Preparation of the standard curve for haemoglobin?

• Label 6 clean dry rest tubes and label them as S1 -S6
• Add 5 ml of Drabkin's solution to test tube numbers S2 - S6
• Add 5 ml of standard solution to test tube no1 (S1). Note, this tube does not contain Drabkin's solution.
• Add 5 ml of standard solution to test tube no S2 containing the Drabkin's solution. Mix well.
• Proportionately reduce the standard concentration from tubes S3-S5 to plot a standard curve. This can be done by transferring 5 ml of the content in S2 tube to S3 tube in which Drabkin's solution is already present. Again transfer 5 ml of this mixture to test tube 4 and mix well. Similarly proceed from test tube No 4 to 5. Mix the contents of the tubes well.
• Test tube no. S6 serves as blank. This tube contains only 5 ml of the Drabkin's Mix contents of all the tubes. Let the tubes stand for 4 minutes for colour development.