Needle-type glucose biosensor with an electrochemically codeposited enzyme in a platinum black matrix

In this study we report the development of a needle-type glucose biosensor for the management of hemorrhagic shock. The immobilization technique depends on the electrophoretic deposition of the glucose oxidase enzyme in an electrochemically grown platinum black matrix. The sensor was coated with Nafion to decrease the effect of interferents. Preliminary tests were carried out to evaluate the sensor performance in vitro. These tests included the measurement of glucose levels in buffer solutions containing various potential physiological interferents, as well as in bovine serum. The preliminary results show the sensor to have inearity up to 33 mM and a diminished response to interferents. The advantages of this technique are its simplicity and high controllability.     

New ideas in neutrino detection

What is new in the field of neutrino detection? In addition to new projects probing both the low and high ends of the neutrino energy scale, an inexpensive, effective technique is being developed to allow tagging of antineutrinos in water Cherenkov (WC) detectors via the addition to water of a solute with a large neutron cross-section and energetic γ daughters. Gadolinium is an excellent candidate since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially available gadolinium trichloride. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields an 8.0 MeV gamma cascade easily seen in detectors like Super-Kamiokande. The uses of GdCl₃ as a possible upgrade for the Super-Kamiokande detector — with a view toward improving its performance as an antineutrino detector for supernova neutrinos and reactor neutrinos — are discussed, as are the ongoing R&;D efforts which aim to make this dream a reality within the next two years.     

Negative chemical ionization and accurate mass measurement applications for a linked gas chromatography/Fourier transform infrared spectrometer/Fourier transform mass spectrometer

Summary The analytical utility of a linked GC/FTIR/ FTMS system operating in accurate mass and negative CI modes is demonstrated. In addition to the complementary information derived from IR and MS search results, accurate mass measurement data (average error of 4.2 ppm) is employed in the analysis of a seven component mixture. A post search filter uses accurate mass data to eliminate spectral search results with incorrect elemental compositions. An alternate positive ion EI and negative ion CI GC/IR/MS analysis is also performed on a mixture of substituted phenyl aldehydes and ketones. The reagent gas, ammonia, is introduced by pulsed valve thus minimizing crossover spectral contamination while maximizing spectral resolution. Proton abstraction by the amide produces an intense (M-1)^– for all compounds in the mixture. Molecular weight information from the negative CI data is used in a post search filter to improve the reliability of both IR and MS search results.

---

Anwendung der negativen chemischen Ionisation und genauer Massenmessungen für ein gekoppeltes GC/FTIR/FTMS-System

Zusammenfassung Die analytische Anwendbarkeit eines gekoppelten GC/FTIR/FTMS-Systems mit akkurater Massenmessung und NCI-Betrieb wird dargestellt. Zusätzlich zu den komplementären Informationen aus IR- und MS- Bibliothekssuchen werden Daten aus akkuraten Massenmessungen (mittlerer Fehler 4.2 ppm) bei der Analyse einer Mischung aus sieben Komponenten mit herangezogen. Im Anschluß an die Bibliothekssuche eliminiert ein Filter mit Hilfe der akkuraten Massen Ergebnisse mit fehlerhafter Elementarzusammensetzung. Von einer Mischung aus substituierten Phenylaldehyden und -ketonen wird eine Analyse mit alternierender Registrierung von positiven EI- und negativen CI-Spektren durch ein GC/IR/-MS-System ausgeführt. Das Reaktandgas Ammoniak wird über ein gepulstes Ventil zugegeben, um bei maximaler spektraler Auflösung minimale Störung durch Verunreinigung zu erhalten. Durch Abstraktion eines Protons von der Amidfunktion werden von allen Komponenten der Mischung intensive (M-1)-Ionen gebildet. Molekulargewichtsinformationen aus dem NCI-Experiment werden als Filter verwendet, mit dem die Zuverlässigkeit des Suchens in IR- und MS-Datenbanken erhöht werden kann.

