Which sequence correctly orders reagent grades from purest to least pure?

Which sequence correctly orders reagent grades from purest to least pure?

• A. UP > AR > CP > USP > TG
• B. UP > AR > USP > CP > TG
• C. AR > UP > CP > USP > TG
• D. TG > USP > CP > AR > UP

Answer: (A)

Purity grades reflect how strict the impurity limits are for a reagent. Ultrapure is used where even trace contaminants can affect results, so it sits at the top as the purest. Analytical Reagent grade is the next level up and is chosen for high-precision analytical work, with very low impurities but not as stringent as ultrapure. Chemical Pure is a general-purpose grade suitable for routine chemical work, less strict than AR. The pharmacopeial standard (USP) is designed for pharmaceutical quality and a specific set of tests, which can be stringent but focus more on compliance and pharmacopeial limits than on every possible impurity; in this framing, it is considered less pure than CP. Technical Grade is the least pure, intended for noncritical or bulk applications. Therefore, ordering from purest to least pure in this scheme is Ultrapure, then Analytical Reagent, then Chemical Pure, then USP, and finally Technical Grade.

Purity grades reflect how strict the impurity limits are for a reagent. Ultrapure is used where even trace contaminants can affect results, so it sits at the top as the purest. Analytical Reagent grade is the next level up and is chosen for high-precision analytical work, with very low impurities but not as stringent as ultrapure. Chemical Pure is a general-purpose grade suitable for routine chemical work, less strict than AR. The pharmacopeial standard (USP) is designed for pharmaceutical quality and a specific set of tests, which can be stringent but focus more on compliance and pharmacopeial limits than on every possible impurity; in this framing, it is considered less pure than CP. Technical Grade is the least pure, intended for noncritical or bulk applications. Therefore, ordering from purest to least pure in this scheme is Ultrapure, then Analytical Reagent, then Chemical Pure, then USP, and finally Technical Grade.