Optical sensors measuring fluorescent dissolved organic matter (fDOM) are increasingly being used in water quality studies because they provide proxy measurements for dissolved organic matter concentrations (DOC). Similarly, chlorophyll-a (chl-a) fluorescence sensors have gained popularity as a means to measure phytoplankton concentration, biomass, and even primary productivity using various approaches. As additional sensors are grouped for in situ monitoring, field calibration checks are becoming quite time consuming for even the basic set of sensors (i.e. pH, specific conductivity, turbidity) that require ongoing verification over timescales ranging from weekly to semi-annual intervals. As such, there is a critical need to establish a means to verify calibrations using a simple, fast, and efficient method in the field to standardize USGS measurements among sensors and across the landscape. Here, we present the results of a mixed standard solution capable of simultaneously verifying calibrations for multiple sensors including fluorescence of dissolved organic matter (fDOM) and fluorescence of chlorophyll-a (fChl).