CS264046B1 - Comparison electrode - Google Patents

Description

1 264046

OjiexTpon cpaBHeHHH OČJiaCTb ΠρΗΜβΗβΗΗΗ Η3θ6ρβΤβΗΗΗ IIpeRJiaraeMoe Η3θ6ρβτβΗΗβ othochtch to anexTpony cpaBHeHHH, cocTonmeMy H3MeTajuiHHecKoro cepe6pa jih6o h3 cepe6pa, ποκρωτοΓο cyjib ^ iHflOM cepe6pa, kototpoe norpyacaioT b βοπηηη pacTBop, HacbímeHHbiň TpyRHo pacTBOpHMoň conbio cepe6paη npeflHa3HaqeHHOMy ηπη Η3ΜβρβΗΗΗ b cpeflax, coflepacaninx BOccTaHOBHTenbHbie ee mecTBa, KOMruieKcoo6pa30BaTanH, HOHb cynh4> Hfla η ηοηη ranoreHHflOB nopo3Hb ηπηB CMeCH.

XapaxTepHCTHKa H3BecTHhix TexromecKHX pemeHHH C flenhio HaomcmeHHH, χοητροπη h perynHpoBaHHH μηογηχ χημηηθοχηχ npofleccoBynoTpe6nHK) T ποτβΗΑΗΟΜβτρΗΗβοκΗβ. μθτοαη, πρπ xoTopbix Η3ΜβρΗΐοτ pa3HOCTb MeatflynoTeHynajiaMH οαηογο flna cooTBeTCTBeHHoro npoflecca πρηγοαηογο HflflHxaTopHoroanexTpofla h anexTpofla cpaBHeHHH. Η πρκ npofleccax anexTpanH3a retrieves Η3Μβρπιοτ noTeHflHan anexTponHTHqecxoroocaaweHHH Meacoy xaTóflOM, όοοτΒβτοτΒβΗΗΟ aHOflOM h anexTpoflOM cpaBHeHHH, Tax-acetyl H flJIH peryJIHpOBaHHH 3ΠβΚΤρθΙΙΗ3ΗΟΓΟ TOXA B 3aBHCHMOCTH KOHHeHTpaiQIH one- OT: pefleneHHoro κοΜΠΟΗβΗτβ pacTBopa. B cooTBeTCTBHH c HHflHxaTopHoro anexTpofla npH-μθηηιοτ MeTannHnecxHe anexTpoflb, CTexnaHHbie anexTpoflb HOHoceHCHTHBHbie sjex-Tpoflb, Tax Ha3btBaeMbie ceHCHTpoflbi. Πππ Η3ΜβρβΗΗΗ KOHfleHTpaflHH HOHOB Cepe6pa H3BeCTHa 3JieKTpOflHan ΚΟΜΠΟΗβΗΤΒ cocTOHman H3 CMecH MeTajma h cojih βτογο MeTanna h nopoacnaiomaH πρκ norpyateHHHb caneBótí pacTBop snexTpoflBHatymyio cnny. 3ra CMecb cnpeccoeaHa ochobhomi · b '' HenopHcřyw HHTerpajibHyro MACC nphnami mětujujom h conbio MeTajma Ballad 6μτβcepe6po cynb h <t> HFL cepečpa (DE-AS 1,423,371) - Oflnaxo taxon HHflHxaTopHbiň an anion TpOfl ΠρβΑΗΒ3ΗΗΗβΗ HM6HH0 flJIH Η3ΜβρβΗΗΗ Η3ΜβΗΗΚ) ΠίβΗΓ.Η XOHfleHTpaflHH hohob ce-pe6pa b cepe6pocoflepacainHx pacTBopax, and He απη πρΗΜβΗβΗΗΗ b xanecTse anexT-pofla cpaBHeHHH.

