HPLC Retention Control of Antibiotics (Metronidazole and Norfloxacine) in Toothpaste


Commercially available toothpaste has been known to include antibiotics. To demonstrate the retention control on the mixed-mode column Primesep 100, toothpaste was spiked with the antibiotics metronidazole and norfloxacin. In a 13 minute method, retention of the antibiotics was controlled by adjustment in ratio of organic in the mobile phase. This method demonstrates the flexibility of using mixed-mode columns such as Primesep 100.



Column Primesep 100, 4.6×150 mm, 5 µm, 100A
Mobile Phase MeCN/H2O
Buffer H2SO4
Flow Rate 1.0 ml/min
Detection UV, 250 nm



Class of Compounds
Drug, Antibiotics, Hydrophilic, Ionizable
Analyzing Compounds Metronidazole, Norfloxacine


Application Column

Primesep 100

The Primesep family of mixed-mode columns offers a wide variety of stationary phases, boasting unprecedented selectivity in the separation of a broad array of chemical compounds across multiple applications. Corresponding Primesep guard columns, available with all stationary phases, do not require holders. SIELC provides a method development service available to all customers. Inquire about our specially-tailored custom LC-phases for specific separations.

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Application Analytes:

Application Detection:
UV Detection
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