and sensitive detection of trace malachite green and its metabolite in aquatic products using molecularly imprinted polymer-coated wooden-tip electrospray ionization mass spectrometry

In this study, a molecularly imprinted polymer-coated wooden-tip (MIPCWT) electrospray ionization mass spectrometry (ESI-MS) method was developed for rapid and sensitive detection of trace malachite green (MG) and its metabolite in aquatic products. Such a method was realized by applying a silicone-modified acrylate molecularly imprinted emulsion (SMAMIE) onto the surface of wooden tips to specially design a MIPCWT solid-phase micro-extraction (SPME) probe for selective enrichment of MG and its metabolite from aquatic products. Subsequently, a high voltage and some spray solvent were applied to the MIPCWT SPME probe, and ESI was induced for direct MS analysis under ambient and open-air conditions. The MIPCWT-SPME probe exhibits a high enriching capacity of approximately 1500–2000 fold toward MG and leucomalachite green (LMG), with detection limit reaching 0.01 μg L−1. In addition, a good linearity is obtained for both MG and LMG, with correlation coefficient values (R2) of no less than 0.998. The present method was successfully applied to analyze MG and LMG in real-life tap water, river water and fish samples, and good recoveries in the range of 93–103%, 92–108% and 106–113%, respectively, were found. All of these demonstrated that our developed MIPCWT-ESI-MS method holds great potential for rapid, direct, sensitive, and reliable detection and analysis of trace veterinary drug residues in aquatic products.

Surface-Modified Wooden-Tip Electrospray Ionization Mass Spectrometry for Enhanced Detection of Analytes in Complex Samples

Replacement of capillary with solid substrates for sample loading and ionization has created many new possibilities for electrospray ionization mass spectrometry (ESI-MS). Surface modification is an attractive strategy to enhance the analytical capability of solid-substrate ESI-MS and allow understanding the relationship between surface activity of solid substrates and analytical properties. In this study, we performed surface modification of wooden tips with hydrophobic (-C18), basic (-NH2), and acidic (-SO3H) functional groups and applied various sampling methods, i.e., extractive sampling and direct loading, to comprehensively investigate the analytical properties of solid-substrate ESI-MS. Our results showed that, for the direct loading method, analytes with weak interactions with solid-substrate surface could be readily sprayed out for detection. While for the extractive sampling method, analytes strongly retained on solid-substrate surface could be selectively enriched and detected, and a washing step after sample loading could effectively remove unbound components for reducing interference. Overall, the insights on the effects of surface-analyte interactions on the analytical features obtained in this study could aid the development of surface-modified strategies for enhancing the analytical capability of solid-substrate ESI-MS.

Biocompatible Surface-Coated Probe for in Vivo, in Situ, and Microscale Lipidomics of Small Biological Organisms and Cells Using Mass Spectrometry

Lipidomics is a significant way to understand the structural and functional roles that lipids play in biological systems. Although many mass spectrometry (MS)-based lipidomics strategies have recently achieve remarkable results, in vivo, in situ, and microscale lipidomics for small biological organisms and cells have not yet been obtained. In this article, we report a novel lipidomics methodology for in vivo, in situ, and microscale investigation of small biological organisms and cells using biocompatible surface-coated probe nanoelectrospray ionization mass spectrometry (BSCP-nanoESI-MS). A novel biocompatible surface-coated solid-phase microextration (SPME) probe is prepared, which possesses a probe-end diameter of less than 5 μm and shows excellent enrichment capacity toward lipid species. In vivo extraction of living biological organisms (e.g., zebrafishes), in situ sampling a precise position of small organisms (e.g., Daphnia magna), and even microscale analysis of single eukaryotic cells (e.g., HepG2) are easily achieved by the SPME probe. After extraction, the loaded SPME probe is directly applied for nanoESI-MS analysis, and a high-resolution mass spectrometer is employed for recording spectra and identifying lipid species. Compared with the conventional direct infusion shotgun MS lipidomics, our proposed methodology shows a similar result of lipid profiles but with simpler sample pretreatment, less sample consumption, and shorter analytical times. Lipidomics of zebrafish, Daphnia magna, and HepG2 cell populations were investigated by our proposed BSCP-nanoESI-MS methodology, and abundant lipid compositions were detected and identified and biomarkers were obtained via multivariate statistical analysis.

Rapid and on-site analysis of amphetamine-type illicit drugs in whole blood and raw urine by slug-flow microextraction coupled with paper spray mass spectrometry

In this study, a slug-flow microextraction (SFME) coupled with paper spray mass spectrometry (PS-MS) method was developed for rapid and on-site analysis of trace amphetamine-type illicit drugs including amphetamine (AM), methamphetamine (MA) and 3,4-methylenedioxy-N-methylamphetamine (MDMA) in complex biological samples such as whole blood and raw urine. The method involved the application of SFME for rapid extraction of trace amphetamine-type illicit drugs from whole blood and raw urine samples, followed by PS for direct MS analysis under ambient and open-air conditions. The experimental parameters including extraction solvent, extraction cycle, high voltage, and spray solvent, etc., were all investigated, and the optimized conditions showed an enhanced sensitivity of 1-2 order of magnitudes compared with PS-MS. The method showed good linearity, with correlation coefficient values (r) of no less than 0.9979 for analysis of AM, MA, and MDMA in human whole blood and raw urine without additional sample pretreatments. The limits of detection and quantification were 0.01-0.05 ng/mL and 0.05-0.2 ng/mL, respectively. Satisfactory recoveries were also obtained, with 74.2-94.9% for whole blood and 80.2-103.6% for raw urine, respectively. All of our experimental results demonstrated that SFME-PS-MS showed great potential for rapid, on-site, in situ, and high-throughput screening of amphetamine-type illicit drugs in various biological samples.