Rapid Sample Analysis Research Articles

Direct analysis of herbicides by paper spray ionization mass spectrometry

Paper spray ionization enables the rapid mass spectrometric analysis of environmental samples without the use of chromatography or sample cleanup techniques.

Microchip electrophoresis for fast and interference-free determination of trace amounts of glyphosate and glufosinate residues in agricultural products.

Fast screening of herbicide residues is becoming important to ensure food safety, but traditional chromatographic methods may not be suitable for rapid on-site analysis of samples with complicated matrices. Here, we describe a method for rapid and sensitive determination of glyphosate (GLYP) and glufosinate (GLUF) residues in agricultural products by electrophoresis on disposable microchips with laser-induced fluorescence detection. With this method, quantitative analysis of trace amounts of GLYP and GLUF can be achieved with relatively simple sample preparation.

Microcalorimeter Q-spectroscopy for rapid isotopic analysis of trace actinide samples

We are developing superconducting transition-edge sensor (TES) microcalorimeters that are optimized for rapid isotopic analysis of trace actinide samples by Q-spectroscopy. By designing mechanically robust TESs and simplified detector assembly methods, we have developed a detector for Q-spectroscopy of actinides that can be assembled in minutes. We have characterized the effects of each simplification and present the results. Finally, we show results of isotopic analysis of plutonium samples with Q-spectroscopy detectors and compare the results to mass spectrometry.

Rapid and Accurate Detection of Urinary Pathogens by Mobile IMS-Based Electronic Nose: A Proof-of-Principle Study

Urinary tract infection (UTI) is a common disease with significant morbidity and economic burden, accounting for a significant part of the workload in clinical microbiology laboratories. Current clinical chemisty point-of-care diagnostics rely on imperfect dipstick analysis which only provides indirect and insensitive evidence of urinary bacterial pathogens. An electronic nose (eNose) is a handheld device mimicking mammalian olfaction that potentially offers affordable and rapid analysis of samples without preparation at athmospheric pressure. In this study we demonstrate the applicability of ion mobility spectrometry (IMS) –based eNose to discriminate the most common UTI pathogens from gaseous headspace of culture plates rapidly and without sample preparation. We gathered a total of 101 culture samples containing four most common UTI bacteries: E. coli, S. saprophyticus, E. faecalis, Klebsiella spp and sterile culture plates. The samples were analyzed using ChemPro 100i device, consisting of IMS cell and six semiconductor sensors. Data analysis was conducted by linear discriminant analysis (LDA) and logistic regression (LR). The results were validated by leave-one-out and 5-fold cross validation analysis. In discrimination of sterile and bacterial samples sensitivity of 95% and specificity of 97% were achieved. The bacterial species were identified with sensitivity of 95% and specificity of 96% using eNose as compared to urine bacterial cultures. In conclusion: These findings strongly demonstrate the ability of our eNose to discriminate bacterial cultures and provides a proof of principle to use this method in urinanalysis of UTI.

Uranium monitoring tool for rapid analysis of environmental samples based on automated liquid-liquid microextraction

A fully automated in-syringe (IS) magnetic stirring assisted (MSA) liquid-liquid microextraction (LLME) method for uranium(VI) determination was developed, exploiting a long path-length liquid waveguide capillary cell (LWCC) with spectrophotometric detection. On-line extraction of uranium was performed within a glass syringe containing a magnetic stirrer for homogenization of the sample and the successive reagents: cyanex-272 in dodecane as extractant, EDTA as interference eliminator, hydrochloric acid to make the back-extraction of U(VI) and arsenazo-III as chromogenic reagent to accomplish the spectrophotometric detection at 655nm. Magnetic stirring assistance was performed by a specially designed driving device placed around the syringe body creating a rotating magnetic field in the syringe, and forcing the rotation of the stirring bar located inside the syringe.The detection limit (LOD) of the developed method is 3.2µgL−1. Its good interday precision (Relative Standard Deviation, RSD 3.3%), and its high extraction frequency (up to 6h−1) makes of this method an inexpensive and fast screening tool for monitoring uranium(VI) in environmental samples. It was successfully applied to different environmental matrices: channel sediment certified reference material (BCR-320R), soil and phosphogypsum reference materials, and natural water samples, with recoveries close to 100%.