Ha npaxTHxe ynoTpe6nnioT 8 xanecTee anexTpofloe cpaBHeHHH oĎbWHbie, yflOČHbie b πρΗΜβΗβΗΗΗ xajioMeJibHbte jih6o cepe6po / cynb <J) HFL cepe6pHHHbie anexTpoflbí ( "HC-2 264 046 cjienoBaHHH TexuHnecKHx ycTpofícTB απη H3BneneHHH cepefípa φοτοΓρΗφΗΗβοκΗΧΦμκο H3 &amp;« ημχ pacTBopoB "/ K} Jíhttphx T.rprocHep - xypnaji "rampant ynq toh" -JleftnííHr 34 (1981) 3 - ετρ. 75). 3neKTpOflbI CpaBHGHHH OTJIHHaiOTCH KOHCTaHTHblM nOTeHUHaJlOM. OHH OTfleneHhl OTH3MepaeMoro pacTBopa ΑΗΗφρπΓΜοίί, KOTopas b HfleaJibHOM cjiynae nponycKaeT Tojib4-co 3apan, bi, and He nacTHiibi. OflHaKO Ha npaKTHKe, π, ηηΦρηγμμ nponycKatoT TaK »e-NAC THIÍbl. B KayecTBe aneKTpoflOB cpaBtieHHH npHMeHaeMwe KajiOMejibHbie hjih cepe6po / cynb-. Φηα cepe6pHHHhie aneicrpoflbí coctoht H3 MeTajunmecKoro sjíeKTpona (pTyrb jihďocepečpo) c h HacwmeHHoro pacTBopa OCAP COM H3 τργη, Ηο pacTBOpHMOň cojih coot MeTanna (KajioMejib jihóo xjiopHfl cepeóp Tax khk βκτιίβηοοτβ hohobMerajuia b HacbímeHHOM pacTBope cojih stoio MeTajma o ?KTHBHocra aHHOHa 33BH-cht, to cxanoK aneKTpoflHoro noreHapana onpeflejiHeTca btophhho ot 3κτηβηοοτηaHHOHa. Ecjih b ajieKTpofl ΑΗφφγκιΐΗργιοτ BemecTBa, Bintínomne Ha paBHOBecne MeroyMGTajuioM h ero Hoho, it H3MeHHeTCH noTeHipiaji 3JieKTpo.ua CpaBHeHHH h H3MepeH-HAH MejKHy HHHHKaTOPHblM H CpaBHHTeJIbHbM SJíeKTpOflaMH pa3HOCTb HOTeHlBiaJlOB 3a-bhcht YXE Ile τοπβκο οτ Η3ΜβΗθΗΗή npou, ECCA 3a kotopwmh .ηοηχθΗ 6μπ cnenHTh .NepBOHAHajlbHO HHJIHK3TOPHMÍÍ 3JieKTpOfl. ΠρΗΜΘΗΘΗΗβΜ HOflXOflíHUHX βΚΒφρΗΓΜ, φρΗΤΤH 3JieKTponHTHHeCKHX ΟΗφΟΗΟΒ ΠΜΤ3Ι0Τ0Η yMeHbfflHTb, Ε (Ηφφγ3ΗΚ> Memaioinnx BeiHeCTB BsjíeKTpofle, XOTH h ee ríanbHoe npejiOTBpameHHe He nocTuraeTCH. Ηφφγ3ΗΠ $ Memaio-niHx BeniecTB, npemne Bcero Rip HenpepbiBHbix H3MepeHHHX, πρηβοαητ to noJi3yneMy'Κ3ΜθΗβΗΗΐο noTeHtiHajia 3JieKTpo.ua cpaBHeHHH h sthm k ero ηθπρηγοηηοοτη, OÓbBIHbie 3JieKTpOflbI CpaBHeHHH CTaHOBHTCH HenpHrOflHblMH npeatne Bcero H3 “3aBoccTaHOBHTejibHbtx semecTB;

