Txoj kev ntsuas av pH tus nqi nrog PH meter (acidity meter)
Cov av kuaj tau muab rho tawm nrog dej lossis tsis muaj ntsev tov (piv txwv li, 1mol / L cov tshuaj potassium chloride tuaj yeem siv rau cov av acidic; 0.01mol / L calcium chloride tov tuaj yeem siv rau cov av nruab nrab thiab alkaline). Qhov ratio ntawm dej rau av yog feem ntau 2.5: 1; Qhov ratio ntawm dej rau av nyob rau hauv saline-alkali av yog 5: 1; peat yog 10:1. Tom qab tag nrho nplawm, sib npaug rau 30 feeb, thiab ntsuas nws nrog lub ntsuas acidity lossis pH ntsuas.
Kev npaj reagent:
1. pH4.01 standard buffer solution: 10.21g potassium hydrogen phthalate (KHC8H4O4, soj ntsuam
Ntshiab, qhuav ntawm 105 degree) yaj nyob rau hauv 1000m1 distilled dej.
2. pH6.87 standard buffer solution: dissolve 3.39g poov tshuaj dihydrogen phosphate (KH2PO4, analytically ntshiab, qhuav ntawm 45 degree) thiab 3.53g anhydrous disodium hydrogen phosphate (Na2HP4, analytically ntshiab, qhuav ntawm 45leds degree dej).
3. pH9.18 standard buffer solution: Nyhav 3.80g ntawm borax (Na2B4O7·10H2O) thiab yaj nyob rau hauv 1000ml ntawm boiled thiab txias distilled dej. Lub raj mis thiab kaw rau kev khaws cia.
Kev sib npaug ntawm kev kho mob ntawm borax: muab borax tso rau hauv ib lub desiccator uas muaj cov kua dej txaus ntawm sucrose thiab ntsev kom sib npaug rau ob hnub thiab hmo ntuj;
4. 1mol/L poov tshuaj chloride tov: Dissolve 74.6g potassium chloride (KCl, analytically ntshiab) hauv 1000m1 distilled dej. Cov pH ntawm cov tshuaj yog 5.5-6.0
5. 0. Siv 10ml ntawm 1mol / L calcium chloride tov nyob rau hauv 500ml beaker, ntxiv 500ml ntawm distilled dej, ntxiv dropwise calcium hydroxide los yog hydrochloric acid tov los kho pH=6, ces siv distilled dej kom txog li 1000ml, uas yog 0.01mol. /L calcium chloride tov.
[instrument]
pH meter los yog acidity meter; pH electrode (los yog pH iav electrode thiab calomel txheem electrode). [Sample processing]
Qhuav cov av qauv thiab dhau los ntawm 2 hli sieve, hnyav 10.0g ntawm cov qauv rau hauv 50ml beaker, ntxiv 25ml
Cov dej uas tsis muaj cov pa roj carbon dioxide los yog 1mol/L potassium chloride tov (acidic av), los yog 0.01mol/L calcium chloride tov (nruab nrab thiab alkaline av), siv zog nplawm nrog iav pas nrig rau 1-2 min, cia sawv ntsug rau 30 feeb, thiab Npaj rau kev txiav txim siab. Nyob rau lub sijhawm no, kev saib xyuas yuav tsum tau them rau lub zog ntawm chav kuaj ammonia thiab cov kua qaub tsis hloov pauv.
[kev txiav txim]
Tig rau lub ntsuas pH (lossis acidity meter) raws li phau ntawv ntsuas, thiab xaiv tus qauv pH ze rau pH tus nqi ntawm cov av extract.
Cov tshuaj quasi-buffer (pH4.01 tsis tov rau acidic, pH6.87 tsis tov rau nruab nrab, pH9.18 tsis haum rau alkaline) yog siv raws li tus qauv, thiab tus nqi pH qhia los ntawm lub calibration ntsuas yog raws li tus qauv. tus nqi. Ntxig cov khoom siv hluav taws xob (lossis pH iav electrode thiab calomel standard electrode) ntawm pH meter rau hauv cov av extract, tig lub beaker maj mam, thiab nyeem pH tus nqi. Tom qab txhua tus qauv raug ntsuas, cov electrodes tau rinsed nrog dej distilled thiab blotted qhuav nrog lim ntawv.
[xav]
Tus nqi pH nyeem los ntawm pH ntsuas. [Cov Lus Qhia]
1. Kev txheeb xyuas qhov tseeb yog 0.1 pH tus nqi, tab sis tus pH ntsuas qhov tseeb tuaj yeem raug rau 0.02pH chav tsev, thiab siv qhov kub thiab txias. 2. Cov qauv av yuav tsum tsis txhob ua kom zoo zoo, nyiam dua nrog 2 hli sieve. Yog tias cov qauv hauv av tsis tuaj yeem ntsuas tam sim, nws yuav tsum yog
Lub raj mis thiab kaw kom tiv thaiv ammonia thiab volatile acids hauv huab cua. Maj mam swirling lub beaker tom qab cov electrode tso rau hauv cov av extract yog tsim nyog los ua kom lub sij hawm sib npaug, uas yog ib qho tseem ceeb tshwj xeeb tshaj yog rau cov tsis zoo buffered los yog siab pH xau. Yog tias tus qauv calomel electrode siv los ua cov khoom siv hluav taws xob, nws yuav tsum tau muab tso rau hauv cov tshuaj sab saud kom txo tau qhov yuam kev.
