Determination of Trichloroacetic Acid in Environmental Studies Using Carbon 14 and Chlorine 36

0079019 - ÚEB 2007 RIV GB eng J - Journal Article
Matucha, Miroslav - Rohlenová, Jana - Forczek, Sándor - Uhlířová, H. - Gryndler, Milan - Fuksová, Květoslava - Schröder, P.
Determination of Trichloroacetic Acid in Environmental Studies Using Carbon 14 and Chlorine 36.
[Stanovení kyseliny trichloroctové v environmentálních studiích užívajících uhlík 14 a chlor 36.]
Chemosphere. Roč. 63, č. 11 (2006), s. 1924-1932. ISSN 0045-6535. E-ISSN 1879-1298
R&D Projects: GA ČR GA522/02/0874; GA ČR GA526/05/0636
Institutional research plan: CEZ:AV0Z50380511
Keywords : decarboxylation method * forest ecosystem * TCA extraction
Subject RIV: DF - Soil Science
Impact factor: 2.442, year: 2006

Radioisotopes carbon 14 and chlorine 36 were used to elucidate the environmental role of trichloroacetic acid (TCA) formerly taken to be a herbicide and a secondary air pollutant with phytotoxic effects. However, use of C-14-labeling posed again known analytical problems, especially in TCA extraction from the sample matrix. Therefore-after evaluation of available methods-a new procedure using decarboxylation of [1,2-C-14]TCA combined with extraction of the resultant C-14-chloroform with a non-polar solvent and its subsequent radiometric measurement was developed. The method solves previous difficulties and permits an easy determination of amounts between 0.4 and 20 kBq (10-500 ng g(-1)) of carrier-less [1,2-C-14]TCA in samples from environmental investigations. The procedure is, however, not suitable for direct [Cl-36]TCA determination in chlorination studies with Cl-36. Because TCA might be microbially degraded in soil during extraction and sample storage and its extraction from soil or needles is never complete, the decarboxylation method-i.e. 2 h TCA decomposition to chloroform and CO2 in aqueous solution or suspension in closed vial at 90 degrees C and pH 4.6 with subsequent CHCl3 extraction-is recommended here, estimated V < 7%. Moreover, the influence of pH and temperature on the decarboxylation of TCA in aqueous solution was studied in a broad range and its environmental relevance is shown in the case of TCA decarboxylation in spruce needles which takes place also at ambient temperatures and might amount more than 10-20% after a growing season. A study of TCA distribution in spruce needles after below-ground uptake shows the highest uptake rate into current needles which have, however, a lower TCA content than older needle-year classes, TCA biodegradation in forest soil leads predominatingly to CO2.

Radioizotopy uhlík 14 a chlor 36 byly použity k objasnění role kyseliny trichloroctové dříve považované za herbicid a sekundární atmosférický pollutant s fytotoxickými účinky. Užití značení uhlíkem 14 však poukázalo znovu na známé analytické problémy, zejména extrakci z matrice vzorku. Proto byla vyvinut nový postup užívající dekarboxylaci [1,2-14C]TCA kombinovanou s extrakcí výsledného 14C-chloroformu nepolárním rozpouštědlem s jeho následným radiometrickým měřením. Metoda řeší předchozí potíže a dovoluje snadné stanovení množství mezi 0.4 až 20 kBq beznosičové [1,2-14C]TCA ve vzorcích z environmentálních studií. Pro stanovení 36Cl-TCA je třeba její předchozí separace. Jsou uvedeny příklady aplikací.
Permanent Link: http://hdl.handle.net/11104/0143920