     

Transfer of radionuclides to fruit

A study has been carried out to determine soil-plant transfer factors relevant to fruit crops. The current default values for¹³⁷Cs, Pu and Am used in the NRPB food-chain model FARMLAND were generally higher than the TFs observed. Lower values would be more appropriate for general assessments. For the United Kingdom, the current approach in which TF values for apples are applied to all domestically produced fruit is considered reasonable. This study also indicates that the assumption that TFs for fruit are the same as those for green vegetables is reasonable for¹³⁷Cs, Pu and Am, but, for⁹⁰Sr, data specific to apples would be preferable.     

Fragmentation studies on lasalocid acid by accurate mass electrospray mass spectrometry

Lasalocid acid is an important polyether ionophore veterinary drug. Polyether ionophores have been the subject of MS study for many years, but this is the first rigorous study of the complex fragmentation processes occurring in ESI MS/MS for lasalocid, underpinned by high-resolution accurate-mass measurement. Initial low-resolution analyses were performed on an ion-trap instrument. High-resolution analyses were performed on a Fourier-transform ion cyclotron resonance mass spectrometer. The MS/MS analysis of the pseudo-molecular ion shows that fragment ions are produced either by beta-elimination or by neutral losses of water. Additional ions were observed in the source dissociation analysis, indicating that additional fragmentation reactions occur in the source region. Some of these ions can then undergo additional ion-ion or ion-molecule reactions before being extracted from the source. The study of both the protonated and sodiated sodium salts shows the same fragmentation pathways, with fragment ions containing two sodiums at low intensity. A fragmentation pathway of the lasalocid acid protonated sodium salt [(M-H+Na)+H]+ (m/z 613) and sodiated sodium salt [(M-H+Na)+Na]+ (m/z 635) is presented. The increased understanding afforded by this study will help in the development of unequivocal analytical methods for lasalocid and related polyether ionophore veterinary drugs.     

Site-specific N-glycosylation analysis: matrix-assisted laser desorption/ionization quadrupole-quadrupole time-of-flight tandem mass spectral signatures for recognition and identification of glycopeptides

The identification of glycosylation sites in proteins is often possible through a combination of proteolytic digestion, separation, mass spectrometry (MS) and tandem MS (MS/MS). Liquid chromatography (LC) in combination with MS/MS has been a reliable method for detecting glycopeptides in digestion mixtures, and for assigning glycosylation sites and glycopeptide sequences. Direct interfacing of LC with MS relies on electrospray ionization, which produces ions with two, three or four charges for most proteolytic peptides and glycopeptides. MS/MS spectra of such glycopeptide ions often lead to ambiguous interpretation if deconvolution to the singly charged level is not used. In contrast, the matrix-assisted laser desorption/ionization (MALDI) technique usually produces singly charged peptide and glycopeptide ions. These ions require an extended m/z range, as provided by the quadrupole-quadrupole time-of-flight (QqTOF) instrument used in these experiments, but the main advantages of studying singly charged ions are the simplicity and consistency of the MS/MS spectra. A first aim of the present study is to develop methods to recognize and use glycopeptide [M+H]+ ions as precursors for MS/MS, and thus for glycopeptide/glycoprotein identification as part of wider proteomics studies. Secondly, this article aims at demonstrating the usefulness of MALDI-MS/MS spectra of N-glycopeptides. Mixtures of diverse types of proteins, obtained commercially, were prepared and subjected to reduction, alkylation and tryptic digestion. Micro-column reversed-phase separation allowed deposition of several fractions on MALDI plates, followed by MS and MS/MS analysis of all peptides. Glycopeptide fractions were identified after MS by their specific m/z spacing patterns (162, 203, 291 u) between glycoforms, and then analyzed by MS/MS. In most cases, MS/MS spectra of [M+H]+ ions of glycopeptides featured peaks useful for determining sugar composition, peptide sequence, and thus probable glycosylation site. Peptide-related product ions could be used in database search procedures and allowed the identification of the glycoproteins.