German Criminal Police Office

About: German Criminal Police Office is a government organization based out in Wiesbaden, Germany. It is known for research contribution in the topics: Population & Mass spectrometry. The organization has 254 authors who have published 338 publications receiving 8489 citations.

Real-time trace detection of security-relevant compounds in complex sample matrices by thermal desorption–single photon ionization–ion trap mass spectrometry (TD-SPI-ITMS) Spectrometry (TD-SPI-ITMS)

Abstract: For the detection of security-relevant substances at low concentrations in complex matrices, coupling of thermal desorption-single photon ionization-ion trap mass spectrometry (TD-SPI-ITMS) was successfully tested. The main advantage of taking solid samples with a wipe pad followed by thermal desorption is the low detection limit by enhanced vapor pressure. Single photon ionization is a soft ionization technique which reduces the target ion fragmentation and shields bulk components with high ionization energies (IE) like nitrogen yielding to clearly arranged mass spectra with significant high mass peaks. To obtain low false-positive and false-negative rates, especially necessary for security-relevant substances, the ion trap mass spectrometer allows identification of signals with MS/MS studies. In this concept, the soft ionization technique fits well with the MS/MS studies, as peaks with high masses are generated yielding significant MS/MS fragments. For the ionization, photon energies between about 8 eV (155 nm) and 12 eV (103 nm) were generated with electron-beam-pumped rare gas excimer lamps (EBEL). Depending on the rare gas used, light with different photon energy is generated, adapted to the substances of interest. So, even most narcotics, having relatively low IEs, can be ionized with 8.4 eV photons without massive fragmentation. For most explosives, photons with higher energy must be used as their IEs are higher. In this work, a mobile setup with a commercial ion trap mass spectrometer has been developed and tested. Even a first real-scenario measurement campaign was accomplished successfully proving the field-suitability of the system.

Can the usual validation standard series for quantitative methods, ISO 5725, be also applied for qualitative methods?

Abstract: Repeatability standard deviation, laboratory standard deviation, and reproducibility standard deviation for quantitative methods according to ISO 5725 series were recently proposed to estimate the precision of qualitative measurements, giving a presence/absence response. In this paper, it is shown that for qualitative methods, the reproducibility standard deviation across laboratories does not reflect the performance of the method as suggested. It is demonstrated that the benefit of the respective laboratory standard deviation is very limited. Alternative performance measures are introduced which are based on another approach also directly linked to ISO 5725. Thereby, meaningful information about the precision of qualitative test methods can be achieved.

Microanalysis in Forensic Science: Characterization of Single Textile Fibers by Total Reflection X-Ray Fluorescence

Abstract: Fibers of different textile materials, such as polyesters, viscose, and wool, were analyzed using TXRF, yielding a "fingerprint-type" trace element pattern. This pattern can be compared with quantitative results obtained from weighable amounts, e.g. 50μg of the material. It can be shown that, besides the omnipresent elements Ca, Fe and Zn, some of these materials contain specific elements, such as P, Mn or Sb, and that an identification is possible using these elements even when very small amounts of sample are involved (i.e. sub-microgram). Since many synthetics contain Ti as a matting additive, the Ti concentration can be used to further differentiate the sample material.