Model 1260 thermostat

Abietic acid and gum rosin stock solutions were dissolved in methanol at a concentration of 1 mg/ml. Standard dilutions were prepared in a range of 2.5–500 µg/ml in acetonitrile. Gum rosin samples were prepared at 500 µg/ml in acetonitrile. Abietic acid was measured by High-Performance Liquid Chromatography (HPLC) on an Agilent 1260 Infinity II HPLC system (Agilent Technologies, Inc.) equipped with a Model 1260 quaternary pump, Model 1260 High Performance autosampler, Model 1260 thermostat, Model 1260 Infinity Thermostatted Column Compartment control module, and Model 1260 diode array detector. Data processing and analysis was performed using OpenLab CDS ChemStation (Agilent Technologies, Inc.). All solvents used were purchased from Sigma-Aldrich Corporation. Chromatographic separation was carried out on an Agilent Poroshell 120 EC-C18 4.6×50mm, 2,7 µm analytical column maintained at 55°C. The optimized mobile phase consisted of isocratic 0.1% aqueous formic acid (1%) and acetonitrile (99%) at a flow rate of 1.50 ml/min over a 4 min run time. The injection volume was 10 µl, and the selected ultraviolet (UV) detection wavelength was 242 nm.