离子色谱法测定奶粉中胆碱含量方法的研究

目的：丰富奶粉中胆碱含量测定的方法,同时对其他同类产品中胆碱含量的测定提供参考。方法样品经盐酸水解,水解液五倍稀释后采用离子色谱仪进行测定。结果离子色谱法对胆碱含量测定的最低检测限为2 mg/kg,相关系数达到0.9998,添加回收率为88.7%~102.5%,平行样标准偏差为0.72~4.15 mg/100 g,相对标准偏差为0.66%~3.30%。结论该方法操作简单,灵敏度高,选择性强,能克服传统方法中繁琐、准确度低等缺陷和不足。

分光光度法和离子色谱法测定水中磷酸盐的比较

目的 比较分光光度法(spectrophotometry, SP法)和离子色谱法(ion chromatography, IC法)测定水中磷酸盐含量的结果,筛选较优方法推广应用。方法 比较SP法与离子色谱法测定水中磷酸盐含量的相关系数r、检出限、定量限、准确度和精密度等,以筛选较优的方法。结果 相关系数r:IC法(0.9992)大于SP法(0.9991);检出限:IC法(0.003 mg/L)低于SP法(0.045 mg/L);定量限:IC法(0.01 mg/L)也低于SP法(0.15 mg/L);精密度(RSD):IC法(0.3%~0.6%)优于SP法(0.7%~1.5%);加标回收率:IC法(97.4%~105%)、SP法(97.1%~103%)。结论 两法比较结果认为,离子色谱法(IC法)操作简单、精密度较高、检出限较低、干扰较少,适用于大批量检测,有推广应用价值。

Rapid Purification of Enhanced Green Fluorescent Protein from Escherichia coli

As an excellent reporter molecule, enhanced green fluorescent protein (eGFP) was widely used for gene expression and regulation and was generally expressed in Escherichia coli strain. A rapid procedure consisting of ammonium sulfate precipitation, size exclusion chromatography, and anion exchange chromatography was devel- oped for the purification of eGFP. Based on the proposed procedure, recombinant eGFP with an electrophoretic pu- rity was achieved in combination with an overall yield of 66% and a purification factor of 17.9. The fluorescent spectrometry of purified eGFP and lysate from E. coli strain expressing eGFP exhibited the same wavelength of ex- citation and emission maxima, indicating that the purification procedure did not influence the construct and fluo- rescent characteristics of desired protein. The procedure mentioned was easy to scale up for the purification of large quantities of eGFP.