Inqaku
Imethylene blue njengesalathisi: yintoni kanye eboniswa kukutshintsha kombala
Ingcali yaselabhoratri yongeza imethylene blue kwibhekha, ilungise i-pH, ize ilinde umbala ukuba ubonise ubumuncu. Akukho tshintsho lucacileyo lwenzekayo. Endaweni yoko, yongeza ithontsi lesisombululo se-asidi ye-ascorbic, uze umbala oluhlaza okwesibhakabhaka unyamalale. Ishukumisa iflaski emoyeni, uze umbala oluhlaza okwesibhakabhaka ubuye. Idayi enye, iindlela ezimbini zokuziphatha ezahluke kakhulu. Oku kudideka ngundoqo weli nqaku: imethylene blue sisalathisi se-redox esiphendula kudluliselo lwee-electron, hayi isalathisi se-pH esiphendula kwiiproton. Xa lo mahluko ucacisiwe, zonke ezinye iinkcukacha ziyahambelana.
Umgaqo osebenzayo ungena kwisivakalisi esinye. Umbala oluhlaza okwesibhakabhaka uthetha ukuba kukho uhlobo olwenziwe i-oxidation. Ukungabi nambala kuthetha ukuba kukho uhlobo oluncitshisiweyo, ileucomethylene blue. Nantoni na ehambisa ii-electron inokutshintsha olu hlobo. Ii-asidi neziseko zodwa azinako, nangona i-pH itshintsha ivoltheji olu tshintsho olwenzeka kuyo.
Isibini esisemva kombala
Imethylene blue eyenziwe i-oxidation yikation ye-methylthioninium, inkqubo ye-phenothiazinium ethe tyaba enezangqa ezintathu, enikezelwa njengetyuwa yekhlorayidi, iPubChem eyibhalisa njenge-methylthioninium chloride. Xa ixutywe namanzi ukuze ibe noxinaniso oluphantsi, imonomer ifunxa ukukhanya kufuphi ne-664 nm, kwaye oko kufunxa kukwenza iliso libone umbala oluhlaza okwesibhakabhaka. Iqabane layo elincitshisiweyo, ileucomethylene blue, linesakhiwo esisisiseko esifanayo, kodwa initrogen yesangqa esiphakathi yongezwe iproton kwaye ichromophore iphazamisekile, ngoko phantse alinambala, yaye ibhendi yalo enamandla ikummandla we-ultraviolet (ingeniso yePubChem yohlobo lweleuco).
Ireakshini iyonke ihambisa ii-electron ezimbini, kodwa inani leeproton lixhomekeke kwi-pH kuba uhlobo oluncitshisiweyo lwamkela iiproton kwimeko ene-asidi. Ingcaciso esisiseko ekubonakaliseni ikhemistri ye-redox inika ipotenshali esemgangathweni ekufuphi ne-+0.53 V kwi-pH 0 kunye nepotenshali esesikweni ekufuphi ne-+0.011 V kwi-pH 7, xa zithelekiswa ne-electrode yehydrogen. Phakathi kwezo ndawo ipotenshali iyatshintsha ngokwe-pH. Ivoltammetry yale mihla kuphononongo lokuziphatha kwe-redox neepotenshali zeedayi ifumana malunga ne-29.5 mV ngeyunithi ye-pH ukusuka malunga ne-pH 4 ukuya kwi-10, ehambelana nenkqubo yee-electron ezimbini neproton enye, kwaye malunga ne-88.5 mV ngeyunithi ye-pH ngaphantsi kwe-pH 4, ehambelana nenkqubo yee-electron ezimbini neeproton ezintathu. Ngoko ipotenshali echaziweyo ngaphandle kwe-pH yayo ayinantsingiselo. Hlala ubuza ukuba leliphi ithambeka neyiphi i-electrode yesalathiso esekelwe kuyo loo nombolo, kuba amaxabiso abhekiselwa kwii-electrode zesilivere akanakuthelekiswa ngokuthe ngqo namaxabiso abhekiselwa kwisikali sehydrogen. Isakhiwo neempawu ezisisiseko zimisela ichromophore, kwaye iphepha elihambelanayo malunga noyilo lokufunda i-redox liyandisa esi sibini ukuya kukhetho lweendlela zokwenza imixube.
