Question

Which of the following grades has the highest purity of lactose?

• A. Technical grade lactose
• B. Food grade lactose
• C. Crude lactose
• D. Pharmaceutical lactose

Hint:

Lactose Refining Grades:
Highest Purity = PHARMACEUTICAL LACTOSE ($> 99.8\%$ purity).
Food Grade = $99.0\%$ purity.
Technical Grade = $95 - 98\%$ purity.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Commercial refining and purity grading of lactose: pharmaceutical grade lactose (USP NF IP) undergoes multiple stages of active carbon deproteinization, demineralization, and recrystallization to achieve $\ge 99.8\%$ lactose monohydrate purity with $< 0.1\%$ ash.
Key Formula or Approach:
\[ \text{Purity Spectrum: } \text{Crude } (85 - 90\%) < \text{Technical } (95 - 98\%) < \text{Food Grade } (99.0\%) < \mathbf{Pharmaceutical \text{ } Grade } (\mathbf{\ge 99.8\%}) \]

Step 2: Detailed Explanation:
Grades of refined commercial lactose derived from dairy whey:
1. Crude Lactose: Raw crystalline cake containing $85\% - 90\%$ lactose with high ash and protein residues.
2. Technical Grade Lactose: $95\% - 98\%$ purity; used in chemical synthesis and industrial fermentation.
3. Food Edible Grade Lactose: $\ge 99.0\%$ purity (moisture $\le 5.0\%$, ash $\le 0.3\%$, protein $\le 0.3\%$); used in infant formulas and confectionery.
4. Pharmaceutical Grade Lactose (USP/NF/EP/IP) (D): Possesses the highest purity ($\ge 99.8\%$ anhydrous crystalline $lpha$-lactose monohydrate), virtually undetectable ash ($< 0.1\%$), and zero heavy metals; used as direct-compression binder-filler tablet excipient and dry powder inhaler carrier.

Step 3: Final Answer:
Therefore, Pharmaceutical lactose has the highest purity, corresponding to option (D).