1, ukuhlonza indlela ye-hydroxypropyl methyl cellulose
(1) Thatha u-1.0g wesampula, amanzi ashisiwe (80~90℃) 100mL, gudluza ngokuqhubekayo, bese upholisa kuketshezi olubonakalayo endaweni yokugeza eqhweni; Faka u-2mL woketshezi eshubhuni yokuhlola, kancane kancane wengeze isixazululo se-sulfuric acid esingu-1mL esingu-0.035% wesihlalo sobukhosi eduze kodonga lweshubhu, bese ushiya imizuzu emi-5. Iringi eluhlaza ivela esibonakalayo phakathi koketshezi olubili.
(2) Thatha inani elifanele le-slime eshiwo ngenhla elisetshenziswe ekukhombeni (ⅰ) bese ulithela epuletini lengilazi. Ngemva kokuhwamuka kwamanzi, kwakhiwa ifilimu ye-ductile.
2, ukuhlaziywa kwe-hydroxypropyl methyl cellulose kokulungiswa kwesisombululo esijwayelekile
(1) Isixazululo esijwayelekile se-sodium thiosulfate (0.1mol/L, ukufaneleka: inyanga eyodwa)
Ukulungiselela: Bilisa cishe u-1500mL wamanzi acwecwe futhi uphole uze ulungele ukusetshenziswa. Kala u-25g we-sodium thiosulfate (isisindo se-molecular singu-248.17, bese uzama ukunemba kuze kufike ku-24.817g uma ukala) noma u-16g anhydrous sodium thiosulfate, uhlakaze ngo-200mL wamanzi okupholisa angenhla, uwaxube abe ngu-1L, bese uwabeka ensundu. ibhodlela, faka ibhodlela ebumnyameni, bese ulihluza ukuze ulisebenzise ngemva kwamasonto amabili.
Ukulinganisa: Isisindo esingu-0.15g sereferensi ye-potassium dichromate ebhakwe esisindweni esingaguquki, esinembile sibe ngu-0.0002g. Faka u-2g we-potassium iodide no-20mL sulfuric acid (1+9), xukuza kahle, beka ebumnyameni imizuzu engu-10, engeza amanzi angu-150mL kanye nesisombululo se-starch esingu-3ml esingu-0.5%, i-titrate nge-0.1mol/L yesisombululo se-sodium thiosulfate, isisombululo siphenduka sibe luhlaza okwesibhakabhaka. kuya kokuluhlaza okukhanyayo ekugcineni. I-Potassium chromate ayizange yengezwe ekuhlolweni okungenalutho. Inqubo yokulinganisa iphindwe izikhathi ezingu-2~3 futhi inani elimaphakathi lithathiwe.
Ukuhlushwa kwe-molar C (mol/L) yesisombululo esijwayelekile se-sodium thiosulfate kubalwe ngale ndlela elandelayo:
Lapho, uM inqwaba ye-potassium dichromate; I-V1 umthamo we-sodium thiosulfate esetshenzisiwe, mL; I-V2 umthamo we-sodium thiosulfate esetshenziswe ekuhlolweni okungenalutho, mL; 49.03 isisindo se-potassium dichromate esilingana ne-1mol ye-sodium thiosulfate, g.
Ngemva kokulinganisa, engeza i-Na2CO3 encane ukuze uvimbele ukubola kwe-microbial.
(2) Isixazululo esijwayelekile se-NaOH (0.1mol/L, ukufaneleka: inyanga eyodwa)
Ukulungiselela: Cishe i-4.0g ye-NaOH ehlanzekile yokuhlaziya yakalwa ebhekhani, futhi amanzi ahlutshiwe angu-100mL ayengezwa ukuze ancibilike, bese edluliselwa ku-1L ye-volumetric flask, futhi amanzi acwecwe afakwa esikalini, futhi abekwa izinsuku ezingu-7-10 kuze kube yilapho. ukulinganisa.
