Abstract
A method of visual mercurimetric titration of chloride ions is widely used in elemental microanalysis for determination of chlorine content in organic substances after their combustion in an oxygen-filled flask. However, when chlorine content is less than 0.5%, the mercurimetric method fails to provide essential accuracy, and a more sensitive method of chlorine coulometric titration by electrogenerated silver ions appeared favorable. We consider a possibility of determining the microgram content of chloride-ions in solutions using a digital coulometric analyzer («Expert-006» produced by «Econics-Expert» (Moscow)) supplemented with an electrolytic cell with silver electrodes. The coulometer was tested in different operation modes to select the optimal electrochemical parameters of ion chloride titration and develop a technique for coulometric determination of chloride ions which in combination with the preliminary burning of the analyzed substances in an oxygen-filled flask provides determination of the residual chlorine in organic matrices at a level of 0.1 – 0.5%. The proposed technique was used to determine the residual chlorine in a number of polymers. The relative error did not exceed 5% at chlorine concentrations of 0.16 – 0.28%.
Highlights
 ïðàêòèêå ýëåìåíòíîãî ìèêðîàíàëèçà äëÿ îïðåäåëåíèÿ õëîðà â îðãàíè÷åñêèõ âåùåñòâàõ øèðîêî èñïîëüçóþò ìåòîä âèçóàëüíîãî ìåðêóðèìåòðè÷åñêîãî òèòðîâàíèÿ õëîðèä-èîíîâ â ðàñòâîðàõ, ïîëó÷åííûõ ïîñëå ìèíåðàëèçàöèè âåùåñòâ ñîææåíèåì â êîëáå ñ êèñëîðîäîì
A method of visual mercurimetric titration of chloride ions is widely used in elemental microanalysis for determination of chlorine content in organic substances after their combustion in an oxygen-filled flask
When chlorine content is less than 0.5%, the mercurimetric method fails to provide essential accuracy, and a more sensitive method of chlorine coulometric titration by electrogenerated silver ions appeared favorable
Summary
 ïðàêòèêå ýëåìåíòíîãî ìèêðîàíàëèçà äëÿ îïðåäåëåíèÿ õëîðà â îðãàíè÷åñêèõ âåùåñòâàõ øèðîêî èñïîëüçóþò ìåòîä âèçóàëüíîãî ìåðêóðèìåòðè÷åñêîãî òèòðîâàíèÿ õëîðèä-èîíîâ â ðàñòâîðàõ, ïîëó÷åííûõ ïîñëå ìèíåðàëèçàöèè âåùåñòâ ñîææåíèåì â êîëáå ñ êèñëîðîäîì.  íàñòîÿùåé ðàáîòå èçó÷åíû âîçìîæíîñòè îïðåäåëåíèÿ ìèêðîãðàììîâûõ ñîäåðæàíèé õëîðèä-èîíîâ â ðàñòâîðàõ ñ ïîìîùüþ öèôðîâîãî êóëîíîìåòðè÷åñêîãî àíàëèçàòîðà «Ýêñïåðò-006», ïðîèçâîäñòâà ÎÎÎ «Ýêîíèêñ-Ýêñïåðò» (Ìîñêâà), äîïîëíåííîãî ýëåêòðîëèòè÷åñêîé ÿ÷åéêîé ñ ñåðåáðÿíûìè ýëåêòðîäàìè. Ïðîâåäåíî èñïûòàíèå ðàáîòû êóëîíîìåòðà â ðàçíûõ ðåæèìàõ, íàéäåíû îïòèìàëüíûå ýëåêòðîõèìè÷åñêèå ïàðàìåòðû òèòðîâàíèÿ õëîðèä-èîíîâ è ðàçðàáîòàíà êóëîíîìåòðè÷åñêàÿ ìåòîäèêà, êîòîðàÿ â ñî÷åòàíèè ñ ïðåäâàðèòåëüíûì ñîææåíèåì àíàëèçèðóåìûõ âåùåñòâ â êîëáå ñ êèñëîðîäîì ïîçâîëÿåò îïðåäåëÿòü îñòàòî÷íûé õëîð â îðãàíè÷åñêèõ ìàòðèöàõ íà óðîâíå 0,1 – 0,5 %.
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