Loo ndawo iphakathi kwisikali sepotenshali yiyo eyenza idayi ibe luncedo. Kwi-pH 7 iphakathi kwezinto ezenza i-oxidation ngamandla athambileyo: inamandla ngokwaneleyo okwamkela ii-electron kubanikeli abalungileyo njenge-ascorbate okanye i-NAD(P)H, kodwa ibuthathaka ngokwaneleyo ukuzidlulisela kwioksijini enyibilikileyo okanye kumaziko e-ferric. Ngoko iyajikeleza endaweni yokubambeka. Ukuncitshiswa kuyawususa umbala wayo. Umoya uyenza i-oxidation kwakhona. Indlela iyafana kuwo omabini amacala.
Kutheni imibuzo ye-pH iqhubeka ivela
Imithombo emithathu yokudideka iphinda ivele kwiilabhoratri nakumagumbi okufundela, kwaye ngamnye unolungiso olucacileyo.
Okokuqala, i-pH itshintsha ipotenshali, nto leyo ekhangeleka njengempendulo kwi-pH. Nyusa i-pH, size esi sibini sibe lula ukuncitshiswa xa ufundo lwe-electrode lungaguquki, ngoko umnikeli omnye ususa umbala wedayi ngokukhawuleza ngakumbi. Kodwa akukho nyathelo lokongezwa kweproton lodwa elivelisa utshintsho olucacileyo ukusuka kumbala oluhlaza okwesibhakabhaka ukuya ekungabini nambala kuluhlu oluqhelekileyo. Uphononongo oluhlalutyayo lwango-2025 lweempawu zemethylene blue luchaza ukuba incopho ye-665 nm ihlala phantse ingatshintshi ukusuka kwi-pH 2 ukuya kwi-12, kukho kuphela utshintsho oluncinci ekufunxeni ukukhanya. Iiproton zilungelelanisa ivoltheji. Ii-electron zitshintsha umbala.
Okwesibini, ileyibhile yolwahlulo lwengqiqo iyalahlekisa. IPubChem ngoku ingenisa inkcazelo yendima evela kwiChEBI ebiza idayi ngokuba sisalathisi se-asidi nesiseko. Loo thegi ayifanele ithathwe njengobungqina bokuba imethylene blue iziphatha njengephenolphthalein okanye imethyl red. Kumsebenzi oqhelekileyo owenziwa kwizisombululo zamanzi, ayenzi njalo.
Okwesithathu, umxube weTashiro uboleka igama. Isalathisi seTashiro ngumxube wemethyl red nemethylene blue apho imethyl red inika impendulo kwi-asidi nakwisiseko, ize imethylene blue inike umbala wangasemva oluhlaza okwesibhakabhaka, ngaloo ndlela iguqule utshintsho olusuka kobomvu luye kotyheli lube lutshintsho oludibeneyo olubonakala ngokucacileyo ngakumbi. Omnye umxube weTashiro othengiswayo uchaza i-pH 4.4 ukuya kwi-6.2, ngoxa umxube ochaziweyo weITW Reagents ubeka umbala obomvu-violet kwi-pH 4.4 ukuya koluhlaza kwi-pH 5.8. Akukho nalunye kula maluhlu oluyindawo yokutshintsha kwemethylene blue ngokwayo. Idayi inceda ukwenza utshintsho lubonakale, ayisiyo into eva olo tshintsho.
Enye imeko engaqhelekanga ifuna isilumkiso. Kufuphi ne-pH 13, iimeko ezine-alkali enamandla zinokuvelisa iimveliso ezibomvu ukuya kwezipinki zohlobo lwe-methylene-violet ngehydrolysis engenakubuyiselwa umva. Loo pinki kukonakala, hayi indawo yokuphela yesalathisi. Yithathe njengophawu lokulahla isisombululo, hayi lokusifunda.
