Method 282.3 - The Determination
of Tributyltin Chloride in Marine
and Fresh Waters by Liquid-Solid
(LSE) and Gas Chromatography with
Electron-Capture Detection(GC/ECD)

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Method 282.3 The Determination of Tributyl tin Chloride in Marine and Fresh
  Waters by Liquid-Solid Extraction (LSE) and Gas Chromatography
             with Electron-Capture Detection (GC/ECD).
                                  Version 1.0
                                 October, 1989
                                  Otis Evans
                                  Betty Jacobs
                                  Arnold Cohen
                  Environmental  Monitoring Systems Laboratory
                      Office of Research and Development
                     U.S. Environmental Protection Agency
                            Cincinnati, Ohio 45268

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                                  DISCLAIMER

     This report has been reviewed by the Environmental  Monitoring Systems
Laboratory - Cincinnati,  U.S.  Environmental  Protection Agency,  and approved
for publication.  Mention of trade names  or  commercial products does not
constitute endorsement or recommendation  for use.
                                      11

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                                     INDEX

Section Number                 Subject

      1             Scope and Application
      2             Summary of Method
      3             Definitions
      4             Interferences
      5             Safety
      6             Apparatus and Equipment
      7             Reagents and Consumable Materials
      8             Sample Collection, Preservation and Handling
      9             Calibration and Standardization
     10             Quality Control
     11             Procedure
     12             Calculations
     13             Method Performance (Precision and Accuracy)
     14             References
                                       111

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                                    TABLES


 1.  Liquid-Solid Extraction and Gas Chromatography Experimental Conditions

 2.  Temperature Program

 3.  Accuracy and Precision Data for Eighteen Determinations of the Method
     Analyte at 0.025 nq/L (100 ml) with Liquid-Solid Extraction and GC/ECD.
     Using a C-18 Silica-Based Column (100 mg.)

 4.  Accuracy and Precision Data for Thirteen Determinations of the Method
     Analyte at 0.1 ng/L (100 mL) with Liquid-Solid Extraction.
     Using a C-18 Polymer-Based Column (Polystyrene)  (100 mg.)

 5.  Accuracy and Precision Data for Eight Determinations of the Method
     Analyte Using a 25 mm C-18 Teflon Enmeshed  (Filter)  Disk.
                                   APPENDICES


 1.  Liquid-Solid Extraction Procedure


                                   FIGURES

1.    GC/ECD Chromatograms from Commercial  C-18 Bonded Porous Silica
     Columns(a),(b) Extracts from Two  Pre-Conditioned Columns,  100 mg, 1 mL
     (different manufacturers).

2.    Schematic Diagram of Sample Filtration  Apparatus

3.    Photographs  of LSE Column Processor

     (a)    Vacuum Manifold Displaying the Arrangement for Column (Cartridge)
            and Disk Extractions

     (b)    Display of the Component  Parts for Disk Extractions Using Glass
            Filter Holder

4.    Photograph of Stainless Steel  Filter  Holder  for 25 mm Extraction (Filter)
     Disks
                                      IV

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5.    GC/ECD Chromatograms of LSE Solutions from C-18 Disks.
     (a)    Extract from Pre-conditioned Disk
     (b)    'Extract from Laboratory Reagent Blank
     (c)    Extract from Sea Water Containing 0.05 Aig/L Tributyltin Chloride

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1.   Scope and Application

     1.1    This method describes  liquid-solid  extraction  (LSE)  procedures
            (1,2) for a particular dissolved organotin  species  in marine and
            fresh waters followed  by  gas  chromatography with  electron-capture
            detection (GC/ECD)  (1,3-5).

                                               Chemical Abstract Services
           	Analvte	               Registry Number (CASRN1
           Tributyltin Chloride                          1461-22-9

     1.2.    The analytical  range has  been verified  to be linear  from 1 ng/L
            to 100 jxg/L of tributyltin chloride as  Sn.

     1.3.    Quantitative measurements can be obtained by generating an
            'external' calibration curve,  or preferably by
            preconcentrating/extracting the aqueous  standards in the same
            manner as the samples.

