10.1021/acsearthspacechem.8b00082.s001 Lauren E. McGraw Lauren E. McGraw Nina D. S. McCollom Nina D. S. McCollom Charity M. Phillips-Lander Charity M. Phillips-Lander Megan E. Elwood Madden Megan E. Elwood Madden Measuring Perchlorate and Sulfate in Planetary Brines Using Raman Spectroscopy American Chemical Society 2018 water peaks measure solutes Quantitative solute analyses ultrapure water show evidence Raman spectroscopic method sample preparation Raman peak height ratios target anion surface geochemical conditions OH peak area ratios Raman Spectroscopy Liquid water Planetary Brines 2018-09-11 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Measuring_Perchlorate_and_Sulfate_in_Planetary_Brines_Using_Raman_Spectroscopy/7128452 Liquid water likely exists on the surface of Mars and below the icy crusts of Europa, Enceladus, and Titan. Pluto, Ceres, and Ganymede also show evidence of liquid water at or near the surface. Quantitative solute analyses would provide critical data needed to understand geochemical conditions throughout our solar system, including potential habitability of planetary bodies. We have developed and tested a Raman spectroscopic method for measuring perchlorate and sulfate in brines and dilute waters that utilizes simple Raman peak height ratios rather than peak area ratios. Ratios of the target anion and OH- bending water peaks yield linear fits with positive slopes and r<sup>2</sup> values >0.99. Calibration fits for each solute–brine combination and ultrapure water yield similar linear equations, suggesting this method can detect and quantitatively measure solutes in complex aqueous solutions. No sample preparation or physical contact with the sample is required. Therefore, this method can be employed without contaminating the fluid or the spacecraft.