<p><br></p><section class="_135editor" data-role="paragraph" style="font-size: medium; max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp; &nbsp; 目前,测定棉纤维含糖的方法,主要有日本的比色法、德国不莱梅苔黑素试验法、美国的色谱法和红外光谱法等。国内有参照日本比色法进行的目视比色测定、参照德国不莱梅苔黑素试验法进行的定量法试验等。我国对色谱法及红外光谱法也进行了探索和研究。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 一、还原糖分离检测法<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 将棉纤维放在沸水中或浸泡萃取其中糖分,溶液采用贝氏(Behedict)、斐林氏(Fehing２Mas２sat)等试剂,主要检测棉纤维外源糖与内源糖总和中的还原糖含量。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (一)贝氏液测定法<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 国内称贝氏液测定法为目视比色测定法,是参照日本比色法的一种测定方法,可直接称为比色法。根据GB/T13785—1992标准,本方法是用比色法快速评定棉纤维含糖程度的一种试验方法。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 1.测定原理<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 棉纤维含糖的主要成分是葡萄糖、果糖和蔗糖。这些糖分还原性和非还原性两类。还原性糖的分子结构中含有的醛基和酮基具有还原性,能与贝氏试剂反应,而非还原性糖的分子结构中不含有醛基和酮基,不能与贝氏试剂反应。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 贝氏试剂由柠檬酸三钠、无水碳酸钠和硫酸铜组成。两液混合后,柠檬酸三钠在碱性溶液中生成蓝色络合物。将含糖的棉纤维加入蓝色贝氏试剂加热共沸,溶液中二价铜离子逐渐被还原成红色的氧化亚铜。溶液中天蓝色铜络合物、二价铜离子还原生成的红色氧化亚铜的成分比率随化学反应而不断变化,溶液呈现各种颜色。由于棉纤维中糖分含量不同,溶液分别显示出蓝、绿、草绿、橙黄、茶红五种颜色。然后将溶液颜色与标准色卡或蒙赛尔色谱色标目测比色,定性地确定棉纤维含糖的高低,见表5-5。</span></p><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; text-align: center; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><img src="http://dayaotex-img.gz.bcebos.com/article/fffspic/biao5-5.png" _src="http://dayaotex-img.gz.bcebos.com/article/fffspic/biao5-5.png" data-ratio="0.2511144130757801" data-w="673" style="max-inline-size: 100%; margin: 0px; padding: 0px; max-width: 100%; width: 464px; overflow-wrap: break-word !important; outline: none 0px !important; height: auto !important;"></p><section align="left" style="max-inline-size: 100%; margin: 0px; padding: 0px; -webkit-tap-highlight-color: rgba(0, 0, 0, 0); font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;</span></p></section><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 2.仪器与试剂<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (1)3～4联并联调温电炉1台。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (2)分度值为0.01g的天平1台。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (3)标准比色样卡或蒙赛尔色谱色标。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (4)1000mL、250mL烧杯各1个;150mL烧杯20个;1000mL、50mL量筒各1个;1000mL容量瓶2个;10mL定量加液管1个;50mL比色管20支;比色架2个。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (5)试剂:分析纯或化学纯无水碳酸钠、分析纯或化学纯柠檬酸钠和分析纯或化学纯结晶硫酸铜。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 3.贝氏试剂配制<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 甲液:柠檬酸钠193g、碳酸钠100g溶于800mL蒸馏水中。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 乙液:硫酸铜17.3g溶于100mL蒸馏水中。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 将甲、乙两液混合稀释至1000mL,即为贝氏试剂。配制好的试剂如不用时,应盖好瓶盖,放在常温背阴处保存,以防失效。使用前先摇动若干下,使溶液充分混合后再用。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 4.试验试样准备<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 实验室样品按GB6097—1985的规定,从批样中抽取。