A mixed-mode (reversed-phase/anion-exchange) stationary phase has been used as the capillary column packing for investigation of the separation of peptide mixtures in pressurized capillary electrochromatography (pCEC). This stationary phase contains both octadecylsilanes and dialkylamines. The amine groups of the stationary phase determine the charge density on the surface of the packing and can produce a strong and constant electroosmotic flow (EOF) at low pH. A comparison was made in terms of the capability of separating tryptic digests between the mixed-mode phase and C18 reversed phase. In addition, the constant EOF enabled the tuning of the retention and the selectivity of the separation by adjusting the mobile phase pH from 2 to 5. Furthermore, the magnitude and the polarity of the electric voltage were demonstrated to greatly influence the elution profiles of the peptides in pCEC. An ion trap storage/reflectron time-of-flight mass spectrometer was used as an on-line detector in these experiments due to its ability to provide rapid and accurate mass detection of the sample components eluting from the separation column.

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Pulsed-delayed extraction using a simple high voltage transistor switch together with various sample purification approaches were used to enhance the resolution in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of oligonucleotides up to 60 bases long. This switch can provide a 0-3 kV voltage pulse with a 75 ns fall time. A resolution of 500-900 was typically observed for samples from 5-mers to 60-mers using pulsed-delayed extraction (PDE) with the switch described herein. The resolution deteriorated to < 100 for oligonucleotides of > or = 65-mers. With the TOF acceleration region configuration used in this work, the resolution was found not to vary significantly over a delay range of 2-5 mus. As the DNA size increased to over 35-mer, HPLC purification was required to retain the enhancement in resolution provided by PDE MALDI-MS.

We report the laser vaporization and multiphoton ionization of two anthracene-labeled molecules, W(6-hydroxyhexyl)-3-(9-anthryl)propionamide and an anthracene-linked deoxythymine monophosphate. Laser vaporization of the anthracene-containing molecules was performed by directing a high-intensity pulse (30-300 mJ/cm2, 2.5 ns) of 532 nm laser light into a thin film of rhodamine 6G (Rh 6G) containing nanomolar quantities of the sample. Resonance-enhanced multiphoton ionization was used to selectively ionize the anthracene moiety in each molecule after vaporization. The So-SI transition of the anthracene molecule at 361 nm was used to excite the molecules, and ionization from this intermediate state was achieved using a 308 nm photon. The ionized products were detected and analyzed by mass spectrometry. The time-ofarrival measurements for the laser-vaporized molecules correspond to a bimodal velocity distribution, composed of a thermal component and a hyperthermal component showing substantial translational energy cooling. The distributions for the anthracene-labeled molecules reveal lower most probable velocities than those for the Rh 6G. A photochemical laser ejection model is proposed to account for the energetic nonthermal velocity distributions measured.

Effective symposia need two strong legs to stand upon: informative presentations of recent research paired with lively discussion of these topics. Although it is easy for the organizers of a symposium to predict the usefulness of the former, as they select the speakers and their topic areas, guaranteeing productive discussion is a far more difficult task. For the Crop Composition Workshop sponsored by the International Life Sciences Institute's Committee on Food and Biotechnology (ILSI IFBIC), the organizers scheduled four roundtable discussions with preselected questions and with rapporteurs drawn from governmental organizations and public-sector research institutes (the authors). It was also the organizers' intent to let these discussions flow on the basis of the experiences of the participants and pressing issues within the overall debate on the role of crop compositional analysis within safety assessment of biotechnology as it exists now and in the future. The goal of this perspective is to summarize the issues raised, providing references when possible, and to describe the consensus statements reached through the course of these discussions.

.057] was also tested in an in vivo gene mutation assay giving negative results. Both hexa-2(trans),4(trans)-dienal .057] and deca-2(trans),4(trans)-dienal .140] were tested in vivo for the induction of micronuclei in rats bone marrow and peripheral reticulocytes after oral or intraperitoneal administration. None of the two substances induced increased frequencies of micronuclei. The Panel concluded that the concern for genotoxicity can be ruled out for the representative substances hexa-2(trans),4(trans)-dienal .057] and deca-2(trans),4(trans)-dienal .140] and therefore also for the other substances in this group 02.153, 02.162, 02.188, 05.064,

The genotyping of the various isoforms of Apolipoprotein E (apo E) has been performed using matrix-assisted laser desorption/ionization (MALDI-MS). The polymerase chain reaction was used to amplify the specific apo E gene sequence followed by digestion with Cfo I (Clostridium formicoaceticum), for generating restriction fragments for rapid and accurate mass analysis. An exonuclease I digestion step was introduced to remove the unused primers after PCR, which can otherwise interfere in the mass spectral analysis. By replacing the gel electrophoresis detection step with MALDI-MS, restriction isotyping of the apo E gene was achieved. Genotyping of an unknown sample and obtained from an independent diagnostic laboratory demonstrated the validity of the MALDI-MS method for the routine analysis of apo E.

Benzophenone .032] has been evaluated as a flavouring substance, in FGE.69, by the EFSA Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food in 2008. Benzophenone was evaluated also by JECFA (2011) and by IARC (2013) based on studies that were not considered in the EFSA opinion on FGE.69. Therefore, the Commission requested the CEF Panel to carry out a review of existing literature on the safety of this flavouring substance. In the framework of the evaluation of benzophenone as a food contact material, the CEF Panel established a tolerable daily intake (TDI) of 0.03 mg/kg body weight (bw) per day (2009). In the present Opinion, the Panel considered the already existing evaluations by EFSA, JECFA, IARC and available literature data on benzophenone toxicity. Moreover, new data on the use levels of benzophenone as a flavouring substance have been provided. The Panel considers that there is no concern with respect to genotoxicity. The Panel considers the endocrine activities of benzophenone and its metabolite 4-hydroxybenzophenone as weak and not directly related to the observed toxic effects including the neoplastic effects in rodents. The Panel confirms that the conservative approach taken by EFSA (2009) to derive a TDI of 0.03 mg/kg bw for benzophenone is appropriate to cover the non-neoplastic effects in the chronic toxicity studies and the neoplastic effects induced in the rodent carcinogenicity studies. The TDI is in the same order of magnitude as the chronic dietary exposure of adults and children to benzophenone (10-20 lg/kg bw per day) for the amount of added flavouring substance. The Panel considers that the calculated TDI and exposure estimate are based on conservative assumptions. The Panel concludes that there is no safety concern for benzophenone under the current condition of use as a flavouring substance.