PH電極(ji)的原(yuan)理(li)和使用維護注(zhu)意事項
核心(xin)提(ti)示：
PH電極又(you)稱PH探頭，是(shi)PH計上與被測(ce)物質接(jie)觸的部分，用來測(ce)電極電位(wei)的裝(zhuang)置。
電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位分析(xi)法所用(yong)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極被稱(cheng)(cheng)(cheng)為(wei)原電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)。原電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)是(shi)一(yi)個系統(tong)，它(ta)的(de)(de)作(zuo)用(yong)是(shi)使(shi)化學反應能(neng)(neng)量(liang)轉(zhuan)成為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)。此電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓被稱(cheng)(cheng)(cheng)為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)勢（EMF）。此電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)勢（EMF）由(you)二個半(ban)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)構成。其中(zhong)一(yi)個半(ban)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)稱(cheng)(cheng)(cheng)作(zuo)測(ce)量(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極，它(ta)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位與(yu)特定(ding)的(de)(de)離(li)子(zi)活度有(you)(you)關；另一(yi)個半(ban)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)為(wei)參比(bi)(bi)半(ban)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)，通常稱(cheng)(cheng)(cheng)作(zuo)參比(bi)(bi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極，它(ta)一(yi)般是(shi)與(yu)測(ce)量(liang)溶(rong)液相通，并(bing)且與(yu)測(ce)量(liang)儀表(biao)相連。最熟悉也是(shi)最常用(yong)的(de)(de)PH指示電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極是(shi)玻(bo)(bo)璃電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極。貝(bei)爾公司T225電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極適用(yong)于醫藥紙(zhi)漿造紙(zhi)、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)鍍、生物制(zhi)藥、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)廠(chang)等行業的(de)(de)純水(shui)，高(gao)純水(shui)的(de)(de)測(ce)量(liang)。它(ta)是(shi)一(yi)支端部吹制(zhi)上對于pH敏感的(de)(de)玻(bo)(bo)璃膜的(de)(de)玻(bo)(bo)璃管(guan)。管(guan)內充填有(you)(you)含飽和AgCl的(de)(de)3 mol/l kcl緩沖溶(rong)液，其pH值為(wei)7。存(cun)在于玻(bo)(bo)璃膜二面的(de)(de)反映PH值的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位差用(yong)Ag/AgCl傳導系統(tong)。
pH電極(ji)使(shi)用維護的注意事(shi)項(xiang)：
1．電(dian)極在測(ce)量(liang)前必須(xu)用已知pH值的(de)標(biao)準緩沖溶液進行(xing)標(biao)定（至少2點(dian)）。
2．在每次(ci)標(biao)定、測量(liang)后進行下一(yi)次(ci)操作前，應該用蒸(zheng)餾(liu)水或去離子水分(fen)清洗電極(ji)，再用被測液清洗一(yi)次(ci)電極(ji)。
3．取下電極(ji)護套時，應避(bi)免電極(ji)的敏感玻璃泡與硬(ying)物接觸，因為任何破損或擦(ca)毛都(dou)使電極(ji)失效。
4．測量結(jie)束(shu)，及時將電(dian)極保護(hu)套(tao)套(tao)上，電(dian)極套(tao)內應放少量飽和(he)KCL液(ye),以(yi)保持電(dian)極球泡的濕潤，切忌浸泡在蒸餾水(shui)中。
5．復合(he)電極的(de)外(wai)參(can)比補充(chong)液(ye)(ye)為3mol／L氯化鉀(jia)溶液(ye)(ye)，補充(chong)液(ye)(ye)可以從(cong)電極上端小孔加(jia)入，復合(he)電極不使用時，蓋上橡(xiang)皮塞，防止補充(chong)液(ye)(ye)干涸(he)，在(zai)線pH電極1般是(shi)凝膠(jiao)的(de)，所以不需要添加(jia)電解液(ye)(ye)。
6．電極的引出(chu)端(duan)必須保持清潔干燥，絕對防止輸(shu)出(chu)兩端(duan)短路，否則將導致測量失準或失效。
7．電極應與輸入阻抗(kang)較高的(de)pH計(ji)≥3×1011Ω 配套(tao)，以使(shi)其保持良好的(de)特(te)性。
8．電極應避免長(chang)期浸在蒸餾水、蛋(dan)白質(zhi)溶液和酸性氟化(hua)物溶液中。
9．電極避免與有機硅油接觸。
10．電(dian)極(ji)(ji)經(jing)長期(qi)使用后，如發現(xian)斜率(lv)略(lve)有降低，則可把電(dian)極(ji)(ji)下端浸泡在4%HF氫(qing)氟(fu)酸 中(zhong)（3~5）s， 用蒸餾水洗凈、然后在0.1 mo l／L鹽酸溶液中(zhong)浸泡，使之(zhi)復新，最好更換電(dian)極(ji)(ji)。
11．被測(ce)溶液(ye)(ye)中如(ru)含有易污(wu)染敏感(gan)球泡(pao)或堵(du)塞液(ye)(ye)接界的(de)物(wu)質而使(shi)電極鈍化(hua)，會出現(xian)斜(xie)率降低，顯(xian)示讀數不準現(xian)象。如(ru)發生該現(xian)象，則(ze)應根(gen)據污(wu)染物(wu)質的(de)性質，用適(shi)當溶液(ye)(ye)清洗，使(shi)電極復新。
