盐度滴定法.doc

HS039Page 7Test Method SubjectSpecification No.SALT, TITRATION METHODHS039盐，滴定法LocationRevision No. HUMBOLDT01Nature Of RevisionIssue DateGeneral Revision.3/30/84ApprovalSupersedes issue of 7/15/81.I.DEFINITION1、 定义：This procedure describes the analysis of sodium chloride using silver nitrate reagent for precipitation of the chloride as the silver salt.该程序描述了用硝酸银分析滴定氯化钠含量。II. SCOPE2、 范围Applicable to J. Hungerford Smith products and other food products having varying amounts of sodium chloride and having little or no other chloride containing salts.适用于汉斯所有添加氯化钠以及其他少量含盐的产品。III.APPARATUS AND REAGENTS3、 仪器和药品A.Fisher Accumet pH Meter, equipped with a reference calomel electrode, and a silver electrode (billet), and an automatic temperature compensator, or equivalent. pH计，配有甘汞电极、银电极并自带温度补偿。B.Buret, 25 ml, 0.10 ml subdivisions, Teflon stopcock, Automatic, VW&R #17550-083 or equivalent. 滴定管，25ml，精度0.10ml，塑料活塞、自动，VW&R #17550-083或等同设备。C.Balance, 160 g capacity, readable to .01g Mettler PN163 #11275-215 or equivalent. 天平，量程160g，精确到0.01g梅特勒PN163 #11275-215或等同设备。D.Beakers, 500 ml, graduated, VW&R #13910-201 or equivalent. 烧杯，500ml，graduated, VW&R #13910-201或等同设备。E.Flasks, volumetric, 1000 ml; VW&R #29619-610 and -653 or equivalent. 量筒，1000 ml; VW&R #29619-610 and -653或等同设备。F.Magnetic stirrer, VW&R #58939-909 or equivalent. 磁力搅拌器，VW&R #58939-909或等同设备。G.Stirring bats, 1 length, Teflon coated, VW&R #58948-138 or equivalent. 1长附塑料套的磁粒，VW&R #58948-138或等同设备。H.Bottle, Aspirator (silver nitrate reagent reservoir), or equivalent. 储液瓶（存放硝酸银）或等同设备。NOTE:If available, an amber bottle should he used; otherwise the bottle should be- painted black or covered to exclude light. 注意：如果有条件，可用棕色瓶；其他瓶子应涂黑或避光。I.Silver nitrate crystals, reagent grade, JTB #3426 or the equivalent. 硝酸银，分析纯，JTB #3426或等同。J.Standard Salt Buffer solution, reagent grade 1.010-5M NaCl. 标准盐缓冲溶液，含1.010-5M NaCl.K.Sodium chloride, reagent grade, JTB #3624 or equivalent. 氯化钠，分析纯，JTB #3624或等同。L.Blender, Waring or equivalent. 搅拌机，瓷的或等同。M.0.020N NaCl standardettes from Chemical Services Labs, P.O. Box 281, Largo, Florida or equivalent. 来自佛罗里达州纳格281号信箱化学服务实验室0.020N 的NaCl标准液。IV.EQUIPMENT PREPARATION AND REAGENT STANDARDIZATION 仪器准备和试剂的标定。A.1.010-5 M NaCl Solution 1.010-5 M NaCl溶液1.Weigh 5.844 g of reagent grade NaCl and transfer quantitatively to a 1000 ml volumetric flask. Make up to a volume and agitate to dissolve. 称取5.844g分析纯NaCl并转移到一个1000ml容量瓶中。加水至刻度线并摇晃至溶解。2.Transfer 10 ml of the above solution to another 1000 ml using a 10 ml pipette. Make up to volume and agitate to mix. 用一支10ml移液管吸取10 ml以上溶液至另一个1000 ml容量瓶3.The solution resulting from step 2 above is again diluted according to the instructions in step 2. 将第2步中吸取的溶液再次稀释。4.Store in a tightly closed container. 将溶液存储于一密闭容器里。5.Quantities in step 2 may be scaled up or down to vary the size of the batch, ie; 5 ml to 500 ml. 20 ml to 2000 ml, etc. 在第2步骤中，溶液会成倍的增加或减少至需要的范围内；5 ml增至500ml，20ml增至2000ml等等。B.pH Meter pH计1.Connect pH Meter to 115-Volt AC in standby mode. 将pH计电源连接于115V交流电上2.Connect reference calomel electrode to the input jack with an adapter. 将参比甘汞电极插入插口。3.Connect the silver billet electrode to the reference jack. 