Apho isebenza khona njengesalathisi se-redox
Ukusetyenziswa kwayo okuqhelekileyo yititration yeeswekile ezinciphisayo yeLane-Eynon. Isisombululo esishushu seFehling esine-alkali senziwa ititration ngeswekile, ize imethylene blue yongezwe kufuphi nendawo yokuphela; umbala oluhlaza okwesibhakabhaka oseleyo uyanyamalala xa amandla okunciphisa eswekile egqitha lawo afunekayo kwi-copper(II). Inkqubo yeAOAC yeLane-Eynon igcina umxube ubila ukuze umphunga ophumayo uthintele ukuphinda wenziwe i-oxidation ngumoya, ngokuqhelekileyo kusetyenziswa amathontsi ambalwa esisombululo sedayi. Utshintsho lombala lubonisa ukuba akusekho bhedu lunokuncitshiswa, nto leyo eyingxelo ye-redox malunga neflaski, hayi ingxelo ye-pH.
Iindlela zakudala zetitrimetry zasebenzisa ingqiqo efanayo kwezinye iindawo. Idayi enoxinaniso oluphantsi yayinokuthatha indawo yesitatshi kwezinye iititration ze-iodimetry apho utywala lwalusenza isitatshi singafaneleki, ngoxinaniso lokusebenza olukufuphi ne-0.05 g ngelitha, nangona idayi egqithisileyo isenokwenza ikhompawundi ye-iodine nedayi njengoko uSinnatt wabonisa ngo-1912. Ingqokelela zeencwadi zezikhokelo zikwadwelisa idayi ukuze isetyenziswe kwi-titanometry nakwi-iodometry. Indlela ye-asidi ye-ascorbic kaGal yango-1936 yanciphisa idayi ngezicatshulwa zevitamin C, yaza yenza ititration ebuyelayo yedayi eshiyekileyo nge-titanium trichloride. Ngoku loo ndlela yeyembali kunokuba ibe yinto esetyenziswa rhoqo, kodwa ibonisa ipateni: umnikeli unciphisa idayi eluhlaza okwesibhakabhaka iye ekungabini nambala, kwaye ukunyamalala kombala oluhlaza okwesibhakabhaka yindawo yokuphela.
Iindlela zeoksijini enyibilikileyo zisebenzisa esi sibini sinye kwicala elichaseneyo. Enye indlela epapashiweyo iqala ngokunciphisa idayi ngeglucose kwi-ethanol enamanzi ne-alkali, ize ivumele ioksijini enyibilikileyo ukuba yenze i-oxidation yohlobo lweleuco olungenambala, ilubuyisele kumbala oluhlaza okwesibhakabhaka phantse ngoko nangoko, kufundwe kufuphi ne-600 nm ukuya kutsho malunga ne-13 micrograms ngemililitha njengoko kuchazwe nguOkumura noHashitani. Musa ukuyibhidanisa netitration eqhelekileyo yeWinkler yeoksijini enyibilikileyo, enendawo yokuphela esebenzisa isitatshi; iNOAA Winkler SOP ichaza malunga ne-1 pesenti yesitatshi. Iindlela zeoksijini zemethylene blue liqela elahlukileyo elinotshintsho lombala oluya kwicala elichaseneyo.
Ibhotile eluhlaza okwesibhakabhaka esetyenziswa eklasini isebenzisa esi sibini sinye ngomlinganiselo omncinci: iglucose kwisisombululo esine-alkali inciphisa idayi eluhlaza okwesibhakabhaka iye kuhlobo olungenambala xa ishiywe imile, kwaye ukuyishukumisa kunyibilikisa ioksijini eyenza i-oxidation kwakhona, iyibuyisele kumbala oluhlaza okwesibhakabhaka. Inkqubo epheleleyo nolawulo lwayo zikwiphepha lomboniso webhotile eluhlaza okwesibhakabhaka, kwaye iindawo zeebhendi notshintsho olubangelwa kukudibana kweemolekyuli zikwiphepha leespektra neziphumo zoxinaniso. Eli nqaku ligcina kuphela indlela esebenza ngayo, kuba inkqubo neespektra nganye zifuna iimeko zazo.
