Comparison of pyrolysis-mass spectrometry with high performance liquid chromatography for the analysis of vancomycin in serum

Mass spectrometry coupled with a pyrolysis inlet system (Pyr-ms) is compared with high performance liquid chromatography (HPLC) for the determination of vancomycin and its crystal degradation products (CDP-Is) in human serum. Quantitative analysis of Pyr-ms was performed by selected ion monitoring (SIM) method at 108 mass:charge ( m/ z) of pyrolysis product of vancomycin. 3-Nitroaniline (138 m/ z) was used as an internal standard. A μ-Bondapak C 18 column and the gradient mobile phase of triethylamine buffer (pH 6.2), acetonitrile and tetrahydrofuran and a photometric detection at 205 nm are found to be the optimum conditions for the HPLC determination of vancomycin and CDP-Is. The limit of detection (LOD=1 ng ml −1), linearity (1 ng ml −1–10 mg ml −1), relative standard deviation (R.S.D.=1%), time analysis (1/2 h) and sample volume (50 μl) of Pyr-ms are far better than of the HPLC method. However, the HPLC method can individually determine the concentration of vancomycin and its degradation products.