共查询到19条相似文献,搜索用时 406 毫秒
1.
研究了乳粉中蛋白质含量的示波滴定法.样品用H2SO4-Na2SO4-CuSO4消化处理,N以NH+4的形式存在于试液中,用过量四苯硼钠沉淀铵,沉淀过滤,过量的四苯硼钠用氯化四乙基铵标准溶液返滴定,以四苯硼钠切口消失为终点,计算出氮含量,再换算为蛋白质含量.本方法终点变化敏锐,不外加指示剂,与通用的标准分析方法相比较,操作简便、快速,测定结果准确可靠,所用分析试剂无毒. 相似文献
2.
3.
电导法快速测定卤水中钾的含量 总被引:2,自引:0,他引:2
文章用四苯硼钠溶液电导滴定法确定终点,测定卤水中的钾的含量。方法简便,测定周期仅需10min左右,所需试剂种类和用量少,准确度和精密度与四苯硼钠重量法接近。方法还适用于各种钾盐和复混肥中钾的测定。 相似文献
4.
目的:研究用十二烷基硫酸钠(sodium dodecyl sulfate,SDS)快速测定奶粉中蛋白质含量的实验条件。方法:一定量的奶粉用蒸馏水溶解后,在一定介质中用0.1000%的SDS溶液滴定,当被滴定溶液析出凝乳状的白色沉淀时,即为终点。研究了温度、pH值及奶粉中淀粉、蔗糖含量对测定的影响,确定了SDS溶液的滴定量与蛋白质含量的关系。结果:用该方法对同一奶粉测定8次,RSD=0.53%,用本法和凯氏定氮法对8份不同奶粉中的蛋白质含量测定,结果无显著性差异(p>0.05)。结论:该方法简便、准确、可靠,适合于奶粉中蛋白质的快速检测,检验一个样品仅仅用4min。 相似文献
5.
酸沉淀提取制浆黑液中的木素 总被引:2,自引:0,他引:2
用硫酸进行酸沉淀提取黑液中木素的实验 ,探讨了酸沉淀终点 pH值对木素提取率的影响 ,保温时间和酸沉淀终点 pH值及黑液固含量对木素留着率的影响 相似文献
6.
牡蛎蛋白的纯化及酶解条件的研究 总被引:8,自引:0,他引:8
本文利用(NH4)2SO4分级沉淀,透析脱盐,DEAE52纤维素柱层析对牡蛎蛋白质进行分离纯化,通过SDS凝胶电泳可知,55%饱和度的(NH4)2SO4沉淀可获得以牡蛎特征蛋白为主的纯化蛋白,其分子量约为55kD.在酶解实验分别采用胃蛋白酶、胰蛋白酶来进行,考察不同条件对水解度的影响.结果是胃蛋白酶酶解的最适酶用量为3%,pH2,温度40℃,水解时间5h,料水比为1:4;而胰蛋白酶的最适酶用量为2%,pH8,温度45℃,水解时间6h,料水比为1:3. 相似文献
7.
8.
9.
甘薯糖蛋白的分离纯化和组成 总被引:10,自引:1,他引:10
甘薯粗糖蛋白经 (NH4 ) 2 SO4 分级沉淀、离子交换以及凝胶柱层析等方法分离纯化后得到一个糖蛋白组分SP -3 2 4,实验中测定了其组成和结构。氨基酸组成中天冬氨酸含量最高 ,占氨基酸总量的 1 3 80 % ,能够构成O 糖肽键的丝氨酸和苏氨酸分别占氨基酸总量的 6 0 5 %和 4 89;单糖组成主要含有葡萄糖、阿拉伯糖、半乳糖 ,其比例为 1 2∶1∶1 1 4,含有痕量的鼠李糖、木糖、甘露糖 ;测定结果表明 ,SP 3 2 4组分含蛋白质 74 0 0 % ,糖 7 80 % ;通过 β 消去反应证明了SP 3 2 4组分中的糖和蛋白是以O 糖肽键结合的。 相似文献
10.
11.
12.
本研究对盐酸副玫瑰苯胺法测定食品中SO2进行改进,以EDTA-2Na代替剧毒试剂四氯汞钠,建立了超声波浸提、无汞盐吸收液检测干果SO2残留的方法,二氧化硫含量在0~10.0μg范围内与吸光度呈良好的线性关系(R2=0.9995),方法的检出限为0.8mg/kg。测定样品的相对标准偏差在3.29%~7.42%之间,回收率在89.17%~104.72%之间。该方法操作简便、重现性好、线性范围宽、减小了对环境的污染,可用于干果中亚硫酸盐的测定。 相似文献
13.