Rapid analysis of forensic samples using an atmospheric solid analysis probe interfaced to a linear ion trap mass spectrometer.

This paper highlights the simplicity of interfacing an Atmospheric Solid Analysis Probe (ASAP) to a Linear Ion Trap Mass Spectrometer and shows that this technique can be used for the rapid generation of high-quality data from a range of sample types with minimal or no sample preparation. For a solid sample or surface deposit, the process entails rubbing a capillary melting tube a few times on the sample to transfer material to the capillary surface and then introducing it into the source of the mass spectrometer. Similarly, for a liquid sample, a capillary tube is dipped into the sample to just coat the surface or a few microliters may be applied to the tip of a capillary before being analyzed by Atmospheric Pressure Chemical Ionization in both positive and negative mode. A rodenticide containing brodifacoum, black tar heroin and its impurities (morphine, codeine, noscapine, papaverine, and monoacetylmorphine), crack cocaine and 1-methylaminoanthraquinone dyestuff were successfully analyzed directly without any sample preparation. All compounds were detected using full scan mass spectrometry (MS), followed by confirmation by MS/MS. Preliminary results suggest that this technique could be used for quantitation. Interfacing the ASAP to an ion trap mass spectrometer allows the ability to perform full scan, MS(n) experiments, and rapid positive/negative switching from a single sample introduction. Because of these features, this instrument is very useful for rapid, routine analysis and for confirmation with the use of in-house MS/MS libraries.

Rapid Identification for Authenticity of Mutton by DAPCI-MS

Following the method of surface desorption atmospheric pressure chemical ionization mass spectrometry(DAPCI-MS),without any pretreatment to the samples,the mass spectra of a series of meat,including pure samples(duck,beef,pork,and mutton)and mutton-flavored meat samples of duck,beef and pork,were obtained directly.The ionization part relied on a self-made equipment of DAPCI.The DAPCI-MS raw data were further analyzed by principle component analysis(PCA).The result shows that the mass spectra of duck,beef,pork,mutton and mutton-flavored fake meat samples are distinguishing,indicating that the PCA model can discriminate the different meat samples successfully.This method can achieve the rapid identification as well as rapid analysis of meat samples at high throughput without any pretreatment.This study provides a method that achieves rapid detection of fake mutton and identification of meat samples for food security.

Rapid phylogenetic analysis of large samples of recombinant bacterial whole genome sequences using Gubbins.

The emergence of new sequencing technologies has facilitated the use of bacterial whole genome alignments for evolutionary studies and outbreak analyses. These datasets, of increasing size, often include examples of multiple different mechanisms of horizontal sequence transfer resulting in substantial alterations to prokaryotic chromosomes. The impact of these processes demands rapid and flexible approaches able to account for recombination when reconstructing isolates’ recent diversification. Gubbins is an iterative algorithm that uses spatial scanning statistics to identify loci containing elevated densities of base substitutions suggestive of horizontal sequence transfer while concurrently constructing a maximum likelihood phylogeny based on the putative point mutations outside these regions of high sequence diversity. Simulations demonstrate the algorithm generates highly accurate reconstructions under realistically parameterized models of bacterial evolution, and achieves convergence in only a few hours on alignments of hundreds of bacterial genome sequences. Gubbins is appropriate for reconstructing the recent evolutionary history of a variety of haploid genotype alignments, as it makes no assumptions about the underlying mechanism of recombination. The software is freely available for download at github.com/sanger-pathogens/Gubbins, implemented in Python and C and supported on Linux and Mac OS X.

