In addition to analysing qualities, the Technical Services Bioanalytics can also quantify proteins. Apart from marker-free quantification, we also determine the relative frequency of proteins in simple and highly complex samples by means of chemically stable isotope labeling on primary amines. We use the commercially available reagent iTRAQ® (isobaric tag for relative and absolute quantification) for this purpose and can thus read out and quantify up to eight samples in parallel. Alternatively, we deploy TMT® (tandem mass tag), which deploys a similar chemical principle and allows up to ten samples to be analysed simultaneously.