Using the facility
Requirements for the sample
The main requirement is that the analyte must be in a solution. Solids and suspensions are not compatible with the ionization methods used. The solute can be either water or organic solvent based. As long as this requirement is fulfilled it matters not whether the sample originally was blood, bone, skin, bark or anything else. From blood components plasma is preferred over serum, but also the latter is not contraindicated. We do not accept radioactive samples or other materials that require special precautions (e.g. certain infectious materials). If necessary, the core facility staff can help with the sample preparation, although in most cases we expect it to be done by users. The needed amount depends on analyzes, but 50-200 microliters is usually sufficient.
Types of analysis
Global metabolic profiling or “untargeted” analysis generates simple EMS spectra of the samples, which can later be analyzed by multivariate statistics or any other means to filter out differences between samples. It does not require preliminary decisions what kind of metabolites could be different between the samples and allows to determine if there are any differences at all. If differences are found it requires additional work to identify the metabolites, and this process is not guaranteed to succeed (i.e. In the end there may be mass spectrometry signals that are highly specific to a group of samples, but we cannot tell for sure, which metabolite it is).
Qualitative determination of specific compounds. If the sample is expected to have high amount of the substance of interest (e.g. chemical synthesis product) an EMS spectra may be sufficient to confirm the presence of correct m/z value. If the sample is expected to contain only trace amounts of the substance (e.g. a drug in biological tissue), more complicated analyses (fragmentation and MRM) may be required. In this case also a sample of the substance may be necessary in order to determine the optimal conditions for its detection in biological matrix.
Quantitative analyzes of specific compounds. Quantification generally requires internal and external standards, rising the cost and time of analyses. Ideally for each quantified substance its pure form and isotope labeled analogue are desired, but these are not always available.
Quantitative analyzes with commercial kits. We are running analyses with AbsoluteIDQ p180 kit from BioCrates. For other commercial kits please consult with the staff.