     1.4.    This method has been evaluated in a single  laboratory and a method
            detection limit (MDL)  has been determined.  Observed detection
            limits will vary with  sample  types  depending on the  nature of  the
            interferences in the sample matrix, the  particular extraction
            device and the  specific instrumentation  used.   For this work the
            MDL was determined  to  be  6.7  parts-per-trillion of analyte as
            tributyltin.

     1.5.    This method should  be  used by analysts  experienced  in LSE, and the
            use of GC and in the interpretation of  gas  chromatograms.

2.   Summary of Method

     2.1.    Samples containing  1-2% methanol (100 mL -  250 mL) adjusted to pH
            4.5 are passed  through one milliliter,  100  milligram octadecyl LSE
            columns or Teflon enmeshed extraction disks at a  rate of 5 mL/min.
            The extraction  devices are air dried and subsequently placed in a
            desiccator for  a least one hour, to ensure  that all  traces of
            water have been removed from  the adsorbent.  The  analyte is
            desorbed with acidified ethyl  acetate (HC1) into  a calibrated  GC
            glass sample vial.  The eluent is then  adjusted to a final volume
            of 0.5 mL with  ethyl acetate  (HC1).  The sample extract is
            refrigerated overnight (4°C)  in order to allow solution
            equilibration.   The tin analyte is  determined  by  capillary column
            GC using electron capture detection (ECO).

3.   Definitions

     3.1.    Field duplicate (FD1 and  FD2)'--Two  separate samples  collected  at
            the same time and placed  under identical circumstances and treated
            exactly the same throughout field and laboratory  procedures.
            Analyses of FD1 and FD2 give  a measure  of the  precision associated


                                      1

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       with sample collection, preservation and storage, as well as with
       laboratory procedures.

3.2.   Field reagent blank (FRB)--Reagent water placed in a sample
       container In the laboratory and treated as a sample in all
       respects, Including exposure to sampling site conditions, storage,
       preservation and all analytical procedures.  The purpose of the
       FRB is to determine if method analytes or other interferences are
       present in the field environment.

3.3.   Laboratory duplicates (LD1 and LD2)--Two sample aliquots taken in
       the analytical laboratory and analyzed separately with identical
       procedures.  Analyses of LD1 and LD2 give a measure of the
       precision associated with laboratory procedures, but not with
       sample collection, preservation, or storage procedures.

3.4.   Laboratory Fortified Blank (LFB)--An aliquot of reagent water to
       which known quantities of the method analytes are added in the
       laboratory.  The LFB is analyzed exactly like a sample, and its
       purpose is to determine whether the methodology is in control, and
       whether the laboratory is capable of making accurate and precise
       measurements at the required detection limit.

3.5.   Laboratory performance check solution (LPC)--A solution of method
       analytes used to evaluate the performance of the GC instrument
       system with respect to a defined set of method criteria.

3.6.   Laboratory reagent blank (LRB)--An aliquot of reagent water that
       is treated exactly as a sample.  It is exposed to all the
       glassware, liquid-solid extraction columns and disks, method
       solvents, and reagents that are used with other samples.  The
       purpose of the LRB is to determine if method analytes or other
       interferences are present in the laboratory environment, the
       reagents, or the apparatus.

3.7.   Laboratory fortified sample matrix (LFM)--An aliquot of an
       environmental sample to which known quantities of the method
       analytes are added in the laboratory.  The LFM is analyzed exactly
       like a sample, and its purpose is to determine whether the sample
       matrix contributes bias to the analytical results.  The background
       concentrations of the analytes in the sample matrix must be
       determined in a separate aliquot and the measured values in the
       LFM corrected for background concentrations.

3.8.   Primary dilution standard solution—A solution of a single analyte
       or several analytes prepared in the laboratory from stock standard
       solutions and diluted as needed to prepare calibration solutions
       and fortified blanks.
3.9.
Stock standard solution—A concentrated solution containing a
single certified standard that is a method analyte, or a
concentrated solution of a single analyte prepared in the

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            laboratory with  an assayed reference compound.   Stock standard
            solutions are  used to prepare primary dilution  standards.

