柠檬汁中总酸(酸度)检测方案(同步热分析仪)

9.Example of measurement KM Application Note NTIZ-99261 Acid Degree of Seasoning Concentrated Lemon Juice Acidbase titration by Automatic Potentiometric Titrator Standard JapaneseAgriculturalStandards 1.Abstract Determination of acid degree of fruit juice is popularly practiced by potentiometricacid-base titration using a glass electrode based on Japanese Agricultural Standards.After pure water is added， titrate with 0.1mol/L sodium hydroxide up to pH8.3， andthe titration volume is converted to citric acid. Sample juice with granular pulp requires filtering. 2.Reference 1)。JAS specification for measurement of fruit drink (Bulletin No. 1225 noticed byMinistry of Agriculture， Forestry and Fisheries， September 29， 1997) B.Cautions in measurement )Handle with care when work on chemicals.2If acidity is high， use a fixed dose mode to shorten measuring time.3 Use pure water for dilution without ambient carbonic gas dissolved in. Filter sample juice if it contains granular pulp. Otherwise， measurement mayresult with poor repeatability. ( 上海市漕溪路222号航天大厦北楼902室 ) 4.Post-measurement care After the electrode is rinsed with pure water， keep its tip dipped in a beaker filledwith pure water in order to avoid it from drying up. 5.Test equipment Main unit： Automatic potentiometric titrator (Standard preamplifier： STD-) Electrode ： StandardCombination glass electrode StandardTemperature compensation electrode 6.Reagent Titrant 0.1mol/L Sodium hydroxide (f=0.9762) Additive Pure water 7.Measurement procedure -Measurement- Deliver approximately 5g sample into a 200mL beaker.23 Add pure water to make it 100mL in total. Titrate with 0.1mol/L sodium hydroxide to obtain acid degree. 8.Formula Acid degree (Citric acid w/w%)=(EP1 - BL1)xFxC1×K1/ SIZE EP1 ： Titration volume(mL ) BL1 Blank level (0.0427mL) F Factor of titrant (0.9762) C1 Concentration conversion coefficient (6.4 mg/mL) (Citric acid=6.4mg equivalent to 1mL of 0.1mo1/L NaOH) K1 Unit conversion coefficient(0.1) SIZE Sample size (g) ( 上海市漕溪路222号航天大厦北楼902室 ) -Ambient condition-一 -Titration parameter- ·Titration curve- Model ： AT-500N ***Result *** Method No. ： 04 Titr.mode ：Auto Intermit Sample No. ： 05-04 Titr.form ： Level Date：1999/06/18 14：41Sample ID ： Method No.： 04 [Titration parameter] Method Name ： Titr.Form ： Level Sample Measurement Buret No. ：1 I.Level 2.74pH Preamp ：STD Conc.1 I.Temp 24.9C Detector No. ：1 Calculation No. ： 05 Titr. Time 00：11：05 Unit ：pH End Point No. . ： 1 Max.Volume ：60.0mL Unit ：[%] Size 4.999g Titr. Wait ： Os Coefficient1 ：(6.4 Direction ： Auto Blank1 ： Conc-1 6.3160% 0.0427mL Factor1 ： 0.9762 EP-1 49.4754mL [Control parameter] EP Data ： Epn-Blank 8.30pH 2.00 9.00 1st Level ：88.3pH 0.0 CPH3 2nd Level ：88.3 pH Gain ：1 Ctrl Speed ：Medium Sampling mV ： 4.0mV Sampling mL ： 0.5mL 50.9 [mL] Name：Kem-1 (The above test results were printed out from titration by AT-500N unit.) 《Titration parameter> Form： of titration / APB No. the burette used in titration / Unit No.： APB Unit File numberDetector No.： the detector used in titration / Max Volume. of titration / Wait Time： before titration startsDirection.： of titration 《Control parameter> 1st Level potential at EP1/ / 2nd Level： potential at EP2/Gain： sensitivity of detection signalCtrl Speed： control of speed / Sampling mV： sampling potential / Sampling mL： data sampling volume 《Result parameter> Calc No.： formula of conc.1/ End Point No. EP order for concentration 1/Unit conversion unitTemp.Comp.： temperature compensation of titration liquid/ C1(mg/mL)： concentration conversion coefficientK1： unit conversion coefficient /Factor： of reagent /Blank1： blank level 1/ EP Data： titration volume formula 上海市漕溪路222号航天大厦北楼902室网址：http：//www.kyoto-kem.net.cn -Measurement results n Sampleg Titration(mL) Acidity(w/w%) Batch processed acidity 123 4.999 4.994 4.998 49.4754 49.4444 49.4588 6.3160 6.3184 6.3151 Mean SD RSD 6.3165% 0.0017% 0.0270% *The above results were obtained by 3 tests of the same sample. *Red underline shows the data from page 3/4. 10.Summary The concentrated fruits juice is a kind of juice reduced from concentration by addingwater. Most of fruits juice sold in the market is made from concentration. Simply described Acidity means the concentration of organic acid.The sample measurement shows a good repeatability with 0.03% relative standarddeviation. Precise andreliable measurement is assured by the automatedpotentiometry. The analysis of acid degree of concentrated lemon juice can be perfectly analyzed byany of the following titration systems manufactured by Kyoto Electronics(KEM). 【AT-610】 【AT-510】 【AT-500N-1】 AwardedProductt ofSupremeTechnology from Kyoto City ·Compact and cost performancemodel Low cost and high performance · Easy view with back light LCD 。Easy key entry by touch panel oflarge color LCD (8-inch wide) ·PC card expands data memory forconvenience and versatility. ● GLP/GMP conformed model ·Simultaneous titration in parallel · Bothpotentiometricand KarlFischer moisture titration(coulometric"volumetric) can beperformed at a time. KMKYOTO ELECTRONICS MANUFACTURING CO.，LTD. Overseas Division： Yamawaki Bldg 9F，4-8-21 Kudan-minami，Chiyoda-ku， Tokyo 102-0074 JAPAN Phone： +81-3-3239-7333，Fax： +81-3-3237-0537 Head Office： 56-2 Ninodan-cho，Shinden，Kisshoin，Minami-ku， Kyoto 601-8317 JAPAN Phone：+81-75-691-4122，Fax： +81-75-691-9961 URL： http：//www.kyoto-kem.com 京都电子工业株式会社-可睦电子(上海)商贸有限公司 上海市漕溪路222号航天大厦北楼902室 电话：021-54488867 电邮： kemu-kem@163. com 网址： http：//www.kyoto-kem.net. cn 京都电子工业株式会社-可睦电子(上海)商贸有限公司电话： 电邮： kemu-kem@com网址： http：//www.kyoto-kem.net. cnTIZ-Ver. 京都电子工业式会社-可睦电子(上海)商贸有限公司电话： 电邮： kemu-kem@ com网址： http：//www. kyoto-kem. net. cnTIZ-Ver.