- 0Phenantrolin Cloroform
ion PÔ (tinh theo /Jg P/ml) trong dung dich nuac.
De dam bao dp chfnh xac ciia phep phan tfch, ndng dp ion PÔ trong dung dich do phai nam trong khoang tii 0,04 ^ 0,8|agP/ml. tuc la cd 2 ^g ^ 40|igP/50ml dung dich dọ Cac dung dich can xac dinh cd ndng dp P 0 [ cao hoac thap hon khoang tren deu phai che hda (pha loang hoac cd dac) trudc khi phan tfch.
c) Xdc dinh ndng do ion octophotphai trong dung dich nudc .
Lay mot the tfch dung dich can xac dinh cd chua lucmg ion PO] tucmg iJng vdi lupng P tir 2 ^ 40 jig, chuyen vao binh dinh muc sach dung tfch 50 ml, them vao đ 10 ml dung dich thudc thu amoni molipdat. 5 ml axit ascobic 2%, them nudc cat den vaeh muc, lac deụ Tien hanh do do hap thu ciia dung dich tren may do quang Hitachi U - 2001 d budc sdng 882 nm vdi cuvet 1 cm.
Ndng dp ciia ion P 0 [ tfnh theo (,ig P/ml dupc xac dinh theo cdng thue: ABS-0,003
C^,,- a i g P / m l ) = .K
^ ' 0,736
Trong đ: C^^^,. (jag P/ml) la ndng do ion octophotphat trong dung dich
can xac dinh dupc tfnh theo |.ig P/ml, ABS la dp hap thu do diuic ciia dung
dich, 0,736 la he sd gdc ciia duemg chuan. K la he sd pha loang.
V.3.Ị2. Xdc dinh ndng dp tong cong cua photphat trong dung dich nudc:
Trong mdi trudng H2S0_, dac ndng, cac dang hpp chat chua ph{,)pho (poli photphat, cac hpp chat co photpho) bi phan huy va chuyen ve dang octophotphat. Vi vay ndng do P tdng cdng dupc xac dinh bang each che hda mSu dung dich vdi H-^SÔ dac. Cach tien hanh nhu sau: Dung pipet hiit chfnh xac the tfch dung dich can xac dinh cd ch0C luong photpho nam trong khoang tu 2-:-40|.ig ch(^ vao cdc chiu nhiet, them 1^3ml H-,S04 dac, dun tren bep each cat den khi bde khdi (trong tii hiit). Pha loang bang nuc'rc. trung hoa bang NaOH den p H = l . Sau đ phan tfch ndng do ion P 0 [ trong dung dich nudc theo phuong phap do quang nhu da neu d muc V.3.1.1c.
Nong dp ciia cac hpp chat chúa P trong dung dich nudc trir octophotphat dupc xac dinh theo cdng thuc:
Trong đ: Cp^^^^g^ la ndng dp ion PO:|'(tfnh theo mgP/1) dupc xac dinh khi che hda mau bang H^SÔ dac. C /^^^,.) la ndng do ion PÔ xac dinh nhu da neu d muc V.3.1.1.C, va Cp la ndng do cac hc;rp chat chua P (tfnh theo P j.ig/ml) ngoai octophotphat.
V.3.2. Phuang phdp xdc dinh ndng dp Al^^ theo phuang phdp chiet - trdc quang
Chiing tdi da tien hanh xac dinh ndng do ion Al-^"*" trong dung dich nude theo phucmg phap chiet - trac quang. Khi cd mat thudc thu 8-hidroxiquinolin trong mdi trudng dem amoni cd pH = 9 ^ 10 phuc chat giiia Al^'' va 8-hidroxiquinolin dupc tao thanh va dupe chiet bang clorofonn. Dua vao dp
hap thu ciia pha huu co sau khi chiet cd the xac dmh dupc ndng do A T ^ trong
mau dung dich can phan tfch.
a) Ghi phd hap thụ
De ghi phd hap thu ciia phuc chat nhdm 8-hidroxiquinolat trong clorc^form, chiing tdi da chuan bi mau do nhu sau:
Cho vao ph6u chiet sach dung tfch 100 ml cac dung dich: 4 ml dung dich Ak^"*" cd nc^ng dp 10 |ig/ml, 10 ml dung dich dem amoni cd pH = 9 ^ 10, lac deụ Chiet lay Ak^^ tir 3 H- 4 lan, mdi lan 5 ml dung dich 8-hidroxiquini>lin
1% trong clorofonn. Cac phan chiet clorofonn dupc tach khdi pha nuc7c va chuyen vao binh dinh muc dung tfch 25 ml, them clorc^form den vaeh muc, lac deu, de yen trong thdi gian 30 phiit.
Tien hanh ghi phd hap thu ciia dung dich nhc)m 8-hidroxiquin()lat trong eloroform tren may do quang Hitachi U - 2001 vdi cuvet I cm trong khoang budc sdne tir 320 -^ 480 nm. Ket qua thuc nghiem ductc dua ra tren hinh 7:
1.590 fiBG fiBG r. 1 o ft W M i l "." • J- '.' '.' liffi ' "^) t^'i ^'i P m HI 440 m
Hinh 7. Pho hap thu cua dung dich nhom 8-hidroxiquinolat trong
cloroform
Tir hinh (7) chiing toi thay ring pho hap thu co cure dai tai buac song 388,5 nm. Chiing toi su dung gia tn buoc song nay cho phep do quang xac dinh nong do Al"^ trong dung dich theo phucmg phap chiet - do quang.
b) Lap duang chudn xdc dinh nong do ion Al^* trong dung dich.
Lay 7 binh dinh miic sach co dung tfch 25 ml, 7 phdu chiet sach co dung tfch lOOml, danh so thu ur tu 1-^7 tuong ung. Diing pipet lay chinh xac nhung the tich dung dich ion Al'^ 10 |ig/ml la: 0 ml, 1 ml, 2 ml, 4 ml, 6 ml, 8ml, 10ml lan lum cho vao cac phlu chiet tu so 1 den so 7, them vao m6i phau chiet 10 ml dung dich dem amoni co pH = 9, chiet (3 ^ 4 lan) ion A l ^ trong m6i phlu chiet, m6i lan b4ng 5 ml 8-hidroxiquinoIin 1% trong cloroform. Cac phan huu ca duac tach ra khoi phlu chiet va chuyen vao cac binh dinh muc co danh so tucmg ung, ihem cloroform den vaeh miic, lie deu, dé yen trong thai