靛酚蓝分光光度法在烟叶样品总氮含量测定中的应用

采用靛酚蓝分光光度法测定烟叶中总氮含量,以探索一种测定烟叶中总氮含量的新方法。将烟叶样品用H2SO4、H2O2消化后,使烟叶中的含氮化合物全部转化为氨态氮,NH 4+在亚硝基铁氰化钠及次氯酸钠存在下,与水杨酸生成蓝绿色靛酚蓝染料,再用分光光度法定量,达到测定总氮的目的。结果表明:该法测定结果与经典半微量凯氏定氮法无显著差异,加标回收率平均可达95.61%,重现性好,精密度高,操作简便,适于大批量烟叶样品总氮的测定。     

Segmentation algorithm for urinary sediment image combiningwavelet transform and 2D Maximum entropy threshold

In order to solve the problem that urine sediment visible components cannot be segmented effectively because of complex components, complicated defocusing in image and poor discrimination between object and background, a method based on combination algorithm wis designed to segment urine sediment. The wavelet transform wis used to erase the effect of defocusing. Then morphology wis utilized to get the subimages that include the particles. The segmentation method combining the wavelet transform based segmentation and the two dimensional entropy threshold based segmentation wis employed to segment urine sediment visible components. Experimental results show that the proposed method can segment urinary sediment images effectively and precisely.     

对2005年版中国兽药典芬苯达唑鉴别方法的商榷

对2005年版《中国兽药典》芬苯达唑鉴别方法中紫外-可见分光光度法测定最大吸收波长存在的问题进行了讨论。建议采用色谱纯甲醇及选择296 nm波长处最大吸收进行芬苯达唑鉴别(1)的测定。     

模拟白酒样品中三聚氰胺的紫外分光光度法分析过程初探

依据三聚氰胺在紫外区220～240nm有灵敏的吸收峰,对建立简便、快速、灵敏的测定模拟白酒样品中三聚氰胺的紫外分光光度法分析过程进行了探索。研究表明,在较低浓度时,相对标准偏差为1.0%,回收率为102%;在高浓度时,可能由于溶液中物质间的相互作用,误差较大。     

紫外分光光度法测定啤酒大麦籽粒脂氧合酶活力的研究

为了明确影响啤酒大麦籽粒脂氧合酶(LOX-1)活力的参数,以甘啤4号啤酒大麦籽粒为研究对象,采用紫外分光光度法探究底物浓度、提取缓冲液p H、反应体系缓冲液p H、提取时间、粗酶加入量∶底物加入量等对LOX-1活力的影响。结果表明,LOX-1活力随底物浓度的增加表现为先增加后减小的趋势,当底物浓度达到0.30mmol·L~(-1)时,LOX-1活力显著高于其它处理;随提取缓冲液p H的增加,LOX-1活力表现为双峰变化趋势,且在p H值5.0处,酶活力为9.85U·g~(-1),显著高于其它处理;粗酶提取时间为30min时,LOX-1活力显著高于其它处理,低于或者高于30min,酶活力均呈现降低趋势;LOX-1活力随反应体系p H的增加,表现为双峰变化趋势,当p H值为6.4时,酶活力最大,且与其它处理间存在显著差异;在其它条件不变,粗酶加入量为50μL的情况下,增加底物加入量,LOX-1活力表现为先增加后减小的趋势,且底物加入量为200μL时,酶活力显著高于其它处理。最终确定紫外分光光度法的测定参数:粗酶提取时间为30min,底物浓度为0.25mmol·L~(-1),提取液和反应体系缓冲液分别为p H值5.0醋酸盐缓冲液与p H值6.4磷酸盐缓冲液,粗酶加入酶量∶底物加入量为1∶4。研究结果为紫外分光光度法在啤酒大麦籽粒LOX-1活力测定中的应用提供了参考。     

蛇床子素分散片处方筛选及溶出度的研究

目的优选蛇床子素分散片处方,并建立溶出度测定方法。方法在单因素试验基础上,采用正交试验以崩解时限、分散均匀性为指标对蛇床子素分散片处方进行优化;采用紫外分光光度法测定分散片中蛇床子素的溶出度,测定波长为322nm。结果最佳处方为蛇床子素10%,崩解剂交联聚维酮20%(外加),填充剂微晶纤维素和乳糖分别为30%和40%,黏合剂为75%乙醇进行湿法制粒压片,优选处方的崩解时间小于10s,分散均匀且全部通过二号筛;蛇床子素在为6～16μg.mL-1(n=6,r=0.999 9)时,线性关系良好,蛇床子素分散片60min内累积溶出百分率为88%。结论蛇床子素分散片制备工艺简单,溶出度高,符合《中国药典》2010年版的相关规定,具有实用价值。     

