[Determination of unknown impurities in cefotiam hexetil by HPLC-MS/MS].

OBJECTIVE: To detect unknown impurities in raw drug material of cefotiam hexetil. METHODS: High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was employed for the determination of impurities in cefotiam hexetil. Agilent SB-C18 column (150 mm x 2.1 mm i. d. , 3.5 microm particles) was used for chromatographic separations of cofotiam hexetil dissolved in deionized water, with mobile phase consisting of (A) 0.1% formic acid and (B) acetonitrile and timed gradient program T (min)/B (%): 0/3, 5/3, 15/20, 20/40, 30/60, 40/80. The flow rate was set at 0. 3 mL/min with DAD detector wavelength fixed at 254 nm. Electrospray ionization source was applied and operated in positive ion MRM mode. The source voltage was kept at 4 kV and cone voltage was 100 V with the mass range m/z 50-1000. Nitrogen was used as nebulizing gas and the nebulizer pressure was 40 psi. The drying gas temperature was 350 degrees C and the drying gas flow was 10 L/min. Results Unknown impurities of cefotiam hexetil were identified. Substance 1 was delta3-isomer of cefotiam hexetil. The structures of 3 other substances were also determined. CONCLUSION: The method is sensitive, rapid and credible for the analysis of cefotiam hexetil and its related impurities, which can be applied in quality control of cefotiam hexetil.

[LC-MS/MS analysis of determination of strychnine and brucine in formaldehyde fixed tissue].

OBJECTIVE: To establish a method for determination of strychnine and brucine in formaldehyde fixed tissue by LC-MS/MS analysis. METHODS: The samples were pretreated with solid phase extraction using SCX cartridges and separated on SB-C18 column with mobile phase 0.1% formic acid : 0.1% formic acid-acetonitrile (75:25). Electrospray ionization (ESI) source was utilized and operated in positive ion mode. Multiple reactions monitoring (MRM) mode was applied. External standard method was applied for quantitation. RESULTS: The chromatographic separation of strychnine and brucine in formaldehyde fixed nephritic and hepatic tissues resulted successfully. The standard curve was linear in the range of 0.002-2.0 microg/g for strychnine and brucine in formaldehyde fixed tissues, and the correlation coefficient was more than 0.996. The limits of detection (LOD) of strychnine and brucine in nephritic tissues were 0.06ng/g and 0.03 ng/g, respectively. The LOD of both chemicals were 0.3 ng/g in hepatic tissues. The extraction recovery rate was more than 74.5%. The precision of intra-day and inter-day were both less than 8.2%. CONCLUSION: Strychnine and brucine can be sensitive to be determined in formaldehyde fixed tissue by LC-MS/MS analysis. It can be applied in the forensic toxicological analysis.