Extra Pure Grade chemicals

What extra pure means

Extra pure is a manufacturer-defined grade used widely in Indian and European catalogues to describe material that is purer and better characterised than laboratory reagent grade, but not tested to the full analytical reagent specification. Assay is typically 98.5 to 99.5% or higher, and the specification includes more impurity parameters than LR, often with limits close to AR for the most common contaminants.

A point of caution: some catalogues abbreviate extra pure as EP, which is also the common abbreviation for the European Pharmacopoeia. These are entirely different things. An extra pure chemical has not necessarily been tested to a Ph. Eur. monograph. We label pharmacopoeial material as Ph. Eur. to avoid ambiguity, and the COA always states the specification basis.

Typical specifications

Parameter	Typical extra pure requirement
Assay	≥ 98.5 to 99.5%
Insoluble matter	≤ 0.01%
Chloride, sulfate	Low hundredths or thousandths of a percent
Heavy metals (as Pb)	≤ 10 ppm
Iron	≤ 5 to 10 ppm

Values in the table are typical of the grade. The limits that apply to a given product are those stated on its specification and lot Certificate of Analysis.

Where it is used

• Synthesis where impurities could affect yield or colour but analytical purity is unnecessary
• Preparation of buffers and media for non-critical applications
• Routine laboratory procedures in industry and academia
• Pilot-scale work where cost per kilogram matters

How it differs from neighbouring grades

LR grade is cheaper and less tightly specified. AR and ACS grades add the full set of impurity tests and are appropriate for quantitative analysis. Pharmacopoeial grades (IP, BP, USP, Ph. Eur.) are tested against official monographs and are intended for regulated pharmaceutical use, which extra pure is not. If you need a pharmacopoeial material, specify the pharmacopoeia by name rather than relying on an abbreviation.

Selecting between grades

Extra pure is a sensible default for synthesis and general use when LR is borderline. For analysis or regulated use, move up to AR, ACS or a pharmacopoeial grade as appropriate.

When requesting a quotation, it helps to tell us which impurities could affect your work. We can then confirm whether the extra pure specification covers them or whether moving to AR would be the safer and ultimately cheaper option.