Simultaneous on-line vacuum single- and multi-photon ionization on an orthogonal acceleration time-of-flight mass spectrometer platform.

The development of orthogonal acceleration time-of-flight (oa-tof) technology is driven forward due to higher mass accuracy and resolving power than conventional linear/reflectron tof instruments. This is achieved with a more accurate definition of starting energies and coordinates of ions by spatial separation of ion generation and orthogonal ion extraction. Consequently, the ability to cover the whole mass spectral range without scanning is not given anymore. Therefore, continuous ion sources are favored for ensuring high duty cycles and thus high temporal resolution. For pulsed ion sources, high repetition rates are mandatory for covering large m/z ranges without losing their high temporal resolution. We have combined an oa-tof with deuterium lamp single-photon ionization (SPI) as a continuous ion source together with a pulsed 2000 Hz excimer (KrF) laser for resonance enhanced multi-photon ionization (REMPI). These two ionization techniques can be used simultaneously. To the best of our knowledge, this system is the first of its kind in combining a vacuum pulsed ionization source with an oa-tof instrument without any other ion storage hardware. The combination of a soft broadband ionization for organics (SPI) in combination with a very sensitive and selective soft ionization (REMPI) can be used for covering the whole mass range or in targeted on-line monitoring cases one or several smaller mass ranges. To demonstrate the simultaneous SPI/REMPI-oa-tof technique, two applicative areas are explored: on-line monitoring of coffee roast gas emissions and e-cigarette vapor. The complementary information from SPI and REMPI signals are combined in a way to exploit the advantages of both ionization types. In a further development step, a second data acquisition card is built into the system. This modification allows the independent storage of data from both ionization methods without mixing. For demonstration, a third example with a GC measurement is provided. The last example shows the possibility of modified sensitivities for different mass regions in REMPI data acquisition without affecting the SPI channel. The newly developed system shows high robustness in terms of measurements in real industrial environments. The simultaneous measurement technique provides a higher density of information in a single measurement, saving time and resources.

Systemic treatment with 4-211Atphenylalanine enhances survival of rats with intracranial glioblastoma.

OBJECTIVE: Increased amino acid transport in brain tumours is used for diagnostic purposes. It has been shown that the α-emitting radionuclide astatine-211 labeled to L-phenylalanine is taken up by glioblastoma cells. We here tested, if systemic treatment with 4-[211At]astatine-phenylalanine (At-Phe) has a beneficial effect on survival of rats with intracranial glioblastoma. ANIMALS, METHODS: The rat glioblastoma cell line BT4Ca was implanted into the prefrontal cortex of female BDIX rats by stereotaxic microinjection (10,000 cells/3 µl; n = 83). 3 days after implantation At-Phe or phosphate buffered saline were injected intravenously. A third group was treated twice, i.e., on day 3 and 10. Health condition was assessed each day by using a score system. Rats were sacrificed on days 6, 10, 13 and 17 after implantation, or when showing premortal health condition to measure tumour volume and necrosis. The proliferation index (PI) was assessed after immunohistochemical staining of Ki-67. RESULTS: Survival time of rats treated twice with At-Phe was significantly prolonged. Additionally, both At-Phe-treated groups remained significantly longer in a better health condition. Rats with poor health status had larger tumours than rats with fair health condition. Overall, irrespective of treatment the PI was reduced in rats with poor health condition. Necrosis was larger in rats treated twice with At-Phe. CONCLUSION: Intravenous treatment with At-Phe enhanced survival time of rats with intracranial glioblastomas and improved health condition. These results encourage studies using local treatment of intracranial glioblastoma with At-Phe, either by repeated local injection or by intracavital application after tumour resection.