Ukulinganisa: Faka u-0.6 ~ 0.8g we-potassium hydrogen phthalate ehlanzekile omiswe ku-120℃ (enembile kuye ku-0.0001g) eflaskini eyi-conical engu-250mL, engeza amanzi acwecwe angu-75mL ukuze uwahlakaze, bese wengeza amaconsi angu-2~3 we-phenolphthalein engu-1% ne-phenolphthalein. isisombululo se-sodium hydroxide esilungisiwe ngenhla size sibebomvu kancane, futhi iphuzu lokugcina liwukuthi umbala awufihli phakathi kuka-30S. Bhala phansi umthamo we-sodium hydroxide. Inqubo yokulinganisa iphindwe izikhathi ezingu-2~3 futhi inani elimaphakathi lithathiwe. Futhi wenze ucwaningo olungenalutho.
Ukuhlushwa kwesisombululo se-sodium hydroxide kubalwa ngale ndlela elandelayo:
Lapho, i-C iyingxube yesisombululo se-sodium hydroxide, i-mol/L; U-M umele ubuningi be-potassium hydrogen phthalate, G; I-V1 umthamo we-sodium hydroxide esetshenzisiwe, mL; I-V2 imele umthamo we-sodium hydroxide esetshenziswe ekuhlolweni okungenalutho, mL; 204.2 isisindo se-molar se-potassium hydrogen phthalate, g imvukuzane ngayinye.
(3) Nciphisa i-sulfuric acid (1+9) (Ukusebenza: inyanga engu-1)
Ngaphansi kokunyakaziswa, engeza ngokucophelela i-100mL ye-sulfuric acid egxilile ku-900mL wamanzi acwecwe, wengeze kancane, ngenkathi uvuselela.
(4) Nciphisa i-sulfuric acid (1+16.5) (Ukusebenza: izinyanga ezi-2)
Ngaphansi kokunyakaziswa, engeza ngokucophelela u-100mL we-concentrated sulfuric acid ku-1650mL wamanzi acwecwe, wengeze kancane. Govuza njengoba uhamba.
(5) Inkomba yesitashi (1%, ukufaneleka: izinsuku ezingama-30)
Kala u-1.0g wesitashi esincibilikayo, engeza amanzi angu-10mL, ugovuze futhi uwajove emanzini abilayo angu-100mL, ubilise kancane imizuzu engu-2, ubeke, futhi uthathe isithako esinamandla ukuze usisebenzise.
(6) Inkomba yesitashi
Isikhombi sesitashi esingu-0.5% sitholwe ngokuthatha u-5mL wesisombululo senkomba yesitashi esilungisiwe esingu-1% bese siwuxuba sibe ngu-10mL ngamanzi.
(7) 30% isixazululo se-chromium trioxide (ukufaneleka: inyanga engu-1)
Kala u-60g we-chromium trioxide bese uyincibilikisa ku-140mL wamanzi ngaphandle kwezinto eziphilayo.
(8) Isixazululo se-Potassium acetate (100g/L, ukufaneleka: izinyanga ezi-2)
I-10g yezinhlamvu ze-anhydrous potassium acetate zincibilikisiwe kusixazululo esingu-100mL sika-90mL i-glacial acetic acid kanye ne-10mL acetic anhydride.
(9) 25% isisombululo se-sodium acetate (220g/L, ukufaneleka: izinyanga ezi-2)
Chaza u-220g we-acetate ye-sodium anhydrous emanzini bese unciphisa ku-1000mL.
(10) I-Hydrochloric acid (1:1, ukufaneleka: izinyanga ezi-2)
Hlanganisa i-hydrochloric acid egxilile namanzi ngesilinganiso sevolumu ye-1: 1.
(11) Isixazululo sebhafa ye-acetate (pH=3.5, ukufaneleka: izinyanga ezi-2)
Chaza i-acetic acid engu-60mL emanzini angu-500mL, bese wengeza u-100mL ammonium hydroxide bese unciphisa ku-1000mL.
(12) Isixazululo sokulungiselela i-nitrate yokuhola
I-159.8mg ye-nitrate yomthofu yachithwa emanzini angu-100mL aqukethe i-1mL ye-nitric acid (ukuminyana 1.42g/cm3), ahlanjululwe ku-1000mL wamanzi futhi axutshwe kahle. Ukulungiswa nokugcinwa kwalesi sixazululo kuzokwenziwa engilazini engenamthofu.
(13) Isixazululo esijwayelekile sokuhola (ukusebenza: izinyanga ezi-2)
Isilinganiso esinembile sika-10mL wesixazululo sokulungiselela i-nitrate yomthofu sihlanjululwe ngamanzi saya ku-100mL.