Itshathi yeemeko zombala: iimeko, izinto ezizivelisayo, nemida
Le theyibhile sisalathiso sokuqala seli nqaku. Funda umqolo wonke ngaphambi kokuthemba nayiphi na indawo yokuphela.
| Imeko | Inkangeleko | Imeko eyivelisayo | Into eyibonisayo | Umda |
|---|---|---|---|---|
| Imonomer eyenziwe i-oxidation, inoxinaniso oluphantsi, ayine-asidi okanye i-alkali | Luhlaza okwesibhakabhaka nzulu, incopho kufuphi ne-664 nm | Isisombululo esizaliswe ngumoya, kungekho mnikeli | Imeko esisiseko elungele ukusetyenziswa | Kuxinaniso oluphezulu incopho iya ngase-610 nm ngenxa yokwenziwa kweedimer, ngoko gweba umbala kuphela emva kokunciphisa uxinaniso |
| Uhlobo lweleuco oluncitshisiweyo, alunayo i-asidi okanye i-alkali | Alunambala | Kukho umnikeli (iglucose kwisiseko, i-ascorbate, i-dithionite, i-NAD(P)H enesikhawulezisi sereakshini) | Amandla okunciphisa agqithile kwimfuno yesalathisi | Umoya uyenza i-oxidation kwakhona, ngoko iindawo zokuphela zibuyela kumbala oluhlaza okwesibhakabhaka ngaphandle kokuba umoya uyakhutshelwa ngaphandle okanye ubekwe phantsi kweemeko ezimiselweyo |
| Uhlobo lweleuco, lune-asidi | Alunambala | Abanikeli abafanayo kwi-asidi, kongezwa iiproton ezingakumbi kwileuco | Okufanayo nokungasentla, kwipotenshali etshintshileyo | Ithambeka lepotenshali liba likhulu ngaphantsi kwe-pH 4, ngoko ulungelelwaniso lwe-pH 7 alusebenzi apho |
| Umxube weTashiro, une-asidi | Bomvu-violet | I-pH engaphantsi malunga ne-4.4 kumxube wemethyl red nemethylene blue | Ubumuncu, obuvela kwimethyl red | Ubonisa imethyl red, hayi imethylene blue; musa ukuwuchaza njengoluhlu lwe-pH lwemethylene blue |
| Umxube weTashiro, kufuphi ne-pH 5.8 ukuya kwi-6.2 | Luhlaza ukuya kongwevu-luhlaza | Umxube ofanayo kufuphi nesiphelo esiphezulu sotshintsho lwawo | Okufanayo nokungasentla | Kuxhomekeke kwindlela umxube owenziwe ngayo; jonga ibhotile, ungathembeli kwinkumbulo |
| Yonakele, ine-alkali enamandla | Pinki ukuya kobomvu | I-pH ekufuphi ne-13, ubushushu, ukuvezwa kwisiseko ixesha elide | Ihydrolysis engenakubuyiselwa umva evelisa iimveliso zohlobo lwe-violet | Ayibuyiselwa umva ngokushukumisa; yilahle uze wenze entsha |
| Umbala ususwe kukukhanya | Luhlaza okwesibhakabhaka obuthathaka, inespektram etshintshileyo | Ukukhanya okubonakalayo okunamandla, ngakumbi xa kukho abanikeli | Ireakshini ezisecaleni eziqhutywa kukukhanya, kuquka iimveliso ezisuswe amaqela emethyl | Khusela izisombululo ezisemgangathweni ekukhanyeni, njengoko umsebenzi wokunciphisa ngokukhanya okubonakalayo wabonisa |
Iindlela zokusilela ezenza indawo yokuphela ingacaci
Umoya ngowokuqala ukukrokrelwa nanini na indawo yokuphela itshintsha. Uhlobo lweleuco lwenziwa i-oxidation kwakhona lula, ngakumbi kwiinkqubo ezine-alkali, ngoko ititration ephele ngokungabi nambala inokuphinda ibe luhlaza okwesibhakabhaka xa ishiywe imile okanye ijikeleziswa ngamandla. Khupha umoya apho ukuzinza kubalulekile, misela indlela efanayo yokushukumisa, uze ufunde ngexesha elimiselweyo.
