Organo tin compounds recentlyhavebecomeof environmental
interest because of their addition to several lists of endocrine
disrupters,
1
and the attributionof shellfishgrowth abnormalities
to the use of tributyl tin as amarine antifouling agent.Although
this interest primarilyhas focusedon the butyl tin series todate,
concernhas grown to includeother organo tin compounds such
as triphenyl tin, a croppesticide.However, theUSEnvironmen-
tal ProtectionAgency (EPA) has not adoptedmethods for the
preparation and analysis of tributyl tin and its breakdown
products of dibutyl tin andmonobutyl tin.This presents the
laboratorywith several challenges.Difficulties arise in the
preparationof samplematrices, ranging fromwater and seawater
to soil andbiota. The tin compounds also are known to exhibit
ligand exchange.When the compounds aremixed in solution, the
exchangewill cause instability,whichultimately accounts for the
short shelf-lifeofmulti-component standards. Finally, these
compounds are applied and found as chlorides.This leads to a
wide range inpolarities and creates difficulty ingas chromatog-
raphy (GC) separation—themost common techniqueused in the
environmental testing industry.
Because an “EPA accepted”methoddoes not exist for this
analysis,most laboratories have decided tonot accept requests or
SamplePreparationandAnalysis ofOrgano
TinCompounds
SampleExtractionMethods:
to subcontract the analysis toone of the few laboratories that
doperform this test. Laboratories often areunder the
impression that the analysiswill require complex techniques,
resulting in a considerable capital expenditure.However, this
does not have tobe the case. In fact, most laboratories could
perform this analysis using the equipment they alreadyhave.
Generally, laboratoriesmust achieve a detection limit of
50pg/L inwater. The additionof organo tin compounds to
the list of endocrine disruptersmay lower that limit to1or
2pg/L.This detection requirement entails either a large-
volume injection, additional concentrationof the extract, or
the use of amore sensitive detector. The steps presented in
this application take all of these factors into account,while
allowing adaptation for a commercial laboratory.
Thismethod is the result of a combinationofmethods
previously reported.
2,3,4
Itwas designed for usewith
equipment that exists inmost commercial environmental
laboratories. Themethod is applicable towater, soil, and
biota samples, and is compatiblewith themonoalkyl through
tetraalkyl tin compounds.The following is a step-by-step
extractionprocedure for thevariousmatrices.
Water Samples:
1.
Measure approx. 1000mL of sample into 2L-separatory
funnel, record volume.
2.
Adjust sample to less than pH 2 usingHCl.
3.
Add surrogate and/ormatrix spike compounds.
4.
Extract using 0.1% tropolone in hexane extraction solvent;
use three serial additions of solvent, 60mL each.
a.
Extraction solvent ismade by dissolving 4g tropolone
into 4L of hexane.
b.
Tributyl (trialkyl) tin can be extractedwithmethylene
chloride, but di andmono butyl tin require the addition of
a chelating agent.
5.
Collect extract intoKuderna-Danish (KD) concentrator,
passing through granular sodium sulfate, 10-60mesh.
6.
Rinsewith extraction solvent.
7.
Concentrate extract to approximately 5mL and transfer to
20mL vial.
Soil Samples:
1.
Measure approximately 30g of sample into a 400mL
beaker. Recordweight.
2.
Add 10mL of 1:1HCl:DIwater.
3.
Add surrogate and/ormatrix spike compounds.
4.
Extract using 0.1% tropolone in hexane extraction solvent
using sonication for 2minutes; use three serial additions
of extraction solvent, 60mL each.
a.
Extraction solvent ismade by dissolving 4g tropolone
into 4L bottle of hexane.
b.
Tributyl (trialkyl) tin can be extractedwithmethylene
chloride, but di andmono butyl tin require the addition
of a chelating agent.
5.
Collect extract intoKuderna-Danish (KD) concentrator,
passing through granular sodium sulfate drying funnel.
6.
Rinse funnel with extraction solvent.
7.
Concentrate extract to approximately 5mL and transfer to
20mL vial.
Biota Samples
Follow procedure for soils, except use a homogenizer (tissuemizer) for the extraction and, if necessary, reserve a sample for percent
lipids determination.
RestekCorporation
(800) 356-1688
Environmental
A
pplicationsnote
Lit. cat.# 59550