将银电极插入插口。4.Connect the automatic temperature compensator to the ATC jack. 将自动温度补偿器插入ATC插口。5.Allow pH Meter to warm up for 15 minutes. 将pH计预热15分钟。6.Place electrodes in beaker of standard NaCl solution. 将电极插入盛有标准盐缓冲液的烧杯中。7.If no temperature compensator is being used, set Function dial at pH and set temperature dial at the temperature of the standard solution. If a temperature compensator is being used set function dial to ATC and set temperature dial to 0. 如果没有自动温度补偿器，将“功能”键拨到“pH”并且将温度指示调至与标准液相同温度。如果自动温度补偿器已被插入ATC插口，使温度补偿至08.Switch meter from standby to use and adjust meter to read 11 using the standardization dial . 转换表盘从备用到使用，用标准刻度盘去读11。9.Switch meter to Standby, rinse electrodes and store in deionized water while not in use. 转换表盘至备用，清洗电极并且在不用时储存于去离子水中。10.Standardize meter at the beginning of each shift. 每次变化都需校准pH计C.0.05N AgNO3 Solution 0.05 N AgNO3溶液1.Decide how many liters of solution is to be made. 确定需要配制多少升溶液。2.Weigh, into a weighing boat or suitable container, 8.5g of AgNO3 for each 1000 mls of solution to be made. 称重，放在一个称量皿或溶液的容器里，每1000 ml溶液中含8.5g AgNO33.Transfer to AgNO3 quantitatively to a 1000 ml volumetric flask. Add 500 to 750 ml of deionized water and agitate to dissolve. 将AgNO3 转移至一个1000 ml容量瓶中。加500至750ml去离子水并摇晃至溶解。4.When dissolved make up volume to 1000 ml, agitate to mix and transfer to AgNO3 storage reservoir. 待全部溶解后加水至刻度线，摇匀并存于AgNO3储液瓶中。5.Using the same volumetric flask, add deionized water to storage reservoir in one liter increments (1000 ml) to make up the total volume to that decided in step 1. 用同样的容量瓶加入1000 ml去离子水以弥补步骤1中确定的总量。6.Mix content of reservoir well and hook to a 25 ml automatic burette. Flush AgNO3 solution thru the line and burette to rinse. 将溶液混合均匀后加入25ml滴定管内，放出超过刻度线的AgNO3溶液。7.Transfer, quantitatively, the content of one standardette representing 40.01 ml of .020N NaCl solution to a 500 ml beaker. Add sufficient distilled water to prevent splashing while titrating. 用标准容器转移40.01 ml浓度为 0.020N的氯化钠溶液到一个500 ml的烧杯里。加入足够量的蒸馏水防止在滴定时喷出。8.Put a stir bar in the beaker and place beaker on a stirrer under the burette. 在烧杯中放入一个搅拌子，并把烧杯放在滴定管下的搅拌器上。9.Immerse the electrodes in the standardette solution and set pH meter to use. 将电极浸泡在溶液中并打开pH计至工作状态。10.Titrate to an end point reading of 11. 滴定至终点pH等于11。11.Calculate the normality of AgNO3 using the following formula: 用以下公式计算AgNO3浓度：12.If normality does not fall between .049 and .051 adjust with AgNO3 or deionized water until it falls within this range. Target for .050N. 如果结果不在0.0490.051范围内，则需调节AgNO3 或蒸馏水直到在这个范围内。标准值为0.050NV.SAMPLE PREPARATION 样品制备A.Homogeneous Products - Analyze well mixed sample as is. 同类产品将样品混合均匀。B.Heterogeneous Products - Whizz approximately 500 ml of well mixed sample until homogeneous and analyze. 不同类产品离心大约500 ml混合均匀的样品并分析。VI.SALT DETERMINATION PROCEDURE 分析程序A.Weigh correct sample size determined from table I into a 500 ml beaker. 根据表一称取相应数量的样本放在一个500 ml烧杯中。B.Add sufficient deionized water to prevent splashing while titrating. 在滴定时加入充足的去离子水放在喷出。C.Place stir bar in sample and place on stirrer under AgNO3 burette. 在样品中放入搅拌子并放于AgNO3 滴定管下的搅拌器上。D.Immerse the electrodes in the sam