(14) 2% isixazululo se-hydroxylamine hydrochloride (isikhathi sokuqinisekisa: inyanga engu-1)
Chaza u-2g we-hydroxylamine hydrochloride ku-98mL wamanzi.
(15) I-Amonia (5mol/L, ukufaneleka: izinyanga ezi-2)
I-175.25g ye-ammonia yachithwa emanzini futhi yahlanjululwa yaba ngu-1000mL.
(16) Uketshezi oluxubile (isikhathi sokuqinisekisa: izinyanga ezi-2)
Xuba i-100mL glycerol, isixazululo esingu-75mLNaOH (1mol/L), kanye namanzi angu-25mL.
(17) Isixazululo se-Thioacetamide (4%, ukufaneleka: izinyanga ezi-2)
I-4g ye-thioacetamide yachithwa emanzini angama-96g.
(18) I-Phenanthroline (0.1%, ukufaneleka: inyanga engu-1)
Chaza i-0.1g o-phenanthroline emanzini angu-100mL.
(19) I-Acid stannous chloride (ukusebenza: inyanga engu-1)
Chaza u-20g we-stannous chloride ku-50mL we-hydrochloric acid egxilile.
(20) Isixazululo sebhafa esijwayelekile se-Potassium hydrogen phthalate (pH 4.0, ukufaneleka: izinyanga ezi-2)
I-10.12g ye-potassium hydrogen phthalate (KHC8H4O4) ikalwe ngokunembile futhi yomiswa kokuthi (115±5) ℃ isikhathi esingu-2~3h. Nciphisa ku-1000mL ngamanzi.
(21) Isixazululo sebhafa esijwayelekile se-Phosphate (pH 6.8, ukufaneleka: izinyanga ezi-2)
U-3.533g we-anhydrous disodium hydrogen phosphate kanye no-3.387g we-potassium dihydrogen phosphate omiswe ku-(115±5) ℃ isikhathi esingu-2~3h kwakalwa ngokunembile futhi kwahlanjululwa ku-1000mL ngamanzi.
3, ukunqunywa kokuqukethwe kweqembu le-hydroxypropyl methyl cellulose
(1) Ukunqunywa kokuqukethwe kwe-methoxy
Ukunqunywa kokuqukethwe kwe-methoxy kusekelwe ekuboleni kwe-hydroiodate acid ngokushisisa ngokuhlolwa okuqukethe i-methoxy ukuze kukhiqizwe i-iodide ye-methane eguquguqukayo (iphoyinti elibilayo elingu-42.5 ° C). I-methane iodide igaywe nge-nitrogen kusixazululo se-autoreaction. Ngemva kokugeza ukuze kukhishwe izinto eziphazamisayo (HI, I2 kanye ne-H2S), umhwamuko we-iodine methane umuncwa isixazululo se-potassium acetate acetic acid esiqukethe i-Br2 ukuze senze i-IBr bese sifakwa i-oxidized ku-iodic acid. Ngemuva kokukhishwa kwe-distillation, izinto ezisesamukeli zidluliselwa emabhodleleni e-iodine futhi zihlanjululwe ngamanzi. Ngemuva kokwengeza i-formic acid ukususa i-Br2 eyengeziwe, i-KI ne-H2SO4 yengezwe. Okuqukethwe kwe-methoxy kungabalwa ngokubeka u-12 ngesixazululo se-Na2S2O3. I-equation yokusabela ingavezwa kanje.
Idivayisi yokulinganisa okuqukethwe kwe-methoxy ikhonjisiwe kuMfanekiso 7-6.
Ku-7-6 (a), A iyiflask eyindilinga-phansi engu-50mL exhunywe ne-catheter. Ibhodlela ifakwe mpo ngeshubhu E ejiya umoya eqondile, engaba ngu-25cm ubude no-9mm ububanzi bangaphakathi. Ingxenye engenhla yeshubhu igotshwe ibe yithubhu ye-capillary engilazi ene-outlet eya phansi kanye no-2mm ububanzi bangaphakathi. Umfanekiso 7-6 (b) ubonisa idivayisi ethuthukisiwe. 1 i-reaction flask, okuyiflask eyindilinga-phansi engu-50mL, futhi ipayipi le-nitrogen lingakwesokunxele. I-2 iyipayipi elijikayo eliqondile; 3 i-scrubber, equkethe uketshezi lokuwasha; 4 iyishubhu yokumunca. Umehluko omkhulu phakathi kwedivayisi kanye nendlela ye-pharmacopoeia ukuthi ama-absorber amabili wendlela ye-pharmacopoeia ahlanganiswe abe yinye, enganciphisa ukulahlekelwa kwesisombululo sokugcina sokumuncwa. Ngaphezu kwalokho, uketshezi lokuwasha ku-scrubber nalo luhlukile endleleni ye-pharmacopoeia, okungamanzi acwecwe, futhi idivayisi ethuthukisiwe iyingxube yesisombululo se-cadmium sulfate kanye nesisombululo se-sodium thiosulfate, esingakhangisa kalula ukungcola kwegesi ehlutshiwe.
