- Tdng ham luang cac kim lôi dugc xac dinh theo phuang phap ICPMS tren thiet b, cua hang Perkin Elmer Sciex Elan 5000 ICPmass spectrometer Ty so khoi lugng dien tich (M/Z)
3. KET QUA VA THAO LUAN
3.L Danh gia phuong phap phan tich ICP-MS
ị /. /. Giai han phdt hien (LOD) vd gi&i han dinh hrang ( LOO)
Ddi vai he thong ICP-MS, LOD va LOQ cd thi dugc tinh theo cac cdng thirc:
L O D = ^ ^ ^ ^ 0)
S-B
LOQ = 1 ^ ^ : ^ (2)
S'B
trong đ: a: dp lech chuin mau tring; CSTD : Nong do mau chuin; S: Tin hieu ciia mlu chuin (so dim, CPS) B: Tin hifu trung binh cua mlu tring sau 10 lan do lap lai (sd dim, CPS).
Tiln hanh do l?p lai 10 lan cac dung djch mau chuin chira 200 ppm Fe, va 100 ppb cac kim loai cdn lai , tinh so dem trung binh rdi thay sd lieu vao cac cdng thirc (1), (2) ta tinh dugc cac gia trj LOD ciia phuang phap phan tich. Kit qua cho thiy LOD cua hau hit kim loai tir 1,8 (ppt) vai Cr va cao nhit la 20,1 (ppt) vdi Fe chimg td phuang phap nay hoan toan phu hgp vdi phan tich lugng vet va sieu vet cac ion kim loai trong thudc đng ỵ
3.1.2. Ddnh gid do chinh xdc cua phep do
De kiem tra tinh dn dinh va do dung ciia thilt bj do, sir dung 3 dung dich chuin kilm tra cd chira đng thdi cac kim loai vdi cac ndng do d khoang dau, giua va cudi ciia dudng chuin dl kiem tra dp dimg ciia cac phep dọ
+ Dung dich 1: Fe cd ndng do 40 ppb, cac ion kim loai cdn lai cd ndng do 20 ppb. + Dung dich 2: Fe cd ndng do 200 ppb, cac ion kim loai cdn lai cd ndng do 100 ppb. + Dung dich 3: Fe cd ndng do 400 ppb, cac ion kim loai cdn lai cd ndng do 200 ppb.
Sir dung cac dudng chuan dugc thiet lap de tim ndng do cac dung djch chuan kiem tra, ket qua thu duoc deu cho sai sd tir -5,47% den 0,66% nhd han rat nhieu so vdi gidi han cho phep ciia AOAC, chirng td phep do ICP-MS cd do dimg rat tdt.
3.2. Xay dyng quy trinh xir li mau thuoc dong y
3,2. L Cdc quy trinh xu li mdu khao sdt
Dua vao mgt sd quy trinh xir li mau thuc vat va cay thudc d theo cac tai lieu khac nhau da cdng bo [2 - 6] chiing tdi chgn mgt sd phuong phap xir li mau cay thudc đng y nhu sau (sir dung 0,5000 gam mlu va sau khi pha mau djnh mire thanh 50 ml):
A- Mdu dugc nung d 550°C trong vdng 2 gid" din khi dugc tro mau tring. Sau đ hda tan tro vdi 10 ml HCl 1 : 1 va Igc.