While we suspect some impurities remain unidentified and/or unquantified, analytical verification of key species such as OAc and K allowed us to better explain observed differences in precursor solubility, deviation from nominal stoichiometry, and correlations to device performance. This work additionally demonstrates that common analytical techniques provide accessible means to evaluate purity levels of perovskite precursors and that practical purification methods can effectively raise the purity of most PbI2. These techniques are relevant to fundamental scientists for understanding the impact of synthetic conditions and intrinsic versus extrinsic material properties, as well as to applied scientists for tactics to improve quality control, performance, and reproducibility.