Forensic Applications of Portable X‐ray Fluorescence Spectrometer: Glass Samples

AbstractPortable X‐ray Fluorescence Spectrometer (PXRF) is a qualitative and semi‐quantitative elemental analysis method. Recently, many researches using PXRF in the elemental analysis of materials have been reported. However, PXRF has not been extensively applied in forensic science, thus this study is devoted to demonstrate the utility of this technique through a rapid elemental analysis of glass samples for preliminary glass discrimination. Major elements such as Si, O, Ca, Al, and Na, as well as traces of Sr, Rb, K, Fe and Sn, in 25 glass samples were analyzed by PXRF. The amounts of some elements, such as Fe, K, Zr, and Sr, vary in different samples, while other elements, such as Th, are consistent in most tested glass samples. The results show that we can discriminate 98.31 % of 7,500 pair‐wise comparisons created from 25 glass samples. This study establishes PXRF as a new rapid method for the preliminary elemental analysis of glass, which shows a potential to be further applied for discrimination of glass samples in forensic field.

Development of a straightforward and robust technique to implement hadamard encoded multiplexing to high-performance liquid chromatography.

High-performance liquid chromatography (HPLC) is an indispensable technique to separate, quantify, and identify a broad range of compounds. Recent advances in HPLC technology led to the development of ultrahigh-performance instruments that allow rapid sample analysis with high efficiency. Nevertheless, there is still the opportunity to increase the sample throughput and to improve the signal-to-noise ratio by the application of multiplexing, where the injected samples are encoded with defined sequences. The obtained signal is then deconvoluted to give conventional chromatograms. In this work we present a method and technique which can be easily implemented in commercially available HPLC instruments to perform multiplexing analysis. Using our approach, multiplexing can be performed on standard laboratory equipment by software control and offers an inherent advantage in sensitivity and minimization of analysis time, demonstrated for the analysis of highly diluted polynuclear aromatic hydrocarbon (PAH) samples in water.

The nutritional contributions of dietary protein sources to tissue growth and metabolism of sea cucumber Apostichopus japonicus (Selenka): Evidence from nitrogen stable isotope analysis

Stable isotope technologies can effectively yield valuable information on the feasibility of estimating incorporation of specific macro- and micro-nutrients, rather than ingestion, through straightforward procedures with high accuracy and rapid sample analysis. In the present study, sea cucumbers were fed five isonitrogenous and isoenergetic diets containing different ratios of Sargassum thunbergii to soybean meal (100:0, 75:25, 50:50, 25:75 and 0:100; in terms of supplied nitrogen content) for 3 mo to assess the nutritional contributions of dietary protein sources. The results revealed that owing to the different enzyme systems and biochemical components of tissue and the discrepancy in dietary protein quality, nitrogen isotopic turnover rates exhibited obvious shifts between the tissues and between the experimental diets. Nitrogen half-lives reached 12.48–20.89 d for intestine and 25.28–40.37 d for body wall, respectively. The faster metabolism in intestine resulted in the higher metabolic contributions to nitrogen turnover (76–79%) than body wall (52–59%). The constant proportional contributions of growth and metabolism between the experimental diets indicated that the tissues kept stable bioenergetic distribution strategy in response to the fluctuation of dietary protein quality. The fractionations (Δ15N) ranged from 2.07‰ to 3.26‰. Calculated by nitrogen isotopic mixing model and estimated Δ15N by time-based turnover model, the biased nutritional contributions of dietary protein sources were observed, demonstrating higher dietary quality and preferential absorption of S. thunbergii for sea cucumber.

OR08: IT’S ABOUT TIME. THE DEVELOPMENT OF THE RAPID OPTIMIZED SINGLE ANTIGEN BEAD (ROB) LABSCREEN® PROTOCOL TO EXPEDITE HLA ANTIBODY TESTING

