Mass Spectrometry For Rapid Analysis Research Articles

Sample preparation and direct electrospray ionization on a tip column for rapid mass spectrometry analysis of complex samples

A handheld pipette tip column electrospray ionization source (PTC-ESI source) was developed for rapid mass spectrometry analysis at ambient pressure. The PTC-ESI source was made up of three main component parts including a micro DC high voltage (HV) power supply, a micropipette and a disposable micropipette tip filled with a plug of adsorbent. A DC high voltage was applied to the sharp point of the micropipette tip column to induce electrospray ionization. The PTC-ESI source was successfully used for direct analysis of basic organic compounds, organic acids and peptides in a simple matrix. In the case of complex samples, micro-extraction based on the adsorbent phase filled in the pipette tip was used to remove impurities and concentrate target analytes prior to ionization. The eluting solution was not pipetted out, but directly dispersed in the form of electrospray from the pipette tip for ionization. The effectiveness of the PTC-ESI source has been further demonstrated by fast analysis of therapeutic compounds and endogenous bioactive chemicals in complex biological samples.

Ultra‐performance liquid chromatography coupled with electrospray ionization/quadrupole‐time‐of‐flight mass spectrometry for rapid analysis of constituents of Suanzaoren decoction

A rapid, sensitive, specific and reliable ultra-performance liquid chromatography coupled with electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS) method with MassLynx™ MassFragment was developed for the analysis of Suanzaoren decoction (SZRD), a Chinese herbal prescription. The analysis was performed on a Waters UPLC BEH C(18) column using gradient elution system. A hyphenated electrospray ionization and Q-TOF analyzer was used for the determination of accurate mass of the protonated or deprotonated molecule and fragment ion in both negative and positive modes. The chromatographic separation was achieved by UPLC, which used a column with 1.7 μm particle packing which enabled higher speed of analysis, peak capacity, greater resolution and increased sensitivity. The constituents of SZRD were identied and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions, relevant literature and the establishment of an in-house molecular formula database. With this method, a total of 22 compounds of SZTD were tentatively identied based on MS and MS/MS data and comparison with available databases. It is concluded that a rapid and robust platform based on UPLC-ESI-Q-TOF-MS was established, which is useful for identifying multiple-constituent of traditional Chinese medicine (TCM) prescriptions. Our present results proved that the established method could provide helpful chemical information for further pharmacological mechanism research of SZRD.

Coupling frontal elution paper chromatography with desorption corona beam ionization mass spectrometry for rapid analysis of chlorphenamine in herbal medicines and dietary supplements

We developed a convenient method by coupling frontal elution paper chromatography with desorption corona beam ionization mass spectrometry (DCBI-MS) for rapid determination of chlorphenamine added in herbal medicines or dietary supplements. In this method, the ethanol extract of the herbal products was spotted directly onto an isosceles triangular filter paper sheet, and then the paper sheet was developed under strong elution condition with the sample zone migrating at the solvent front. The analyte was finally condensed at the V-shaped tip which could then be placed under the visible plasma beam of DCBI for ionization. The overall procedure took less than 5 min. The frontal elution paper chromatography on a triangular plate used in this work improved the signal intensity of chlorphenamine by 30-fold due to the analyte condensing at the tip and the reduction of the background suppression. Furthermore, the paper sheet also functioned as a filter in the analysis of solid or powder samples, which can increase the analytical throughput by omitting the step of centrifugation. The proposed method in current study was successfully applied in the determination of chlorphenamine in herbal medicines. Chlorphenamine was detected in four of the twelve types of herbal medicines examined in this study. The limit of detection was 200 ng/mL (2.0 ng absolute) in full-scan positive-ion mode and the linear range was from 5.0 μg/mL to 50 μg/mL with satisfactory linear coefficient ( R 2 (the square of the correlation coefficient) = 0.895). Good reproducibility was achieved with relative standard deviations (RSDs) less than 15.0% and the recoveries of chlorphenamine ranged from 84.3 to 90.6%.

Applications of silver nanoparticles capped with different functional groups as the matrix and affinity probes in surface‐assisted laser desorption/ionization time‐of‐flight and atmospheric pressure matrix‐assisted laser desorption/ionization ion trap mass spectrometry for rapid analysis of sulfur drugs and biothiols in human urine

A strategy is presented for the analysis of sulfur drugs and biothiols using silver nanoparticles (AgNPs) capped with different functional groups as the matrix and affinity probes in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) and atmospheric pressure-matrix assisted laser desorption/ionization ion trap mass spectrometry (AP-MALDI-ITMS). Biothiols adsorbed on the surface of AgNPs through covalent bonding were subjected to ultraviolet (UV) radiation that enabled desorption and ionization due to the excellent photochemical property of NPs. The proposed method has been successfully applied for the determination of cysteine and homocysteine in human urine samples using an internal standard. The limit of detection (LOD) and limit of quantification (LOQ) for cysteine and homocysteine in urine sample are 7 and 22 nM, respectively, with a relative standard deviation (RSD) of <10%. The advantages of the present method compared with the methods reported in the literature for biothiol analysis are simplicity, rapidity and sensitivity without the need for time-consuming separation and tedious preconcentration processes. Additionally, we also found that the bare AgNPs can be directly used as the matrix in MALDI-TOF MS for the analysis of sulfur drugs without the addition of an extra proton source.