磁处理对大豆中大豆异黄酮的作用

采用不同磁场强度不同时间处理大豆萌发种子,通过分光光度计法测量大豆异黄酮的含量。研究结果表明：磁场可以改变大豆中大豆异黄酮的含量,在不同的磁场及处理时间条件下,大豆中大豆异黄酮的含量不同。其中150mT处理1h,100mT处理1．5h的大豆中大豆异黄酮含量最大,相比对照分别增加了9．3％,11．8％。该实验结果发现,磁场强度与处理时间的乘积为150mT·h时,大豆异黄酮含量最高。     

双波长法测定常用淀粉原料中直链淀粉、支链淀粉及总淀粉含量

建立了双波长法测定常用淀粉原料中直链淀粉、支链淀粉和总淀粉含量的方法。按照双波长测定的等吸收点作图法确定2种淀粉的测定波长和参比波长,直链淀粉的测定波长分别为630、480 nm,支链淀粉的测定波长分别为550、735 nm。结果表明,直链淀粉浓度在0~36 μg/mL、支链淀粉浓度在40~100 μg/mL范围内线性关系良好,符合比耳定律,具有较高的精确度和准确度。常用淀粉原料的总淀粉含量在66.51%~83.65%,其中绿豆淀粉和豌豆淀粉的直链淀粉含量比明显高于其他淀粉原料;糯米粉中的支链淀粉含量最高,其直链淀粉含量过低,导致吸光值太小而检测不出。     

Determination of molybdenum in plant tissue by graphite furnace atomic absorption spectrophotometry (GFAAS)

Abstract

The analysis of molybdenum in plant tissue using graphite furnace atomic absorption spectrophotometry (GFAAS) is described. The method involved wet digestion using a mixture of sulphuric, nitric and perchloric acids followed by a solvent extraction procedure. Molybdenum was extracted into di‐iso butyl ketone (DIBK) as the iron‐thiocyanate complex. The extract was then analysed for molybdenum by GFAAS.

The results of analyses of the reference plant materials (orchard leaves and citrus leaves) of the National Bureau of Standards (NBS) compared very well with the certified values. Other types of plant tissue were also analysed and the results correlated well with those obtained by an alternative method.     

Fiber‐optic spectrophotometry of cowpea nodules treated with nitrate or ammonium

Abstract

Cowpea nodules (Vigna unguiculata [L.] Walp. cv. CB5) were pierced with two opposing optical fibers (280 μm diameter), and absorbance spectra of 0.1 mm of nodule tissue were recorded from 415 to 600 nm using a modified spectrophotometer with a nodule sampling stage.

The nodule spectra exhibited two absorbance bands, a major band in the near‐UV (415–450 nm) and a lesser one in the green‐yellow region (510–585 nm); the latter exhibited a prominent peak at 550 nm. Nodule spectra were consistent with the superposition of the spectra of ferroleghemoglobin (Lb²⁺), oxyleghemoglobin (Lb²⁺‐ O₂), and cytochrome c (550 nm). The detection of leghemoglobin in vivo was confirmed by demonstrating the reversibility of binding of CO to Lb, and by comparing the spectra of live nodules with those obtained from anaerobic leghemoglobin preparations.

The effects on the nodule spectra of two successive applications (36 and 39 days after planting) of 5 and 10 mM NO₃ ^‐ or NH₄ ⁺ to the nutrient solution bathing the nodulated roots were determined. The spectra of NO₃ ^‐‐ and NH₄ ⁺‐treated nodules were indistinguishable; in each case the height of both the near‐UV and green‐yellow absorbance bands decreased with treatment. Treatment with N caused a significant reduction in the area of the green‐yellow absorbance band.

The spectra of green leghemoglobin pigments were obtained from senescent nodules; these exhibited a reduction in the height of the near‐UV absorbance band and a flattening of the green‐yellow band similar to that of nodules treated with N, but the broadening of the near‐UV band was greater in green nodules.