I-pipette yensimbi: 5mL (5), 10mL (1); I-Burette: 50mL; Ibhodlela lokulinganisa i-iodine: 250mL; Hlaziya ibhalansi.
I-Reagent phenol (ngoba iqinile, ngakho-ke izohlanganiswa ngaphambi kokuphakela); I-carbon dioxide noma i-nitrogen; I-Hydroiodate acid (45%); Ukuhlaziywa kokuhlanzekile; Isixazululo se-Potassium acetate (100g/L); I-Bromine: ihlanzekile ngokuhlaziya; I-asidi ye-Formic: ihlanzekile ngokuhlaziya; 25% isisombululo se-sodium acetate (220g/L); I-KI: ukuhlanzeka kokuhlaziya; Hlanza i-sulfuric acid (1+9); Isixazululo esijwayelekile se-sodium thiosulfate (0.1mol/L); I-Phenolphthalein inkomba; 1% isisombululo se-ethanol; Inkomba yesitashi: 0.5% isitashi emanzini; Hlanza i-sulfuric acid (1 + 16.5); 30% isixazululo chromium trioxide; Amanzi angenayo i-organic: engeza i-10mL dilute sulfuric acid (1+16.5) kuya ku-100mL amanzi, ukushisa kube abilayo, bese wengeza u-0.1ml0.02mol / L we-potassium permanganate titer, ubilise imizuzu engu-10, kufanele uhlale ubomvana; 0.02mol/L isixazululo se-sodium hydroxide titration: Ngokwendlela yesithasiselo ye-Pharmacopoeia yaseShayina, isisombululo se-sodium hydroxide titration esingu-0.1mol/L salinganiswa futhi sahlanjululwa ngokunembile saba ngu-0.02mol/L ngamanzi abilisiwe futhi apholile.
Engeza cishe u-10mL wesisombululo sokugeza eshubhuni yokuwasha, engeza u-31mL wesisombululo sokumuncwa esisanda kulungiswa eshubhuni yokumunca, faka ithuluzi, ukale cishe u-0.05g (okunembile kuya ku-0.0001g) wesampula elomisiwe elomisiwe ukuze libe nesisindo esingaguquki ku-105. ℃ eflaskini yokusabela, bese wengeza i-5mL hydroiodate. Ibhodlela lokusabela lixhunywa ngokushesha ku-condenser yokutakula (umlomo wokugaya uswakanyiswe nge-hydroiodate), futhi i-nitrogen iphonswa ethangini ngesilinganiso samabhamuza angu-1 ~ 2 ngomzuzwana. Izinga lokushisa lilawulwa kancane ukuze isitimu soketshezi olubilayo sikhuphuke siye kuhhafu wobude be-condenser. Isikhathi sokuphendula sincike kumvelo yesampula, phakathi kuka-45min no-3h. Khipha ishubhu elimuncayo bese udlulisa ngokucophelela ikhambi elimunca eflaskni ye-iodine engu-500mL equkethe u-10ml wesisombululo se-sodium acetate esingu-25% kuze kube yilapho isamba sevolumu sifinyelela cishe ku-125mL.
Ngaphansi kokunyakaziswa njalo, kancane kancane wengeze i-formic acid drop by drop kuze kube yilapho okuphuzi kuyanyamalala. Engeza ukwehla kwenkomba ebomvu ye-methyl engu-0.1%, futhi umbala obomvu awupheli imizuzu emi-5. Bese wengeza amaconsi amathathu e-formic acid. Yiyeke ihlale isikhashana, bese wengeza u-1g we-potassium iodide kanye no-5mL we-dilute sulfuric acid (1+9). Isixazululo sifakwe i-titration nge-0.1mol/L yesisombululo esijwayelekile se-sodium thiosulfate, futhi amaconsi angu-3 ~ 4 wesikhombi sesitashi esingu-0.5% angeziwe eduze nendawo yokugcina, futhi ukuphindaphinda kwaqhubeka kuze kube yilapho umbala oluhlaza unyamalala.
