• AN 9151

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    • Abstract: TePT = Tetrapropyltin (ISTD) 0.702. TPT = Tripropyltin (SURR) 0.461. TeBT = Tetrabutyltin. 0. ... TePT = Tetrapropyltin (ISTD) 1.000. TPT = Tripropyltin (SURR) 0.086. TeBT = Tetrabutyltin ...

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AN 9151
Analysis of Organotin Compounds in Tissues and Sediments Using
Accelerated Solvent Extraction and Large Volume Injection GC/FPD
Gregory G. Salata, Thomas J. McDonald, Bernie B. Bernard B&B Laboratories, 1902 Pinon Dr., College Station, TX 77845
Don Clay, Rollen Anderson, Flavio Bedini, Albino Sironi, Thermo Finnigan GC and GC/MS Division
Introduction where the concentration of organotin is compounds into a solvent followed by
suspected requires testing for these derivatization before analysis. This
The analysis of organotin compounds compounds. requires considerable expenditure of
such as: Tetrabutyltin, Tributyltin, labor and materials to carry out the
Dibutyltin, and Monobutyltin from One of the difficulties with any analytical extraction part of the method. The sol-
environmental and marine tissue samples method used with biological samples is vent must be concentrated to maintain
is an application of considerable interest. separating the components of interest good detection limits, and large
These compounds were used in anti- away from the biological interferences. quantities of solvent must be disposed
fouling coatings for marine use for many This report describes a methodology of or reclaimed and tested before reuse.
years. Now there is concern over their which yields excellent sensitivity while
impact on marine life in the bays and reducing the extraction and solvent In this method, an On-Column Large
harbors where the greatest concentration concentration workload. Volume Injection (OCLVI) technique
has accumulated. Construction or eliminates the concentration step, yet
remediation work in any of these sites Description still maintains good detection limits.
The instrumentation used for OCLVI
The analysis of these compounds is consisted of an Autosampler with
usually done by extracting the organotin injection parameters calculated and
controlled from a unique software
Solvent
Start Vapors
SVE
Injection
Open
Liquid Sample Flowing
into the Precolumn Figure 2A
Sample Injection
Analytical
column Desolvation Precolumn Carrier
Gas
Solvent
Vapors
Start
Injection SVE Volatiles
Stop
Injection
Open
Semivolatiles
Figure 2B
Liquid
Sample Solvent Evaporation
Layer
Carrier
Analytical
Desolvation Precolumn Gas
column
SVE
Closed Volatiles
SVE Figure 2C
Delay
Time
Semivolatiles Component Transfer
SVE Carrier
Analytical Gas
Closed
column Retained Liquid Sample
Figure 1: Components of an on-column
Large Volume Injection instrument.
AN 9151 Page 1 of 3
program, a patented Cold-on-Column
inlet, a desolvation precolumn, a tee 40
fitting, and a heated Solvent Vapor Exit Compound Name ng Sn
valve (Figure 1). In OCLVI, 50 to 200
on-column
35
microliters of extract are injected into a TePT = Tetrapropyltin (ISTD) 0.702
TPT = Tripropyltin (SURR) 0.461
desolvation precolumn (Figure 2A). The 30
TeBT = Tetrabutyltin 0.477
TBT = Tributyltin 0.443
injection conditions for both the DBT = Dibutyltin 0.420
25
Autosampler and the Gas Chromato- MBT = Monobutyltin 0.452
graph are under computer control to 20
allow precise evaporation of the solvent
without loss of the components of 15
interest (Figure 2B). After most of the
solvent has been vented, the remaining 10
liquid containing the volatile compounds
5
is allowed to proceed onto the analytical
column very much like a splitless
injection (Figure 2C). The OCLVI
0
technique can be used to achieve lower -5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
detection limits if the sample is Minutes
concentrated before injection. It can also Figure 3: Chromatogram of 50 µL injection of mid level standard.
be used to increase productivity with
standard detection limits by eliminating
the need for the time consuming
concentration step. In this case, the 50
Compound Name ng Sn
intent was to maximize productivity. on-column
40
