USP Methods for the Analysis of an Analgesic Mixture Using the Legacy L1 Column


Application Notes: Acetametaphin, aspirin, and caffeine tablets contain not less than 90 percent and not more than 110 percent of the labeled amounts if acetametaphin, asprin, and caffeine according the USP methods. USP HPLC method for separation of acetaminophen, aspirin and caffeine was developed on Legacy L1 column according to US Pharmacopeia methodology. L1 classification is assigned to reversed-phase HPLC column contains C18 ligands. Support for the material is a 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: Acetaminophen, Aspirin, Caffeine, benzoic acid, and salicylic acid

Mobile phase: MeOH/H2O/AcOH 28/69/3

Detection technique: UV

Reference: USP30: NF35


Column Legacy L1, 4.6×150 mm, 5 µm, 100A
Mobile Phase MeOH/H2O/AcOH 28/69/3
Buffer AcOH
Flow Rate 1.0 ml/min
Detection UV, 270 nm



Class of Compounds
Drug, Acid, Hydrophobic, Ionizable
Analyzing Compounds Acetaminophen, Caffeine, Aspirin, Benzoic acid, Salicylic acid


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:
Acetaminophen (Paracetamol)
Benzoic 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.