Background The LABScreen single antigen bead (SAB) luminex assay is routinely used for HLA antibody detection. Compared to flow or ELISA based assays, SAB assay allows for relatively rapid testing and analysis of multiple patient samples. Despite this, SAB assay is time intensive and not optimal for use in urgent cases. The goal of this study was to develop a rapid SAB protocol without compromising assay sensitivity. Methods Initially, positive control (PC) sera were used to test the effects of varying centrifugation time (1 vs 5 min), serum incubation (15 vs 30 min), IgG -PE incubation (5 vs 30 min), serum volume and IgG-PE concentration on SAB assay results. Based on this data, the Rapid Optimized SAB (ROB) protocol (70% assay time savings) was developed and compared to the standard SAB (SS) assay by parallel testing of 26 sera (17 pos/9 neg) in Halifax Lab. Protocols were compared with respect to MFI (Pearson correlation coefficient) and HLA antibody assignment (2000 MFI cutoff). Pilot evaluation with 3 ABH proficiency testing (PT) sera was performed in Santa Casa Lab. Results Reducing centrifugation from 5 to 1 min had no impact on SS assay results. When incubation times with serum, IgG-PE, or both were reduced, mean PC MFI were decreased compared to the SS protocol (by 25%, 26% and 47% respectively). In contrast, mean PC MFI were significantly enhanced (> 50%) when higher IgG-PE concentration was used. Next, the ROB protocol was formulated and compared to the SS protocol using 26 sera. HLA antibody reactivity patterns were similar with both protocols for all sera with excellent MFI correlation ( r 2 = 0.99). The ROB protocol had higher mean MFI (by 10.3%) compared to the SS protocol resulting in slight increase in positive rxns (1007/3167 vs 985/3167; 31.8% vs 31.1%; MFI > 2000). ROB+/SS- rxns ( n = 33; 0.97/ panel) had SS MFI range of 1122–1980, while ROB-/SS + rxns ( n = 10; 0.29/panel) had ROB MFI range of 1565–1703. No false positive rxns were seen in 9 antibody negative sera. ROB vs SS MFI correlation with 3 ABH PT sera in Santa Casa Lab was excellent ( r 2 = 0.99) with a single ROB+/SS- rxn (2612 vs 1978 MFI). Conclusion ROB protocol correlates well with the standard LABScreen protocol and reduces assay time by 70%. ROB protocol implementation will expedite HLA antibody testing in urgent cases and improve turn-around time for routine testing.

Standardization of solvent extraction procedure for determination of uranium in seawater

Solvent extraction procedure using ammonium pyrolidine dithiocarbamate complexing agent in methyl isobutyl ketone organic phase and acid exchange back-extraction is described for the simultaneous quantitative pre-concentration of uranium in seawater followed by its determination by differential pulse adsorptive stripping voltammetry. Solvent extraction time is optimized for extraction of uranium from seawater. Solvent extraction efficiency for uranium in seawater at different pH was carried out. The method gives a recovery of 98 ± 2 % for 400 mL sample at pH 3.0 ± 0.02, facilitating the rapid and interference free analysis of seawater samples.

Rapid analysis of raw solution samples by C18 pipette-tip electrospray ionization mass spectrometry

A C18 pipette-tip electrospray ionization mass spectrometry technique was developed for rapid analysis of raw solution samples. In this technique, a C18 pipette tip was employed for rapid purification and enrichment of analytes in raw sample solutions. The adsorbed analytes were eluted by solvents supplied by a syringe and a syringe pump, and a high voltage was applied onto the syringe needle to induce electrospray ionization at the pipette tip end for mass spectrometric analysis. This technique is simple, easy to assemble, enables generation of stable and reproducible signals, and can be conveniently used for qualitative and quantitative analysis of raw solution samples. Analysis by the technique only involved simple sample preparation procedures followed by direct mass spectrometric detection, all of which could be completed within minutes, while the analytical performances of the technique, including the limit of detection, limit of quantitation, liner range, accuracy and precision, were comparable to those by conventional methods.

Building blocks for automated elucidation of metabolites: natural product-likeness for candidate ranking.