至少抽取32丛、每丛约300mg,构成8～10g的试验样品;将试验样品中的棉子、子屑、叶屑、尘土等杂质去除,充分混匀,从中取出5个试验试样。每个试验试样重1.00g±0.01g。余样备用。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 5.测定步骤<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (1)空白测定:在150mL烧杯中,加40mL蒸馏水和10mL贝氏试剂,加热煮沸1～2min,倒入比色管中作为含糖“无”的标样(此标样必须每天配制1次)。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (2)试验试样测定:将称准的5个试验试样分别放入5个150mL的烧杯中,各加40mL蒸馏水、10mL贝氏试剂,放在电炉上加热,煮沸1～2min,并不断搅拌。取下烧杯,用镊子将棉样挤干取出,把剩下的约30mL溶液倒入比色管中。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (3)目视比色:在比色管架后面贴上一张白纸,利用自然光线进行目视比色。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 6.含糖判定<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 根据溶液呈现的颜色,对照标准色卡或蒙赛尔色谱色标与空白试样,分别定出每个试验试样的含糖程度(表5-5)。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 五个测定结果中,上下两档中有两个及两个以上的下档,则定为下档,否则定为上档。测定结果中的最大与最小超过两档,如无、微量、少量与稍多应增删1～2个试验试样。若全部测定结果的最小档有两个及两个以上者,则定为最小档,否则定为上一档。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 贝氏液测定法的特点是操作简便,易于掌握。但由于氧化亚铜沉淀很快,故该法颜色稳定性差,无法用分光光度计进行定量比色。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 为解决颜色稳定性差的问题,有人研究利用贝氏试剂与还原糖反应后,再与磷钼酸反应能生成显色络合物的特性,开发了用仪器比色法测定棉纤维中还原糖的方法。此法虽为定量测定棉纤维中还原糖提供了可能,但还没有得到普及。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; (二)斐林氏液测定法<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 斐林氏液是一种氧化剂,分A液和B液。A液中含有硫酸铜和次甲基蓝;B液中含有酒石酸钾钠和黄血盐。在碱性溶液中,硫酸铜与氢氧化钠作用,生成天蓝色的氢氧化铜沉淀后,立即与酒石酸钾钠起反应,生成深蓝色的氧化铜和酒石酸钾钠的络合物———酒石酸钾钠铜,反应式如下式所示。</span></p><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; text-align: center; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><img src="http://dayaotex-img.gz.bcebos.com/article/fffspic/gongsi010.png" _src="http://dayaotex-img.gz.bcebos.com/article/fffspic/gongsi010.png" data-ratio="0.5739644970414202" data-w="676" style="max-inline-size: 100%; margin: 0px; padding: 0px; max-width: 100%; width: 464px; overflow-wrap: break-word !important; outline: none 0px !important; height: auto !important;"></p><section align="left" style="max-inline-size: 100%; margin: 0px; padding: 0px; -webkit-tap-highlight-color: rgba(0, 0, 0, 0); font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;</span></p></section><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; font-size: 14px; line-height: 1.5em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 红色的氧化亚铜沉淀与斐林氏液中的黄血盐生成可溶性化合物。用蓝色次甲基蓝作指示剂,当斐林氏液中的铜全部被糖还原后,还原糖立即使次甲基蓝还原为无色,说明已经中和。通过计算即可得到含糖量。<br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;">&nbsp;&nbsp;&nbsp; 斐林氏液测定法不仅能测出棉纤维中的总糖量,还能测出还原糖的量。与其他方法比,斐林氏液测定法是测定棉纤维含糖最准确的方法。但实验操作要求严格,测定时间长。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p></section><section class="_135editor" data-role="paragraph" id="autoparagraph" style="font-size: medium; max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; font-family: 微软雅黑, &quot;Microsoft YaHei&quot;, sans-serif; font-size: 17px; caret-color: rgb(255, 0, 0); overflow-wrap: break-word !important; outline: none 0px !important;"></p></section>