This document describes a method for determining naproxen levels in serum using a Zorbax SPE C18 cartridge. The method uses solid phase extraction to significantly reduce the levels of interfering substances. The target analyte is then quantified by reversed-phase HPLC.
The document details an analytical procedure for determining levels of naproxen, a pharmaceutical compound used for pain relief, in blood serum. The primary challenge addressed is the interference caused by high protein content in the sample matrix.
To overcome this, the method utilizes a Zorbax SPE C18 cartridge to significantly reduce interfering substances before quantitation via reversed-phase HPLC. The text provides specific instructions for sample preparation, including pretreatment and washing steps, as well as details on the internal standard used (nitrobenzene) and the final HPLC conditions.
| Cartridge Capacity | 100 mg, 1 ml |
|---|---|
| Part Number | 5184-3590 |
| Column Type | Zorbax SB-C8, 4.6 mmx 150 mm, 3.5 pm |
| Mobile Phase Composition | 50% Acetonitrile in 25 mM Ammonium acetate |
| Detection Wavelength | 240 nm |
| Flow Rate | 1.0 mL/min. |
Nitrobenzene is used as an internal standard for High Load and Low Load samples to ensure accurate quantitation.
It significantly reduces levels of interfering substances, such as blood proteins, allowing the analyte to be clearly detected and quantifiable.
The recovery for a high load (10 pg/ml) was 99.25%.