Analytical interferences of mercuric chloride preservative in environmental water samples: determination of organic compounds isolated by continuous liquid-liquid extraction or closed-loop stripping

Analytical interferences were observed during the determination of organic compounds in groundwater samples preserved with mercuric chloride. The nature of the interference was different depending on the analytical isolation technique employed. (1) Water samples extracted with dichloromethane by con...

Full description

Saved in:
Bibliographic Details
Published in:Environmental science & technology 1992-07, Vol.26 (7), p.1307-1312
Main Authors: Foreman, William T, Zaugg, Steven D, Faires, Lynda M, Werner, Marilyn G, Leiker, Thomas J, Rogerson, Peter F
Format: Article
Language:English
Subjects:
Chemicals
Engineering
Engineering, Environmental
Environmental Sciences
Environmental Sciences & Ecology
Groundwater
Life Sciences & Biomedicine
Science & Technology
Technology
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Analytical interferences were observed during the determination of organic compounds in groundwater samples preserved with mercuric chloride. The nature of the interference was different depending on the analytical isolation technique employed. (1) Water samples extracted with dichloromethane by continuous liquid-liquid extraction (CLLE) and analyzed by gas chromatography/mass spectrometry revealed a broad HgCl2 "peak" eluting over a 3-5-min span which interfered with the determination of coeluting organic analytes. Substitution of CLLE for separatory funnel extraction in EPA method 508 also resulted in analytical interferences from the use of HgCl2 preservative. (2) Mercuric chloride was purged, along with organic contaminants, during closed-loop stripping (CLS) of groundwater samples and absorbed onto the activated charcoal trap. Competitive sorption of the HgCl2 by the trap appeared to contribute to the observed poor recoveries for spiked organic contaminants. The HgCl2 was not displaced from the charcoal with the dichloromethane elution solvent and required strong nitric acid to achieve rapid, complete displacement. Similar competitive sorption mechanisms might also occur in other purge and trap methods when this preservative is used.
ISSN:0013-936X
1520-5851
DOI:10.1021/es00031a004