The magical triethylamine
1. Test method
Cefodizime sodium molecular structure
Cometro HPLC system
Column: Comasil BDS C18 250 * 4.6mm, 5μm
Mobile phase: phosphate buffer solution (0.87g potassium dihydrogen phosphate and 0.22g anhydrous disodium hydrogen phosphate, diluted with water to 1000ml, shake well) -acetonitrile-triethylamine
Detection wavelength: 262nm
Flow rate: 1ml / min
Sample: Cefodizime sodium sample (0.2mg / ml)
Injection volume: 10μl
2. Experimental results and analysis
1. Pharmacopoeia standards
Mobile phase: phosphate buffer solution-acetonitrile = 920: 80
Retention Time
Theoretical plates (USP)
Asymmetry
21.970
2291
1.97117
Symmetry 1.97, severe tailing, low column efficiency
2. Add 1% triethylamine
Mobile phase: phosphate buffer solution-acetonitrile-triethylamine = 92: 8: 1, phosphoric acid pH = 6
No peak at 40min, increase the proportion of organic phase acetonitrile in the mobile phase, shorten the retention time.
3. Mobile phase: phosphate buffer solution-acetonitrile-triethylamine = 80: 20: 1, phosphoric acid adjusted pH = 6
Retention Time
Theoretical plates (USP)
Asymmetry
4.253
9450
1.11056
3. Conclusion
The molecular structure of cefodizime sodium contains more basic groups, which easily interacts with the remaining silanol groups in the C18 column and causes severe peak tailing. The addition of triethylamine can effectively shield these The interaction can also enhance the non-polar interaction between the chromatographic column and the cefodizime sodium molecule, and the chromatographic peak is significantly improved.
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