     3.10.   Calibration  standard  (CAL)--A solution prepared  from  the  primary
            dilution standard solution and/or stock standard  solution.   The
            CAL  solutions  are used to calibrate the instrument  to response
            with respect to  analyte concentration.

     3.11.   Quality control  sample (QCS)--A sample matrix containing  method
            analytes or  a  solution of method analytes  in a  water  miscible
            solvent which  is used to fortify reagent water  or environmental
            samples.  The  QCS is  obtained from a source external  to  the
            laboratory,  and  is issued to check laboratory performance with
            externally prepared test materials.

     3.12.   Speciation--The  determination of specific  individual  physico-
            chemical forms of an  element.

     3.13.   Organometallic compounds--.Compounds in which the  carbon  atoms of
            organic groups are bound to metal atoms.

     3.14.   Liquid Solid Extraction (LSE)--A sample preparation technique
            based on the separation mechanisms of liquid chromatography (1C).
            The  solubility and functional group interactions  of sample,
            sorbent and  solvent are optimized to effect extraction and/or
            elution.  Also,  more  commonly known as solid-phase  extraction
            (SPE).

4.   Interferences

     4.1.   Interferences  in this method may be caused by contaminants in
            solvents, reagents, glassware, Teflon and  polycarbonate  bottles,
            liquid-solid extraction columns and disks  and other sample
            processing apparatus  that lead to artifacts or  elevated  baselines
            in gas chromatograms.  All reagents and apparatus must be
            routinely demonstrated to be free from interferences  under the
            conditions of  the analysis by running field and laboratory reagent
            blanks,  including extracts of preconditioned columns.

            4.1.1. Glassware, Teflon and polycarbonate bottles must be
                    scrupulously  cleaned.  All glassware, Teflon  and
                    polycarbonate bottles should be soaked  in 50% nitric acid
                    and  rinsed thoroughly with organic free deionized,
                   distilled water.

            4.1.2.  The  glassware, Teflon and polycarbonate bottles used for
                    organometal  solution preparation  and  storage  should be
                    sealed and  stored containing deionized, distilled water.

            4.1.3.  The  use  of  high  purity  reagents and  solvents  helps to
                    minimize interference problems.   Purification of solvents
                    by  distillation  in  all-glass  systems may be required.

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         4.1.3.1.  The extracting solvent, ethyl acetate, may
                   contain impurities, e.g., preservatives, etc.
                   and/or water which may give rise to extraneous
                   peaks and exacerbate the thermal sensitivity of
                   TBT chloride by enhancing its degradation in the
                   Injection port liner.  Solvent blanks should be
                   analyzed for each new bottle or solvent before
                   use.  An interference free solvent is a solvent
                   containing no peaks yielding data at 0.5 times
                   the MDL and at the retention times of the
                   analytes of interest.  Indirect daily checks on
                   the extracting solvent are obtained by
                   monitoring laboratory reagent blanks (3.6) and
                   periodically monitoring the solvent by obtaining
                   solvent blank chromatograms.  Whenever an
                   interference is noted in the laboratory reagent
                   blank, either impurity peaks or a depressed
                   analytical signal, the analyst should analyze
                   another solvent blank.  Generally, low level
                   interferences can be removed by solvent
                   redistillation.  The solvent container should be
                   kept tightly closed to minimize exposure to
                   moisture.  Additionally, to insure a "dry"
                   solvent the non-acidified ethyl acetate may be
                   passed through a sodium sulfate drying column,
                   preferably just prior to use.

4.1.4.   Liquid solid extraction columns and disks may contain
         interfering impurities (Figures la and Ib) which can be
         extracted by the solvent.  Additionally, sample water
         retained in the column interstices can give rise to a
         negative interference, i.e., the analyte signal decreases
         in magnitude over time (Section 4.1.3.1.).

