Trude khi lieii hanh phan tfch lugng vet idl trong cac mSu sinh hgc, can phiii phan luiy mfiu nghiem. Muc dfch ciia giai doiin nay la loiii trir cac chat huu ca vii v6 ca cd mat trong mfiu phan tfch, cac chat nay cd the se iinh hudng deii lieii trinh pluin tfch. Tiiy ihugc vao piiuang pluip phan tfch cung nhu đi lugng phan ifch de lua chgn phuong phiip phan hiiy mfiu thfch hgp. Khi chgn phuang phiip phan huy mfiu
de phan tfch idt can phai quan lam 66n dac tfnh hda hgc ciia idl de Iranh su mil't idt
cd the Xiiy ra trong giai doan phan hiiy mSụ Trong moi Irudng kiem hoac trong moi trudng cd cac chat oxi hda miinh idl tdn tiii d diing 10 3 rat ben va chi bay hai d nhiet do > 650"C [43], Sau day la mgl sd phuang phap phan hiiy mSu nghiem de Xiic dinh lugng vet idl trong Ciic mau sinh hgc [3], [26], [63], [121].
1.4.1. Phuong pliiip udt
Tiieo phuang phap nay, mfiu dugc phan hiiy bang cac dung dich cd tfnh oxi hda niiinh. Tdc do phan hiiy phu thuge vao ban chat ciia cau tii* can xac dinh,lugng miiu, kfch thude mfiu, dung dich phan hiiy, nhiet do va khuay ca hgc. Nhung dung
dich thudng dugc six dung la:
Hdn hgp iixit dac gdm: H2SO4 + HNO3 + HCIO4, vdi hdn hgp niiy, ciin phiii dua nhiet do trong binh phan hiiy tú 200**C-250'"C de dudi cac axil cdn du vii khii nang ket tiia ciia mot sd mudi trong dung dich [52], [65].
Dung dich axit cloric (HCIO3) 28% (trong mgl sd trudng hgp ngudi ta cd the them mot lugng nhd Na2Cr04 de tang tfnh oxi hda). Khi sii" dung dung dich niiy ciln dun ndng binh phan iíng d nhiet do tu I05"C den I60''C tuy theo biin chiíl
ciia Ciíu ui phiin tfch. Can luu y la d nhiet do > 105"C, axil percioric bdc khdi gay doc hiii vii nhung mudi Uxo thanh cd the gay nd neu khong cd he thdng thong hiil hoi khf doc thfch hgp [65], [142].
Ddi vdi nhung dich sinh hgc (nude lieu, sua), cd the six dung nhuiig chiit oxi hda miinh nhu: (NH4)2S20ji bao hda, hoac K2S2OX+ biic Xii cue tfm, liim lac nhan phan hiiy mAu [72], [92], [127].