TaK HanpHMep, ajieKTpo / IM cpaBHeHHH npHMeHHjoTcn β 3βτομητη3ηροβ3ηημχ 3ηθκτ-pojiH3Hbix ycTpoňcTBax, cnywamHx hjih pereHepauHH cepeópa H3 oTpa6oTaHHbix φοτο-ΓρΗφΗΗβΟΚΗΧ φΗΚΟ35ΚΗΗΧ paCTBOpOB H flJIH OCBeWeHHH 3THX paCTBOpOB HeJThK C) HXΗΟΒΟΓΟ npHMeHeHHH. 3th 3JieKTpO, £ LBI CpaBHeHHH, NPH ΠΟΜΟΠξΗ KOTOpblX peryjIIipyiOT3jieKTponH3Hbift flow b 33BHCHMOCTH οτ aKTyajibHoň KOHiieHTpaujiH cepeópa, pa3py-maioTCH πρκ HenpepbiBHoň npoH3BoncTBeHHoň 3KcnJiyaTaiiHH b TeneHHe οτ oRHoroρ, ο neTbipex MecnneB. IIpHHHHoň pa3pymeHHn hbjihmtch coflepacamneca β Φηκοβ3κηομpacTBope (HanpHMep, τΗοογπΒφβτΗΜβ, cepeÓpHHHbie η οβρβδροτκοογπΒφΒΤΗΗβ com-njieKCHbie Hohm) oóoramaiofflHecH (nanpHMep hockey 6poMH.ua h uoíma ΦοτογρθΦη n-qecKHe CTaÓHJiH3aTopbi) η NPH pa3pyineHHH oópasyiomnecH (HanpHMep, cepoBo, qopoflh Hohm Cyn-dark ) BemecTBa. IlepBOHanajibHHň noTeHiinaji aneKTpoflOB cpaBHeHHH H3 MeHaeTca BCJiencTBHe óonbnioro KOjinnecTBa bo3moikhmx peaKUHň h peaKpnoHHbix προ-b ΛΥΚτοβ TeneHHe κοροτκοΓΟ BpeMeHH τηκημ oópa3OM, ητο TOHHoe H3MepeHHe co-OTBeTCTBeHHO peryjiKpoBKa, ΗβΒθ3Μθ «όο.

Uejib H3o6peTeHHH

Heaibio Η3ο6ρβτβΗΗΗ HBjíneTCH pa3pa6oTKa 3jieKTponoB cpaBHeHHH, npejiHa3HaneH-HBK flJis H3MepeHHň b CPEP; ax coAepmamHX BoecTaHOBHTejibHbie BemecTBa, κοΜππεκ-coo6pa3OBaTejibHbie coemnHeHHH, Hohm cyjn = H, q h Hohm ranoreHHflos, κοτορκβ OC-T3I0TCH pe3HCTHBHbIMH Β ΤβΗβΗΗΘ npOHOJPKHTeJlbHOrO ΒρβΜβΗΗ Η ΠρΗ ΗβΠρβρΗΒΗΟίί3KcruiyaTaiiHH b TAKORA po.ua xHMHnecKHx npoueccHMX pacTBopax noiwepwBaioT koh-CTaHTHbi noTeHiinaJi.

CymHQCTb Η3θ6ρεΤβΗΗΗ ' "UA / ianen Η3θόρβτβΗΗΗ HBJíneTCH pa3pa6oTKa 3JieKTpo.ua CpaBHeHHH hjih H3Mepe-HHft B cpeflax, coflepacaDiHX nopo3Hb hjih β cMecn BoccTaHOBHTeJibHbie BemecTBa - 3-264046 KOMrmeKcoo6pa3OBaTejibHbie coeflHHeHHH, Hohm cyni Mfla h ^ Hohm ranoreHHflOB, npnκοτοροΜ αηΦΦυηαηρυιοιιιηθ to H3MepHeMoro pacTBopa b sjíeKTpqn eemecTBa He Mewa · Lot aKTHBHocTH hohoba cepečpa, HajiHUHOň b aneKTpofle cpaBHeHHH h onpenenHiomeňCTa6HJifcnocTb noTemxnajia. cooTBeTCTBHH b C Η3θ6ρβτεΗΗβΜ, penieHHe 3aflaun COCTOHT b TOM b HTO 3neKT'poflax cpaBHeHHH, coctohihhx MeTajuiH m ^ ecKoro cepefípa jih6o H3 ουπβΦηαομ cepe6pa noKpbrroro cepe6pa , b norpyxceHHoro HacMmeHHbiň TpyqHO pacTBopHMoň conbíocepe6pa BOflHbiň pacTBop, conbío cepéópa HBnneTCH cyπbφH, ^ cepe6pa and βο, π, ημηpacTBOp flonanHHTenbHo nacbímeH BemecTBOM, oTflaronpiM ηοημ εγτίΒφΗΑΗ tbkhm očpa-3om, hto 06a BenjecTBa oópa3y »T ocanoK. BeiqecT BOM, OTflaioinHM god ογι ^ φΗΑβ HBI-jineTCH npeuMymecTBeHHO τρυηηο pacTBOpHMbiň cyJib $ HA MeTanna, HMeioupiň 6anbniHftnpoflyier pacTBOpHMocTH no cpaBHeHHH) C ογηΒφκηοΜ cepeópa, κβκ το ογηΒφΗΑ-HHH-x ηκ6ο ογπΒφΗΑ Mahranich (II). IIpHMeHHTCH MoryT Taxation coeflHHe ^ HHH cepbl, B HaCTHOCTH ΤΗΟΜΟΗβΒΗΗβ. íÍ3MepeHHH noŤeHAHanbHbix pa3H0CTeií h noTeHipianoB BbmeneHHH b coflepxcamHXBoccTaHOBHTenbHbie BemecTBa, KOMnneKcoo6pa3OBaTenk, HOHH ranoreHHflOB h Hohm; ογηΒφΗΑβ pacTBopax ajih onpeneneHHH KOHneHTpanHH, kohtpohh h perynupoBaHHHCTaHOBHTCH BO3MO3KHMMH ΠρΗ ΠρΗΜβΗΘΗΗΗ 3THX COOTBeTCTByiOIUHX Η3θ6ρβΤβΗΗΙ0 3ηβΚΤ ~ poflOB cpaBHeHHH, κοτορΜβ TaioKs npn HenpepbiBHoň 3KcnnyaTaijHH noflnepjKHBaioT no-ctohhhmíí noTeHipían η κοτορΜβ He pa3pymaioTCH αηΦΦυηαηροβηηηθμ BemecTB, conep- «amnxcH b pacTBope.

