A reagent's impurity profile sets the floor of what your method can detect. In analytical work the grade is not a quality badge — it is a specification you are designing against, which is why protocols name one.
Analytical Reagent grade denotes purity suitable for quantitative analysis. ACS grade means the material meets the specifications published by the American Chemical Society's Committee on Analytical Reagents — a defined list, not a general claim. Chromatography grade adds low UV absorbance for use as a mobile phase or standard. If a method names one, substituting another changes the method.
AR, ACS and HPLC describe purity for laboratory use and carry no compendial status. Material destined for a medicinal product needs a pharmacopoeial grade, which is a different specification answering to a different authority.
A reagent bought in a size you cannot use before it degrades is the wrong purchase whatever the assay says. Say what quantity you actually consume in a working period, and buy to that.
The catalogue is on the TSS storefront and is searchable by name and CAS number.
A standard redox reagent, used in titrimetry and as an oxidising agent in analytical procedures.
Used as an oxidising agent in synthesis and in analytical preparation work.
These four turn an enquiry into something that can be quoted without a round trip.