         4.1.4.1   Ethyl acetate can extract compounds from the
                   polypropylene housing, polyethylene frit, and
                   the C-18 bonded porous silica of the liquid-
                   solid extraction cartridges.  Phthalates,
                   quinones, alkanes, cresols, etc. have been
                   identified in column extracts (b).  A
                   representative number of columns in a given
                   batch (lot) should be analyzed before use.  An
                   interference free column is a column containing
                   no peaks yielding data at 0.5 times the MDL at
                   the retention time of interest.  Variability  in
                   background between column lots and within a
                   particular column necessitates careful checking
                   of column performance via analyses of column
                   extracts.

                   Water must be completely removed from the
                   liquid-solid extraction  cartridges and disks.

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                             Water aids In the thermal decomposition of
                             trlbutyltin (TBT) resulting in decreased analyte
                             response.  The extraction devices should be air-
                             dried and placed in a desiccator for an extended
                             period of time (Table 3).

           4.1.5.    Syringes, and splitless injection port liners must be
                    cleaned carefully, re-silanized (if appropriate), and/or
                    replaced as needed.

                    4.1.5.1.  At the end of each day's analyses it is
                             recommended that a solvent blank be analyzed.
                             The solvent blank should effectively clean the
                             syringe and remove trace amounts of TBT
                             chloride.  TBT chloride has been found to be
                             incompatible with some solvents, e.g.,
                             methyltert-butyl ether (MTBE).  The syringes
                             tend to "freeze" and require frequent cleaning.

                    4.1.5.2.  Splitless injection port liners have a finite
                             life and should be checked frequently.  Aging of
                             the injection port liner is indicated by
                             diminished peak height and significant peak
                             broadening (7.8).  It is recommended that the
                             liner be changed or re-silanized every three
                             days.  However, useful liner life may depend on
                             a) frequency of analyses, b) concentration of
                             the organotin analyte, etc.

           4.1.6.    Interfering contamination (carry over) (see 9.3.1.) may
                    also  occur when a sample containing low concentrations of
                    analytes is analyzed immediately following a sample
                    containing relatively high concentrations of analytes.  A
                    preventive technique is between-sample rinsing of the
                    syringe.  After analysis of a sample containing high
                    concentrations of analytes, one or more laboratory reagent
                    blanks  should be analyzed.

           4.1.7.    Matrix  interferences may be caused by contaminants that
                    are present in the sample.  The extent of matrix
                    interference will vary considerably from source to source,
                    depending upon the sample type.
5.   Safety

     5.1.   The toxicity or  carcinogenicity of each reagent chemical used in
           this method has  not been precisely defined; each chemical should be
           treated as a potential health hazard, and exposure to these
           chemicals should be minimized.  Each laboratory is responsible for
           maintaining a  current awareness file of OSHA regulations regarding
           the safe handling of chemicals used in this method.  A reference
           file of material safety data should also be made available to all
           personnel involved in the chemical analysis.  Additional references

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      (9-11) to laboratory safety should be identified and made available
      for the information of the personnel using this method.

5.2.   Tributyltin (TBT) chloride is an extremely toxic substance (12,
      13).  Pure standard material (liquid) and stock standard solutions
      of this compound should be handled with suitable protection to
      skin, eyes, etc.

      5.2.1.   In the event of eye exposure - flush with copious amounts
               of water.

      5.2.2.   In the event of skin exposure - remove any contaminated
               clothing and flood skin with large volumes of water.

      5.2.3.   In the event of accidental ingestion - seek medical
               attention promptly.

5.3.   TBT chloride should be kept away from heat, sparks or open flames.
      It is a COMBUSTIBLE LIQUID.  In contact with acid or acid fumes,
      highly toxic chloride fumes can be emitted.

5.4.   TBT chloride spills should be covered with dry sand or dry
      vermiculite, mixed well and transferred to specially marked
      containers.

5.5.   Solution pH adjustments should be made in the hood.

5.6.   Disposal of waste (solvents, analyte(s), etc.) from the system
      should be according to local regulations.

Apparatus and Equipment  (All specifications are suggested.)

6.1.   Sample containers-- One liter polycarbonate, Teflon, or amber glass
      bottles fitted with Teflon-lined or polycarbonate lined screw caps.
      Bottles in which high purity solvents were received can be used as
      sample containers.  These bottles must be" thoroughly cleaned,
      sealed and stored containing deionized, distilled water prior to
      use.