Ukukhanya kokwesibini ukukrokrelwa. Idayi iyasebenza kwiireakshini zekhemistri eziqhutywa kukukhanya, kwaye ukuyikhanyisa xa kukho abanikeli kunokuwususa umbala ngeendlela eziquka iimveliso ezisuswe amaqela emethyl. Gcina izisombululo zedayi zohlalutyo ebumnyameni, kwaye musa ukufunda iindawo zokuphela phantsi kwezibane ezinamandla zetafile yaselabhoratri.
Uxinaniso lolwesithathu. Ikation eyenziwe i-oxidation iyapakishana yenze iidimer namaqela amakhulu ngakumbi, enebhendi etshintshele kufuphi ne-610 ukuya kwi-615 nm, ngoko isisombululo esinoxinaniso oluphezulu sibonakala siphambukile kwincopho ngaphandle kokuba asicocekanga. Nciphisa uxinaniso de kufikelelwe kwimeko yemonomer ngaphambi kokugweba iispektra okanye iindawo zokuphela.
Imithombo emibini engabonakali lula yokuphambuka ifanele ichazwe kuba ichaphazela ngokukhethekileyo umsebenzi woxinaniso oluphantsi. Idayi incamathela ngendlela enokulinganiswa kumphezulu apho iglasi idibana namanzi, nto leyo ephambukisa izisombululo ezisemgangathweni ezinoxinaniso oluphantsi nemilinganiselo yezantya zeereakshini; izitya zepolymer okanye iikhuveti zepolymer sisisombululo apho ukuchaneka kubalulekile. Kwaye idayi ethengiswayo inokuthwala ukungcola kweethiazine ezinxulumeneyo kuquka i-Azure B, uphando lwembali lokucoca olwakususa ngokucacileyo, ngoko umsebenzi wohlalutyo ufanele uchaze ibakala kunokucinga ukuba yonke ibhotile ebhalwe imethylene blue iyafana ngokwekhemistri. Iinkcukacha zespektram malunga notshintsho olubangelwa kukudibana kweemolekyuli zigcinwa ngabom kwiphepha leespektra.
Uluhlu olufutshane lokukhangela kwitafile yaselabhoratri
Sebenzisa ibhafa ukuzinzisa i-pH yesisombululo, uze ubhale i-pH ecaleni kwayo yonke ipotenshali nendawo yokuphela. Misela iimeko zeoksijini: ukubila kunye nesigqubuthelo somphunga kumsebenzi wohlobo lweLane-Eynon, isigqubuthelo segesi engasebenziyo okanye ixesha elimiselweyo kwezinye iindlela. Sebenza ngoxinaniso oluphantsi ngokwaneleyo ukuze ubone imonomer, khusela izisombululo ekukhanyeni, khetha izixhobo zepolymer kuxinaniso oluphantsi, uze ubhale ibakala ledayi. Ukuba injongo yi-pH ngokwenene, sebenzisa isalathisi sokwenene se-asidi nesiseko okanye umxube weTashiro ochazwe ngokucacileyo, uze uchaze uluhlu lomxube njengoluhlu lomxube, ungaze uluchaze njengoluhlu lwemethylene blue.
Ingcamango ihlala icacile xa kulandelwa olu qeqesho. Imethylene blue ibonisa imeko ye-oxidation ngokucaca okungaqhelekanga kuba iimeko zayo ezimbini zinokufunxa ukukhanya okubonakalayo okwahluke kakhulu. Thatha umbala njengofundo lwe-redox olwenziwa kwi-pH echaziweyo, phantsi kweemeko zeoksijini nokukhanya ezichaziweyo, kusetyenziswa ibakala ledayi elichaziweyo, kwaye iya kuba luncedo olufanelekileyo kwititration. Yithathe njengelitmus, kwaye iya kuhlala ikulahlekisa.