Applicability of internal standard in determination of cyclamate in wine by HPLC-tandem mass spectrometry / 上海预防医学

Objective] To discuss the applicability of internal standard in determination of cycla-mate in wine by HPLC-tandem mass spectrometry . [ Methods] After dilution wine sample was deter-mined by HPLC-tandem mass spectrometry and quantified by external and internal standard methods respec-tively. [Results] The results by the 2 quantitation methods differed 11.2%in average, and the maxi-mum relative deviation was 16.2%.And the result by external standard quantitation method proved to be consistent with that by the international standard GB/T 5009.97-2003. [ Conclusion] The difference in results is thought to originate from matrix effect in HPLC-tandem mass spectrometry and the improper in-ternal standard compound applied .

Preliminary study on cryopreservation of tissue engineered bone at -8 degrees C / 中国骨伤

<p><b>OBJECTIVE</b>To study the effects of various methods of cryopreservation on the bioactivity of tissue engineered bone.</p><p><b>METHODS</b>MSCs were cocultured with partialy deproteinised bone to produce tissue engineered bone. The experiment was divided into A, B, C and D group. Group A: Tissue engineered bone was stored in preservation solution with cryopreservation medium. Group B: Tissue engineered bone was stored in preservation solution without cryopreservation medium. Group C: Tissue engineered bone was stored without cryopreservation. Group D: MSCs were cultured without cryopreservation. The tissue engineered bone of group A and B had been cryopreserved at -80 degrees C for three months and thawed three months later. The electronic scanning microscope was used to evaluate the adhesion and distribution of MSCs, cell viability was measured by MTT, ALP activity was detected by p-nitrophosphate, cell cycle was analysed by flow cytometry.</p><p><b>RESULTS</b>MSCs could adhere to the surface of the material and distribute in the hole of material. The cell viability of MSCs adhered to the material was C > A > B group (P < 0.01, P < 0.05). The ALP activity of MSCs adhered to material was C > A > B group (P < 0.01). The cell cycles of different groups did not change significantly; the abnormal cells were not observed.</p><p><b>CONCLUSION</b>The choice of proper cryopreservative solution could optimize the bioactivity of tissue engineered bone.</p>