Limiting contamination of LC-MS systems and reducing downtime associated with maintenance and cleaning is essential for productivity. We developed a simple device that creates a gas curtain barrier to prevent ions entering the MS inlet. The gas can be quickly and easily applied when certain contaminant ions are known to elute. We show the device can prevent the build up of contaminants on the heated transfer capillary following >100 injections of a crude tissue lysate and improves peptide identifications. The device may provide a promising approach towards improving instrument robustness.