10.13. Xc nh hm lng methanol v propan-2-ol.

 

Phng php

Tin hnh phng php sc k kh (Ph lc 5.2), s dng cc dung dch sau:

Dung dch th

Thm 2,0 ml dung dch chun ni vo bnh nh mc dung tch 50 ml c cha dch ct mu th (dch ct thu c t phng php 3, chuyn lun xc nh hm lng ethanol, Ph lc 10.12), iu chnh hm lng ethanol ti 10% (tt/tt) bng cch pha long vi nc hoc vi ethanol 90% (tt/tt) (TT) va t ti 50 ml dung dch th, ty theo hm lng ethanol trong dch ct cao hay thp hn 10,0 % (tt/tt).

Dung dch i chiu

Chun b 50 ml dung dch cha 2,0 ml dung dch chun ni, 10 % (tt/tt) ethanol (TT), 0,05% (tt/tt) propan-2-ol (TT) v mt lng methanol khan va c nng tng cng ca methanol trong dung dch ny l 0,05% (tt/tt)k c lng methanol cha trong ethanol (TT).

Dung dch chun ni

Chun b mt dung dch cha propan-2-ol 2,5%.

 

Qu trnh sc k

C th thc hin bng cch s dng ct thy tinh nhi ht xp copolyme ethylvinylbenzen divinylbenzen (125 - 150mm) vi nhit ct t v duy tr 130 oC, bung tim 200 oC, detector 220 oC. Tim 1 ml mi dung dch trn. T cc sc k thu c tnh hm lng methanol v propan-2-ol c trong sn phm gc.

 

nhy ca phng php

Vi phng php ny c th pht hin c hm lng methanol v propan-2ol thp hn ti 0,025% (tt/tt).