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ABSTRACT: Developed originally as an antimalarial agent, the hydroxychloroquine sulfate (HCQ) is often used as a slow-acting anti-rheumatic drug in treating of disorders of connective tissue. The methods of quantification of HCQ sulfate, despite the undeniable advantages, have certain limitations, such as: high cost of operation and maintenance of equipment, sample processing and analysis of the results relatively complicated. However, the simplicity of the process and velocity of the spectrophotometry by absorption in the UV-Vis region corroborate the usefulness of this methodology. This work describes the application of QbD in the development, optimization and validation of an analytical method by absorption spectrophotometry in the UV-Vis region for quantification of HCQ sulfate. The method was developed from the sample preparation used in the determination of HCQ in dosage form according to th