评定螺旋藻片中氮含量测定的不确定度。方法 采用《中国药典》2015年版第四部氮测定法中第一法(常量法),测定出螺旋藻片中的含氮量。根据测量不确定评定的要求与表示的要求,通过获得的检测数据对螺旋藻片中氮含量测定的不确定度进行评定。结果 当氮含量的结果为:20.59mg/片时,常量法测定螺旋藻片氮含量的合成标准不确定度为0.196mg/片,扩展不确定度为0.39mg/片,螺旋藻片中氮含量测定的结果为:(20.59±0.39)mg/片,(k=2,p=95%)。结论 在测定过程中,测量不确定度的主要来源于试样测定重复性实验引入的不确定度和试样滴定过程引入的不确定度。因此, 对常量法测螺旋藻片氮含量的不确定度评定时, 应控制好试样的消化、蒸馏,同时控制好试样的滴定,以确保数据的准确可靠。 相似文献
14.
通过比较提出了用直接称量滴定法测定盐产品中Cl-、Ca2 、Mg2 、SO24-含量,使检测过程变得更加简便、快捷、准确.借助于结果不确定度的评价,使方法准确度得以验证和优化.从而在确保结果准确性的前提下大大提高检测速度,减轻检测人员劳动强度. 相似文献
15.
浅谈输卤管道堵管事故处理与预防 总被引:2,自引:0,他引:2
湖北蓝天盐化厂的矿山属Na2SO4型。Na2SO4含量平均值在40g/L。长时间用一条管道回卤,使Na2SO4附着在回卤管的拐角处并逐渐增多,到一定条件下,可以将回卤管道完全堵死。在生产中,我们总结出较为简便、实用的方法,有效地防止了结晶堵管事故的发生,保证了供卤工作的正常进行。 相似文献
16.
A new cloud-point extraction and preconcentration method using a cationic surfactant, Aliquat-336 (tricaprylylmethylammonium chloride), has been developed for the determination of cyanobacterial toxins, microcystins, in natural waters. Sodium sulfate was used to induce phase separation at 25 degrees C. The phase behavior of Aliquat-336 with respect to concentration of Na2SO4 was studied. The cloud-point system revealed a very high phase volume ratio compared to other established systems of nonionic, anionic, and cationic surfactants. At pH 6-7, it showed an outstanding selectivity in analyte extraction for anionic species. Only MC-LR and MC-YR, which are known to be predominantly anionic, were extracted (with averaged recoveries of 113.9 +/- 9% and 87.1 +/- 7%, respectively). MC-RR, which is likely to be amphoteric at the above pH range, was not detectable in the extract. Coupled to HPLC/UV separation and detection, the cloud-point extraction method (with 2.5 mM Aliquat-336 and 75 mM Na2SO4 at 25 degrees C) offered detection limits of 150 +/- 7 and 470 +/- 72 pg/mL for MC-LR and MC-YR, respectively, in 25 mL of deionized water. Repeatability of the method was 7.6% for MC-LR and 7.3% for MC-YR. The cloud-point extraction process can be completed within 10-15 min with no cleanup steps required. Applicability of the new method to the determination of microcystins in real samples was demonstrated using natural surface waters collected from a local river and a local duck pond spiked with realistic concentrations of microcystins. Effects of salinity and organic matter (TOC) content in the water sample on the extraction efficiency were also studied. 相似文献
17.
以脱脂蚕蛹为原料,采用Na2SO3为提取溶剂,通过单因素试验和正交试验确定提取蛋白质的优化条件。结果表明,蛋白质提取率的最大影响因素是Na2SO浓度,其次是提取温度,再次是料液比,而提取时间的影响最小。优化后的提取方案是Na2SO3浓度为1%、提取温度90℃、提取时间120 min、料液比1∶14。在此条件下进行一次提取,提取率可达22%以上,进行2次提取,提取率可达30%以上。 相似文献
18.
19.
ABSTRACT: Fresh and frozen-thawed cod raw materials were subjected to brining, dry salting, and rehydration. The effects of salting and desalting on fillet water-related properties, salt content, and salt distribution were studied using 23Na MRI, 23Na NMR, and low-field (LF) 1H NMR. The results were compared with the Volhard titration method for salt determination, fillet pH, water content, and water-holding capacity. The rehydrated end product showed significant difference only with respect to water-holding capacity (unfrozen raw material higher) when fresh and frozen-thawed raw materials were compared. Excellent correlation was obtained between quantitative salt determinations using 23Na NMR and Volhard titration. When using a typical salting method, it was shown that the salt uptake and salt distribution in the fillets were inhomogeneous. Proton relaxation times, obtained from LF 1H NMR, were processed using either a 2-exponential model or the CONTIN algorithm. In several instances, a clear dependence on fillet pH, water-holding capacity, or salt content during fish processing was observed. Our results indicate that NMR and MRI can be used as useful tools to evaluate and optimize fish processing unit operations and that rapid (LF) NMR methods have the potential for replacing traditional salt and water-related analytical methods. 相似文献