GB/T 38741-2020 in English

Technical background of the standard

This standard was proposed by the National Oral Care Standardization Technical Committee (SAC/TC 492) and was formulated to meet the testing needs of antibacterial ingredients in oral care products. With the maturity of high performance liquid chromatography technology, this method has achieved the simultaneous determination of multiple bactericides in complex matrices.

Core principle of the method

After ultrasonic extraction with formic acid-methanol-water mixed solution, separation was performed on a C8 chromatographic column, and a gradient elution program (0.1% trifluoroacetic acid system) was used to achieve baseline separation of the five target substances. The detector wavelength was set to 280nm, and the external standard method was used for quantification.

Key Technical Points

Sample pretreatment

Weigh 1.0g of sample accurately, mix with a vortex oscillator, extract with ultrasound for 15min, and centrifuge at 10000r/min to ensure extraction efficiency. Special attention should be paid to the storage of standard substances away from light (0-4℃).

Optimization of chromatographic conditions

The use of trifluoroacetic acid system can significantly improve the peak shape:

• Initial ratio 30% organic phase (0-2min)
• Increase to 50% organic phase in 10min
• Reach 80% organic phase for elution in 20min

Mass spectrometry confirmation method

When the test result is in doubt, LC-MS/MS confirmation is required according to Appendix C:

1. Use a C8 column with a particle size of 1.7μm to improve separation efficiency
2. Switching between positive and negative modes of electrospray ionization (ESI)
3. Multiple reaction monitoring (MRM) mode to ensure specificity

Implementation suggestions

Laboratory preparation

Required configuration:

• Diode array detector class=instrument>High Performance Liquid Chromatograph
• Analytical balance with an accuracy of 0.0001g
• Refrigerated centrifuge with a speed of more than 10000r/min

Quality Control

Each batch of tests should include:

• Blank control
• Spike recovery test (recovery rate must be 80-110%)
• Parallel sample determination (RSD≤10%)