Triple-quadrupole ICP-mass spectrometer (ICP-MS/MS) for element analysis of biological samples

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The members of the DFG graduate school Microbial Substrate Conversion (GRK - MiCon) at Ruhr University Bochum want to obtain a triple-quadrupole ICP-mass spectrometer for the element analysis of biological samples. The ICP-MS/MS system will add a new functionality and will be accessible to users in the mass spectrometry center of the Faculty of Biology and Biotechnology. Eleven principal investigators and 22 doctoral candidates of the GRK - MiCon study substrate conversion of microbial enzymes and enzyme complexes. Many of the proteins of interest contain metal cofactors. To study the proteins and their cofactors as well as the biological function of microbial natural products (ionophores, siderophores) an ICP-MS/MS is needed that allows the determination of the element composition of biological samples in aqueous solutions, some of which contain strong acids or organic solvents. High sensitivity and precision of the measurements of all relevant elements is needed, e.g., to determine the cofactor loading of proteins using small amounts of a sample by comparing metal content and known sulfur content. It will also allow to characterize cellular ion homeostasis after ionophore treatment when ionophore amounts are limited. In addition to biological materials, the composition of abiotic materials, such as cultivation media or soil extracts, will be analyzed to characterize the (natural) habitats of microbes and plants. The element composition of such samples can be of high complexity and variable. To address the interferences in different samples and matrices, a triple-quadrupole ICP-MS is needed that allows the elimination of interferences by helium collision (also possible with single-quadrupole instruments) and the use of different reaction gases (oxygen, hydrogen, ammonia, only possible in triple-quadrupole instruments). A medium throughput autosampler will be used for sample injection. Low surface interaction and effective wash routines will minimize sample carryover. A rapid semiquantitative analysis will provide the user with an unbiased overview of the masses across the periodic table and will support the development of quantitative methods by informing the choice of elements for mass calibration and calibration solutions for quantitation. It will further help devise strategies to experimentally address potential interferences and allows the detection of unexpected analytes. The software should provide intuitive visualization of semiquantitative and quantitative results and support data export in current table formats.