Esimeni esifanayo, ukuhlolwa okungenalutho kwenziwa.
Ukubalwa kokuqukethwe okuphelele kwe-methoxide:
Lapho, i-V1 imele umthamo (mL) wesisombululo esijwayelekile se-sodium thiosulfate esidliwe amasampula e-titration; I-V2 umthamo wesisombululo esijwayelekile se-sodium thiosulfate esisetshenziswe ekuhlolweni okungenalutho, mL; C ukuhlushwa kwesisombululo esijwayelekile se-sodium thiosulfate, i-mol/L; U-M ubhekisela esilinganisweni sesampula esomisiwe, g; I-0.00517 ingu-0.1mol/L sodium thiosulfate ku-1ml ngayinye okulingana no-0.00517g we-methoxy.
Ingqikithi yokuqukethwe kwe-methoxy imele isamba se-methoxy kanye nenani le-hydroxyproxy lokubala i-methoxy, ngakho isamba se-alkoxy kufanele silungiswe okuqukethwe kwe-hydroxyproxy okuwumphumela ukuze kutholwe okuqukethwe kwe-methoxy okuyiyonayona. OKUQUKETHWE I-HYDROXYPROPOXY KUFANELE KUQALE KULUNGISIWE NGENXA YE-PROPENE EKHISHWE NGU-HI NGE-HYDROXYPROPYL NGOKUQHUBEKA K=0.93 (INANI LENOMBOLO ELIKHULU LAMASAMUKELI ESIMISWA INDLELA kaMorgan). Ngakho-ke:
Okuqukethwe kwe-methoxy okulungisiwe = okuqukethwe okuphelele kwe-methoxy - (okuqukethwe kwe-hydroxypropoxy × 0.93×31/75)
Lapho izinombolo 31 kanye ne-75 ziyi-molar mass yamaqembu e-methoxy ne-hydroxypropoxy, ngokulandelanayo.
(2) Ukunqunywa kokuqukethwe kwe-hydroxypropoxy
Iqembu le-hydropropoxy kusampula lisabela ne-chromium trioxide ukukhiqiza i-acetic acid. Ngemva kokukhishwa kusixazululo se-autoreaction, okuqukethwe kwe-chromic acid kunqunywa ngokubhalwa kwe-titration ngesisombululo se-NaOH. Ngenxa yokuthi inani elincane le-chromic acid lizokhishwa ohlelweni lwe-distillation, isisombululo se-NaOH sizophinde sidliwe, ngakho okuqukethwe kwale chromic acid kufanele kunqunywe ngokuqhubekayo nge-iodimetry futhi kukhishwe ekubalweni. I-equation yokusabela ithi:
Izinsimbi kanye nama-reagents Isethi ephelele yamathuluzi okunqunywa kwamaqembu e-hydroxypropoxy; Ibhodlela le-Volumetric: 1L, 500mL; Isilinda sokulinganisa: 50mL; I-Pipette: 10mL; Ibhodlela lokulinganisa i-iodine: 250mL. I-burette eyisisekelo: 10mL; Isixazululo esijwayelekile se-sodium thiosulfate (0.1mol/L); Hlanza i-sulfuric acid (1 + 16.5); Hlanza i-sulfuric acid (1+9); Inkomba yesitashi (0.5%).
I-7-7 iyithuluzi lokunquma okuqukethwe kwe-hydroxypropoxy.
