Label-free in vitro potency assays are an emerging field in drug discovery to enable more physiological conditions, to improve the readout quality, and to save time. For this approach mass spectrometry (MS) is a powerful technology to directly follow physiological processes. The speed of this methodology, however, was for a long time not compatible with chemiluminescence- or fluorescence-based assays. Recent advances in matrix-assisted laser desorption/ionization (MALDI) instrumentation paved the way for high-throughput MS analysis of label-free assays for large compound libraries, whereas electrospray ionization (ESI)-based mass spectrometers equipped with RapidFire autosamplers were limited to medium throughput. Here we present a technological advancement of the RapidFire device to enable cycle times of 2.5 s per sample. This newly developed BLAZE-mode substantially boosted the ESI-MS analysis speed, providing an alternative technology for label-free high-throughput screening.

The distillation cuts between head, heart and tail fraction of a fruit distillate are still done in an empirical fashion, based on the distiller's sensorial experience. There has been an unmet need for a long time to provide an objective method for determining the point of tails independent of fruit type and distillation technique. In this study, the authors provide a new method for separating the tail robustly from the heart fraction. For the first time, this is based on an in-line measurement of conductivity together with a suited algorithm for differentiating the conductivity increase before and after the point of tails. The method has been validated with three different fruit mashes of different sugar content, distilled applying different levels of rectification due to different settings of the dephlegmator of the still. Verification with sensory analysis confirmed the validity of the method.

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Using a novel in-line measurement technique for monitoring the distillate conductivity of apple spirits, the authors demonstrated that a more economic strategy of running a batch column still providing lower heating and cooling energy was able to shift higher levels of carboxylic acids more toward the cut point of tails. By means of more aggressive heating and cooling, the relative volatility of tail congeners was increased, enabling them to enter the condenser already at the beginning of the distillation. Especially during column distillation, reflux rates can heavily impact the transition of less volatile congeners into the product contributing either to an unclean taste when too enriched or to a lack of aroma intensity when too depleted. It was shown that with the selected strategies, the risk of depletion of aroma compounds is higher with increased ethanol fortification and unclean taste can easily be avoided even if higher levels of carboxylic acids are present, especially when the cut of the tail fraction is done appropriately using the described conductivity method.