6.2.   Balances

      6.2.1.   Analytical, capable of accurately weighing to the nearest
               0.1 mg.

      6.2.2.   General purpose laboratory, metric, suggest automatic
               calibration, full-range taring, readability to 0.01 g.

6.3.   pH meter—Laboratory, capable of measuring to at least 0.01  pH
      units.

6.4.  Filtration Apparatus.

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      6.4.1.    Macro filtration—To  filter  sample waters.   Use 250 ml
               glass reservoir (connects  to  1L  bottle  or  vacuum flask),
               funnel  base  and stopper, clamp,  SS holder,  screen and
               Teflon  gaskets  (Figure  2).   Recommend using 47  mm filter
               (Millipore Type HA, 0.45
      6.4.2.    Laboratory  or aspirator  vacuum  system.   Sufficient
               capacity to maintain  a slight vacuum  of  13  cm (5 in)  of
               mercury in  the vacuum flask.

6.5.  Volumetric flasks, various  sizes.

6.6.  Beakers, various sizes.

6.7.  Liquid-Solid Extraction Apparatus.

      6.7.1.    LSE column  processor-vacuum manifold  (stainless steel
               basin), vacuum hose  fitting, cover  with  luer fittings  and
               gasket), vacuum gauge controller, vacuum manifold luer
               plugs (Figure 3a)  or  equivalent.

               6.7.1.1. Glass microanalysis (filter) holder,  25 mm
                         (filter  size),  2.1 cmz-filtration  area,
                        graduated  volume- 15 mL, removable stainless-
                        steel mesh  support screen and  PTFE gasket.
                        Modified to fit column  processor  (Figure 3b) or
                        used in  an  arrangement  analogous  to Figure  2.

               6.7.1.2. 304 stainless  steel syringe (pressure filter)
                        holder,  25  mm  (Figure 4).  Should accommodate a
                         syringe  with luer fittings, also  accepts LSE
                        column/cartridges for easy  interfacing to
                        column processor vacuum manifold.   (Female  LUER-
                        LOK® -  inlet  and male  luer slip  outlet).
                        Should have a  stainless-steel  support screen,
                         PTFE gasket's and o-rings.  Can also be used in
                        arrangement analogous to  Figure 2 with a No. 18-
                        20 LUER-LOK®  syringe needle,  to  accommodate
                         laboratory/aspirator  vacuum system_or manual
                         sample loading via metal  LUER- LOK^ tipped  glass
                         syringe.

                         6.7.1.2.1.   Syringe-glass  with LUER-LOK® TIP,
                                     50 mL.

      6.7.2.   Extraction  Column  Reservoirs,  75  mL.

      6.7.3.   Extraction  Column  Adaptors,  1,3,6 mL.

6.8.  Digital Automatic Pipettes, variable volumes.

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           6.8.1.   Disposable pipette tips, sizes: 1-100 /il, 10-1000 M! -

     6.9.   Gas Chromatography System

           6.9.1.   The GC must be capable of temperature programming and
                    equipped with a linearized electron capture  detector,
                    fused silica capillary column, and splitless injector.   An
                    auto-sampler/injector is desirable.  An on-column injector
                    system may be an alternative to splitless injection
                    because tributyltin compounds are thermally sensitive and
                    may decompose in the injection port liner.  Additionally,
                    in the presence of residual water thermal decomposition is
                    enhanced.  NOTE:  Element selective/specific detection,
                    e.g., atomic absorption spectrometry, induction-coupled
                    plasma spectrometry, induction-coupled plasma/mass
                    spectrometry coupled with ion Chromatography (1C) or
                    liquid Chromatography (LC) may be acceptable alternatives
                    to electron-capture detection.

           6.9.2.   GC analytical column

                    6.9.2.1.  Fused silica capillary column.  Any capillary
                              column that provides adequate resolution,
                              capacity, accuracy, and precision can be used.
                              A 30 m X 0.32 mm i.d. column with a 0.25 pm
                              (bonded) film thickness is recommended. (J & W
                              DB-1 or equivalent).

