Metabolomics, the quantification of intracellular metabolites, is a powerful tool that has proven useful in microbial strain and fermentation process development. The crucial step is the rapid quenching of the cellular metabolism to preserve the intracellular situation as it is in the bioreactor until (MS-based) analysis. For microbial systems and plants this can be achieved by using ice-cold methanol (-40 degrees C) or liquid nitrogen, but for mammalian cells in suspension no reliable technique is yet available. Here, a metallic microstructure heat exchanger is presented which allows cooling of a CHO cell suspension from cultivation temperature (37 degrees C) to 0 degrees C in less than one second without any detectable cell damage or cell disruption even at very high cell densities up to 8 . 10(6) cells/mL.