BackgroundIn metabolomics experiments, spectral fingerprints of metabolites with no known structural identity are detected routinely. Computer-assisted structure elucidation (CASE) has been used to determine the structural identities of unknown compounds. It is generally accepted that a single 1D NMR spectrum or mass spectrum is usually not sufficient to establish the identity of a hitherto unknown compound. When a suite of spectra from 1D and 2D NMR experiments supplemented with a molecular formula are available, the successful elucidation of the chemical structure for candidates with up to 30 heavy atoms has been reported previously by one of the authors. In high-throughput metabolomics, usually 1D NMR or mass spectrometry experiments alone are conducted for rapid analysis of samples. This method subsequently requires that the spectral patterns are analyzed automatically to quickly identify known and unknown structures. In this study, we investigated whether additional existing knowledge, such as the fact that the unknown compound is a natural product, can be used to improve the ranking of the correct structure in the result list after the structure elucidation process.ResultsTo identify unknowns using as little spectroscopic information as possible, we implemented an evolutionary algorithm-based CASE mechanism to elucidate candidates in a fully automated fashion, with input of the molecular formula and 13C NMR spectrum of the isolated compound. We also tested how filters like natural product-likeness, a measure that calculates the similarity of the compounds to known natural product space, might enhance the performance and quality of the structure elucidation. The evolutionary algorithm is implemented within the SENECA package for CASE reported previously, and is available for free download under artistic license at http://sourceforge.net/projects/seneca/. The natural product-likeness calculator is incorporated as a plugin within SENECA and is available as a GUI client and command-line executable. Significant improvements in candidate ranking were demonstrated for 41 small test molecules when the CASE system was supplemented by a natural product-likeness filter.ConclusionsIn spectroscopically underdetermined structure elucidation problems, natural product-likeness can contribute to a better ranking of the correct structure in the results list.

Interface solution isoelectric focusing with in situ MALDI-TOF mass spectrometry.

This paper describes a simple and reusable microfluidic device combining solution IEF (sIEF) with MALDI-TOF MS for rapid proteomic and metabolic analysis of microliter samples. The device contains two glass plates with nanoliter microwell arrays, which can be assembled to form a fluidic path for sIEF separation, and reconfigured for dividing separated bands. One microliter samples can be loaded and separated by sIEF into static bands in 10∼30 min. After a slipping operation, the static IEF bands can be divided into nanoliter droplets in microwells without mobilization, and the device can be opened for in situ MALDI-TOF MS detection without loss of separation resolution. The performance of the device is characterized by separating and identifying intact proteins. The applicability in metabolic analysis is demonstrated by preliminary experiments on profiling small molecular metabolites in cerebrospinal fluid microdialysates from rat brain.

Antibody quantum dot conjugates developed via copper-free click chemistry for rapid analysis of biological samples using a microfluidic microsphere array system.

Antibody-based proteomics is an enabling technology that has significant implications for cancer biomarker discovery, diagnostic screening, prognostic and pharmacodynamic evaluation of disease state, and targeted therapeutics. Quantum dot based fluoro-immunoconjugates possess promising features toward realization of this goal such as high photostability, brightness, and multispectral tunability. However, current strategies to generate such conjugates are riddled with complications such as improper orientation of antigen binding sites of the antibody, aggregation, and stability issues. We report a facile yet effective strategy to conjugate anti-epidermal growth factor receptor (EGFR) antibody to quantum dots using copper-free click reaction, and compared them to similar constructs prepared using traditional strategies such as succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC) and biotin-streptavidin schemes. The Fc and Fab regions of the conjugates retain their binding potential, compared to those generated through the traditional schemes. We further applied the conjugates in testing a novel microsphere array device designed to carry out sensitive detection of cancer biomarkers through fluoroimmunoassays. Using purified EGFR, we determined the limit of detection of the microscopy centric system to be 12.5 ng/mL. The biological assay, in silico, was successfully tested and validated by using tumor cell lysates, as well as human serum from breast cancer patients, and the results were compared to normal serum. A pattern consistent with established clinical data was observed, which further validates the effectiveness of the developed conjugates and its successful implementation both in vitro as well as in silico fluoroimmunoassays. The results suggest the potential development of a high throughput in silico paradigm for predicting the class of patient cancer based on EGFR expression levels relative to normal reference levels in blood.

