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Based on the initial purge calculations allied to the additional non‐trace analysis, a control summary table (Table 3.10) is presented below.

Table 3.10 Proposed high‐level control summary table for potential MIs ethyl bromoisobutyrate 2, hydroxylamine, and alkyl chloride 8.

Impurity	Point of potential formation/introduction and summary of rationale for impurity purging	Required purge and predicted purge	Control
	Starting material in Stage 1a (2 eq.), four steps from drug substance (DS). Consumed to low level (<5%) in Stage 1b; reactive during processing (Stage 4); soluble in isolation solvents (Stages 4 and 5).	Required purge = 20 Predicted purge = 1.0 × 105 Purge ratio = 5000	Option 4 – controlled through chemical reactivity and physical processing.
NH2OH	Reagent in Stage 2 (2.5 eq.), four steps from DS. Reactive during processing (Stages 2, 3, and 4), highly soluble in isolation solvents (Stages 2, 3, 4, and 5).	Required purge = 39 Predicted purge = 1.0 × 108 Purge ratio = 2.56 × 106	Option 4 – controlled through chemical reactivity and physical processing.
	Starting material in Stage 4 (1.15 eq.), two steps from DS. Confirmed at low level (c. 0.2%) within Stage 4b product following additional reactivity with aqueous base used within the process and solubility within the isolation solvent. Additional solubility anticipated in Stage 5 isolation solvent.	Required purge = 30 Predicted purge =1000 Purge ratio = 33 Measured purge = 75 (Stage 4b) Measured purge ≥ 150 (Stages 4b and 5)	Option 4 – controlled through chemical reactivity and physical processing.

Further options for control could be considered specifically in the case of chloromethyl oxadiazole 8 where an Ames test could be performed to assess whether or not it is mutagenic.