           6.9.3.   GC syringes

                    6.9.3.1.  Micro liter syringe(s) - 10 nl, Hamilton 701N
                              series or equivalent.

7.    Reagents and Consumable Materials

     7.1.   Helium carrier gas and 5% methane in argon (make-up) gas, as
           contaminant free as possible.

     7.2.   Ethyl Acetate (CAS-141-78-6)--Spectrophotometry or Gas
           Chromatography grade.  It may be necessary to redistill the solvent
           if impurities are observed which co-elute (interfere) with the
           analyte of interest.

           7.2.1.   Acidified ethyl acetate: 15 /iL  of  20% HC1/50 ml  solvent.

     7.3.   Methanol (CAS-67-56-l)--High purity solvent.

     7.4.   Acetic acid, Glacial  (CAS 64-19-7)--Ultrex grade  for pH adjustment.

     7.5.   Ammonium hydroxide (CAS-1336-21-6)--Ultrex grade, 20%, for pH
           adjustment.


                                       8

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7.6.  Hydrochloric acid (CAS-7647-01-0)--Ultrex  grade,  for preparation of
      acidified ethyl  acetate:   15  Atl  of 20% HC1/50 ml solvent.

7.7.  Deionized, distilled  water (CAS-7732-18-5)— Prepared by passing
      distilled water  through mixed bed  cation and  anion  exchange resins.
      This water was adjusted to pH 4.5  (7.4  and 7.5).   In this method,
      this term will be used  interchangeably  with reagent water.  Water
      in which an interference  is not  observed at the method detection
      limit (MOL) of the compound of interest.
7.8.   Stock standard solution  (100  /ig/mL)— Tributyltin chloride as tin
      (Sn).  Tributyltin  chloride,  95  + %, liquid,  d.  1.20720 (CAS-1461-
      22-9).   An individual  solution of analyte  is  prepared by  dissolving
      56.8 uL in 250 ml of methanol  (7.3).  The  neat  liquid organometal
      is pipetted into a  250 ml  acid cleaned/pre-aged  volumetric flask
      and diluted to volume.   Transfer this solution  to a  250 ml Teflon
      bottle  and refrigerate (4°C)  in  the dark.  This  solution  can  be
      stored  and used for at least  six months.

7.9.   Primary dilution standard  solution  (10 jug/mL)— The stock  standard
      solution is diluted further with methanol  to  prepare a 10 Mg/mL
      solution.   Pipet 1  mL  into a  10  ml  volumetric flask  and dilute to
      volume  with methanol.

7.10.  Secondary  dilution  standard solution (1 /xg/mL)—Pipet 100 ^L of
      the primary dilution standard solution into a 10 ml  volumetric
      flask and  dilute to volume with  methanol.  Note:   Further dilutions
      as needed  should be made to prepare less concentrated standard
      solutions.  Minimize the generation of excess organotin waste by
      using small  volumes;  i.e., <10  mL.

7.11.  Calibration Solutions—A series  of  calibration  solutions  (working
      standards) are prepared  by pipetting the appropriate volume and
      concentration of standard  solution  and diluting  to 10 ml  with
      acidified  ethyl acetate  (7.6).   Prepared external  calibration
      solutions  range from 0 to  100 ppb of analyte.  These solutions
      should  be  refrigerated and stored in the dark until  used.  These
      solutions  should remain  tightly  closed to  minimize evaporation.
      HANDLE  WITH CARE.

7.12.  Extracted  external  standard solutions — Prepare the calibration
      standards  in water  (7.7) to be taken through  the liquid solid
      extraction (LSE) procedure.   Assume 100% extraction  efficiency and
      prepare calibration standards to cover the range from 1 ppb to 100
      ppb of  analyte.  For example,  a  100 mL sample solution containing
      •0.1 ng/mL  of analyte when  extracted, eluted,  and brought  to a final
      volume  of  0.5 mL in acidified ethyl acetate should yield  a signal
      equivalent to a 20  ng/mL solution.

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           NOTE:   It is recommended that the calibration standards be taken
           through the LSE procedure for quantitation of the analyte.  This
           corrects for losses in extraction and concentration.

