Small-angle X-Ray scattering (SAXS) lets researchers study peptide structure in solution without crystallization, complementing chromatography and light-scattering methods in the analytical laboratory. What SAXS shows: Scattering curves are used to estimate radius of gyration, overall shape envelopes, and signs of aggregation or unfolding in solution. Buffer subtraction, concentration series, and radiation-damage checks are essential controls, because scattering is sensitive to even small amounts of aggregate. Use in a QC workflow: SAXS is typically paired with SEC, DLS, and HPLC-MS so solution-structure findings are cross-checked against purity, identity, and size-distribution data. Report concentration, buffer, temperature, and data-processing models with every result. Limitations: SAXS provides low-resolution structural information and model-dependent interpretations; it supports, but does not replace, quantitative purity and identity testing by HPLC and mass spectrometry. Disclaimer: For laboratory research purposes only. Not for human consumption. The methods described are analytical laboratory techniques; no medical or therapeutic claim is made. Citations: Standard SAXS methods literature for biomolecular solution scattering and Guinier analysis.