Bbino ycTaHOBneHO, HTO Ha3BaHHbie κομποηθητμ nponeccHbix pacTBopoe, Tax-Ha npHMep, ΚΟΜΠΟΗβΗΤΜ OTpaČOTaHHMX φΗΚΟΗΜΗΜΧ paCTBOpOB, ΗΘ OKa3bIBaiOT ΜβΙΠΗΙΟΙΙξεΓΟβηηηηηη Ha aneKTpoflbí, aKTHBHOCTb Hohai MeTanna κοτορΜχ oupenenneTCH aKTHB-HOCTbK) εγΠΒφΗΑβ. Ακτηβηοοτβ hohob cepe6pa b ě p p p pa pa pa cpaBHeHHH οπρεηβηΗβτοΉ btophhho koh-neHTpanneň ουπβHTηαημχ hohob TpynHopacTBopHMoro ουπβΦη, π ^ cepeSpa. OTflaiomee> Hohm cymal> Hfla BemecTBO o6ecneHHBaeT ocawAeHHe b βηαθ ογηΒφκηΗ cepe6pa ηκφ-b ΦυηαηρyramtHx aneKTpofle H3 H3MepHGMoro, HanpHMep, «3 Φηκοηχηογο pacTBopahohob cepeópa, κοτσρωβ not βηηηιοτ τηκημ oÓpaaoM Ha Note, HflHan. ^ ^ Pyrne coflepjKa -mnecH b H3MepneMOM pacTBope c h pearnpyioinHe ηοηημη cepe6pa BemecTBa He Oka-3biBaioT Meniawtqero bhhhhhh Ha Taxoro pofla οπβκτρορ ;, τθκ κβκ εγηπφΗΑ cepeSpaHBHHeTCH Camm TpynHo pacTBOpHMbiM coeflHHeHHeM cepečpa η τβκ onpeflenfleMaHH0H3MH εγπΒφΗΑβ aKTHBHOCTb hohoba cepe6pa b aneKTpofle CpaBHeHHH He nOflflaeTCHHX BHHHHHH.

IIpHMepbl BblHOHHeHHH Η3θ6ρετβΗΗβ 6onee ποαρο6ηο o6bHCHeHO cneflywmHMH npHMepaMH BbmonHeHHH.IIpHBefleHHbie npHMepbi othochtch to aneKTpoflaM cpaBHeHHH, κοτορωε mojkho npHMe-ηητβ NPH perynnpyeMOM b aaBHCHMOCTH rpm KOHneHTpanHH hohoba cepe6pa sneKTponH · * 3e OTpaÓOTaHHblX φΗΚΟΒ) ΚΗΜΧ paCTBOpOB, ΧΟΤΗ STOH H He OrpaHHMHBaiOTCH BO3MOJK "HOCTH HX npHHOWeHHH . IIpHMep 1.