Development and evaluation of IgY ImmunoCapture PCR ELISA for detection of Staphylococcus aureus enterotoxin A devoid of protein A interference

In the present study, a sensitive and specific IgY mediated ImmunoCapture-PCR-ELISA (IC-PCR-ELISA) was developed for the detection of staphylococcal enterotoxin A (SEA) from culture supernatants and suspected contaminated samples. Due to the virtue of avian immunoglobulins (IgY) to have the least affinity towards staphylococcal protein A (SpA) responsible for false positives, we employed anti-SEA IgY for capture of SEA toxin and revealed with SEA specific rabbit antibodies conjugated to a 524bp DNA marker. Biotin-11-dUTP was incorporated during PCR amplification and post PCR analysis was performed by PCR-ELISA. Unlike IgG immunocapture, IgY mediated immunocapture of SEA was free from false positives due to protein A. The developed assay was specific to SEA except for minor cross reactivity with staphylococcal enterotoxin E (SEE). Several raw milk samples were evaluated for the presence of SEA with and without enrichment. Three samples were found to be positive for SEA after enrichment for 8h. Though IC-PCR-ELISA for SEA showed 100% correlation with PCR analysis for sea gene, the assay was unique in terms of sensitivity of detecting ~10pg/ml of SEA toxin from spiked milk samples. Result of IC-PCR-ELISA was further confirmed by conventional methods of isolation and characterization. The presented method can be very useful for rapid analysis of milk samples for SEA contamination and can be further extended for detection of multiple SE's in different wells of same PCR plate using common DNA substrate.

DART–TOF–MS based metabolomics study for the discrimination analysis of geographical origin of Angelica gigas roots collected from Korea and China

Rapid and efficient identification of the geographical origin of Angelica gigas roots (dang-gui) was performed using DART–TOF–MS (direct analysis in real time–time of flight–mass spectrometry) based metabolomics. As an ambient desorption/ionization technique, DART–TOF–MS can provide soft ionization and rapid analysis of samples with little sample preparation so it has been advantageously applied to high-throughput metabolomics analysis. In order to develop an efficient tool for discriminating, particularly geographical origin of raw herbal medicine, we employed DART–TOF–MS fingerprinting on dang-gui from Korean and Chinese markets. Principal component analysis of DART–TOF–MS fingerprints gave distinctive clustering information among two species of A. gigas and A. sinensis so that we used only A. gigas species for the sequential experiment. Orthogonal projections to latent structures-discriminant analysis of A. gigas samples revealed the separation between samples cultivated in two countries. Major discriminating components were elucidated as decursin/decursinol angelate, unidentified molecular ion of m/z 247 (protonated ions of molecular formula of C14H14O4) and another molecular ion of m/z 432. DART–TOF–MS based chemical fingerprinting with the multivariate analysis of dang-gui was shown to be efficient and accurate way to identify its geographical origin, between Korea and China.

Determination of B/Ca of natural carbonates by HR-ICP-MS

We report a new method for HR-ICP-MS based accurate and precise B/Ca determination from low mass natural carbonates (≤5 µg CaCO3), utilizing a mixed acid matrix (0.1 M HNO3 and 0.3 M HF) and accurate matrix matching technique. Our procedural B/Ca blank of 2.0 ± 1.0 µmol/mol, internal precision ≤1.0%, average within run external precision ≤4.0% (2σ), and rapid sample analysis (60 samples/day) make the method well suited for routine measurements. Established methods of B/Ca determination require ≥65 µg CaCO3 to achieve a comparable external precision of 3.5% (2σ). We report a B/Ca detection limit of 2 µmol/mol compared to ≥10 µmol/mol for previous methods, a fivefold improvement. The method presented here can determine a wide range of B/Ca (9.0–250 µmol/mol) in mass limited samples with considerable tolerance for matrix matching efficiency (≤±30%). The long-term reproducibility of B/Ca measured on Cambridge in-house consistency standards containing <20, ∼85, and ∼200 µmol/mol of B/Ca are ±3.7% (2σ, n = 100), ±3.9% (2σ, n = 150), and ±3.2% (2 s, n =180), respectively. A host of other trace element to Ca ratios can also be determined at comparable external precision from samples containing ≤5 µg CaCO3. This method is suitable for trace element analysis of single foraminifera shells.