Application Example - Determination of Metronidazole, Chloramphenicol, Lincomycin and Clindamycin in Cosmetics

Introduction

Antibacterial compounds have anti-inflammatory and sterilizing effects, so they may be used in cosmetics or shampoos such as acne and dandruff. However, as prescription antibiotics, long-term contact with the human body will cause various adverse reactions such as allergy and anemia. The "Hygienic Standards for Cosmetics" (2007 edition) promulgated by the Ministry of Health clearly stipulates that,

The use of various antibiotics such as metronidazole in cosmetics is prohibited.

Experimental part

Chromatographic conditions

Instrumentation: Agilent 1290 Infinity II LC System/6470 Triple Quadrupole Fluid

Mass spectrometry system (LC/QQQ)

Column: Agilent ZORBAX SB-Aq, 2.1 × 100 mm, 1.8 µm

Injection volume: 2 µL

Mobile phase: A) 0.1% formic acid in water

B) Acetonitrile

Gradient program: time/min B%

                    0 5

                    5.0 5

                    5.1 95

                    7.0 95

                    7.1 5

Flow rate: 0.3 mL/min

Column temperature: 30 °C

Separation time: 8.5 min

MS conditions

Ion source: ESI

Drying air flow: 5 L/min

Drying gas temperature: 350 °C

Nebulizer pressure: 45 psi

Sheath gas flow: 12 L/min

Sheath gas temperature: 400 °C

Capillary voltage: 3500 V

Ionization mode: time/min mode

                  0 positive ions

                  4.3 Negative ions

MRM parameters: the following table