Capillary high performance liquid chromatography coupled with electrospray ionization mass spectrometry for rapid analysis of pinane monoterpene glycosides in Cortex Moutan

In this study, a rapid and reliable assay has been developed for quantification of pinane monoterpene glycosides in cortex Moutan; it is based on capillary high performance liquid chromatography coupled with electrospray ionization mass spectrometry (capillary HPLC-ESI MS). This method utilizes capillary HPLC for the separation of seven pinane monoterpene glycosides in a methanol extract of the botanical sample followed by negative ion electrospray ionization and single ion monitoring (SIM). The compounds of interest in the sample were unambiguously identified on the basis of information about retention time and quasi-molecular ions ([M-H](-)) or adduct ions ([M+HCOO](-)). Validation parameters of the method were established. The linearity range was 1.01-105.5 microg/mL with the square of correlation coefficients lying in the range of 0.9965-0.9997, limits of detection were on the fmol level, the average recoveries varied between 91.8 and 101.0%, and good precision values (RSD, 1.2-4.91%) for peak area were obtained. After validation, the applicability of the method for determination of these pinane monoterpene glycosides in cortex Moutan has been demonstrated.

Direct combination of immersed single‐drop microextraction with atmospheric pressure matrix‐assisted laser desorption/ionization tandem mass spectrometry for rapid analysis of a hydrophilic drug via hydrogen‐bonding interaction and comparison with liquid‐liquid extraction and liquid‐phase microextraction using a dual gauge microsyringe with a hollow fiber

This study presents the feasibility of direct coupling of the immersed single-drop microextraction (SDME) technique with atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) for the rapid analysis of a hydrophilic drug (dopamine) from aqueous solution and human urine in an ion trap tandem mass spectrometer through hydrogen-bonding interaction of dopamine with the extraction solvent (octanol). The optimum conditions for the SDME experiments coupled to AP-MALDI/MS were: stirring rate, 240 rpm; extraction time, 5 min; sample pH value, 8; and matrix concentration, 2000 ppm, using alpha-cyano-4-hydroxycinnamic acid (alpha-CHCA) as matrix. The limits of detection (LODs) for the SDME/AP-MALDI-MS experiments were 25 and 40 ppm in water and human urine, respectively. In a comparison of this method with the traditional liquid-liquid extraction (LLE), the SDME method shows better LODs than the LLE (40 ppm) and the same LODs (25 ppm) as the liquid-phase microextraction using a dual gauge microsyringe with a hollow fiber (LPME/DGM-HF). However, the SDME method is more convenient than the LPME/DGM-HF method.

Automated, on‐line two‐dimensional nano liquid chromatography tandem mass spectrometry for rapid analysis of complex protein digests

Evaluation of cellular processes and their changes at the level of protein expression and post-translational modifications may allow identification of novel proteins and the mechanisms involved in pathogenic processes. However, the number of proteins and, after tryptic digestion, of peptides from a single cell can be tremendously high. Separation and analysis of such complex peptide mixtures can be performed using multidimensional separation techniques such as two-dimensional gel electrophoresis or two-dimensional-high-performance liquid chromatography (2-D-HPLC). The aim of this work was to establish a fully automated on-line 2-D-HPLC separation method with column switching for the separation of complex tryptic digests. A model mixture of five proteins as well as a nuclear matrix protein sample were digested with trypsin and separated using a strong cation exchange (SCX) column in the first dimension and nano reversed phase in the second dimension. Separated peptides were detected using an ion trap mass spectrometer. The advantages of this new fully automated method are rapid sample loading, the possibility of injecting large volumes and no introduction of salt into the mass spectrometer. Furthermore, column switching allows the independent control and optimization of the two dimensions independently.

Non-equilibrium solid-phase microextraction coupled directly to ion-trap mass spectrometry for rapid analysis of biological samples.

To determine sub-ppb levels of drugs in biological samples, selective, sensitive and rapid analytical techniques are required. This work shows the possibilities for high-throughput analysis of solid-phase microextraction (SPME) directly coupled to an ion-trap mass spectrometer equipped with an atmospheric pressure chemical ionisation source. As no chromatographic separation is performed, the SPME procedure is the time-limiting step. Direct immersion SPME under non-equilibrium conditions permits the determination of lidocaine in urine within 10 min. After a 5 min sorption time with a 100 microm polydimethylsiloxane-coated fibre, the extraction yield of lidocaine from urine is about 7%. When applying 4 min desorption, using a mixture of ammonium acetate buffer (pH 4.5) and acetonitrile (85 + 15 v/v), about 10% of the analyte is retained on the fibre. An extra cleaning step of the fibre is therefore used to prevent carry-over. By use of tandem MS, no matrix interference is observed. The detection limit for lidocaine is about 0.4 ng ml(-1) and the intraday and interday reproducibility are within 14% over a concentration range of 2-45 ng ml(1).

Application of Solid Phase Microextraction and Gas Chromatography/Time-of-Flight Mass Spectrometry for Rapid Analysis of Flavor Volatiles in Tomato and Strawberry Fruits

Solid phase microextraction (SPME), a relatively new sampling technique, was examined as a means to investigate volatile compounds produced by tomato (Lycopersicon esculentum Mill.) and strawberry (Fragaria × ananassa Duch.) fruit. SPME had sufficient sorptive capacity to permit detection of aroma compounds having a variety of functional groups. The advantages of using SPME were its simplicity, absence of solvent, and speed. Fiber cleaning, sample collection, and desorption required ∼6 min. The total analysis time was ∼10 min per sample when SPME was combined with rapid gas chromatographic (GC) separation and time-of-flight mass spectrometry (TOFMS). The major volatile compounds detected from tomato and strawberry and their relative abundance were comparable with published results from purge-and-trap/GC/FID analyses. One of the primary flavor impact compounds in strawberry, 2,5-dimethyl-4-methoxy-3(2H)-furanone was detected by using SPME/GC/TOFMS. SPME appears to be suitable for rapid and quantitative analysis of volatile aroma compounds in tomato and strawberry fruit. Keywords: Lycopersicon esculentum; Fragaria × ananassa; headspace; aroma; chromatography; time-of-flight mass spectrometry