Ku-7-7 (a), D iyi-25mL ye-double-neck distilling flask, B iyishubhu le-steam generator engu-25mm×150mm, C iyishubhu yokuxhuma ukugeleza, A iyibhavu yokushisisa kagesi, u-E uyikholomu ye-shunt, G iyi-flask eyi-conical enepulaki yengilazi, ububanzi bangaphakathi bokugcina buyi-0.25-1.25mm, ifakwe ku-flask ye-distilling; F iyishubhu ejiyayo exhunywe ku-E. Kudivayisi ethuthukisiwe eboniswe ku-FIG. 7-7 (b), 1 i-reactor, okuyiflask yokugaya engu-50mL; 2 inhloko yokuhluza; I-3 iyifaneli yengilazi engu-50mL yokulawula isivinini sokugeleza kwamanzi aphilayo; 4 ipayipi le-nitrogen; 5 yipayipi elijiyayo. Umehluko obaluleke kakhulu phakathi kwedivayisi eguquliwe kanye nendlela ye-pharmacopoeia ukufakwa kwefenisha yengilazi ukulawula izinga lokugeleza kwamanzi, ukuze izinga lokukhishwa kwe-distillation likwazi ukulawulwa kalula.
Izindlela zokuhlola kusampula ye-105 ℃ yokoma kuya esisindweni esingaguquki cishe ngu-0.1 g (0.0002 g), kusho okunembayo ebhodleleni lokukhipha isisu, engeza u-10 ml wesisombululo esingu-30% se-chromium trioxide, i-flask yokugcoba enkomishini yokugeza uwoyela, izinga loketshezi lokugeza uwoyela ehambisana ne-chromium trioxide liquid surface, okokusebenza okufakiwe, amanzi okupholisa avulekile, i-nitrogen, yefekthri yethu ukulawula izinga le-nitrogen cishe ibhamuza elilodwa ngomzuzwana. Ngaphakathi kwemizuzu engama-30, ukugeza kwamafutha kwakushisiswe ku-155 ℃ futhi kugcinwe kulokhu kushisa kuze kube yilapho isisombululo esiqoqiwe sifinyelela ku-50mL. I-distillation yamiswa ukuze kukhishwe ibhavu lamafutha.
Geza udonga lwangaphakathi lwe-cooler ngamanzi a-distilled, hlanganisa amanzi okugeza kanye ne-distillate ebhodleleni le-iodine engu-500mL, engeza amaconsi angu-2 e-1% ye-phenolphthalide indicator, i-titrate ne-0.02mol/L ye-sodium hydroxide solution ku-pH value engu-6.9~7.1 , bese ubhala inani eliphelele le-sodium hydroxide esetshenzisiwe.
Engeza u-0.5g we-sodium bicarbonate kanye no-10mL we-sulfuric acid ehlanjululwe (1+16.5) ebhodleleni le-iodine futhi uliyeke lime kuze kungabi bikho ikhabhoni ekhiqizwayo. Bese wengeza u-1.0g we-potassium iodide, uyixhume ngokuqinile, uyinyakazise kahle bese uyishiya ebumnyameni imizuzu engu-5. Bese wengeza 1mL 0.5% inkomba isitashi futhi titrate it nge 0.02mol/L sodium thiosulfate kuze kube sekugcineni. Bhala phansi umthamo we-sodium thiosulfate esetshenzisiwe.
Kokunye ukuhlola okungenalutho, izinombolo zevolumu ye-sodium hydroxide kanye ne-sodium thiosulfate titrators ezisetshenzisiwe zarekhodwa ngokulandelana.
Ukubalwa kokuqukethwe kwe-hydroxypropoxy:
Lapho, K kuyisithombe se-coefficient yokulungisa sokuhlolwa okungenalutho: I-V1 iyivolumu ye-sodium hydroxide titration esetshenziswe isampula, mL. I-C1 ukuhlushwa kwesisombululo esijwayelekile se-sodium hydroxide, i-mol/L; I-V2 ivolumu ye-sodium thiosulfate titration esetshenziswe isampula, mL; I-C2 ukuhlushwa kwesisombululo esijwayelekile se-sodium thiosulfate, i-mol/L; M yisampula yesisindo, g; I-Va ingumthamo we-sodium hydroxide titration esetshenziswe ekuhlolweni okungenalutho, mL; I-Vb ingumthamo we-sodium thiosulfate titration esetshenziswe ocwaningweni olungenalutho, mL.
4. Ukunqunywa komswakama
Ibhalansi yokuhlaziya yezinsimbi (enembile ku-0.1mg); Ibhodlela lokulinganisa: ububanzi 60mm, ukuphakama 30mm; Ukomisa ihhavini.
Indlela yokuhlola inesisindo esinembile sesampula 2~ 4G (
Isikhathi sokuthumela: Sep-08-2022