Cepe6pHHHaH npoBonoKa hhh cepeČpHHHaH npoBonoKa, ποκρΜΤβπ ουπβΦηαομ cepe6pa norpyweHa b βοαημη pacTBop, HacbímeHHMH ουπβΦηαομ cepe6pa, ογηπφΗΑΟΜipiHKa η τηοουπβΦητομ ΗβτρΗΗ η coflepsamaň 3th BemecTBa b BHfle ocaflKa. BH μ BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH BH H H H H H H H H ep ep ep ep ep ep ep ep ep. Taxoft sneKTpofl cpaBHeHHH momho npH'ΜβΗΗΤΒ flflH H3MH BH OTpaGoTaHHblX φΗΚΟΒΚΗΜΧ pacTBopax H OH HMeeT rof3floπροηαπκΗτβπΒΗΜίί cpok cnyjKóbi no cpaBHeHHio c 66μμημμη βπθκτροαημη cpaBHeHHH. 4 264046

Tpyqno pacTBOpHMbiň cyn ^ Hq qHHKa b aqeKTpoqe cjiyxHT qjiH oTqanH hohob cynb- $ Hfla, κοτορΗθ cBnabiBaioT #H (i) <i> yHflHpyiainne b aneKTpoq hoh cepeppa. ΠρημθηθηηθTHocyjib <t> aTa b εκφΟΗβ ββ HB-nneTCH onpeqenHminHM qnH φyHκ ^ nn anEKTpoqa. Π γ-f γ ΤΗΟ ΒΤ J J Ď ero ero f f f f f f f f f B B B c c c c c c c c c c c c c c npHMep 2.

CepeGpHHHaH npoBOJioKa jthGo cepeópHHHaH προΒοποκβ, Cyn noKpbrraH HqoM ^ ce · pe6pa norpyxeHa b BoqHbiň pacTBop, HacbnueHHbiň cyj qqoM cepečpa ^, ^ cyj nqoMqHHKa xnopHflOM khjihh h h b coqepxamqň MET BemecTBa BHqe ocaqKa. 3πβκτροπΗ-THnecKaH cBH3b c H3MepneMbiM pacTBopoM ocymecTBJíeHa .nocpeqcTBOM οηεκτροπΗΤΗ-necKoro οκφοΗε, 3anoJiHeHHoro HacbimHHbM pacTBopoM xjiopnqa κηπηη h coqepJKainHtoocaflOK xjiopnqa KajiHH. npHMep 3.

Cepe6pHHHaH npoBonoKa south cepeSpHHHan npoBonoKa, noKpbrraa cynbiiiHqoM cetyl pe6pa norpyxeHa b menonHbiH BoqHbiň pacTBop, HacbnneHHbiň cynbdiHqoM cepeSpa, τηομοηθβηηοη cyji h ^ h coqepxamHH atom ηβτρηη 3th BeqecTBa b BHqe ocaqKa. B9T0M ajieKTpoqe qnH OTqann hohob cyj ^ Hqa b tnenoHHoo cpeqe cjiyxHT τηομοηθ-BHHa. , IIpHMep 4. B KanecTBe coeqHHeHHH, orqaiomero could cy.πbφHqa, βμθοτο cyqbφHqa qHHKa, Ha3BaHHoro b npHMepe 1, πρημοηοη cyπbφHq MaHraHa.

