4.1 Potassium permanganate solution, standardized 0.1000 ± 0.0005N KMnO4.
4.2 Sodium thiosulfate solution, approximately 0.2N Na2S2O3. Normality known with an accuracy of ±
0.0005N.
4.3 Potassium iodide solution, 1.0N KI.
4.4 Sulfuric acid, 4.0N H2SO4.
4.5 Starch indicator solution, 0.2%.