High-performance Electrospray Ionization Mass Research Articles

Electrospray ionization in concentrated acetonitrile vapor improves the performance of mass spectrometry for proteomic analyses

Suppressing the background interferences and enhancing the analytes signals are long-term goals in high performance electrospray ionization mass spectrometry (ESI–MS) analyses. We observed that performing electrospray in the presence of a concentrated acetonitrile atmosphere suppresses background interferences and enhances peptide signals. An enclosed nanoESI source was utilized to provide a stable atmosphere of concentrated acetonitrile vapor for high performance ESI–MS analyses. The median MS signal intensity increased by 5 times for a set of 23 BSA tryptic peptides in direct ESI–MS analysis. Further, the number of reproducibly and precisely quantified peptides could be improved 67% in six replicate label-free quantitative proteome analyses by this strategy.

Detection of drug resistance in Mycobacterium tuberculosis.

Detection of drug resistance in Mycobacterium tuberculosis.

HPLC-UV-MS profiles of phenolic compounds and antioxidant activity of fruits from three citrus species consumed in Northern Chile.

Peels and edible pulp from three species of citrus including Citrus aurantifolia (varieties pica and sutil) and Citrus x lemon var. Genova widely cultivated and consumed in Northern Chile (I and II region) were analyzed for phenolic compounds and antioxidant activity for the first time. A high performance electrospray ionization mass spectrometry (HPLC-UV-ESI-MS) method was developed for the rapid identification of phenolics in extracts from peels and juices of all species. Several flavonoids including one kaempferol-O-hexoside (peak 16) and one hesperidin derivative (peak 22) three quercetin derivatives (peaks 4, 19 and 36), five isorhamnetin derivatives (peaks 5, 23, 24, 26 and 29) four luteolin derivatives (peaks 14, 25, 27 and 40), seven apigenin derivatives (peaks 2, 3, 12, 20, 34, 35 and 39), seven diosmetin derivatives (peaks 7–9, 17, 21, 31 and 37), three chrysoeriol derivatives (peaks 10, 18 and 30), and four eryodictiol derivatives (peaks 6, 13, 15 and 38) were identified in negative and positive mode using full scan mass measurements and MSn fragmentations. Ascorbic acid content was higher in the pulps of the varieties Genova and Sutil (60.13 ± 1.28 and 56.53 ± 1.06 mg ascorbic acid per g dry weight, respectively) while total phenolic content was higher in Pica peels followed by Sutil peels (34.59 ± 0.81 and 25.58 ± 1.02 mg/g GAE dry weight, respectively). The antioxidant capacity was also higher for Pica peels (10.34 ± 1.23 µg/mL in the DPPH assay and 120.63 ± 2.45 µM trolox equivalents/g dry weight in the FRAP assay). The antioxidant features together with the high polyphenolic contents can support at least in part, the usage of the peel extracts as nutraceutical supplements, especially to be used as anti-ageing products.

Antioxidant capacity, polyphenolic content and tandem HPLC–DAD–ESI/MS profiling of phenolic compounds from the South American berries Luma apiculata and L. chequén

Native Myrtaceae fruits were gathered by South American Amerindians as a food source. At present, there is still some regional consume of the small berries from trees belonging to genus Luma that occurs in southern Chile and Argentina. The aerial parts and berries from Luma apiculata and Luma chequen were investigated for phenolic constituents and antioxidant capacity. A high performance electrospray ionisation mass spectrometry method was developed for the rapid identification of phenolics in polar extracts from both species. Thirty-one phenolic compounds were detected and 27 were identified or tentatively characterised based on photodiode array UV–vis spectra (DAD), ESI–MS–MS spectrometric data and spiking experiments with authentic standards. Twelve phenolic compounds were detected in L. apiculata fruits and 12 in the aerial parts while L. chequen yielded 10 compounds in fruits and 16 in aerial parts, respectively. From the compounds occurring in both Luma species, seven were identified as tannins or their monomers, 15 were flavonol derivatives and five were anthocyanins. The whole berry and aerial parts extracts presented high antioxidant capacity in the DPPH assay (IC50 of 10.41±0.02 and 2.44±0.03μg/mL for L. apiculata, 12.89±0.05 and 3.22±0.05 for L. chequen, respectively), which can be related to the diverse range of phenolics detected. The antioxidant capacity together with the high polyphenolic contents and compounds identified can support at least in part, their use as botanical drugs. From the compounds identified in both species, 3-O-(6″-O-galloyl)-hexose derivatives of myricetin, quercetin, laricitrin and isorhamnetin are reported for the first time for the genus Luma.

The future of diagnostics and new technologies

Unusual events in infectious disease take a long time to discover either because the agents are not correctly identified or because they are lost in the noise of the normal background of disease. On a global basis, the earliest detection of an outbreak of a known disease agent requires an average of 23 days, and it takes an average of 35 days for official laboratory confirmation. Such lags could lead to catastrophic public health consequences. Although there have been significant advancements in the development of diagnostic and infectious disease surveillance technologies over the past decade, there remains a significant gap in strategic implementation of these technologies in a fashion that delivers value for early detection. Bridging this gap is critical for demonstrating real-time capacity for coordinated planning and response. I will describe a new commercial platform, the Abbott PLEX-ID, which fits these requirements. The platform is under commercial development by Abbott for the worldwide diagnostics market. The platform couples nucleic acid amplification to high-performance electrospray ionisation mass spectrometry and base-composition analysis. This enables the identification and quantification of a broad set of pathogens, including bacteria, major groups of pathogenic fungi and the major families of viruses that cause disease in humans and animals. This paradigm was validated when the US Navy identified early cases of pandemic H1N1 influenza virus as it entered the US, using the Abbott technology in parallel with the CDC sequencing effort.

Ibis T5000: a universal biosensor approach for microbiology

We describe a new technology, the Ibis T5000, for the identification of pathogens in clinical and environmental samples. The Ibis T5000 couples nucleic acid amplification to high-performance electrospray ionization mass spectrometry and base-composition analysis. The system enables the identification and quantification of a broad set of pathogens, including all known bacteria, all major groups of pathogenic fungi and the major families of viruses that cause disease in humans and animals, along with the detection of virulence factors and antibiotic resistance markers.