USP Methods for the Analysis of Aspirin (Acetylsalicylic acid (ASA)) Using Legacy L1 Column


Application Notes: Aspirin is one of the oldest analgesics. While it is one of the oldests analgesics, it is still widely used today, and is still one of the most common drugs. According to the USP methods, aspirin contains not less than 99.5% and no more than 100.5 percent of aspirin calculate on a dried basis. The USP HPLC method for the separation of aspirin was developed on Legacy L1 column according to the US Pharmacopeia methodology. L1 classification is assigned to reversed-phase HPLC column containing C18 ligand. Support for the material is spherical silica gel with particles size 3-10 um and pore size of 100-120A. Resolution between critical pairs corresponds to rules and specifications of USP.

Application Columns: Legacy L1 C18 HPLC column

Application compounds: Aspirin and salicylic acid

Mobile phase: 20 mM AmFm pH 3.0/MeCN- 75/25

Detection technique: UV

Reference: USP35: NF30


Column Legacy L1, 4.6×300 mm, 5 µm, 100A
Mobile Phase MeCN – 25%
Buffer AmFm pH 3.0 20 mM –  75%
Flow Rate 1.0 ml/min
Detection UV, 250 nm



Class of Compounds
Drug, Acid, Hydrophobic, Ionizable
Analyzing Compounds Aspirin (Acetylsalicylic acid (ASA))


Application Column

SIELC Legacy L1 HPLC column

Legacy L1

SIELC's family of Legacy columns is based on the United States Pharmacopeia's (USP) published chromatographic methods and procedures. Numerous brands have columns used in USP reference standards and methods. USP has created various designations to group together columns with similar types of packing and properties in the solid phase. SIELC's Legacy columns adhere to these strict requirements and properties, allowing you to easily replace older columns that are no longer available without needing to significantly modify your method or SOPs.

Select options
Application Analytes:
Acetylsalicylic Acid

Application Detection:
UV Detection
SIELC Technologies usually develops more than one method for each compound. Therefore, this particular method may not be the best available method from our portfolio for your specific application. Before you decide to implement this method in your research, please send us an email to so we can ensure you get optimal results for your compound/s of interest.