Absolute quantification is a challenge with many paths to reach the final goal of quantifying metabolites in absolute units (e.g. Molarity and molality). Utilizing an external reference standard (ERF) is an attractive method for quantifying in vivo metabolites due to the ability for direct comparison between a known concentration of a metabolite and the in vivo data. A major concern in utilization of an ERF is the differences in coil loading between in vivo and in vitro measurements. To that end, this work describes a method to calibrate and adjust the transmitter voltage in order to maximize signal detection independently of coil load.