排序方式: 共有15条查询结果,搜索用时 31 毫秒
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建立一种木聚糖酶活力的微量测定新方法--3-甲基-2-苯并噻唑酮腙(MBTH)法。根据木聚糖及其酶解产物的特殊性,研究MBTH法的显色条件,并以多点测定法对酶活力测定中的几个关键参数进行探讨。结果表明:蛋白质在其质量浓度低于30μg/mL时对测定无干扰;木聚糖溶液的最佳测定质量浓度为4mg/mL;较高的酶解温度会使木聚糖酶在测定过程中失活,因此,酶活力测定的最佳温度为30℃,而远低于该酶的最适温度;酶解时间为60min以内;酶解产物与MBTH试剂的反应时间应控制在13~16min之间,以15min为最佳。以酶解时间为30min计,本法检测限为0.135mU/mL,定量限为0.451mU/mL,适当延长酶解时间可相应提高酶活力检测灵敏度。该法准确度高,结果稳定,灵敏度远高于DNS法。 相似文献
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在优化溶菌酶水解参数的基础上,运用3-甲基-2-苯并噻唑酮腙(MBTH)比色法研究了溶菌酶对不同脱乙酰度的壳聚糖的水解敏感性。结果表明:在70℃、pH值4.5、壳聚糖质量浓度5 mg/mL的条件下,溶菌酶在壳聚糖的脱乙酰度为41.7%时体现出最高敏感性。 相似文献
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Acrolein can be at the origin of an important organoleptic defect in beverages made from apples. Its content was investigated in freshly distilled Calvados and cider. The specificity of 3-methylbenzothiazolone hydrazine (MBTH) towards carbonyl compounds was used in order to derive acrolein in azines. Azines were separated and detected by gas chromatography coupled with a nitrogen-phosphorus Detector. Results showed that acrolein concentrations could be quickly determined in either Calvados or cider. Accuracy of quantification was better than 6% for concentrations about 1 mg/l in freshly distilled Calvados and 10% for concentrations about 10 μg/l in ciders. Acrolein content was found between 0.7 and 5.2 mg/l in samples of freshly distilled Calvados whereas it was between 7 and 15 μg/l in samples of cider. This method of quantification was applied to study disappearance kinetics of acrolein in cider. Acrolein content was found to decrease rapidly during the first hours and to change very slowly after a few days. Its behaviour during a distillation was also investigated showing that in spite of its high volatility it could also be found in the last fractions of distillation. 相似文献
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改进MBTH分光光度法测定室内空气中甲醛的含量 总被引:1,自引:0,他引:1
改进了MBTH(酚试剂)测定室内空气中甲醛的方法。用乙醇做溶剂制备酚试剂吸收液,稳定性和灵敏度增强,优化了测定条件,最大吸收波长633 nm,显色温度20~25℃,显色时间25 min,显色剂用量2~2.5 mL,加标回收率达到96%以上,样品测定结果与国标偏差不超过3%,适用于甲醛含量测定;根据颜色对应的浓度制作比色卡。该方法精密度高、准确性好,简单、快速,可用于空气中甲醛含量的测定。 相似文献
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