This application note has demonstrates the versatility of direct injection using the ACQUITY UPLC I-Class System combined with the Xevo TQ-S Mass Spectrometer for the analysis of phenoxyacetic herbicides in natural spring water. The limit of detection (LOD) for the majority of the phenoxyacetic acids in this study was 2.5 ng/L, which exceeded the detection requirements of the U.S. EPA and European Union Directives. The high sensitivity of the Xevo TQ-S enabled excellent quantitation for acidic herbicides using a 100-μL injection without any pretreatment prior to injection. The recovery data showed good results with excellent CV’s below 5% for the spring water samples. RADAR Technology was used during the chromatography optimization process to identify potential interferences or matrix effect zones.