ΦορΜγΠΗ H3O6peTeHHH first 3qeKTpoq cpaBHeHHH, npeqHa3HaneH qnN H3MepeHnň b cpeqax, coqepxamHx no-pO3Hh ΗΠΗ B CMeCH BOCCTaHOBHTeJIbHbie ΒβΠξβΟΤΒβ, KOMIUieKCOO6pa3OBaTenH, Hohm cyjH Hfla h ^ h Hohm rajioreHHqoB coctohihhh H3 MeTajuiHnecKoro cepe6pa, qn6o H3 ^ Cyn nqoM cepeSpa ποκρμτογο cepeSpa, norpyateHHoro b BoqHbn pa — vctbop, HacbimHHbi TpyqHo pacTBopHMbiM ογπΒφΗβΟΜ cepe6pa o τ πηηηιοπιηη ca · TeM, hto BoqHbi pacTBop qonoJiHHTeJibHO HacbnneH BemecTBOM, oTqarouiHM hohmcynbAnqa. 2, 3, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, respectively. 3. 3neKTpoq cpaBHeHHH no nyHKTy 2., oTJiHnaiomHHCH τθμ, μτο TpyqHo pacTBopH-Mbím cy «bφHqoM MeTanna, OTqaioinHM hohm cym> 4> Hqa, πηπετοΗ εγπΒφιιη qHHKa, πη6ο, cyqbφHq MaHraHa (II). 4. SneKTpoq cpaBHeHHH no nyHKTy 1., oTJiHqaKmHiícs τθμ, ητο BeinecTBOM, OT-qaiomHM hohm ογπΒφΗηβ HBjíHeTCH opHHnecKoe coeqHHeHHe cepbi. 5. SneKTpoq cpaBHeHHH no nyHKTy 4., o τ π η η and kjihh h c η τθμ, ητο opraHHqecKiiMcoeqHHeHHeM cepu qnn OTqann hohob ογπΒφΗηε HBJíneTCH THOMoneBHHa.

Pe3K) Me ann3ο6ρετβΗΗβ othochtch k sneKTpoqy cpaBHeHHH, cocTOHqeMy H3 MeTannHnecKO-l * o cepe6pa jihóo H3 cymM}) HqoM cepeópa ποκρμτογο cepe6pa, norpyxeHHoro b Boq- 5 - ’264046

Hbift pacTBop, HacbiineHHMH TpynHO pacTBOpHMo cojibio cepe6pa h npeflna3Ha ^ eHHOMyfljifl rtaMepeHHn b cpeflax, conepwaiuHx Be * meCTBa, KOMnneKcoo6pa30BaTejiH, hohm cyjib $ Haa h hohm ranoreromoB. I ^ enb H3o6-ρβτβΗΗΗ - noBbmieHHe ycToftanBocTH aneKTpona ορββηθηηη τβκημ o6pa3OM, hto npHHenpepbiBHoň sKcnjiyaTaipnj b cpenax Taxoro pop, and ero noTenunan ocTaeTcn koh-CTaHTHBM. 3anana Hea3ο6ρετβΗΗ »- HeaaBHCHMOCTb οτ« ΗφφγΗβΗργιοπίΗΧ B aneKTpop; eenjecTB aKTHBHocTH hohob cepe6pa; C 3Toň uenbio BOftHbi pacTBop Tax HacbnueH cyní4> nflOM ce-pe6pa h flonojiHHTenbHO BemecTBOM, OTnaionptM hohm cyjib $ Hfla, hto 06a BemecTsa, oĎpaayjOT oca # oK. B xanecTBe eentecTBa, OTflawmero hohm cyjib ^ p; and πρημθηηιοτTpyflHO pacTBOpHMbiň cyni4> Hfl MeTajina jih6o opraromecKue coeAHHeHUft cepbi.

HpHSHaHO K3θθρβΤβΗΗβΜ ΠΟ ρββγϊΙΒΤβΤβΗ 3KCnepTH3bl, OCymeCTB í ň ň ň ň ef ef CT B ň ň ň ň ň f f f f f f f.

Claims (5)

- 6 - 264046 SUBJECT OF THE INVENTION 1 · A reference electrode for measurement in environments containing separately or in a mixture reducing agents, complexing agents, sulfide ions and halide ions consisting of metallic silver or silver, coated with silver sulfide, immersed in water. -flux, saturated with a sparingly soluble silver sulfide, characterized in that the aqueous solution is saturated with a sulfide-releasing substance. Comparative electrode according to claim 1, characterized in that the sulfide release agent is a sparingly soluble metal sulfide, with a high solubility product compared to silver sulfide. Comparative electrode according to claim 2, characterized in that the sparingly soluble ion sulfide metal sulfide is zinc sulfide or manganese sulfide. 4. A comparative electrode according to claim 1 wherein the sulfide-releasing agent is an organic sulfur compound. 5. A comparative electrode according to claim 4, wherein the organic sulfur-releasing compound is sulfided with thiourea.