TePT = Tetrapropyltin (ISTD) 1.000
TPT = Tripropyltin (SURR) 0.086
Experimental TeBT = Tetrabutyltin BDL
30 TBT = Tributyltin 0.122
DBT = Dibutyltin 0.046
MBT = Monobutyltin 0.007
Water, tissue, and sediment method
detection limit studies were performed 20
using traditional extraction methods.
The extraction solvent was 0.05% 10
Tropolone in Hexane. Water samples
were extracted in separatory funnels, 0
tissues were macerated with Sodium
Sulfate and a Tissuemizer, and sediments 0 2 4 6 8 10 12 14 16
Minutes
were mixed with Sodium Sulfate and
Figure 4: Chromatogram of 50 µL injection of sample extract from tissue.
extracted on a shaker table. The Hexane
extracts were concentrated to 10 mL,
after which 1 mL of Grignard reagent
(Pentylmagnesium Bromide) was added
Minimum Detection Limits for Butyltin Compounds in Various Samples
and the samples were gently shaken for
1 hour. The Pentylmagnesium Bromide
reacts with the Chloride of the mono, di, Water (1000 mL) Tissue (10 g wet) Sediment (15 g dry)
and tri Butyl Tin compounds substituting
the pentyl group and making them ng Sn/mL ng Sn/g wet ng Sn/g dry
chromatograph more easily. Adding
approximately 4 mL of concentrated
Monobutyltin 0.010 0.174 0.224
Hydrochloric Acid to the samples then
neutralized the Grignard reagent. The
Dibutyltin 0.012 0.539 0.292
upper Hexane layer was removed from
the sample using a pipet, and the acid Tributyltin 0.009 1.311 0.370
fraction was back extracted twice more
with Hexane. The extract was Tetrabutyltin 0.007 0.763 0.434
concentrated to 1 mL and passed through
a cleanup column packed with 16 grams
of 60/100 mesh Florisil. The final Table 1: Detection limits obtained from water, tissue and sediment samples
extract was concentrated to 10 mL,
spiked with Tetrapropyltin as an internal
standard, and 50 µL was then injected
into the GC. The chromatogram shows
AN 9151 Page 2 of 3
excellent peak shapes, indicating the
transfer into the analytical column is a
narrow band. A chromatogram of a
standard mix is shown in Figure 3.
There is minimal detector response to the
DI Brooks
“Providing Scientific Services on a Global Basis”
solvent, and peak shapes are narrow and
well defined. All the compounds of Information about TDI-Brooks
interest are well separated from the services and publications
solvent response and the other peaks. can be obtained from our Website:
Figure 4 shows a chromatogram of a www.tdi-bi.com
tissue sample extract. Note the clean
baseline with virtually no interfering
peaks in the region of the organotin Copies of this and other applications
compounds. The amount of Tin injected as well as technical information
on-column is approximately 0.1 ng TBT can be obtained from our website:
for this sample showing the sensitivity of
this method. The detection limit was www.thermofinnigan.com
0.01 ng TBT on-column calculated on
the lowest standard. This was based on a
50 microliter injection from a 10 mL
solvent volume. The detection limits
could have been lowered further by
either concentrating this solvent volume,
or extracting a larger sample. This
procedure was chosen to balance
laboratory productivity with sensitivity.
The combination of selective detection
of Tin compounds with the Flame
Photometric Detector and a relatively
simple sample cleanup procedure gives a
method which is robust and sensitive.
Conclusion
The use of the Large Volume Injection
technique allows higher productivity
while maintaining method sensitivity.
This is an important consideration for an
analytical laboratory utilizing methods
where sample preparation time is
lengthy. Solvent extraction and evapo-
ration is a labor intensive procedure
which is not easily automated. The
injection of large volumes of solvent
extracts can be carried out reproducibly
with proper instrumentation, as shown
here.
In this application, the use of OCLVI
allowed the extraction of smaller
samples, increasing sample throughput
for the laboratory. The extracts were less
concentrated than the traditional larger
sample sizes, but the ability to inject
large volumes maintained the detection
limits for the method at the same levels.
AN 9151 Page 3 of 3


Use: 0.7125