     7.13. Liquid-solid extraction cartridges  (columns) and disks.

           7.13.1.  The columns are comprised  of polypropylene sample
                    reservoirs, and polyethylene fritted disks.  The columns
                    should not contain adipates, quinones, phenols,
                    phthalates, siloxanes, and cresols, etc.that can be
                    extracted from the plastic by the eluting solvent.  The
                    columns are prepacked with approximately 100 mg of silica
                    gel bonded phase (C-18) material.  The packing should have
                    a narrow size distribution and should not leach any
                    organic compounds into ethyl acetate.  One hundred
                    milliliters of water should pass through the column in
                    about 20 minutes with the  assistance of a slight vacuum.

           7.13.2.  Polymer-based extraction columns have the same
                    specifications as their silica based counterparts.  The
                    same restrictions also apply for the leaching/extraction
                    of certain organic plasticizers.  One hundred milliliters
                    of water should pass through the column in about 1\
                    hours.  This, however, is dependent on the degree of
                    cross-linking.

           7.13.3.  Teflon enmeshed filter disks feature chemically bonded
                    silica particles enmeshed  in an inert PTFE matrix to
                    create a mechanically stable sorbent disk.  The 25 mm disk
                    should pass 100 ml of sample in approximately 20 minutes
                    with the assistance of a slight vacuum.

8.   Sample Collection Preservation and Handling

     8.1.  Sample collection.  Samples should be collected in pre-aged
           polycarbonate or glass containers.  All samples should be collected
           in duplicate.  The containers should not be pre-rinsed with sample
           prior to collection.

           8.1.1.   When sampling from a water tap, open the tap and allow the
                    system to flush until the water temperature has
                    stabilized.  Adjust the flow to about 500 mL/min. and
                    collect duplicate samples  from the flowing stream.

           8.1.2.   When sampling from an open body of water (fresh or sea
                    water), fill the sample container with water from a
                    representative area.  Sampling equipment, including
                    automatic samplers, must be free of plastic tubing and
                    other components that may  leach interferents into the
                    water.  Automatic samples  that composite samples over time
                                      10

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                    should use refrigerated polycarbonate or glass  sample
                    containers (14-16).

     8.2.   Sample  preservation.  All samples should be iced or refrigerated  at
           4°C from the time of collection until  filtration.  The samples
           should  be filtered as soon as possible (Figure 2} upon return to
           the laboratory.

     8.3.   Holding time(s).  Samples should be analyzed immediately.   If
           immediate sample analysis is not possible, the pH of  the sample
           should  be adjusted to 4.5 (optimum pH for analyte extraction),
           with  subsequent refrigeration at 4°C.   The maximum sample  (aqueous)
           holding time should be 2 days.

           8.3.1.    Alternate.  It is recommended that sample filtration,  pH
                    adjustment and extraction be performed  upon  immediate
                    return to the laboratory.  Laboratory studies confirm  the
                    extraction, storage and preservation of tributyltin on
                    column for at least one month.  Note:   The implications
                    are that LSE of TBT is amenable to field sampling,
                    extraction (preconcentration), storage  and preservation.

     8.4.   Field Blanks

           8.4.1.    Processing of a field reagent blank (FRB) is recommended
                    along with each sample set, which is composed of the
                    samples collected from the same general sample  site at
                    approximately the same time.  At the laboratory,  fill  a
                    sample container with reagent water, seal and ship  to  the
                    sampling site along with the empty sample containers.
                    Return the FRB to the laboratory with filled sample
                    bottles.

                    NOTE:  The prevention of contamination  and losses are  of
                          paramount importance in TBT special ion and
                          analysis.  Potential sources of  contamination  in
                          the laboratory environment are:  dust, reagent
                          impurities and sample contact with the laboratory
                          apparatus (resulting in contamination by leaching
                          or  surface desorption).  Depletion via adsorption
                           (14-16) should also be strongly  considered.

9.   Calibration and Standardization

     9.1.   Demonstration  and documentation of acceptable initial calibration
           is required before  any samples are analyzed and  is required
           intermittently  throughout sample  analysis as  indicated by results
           of continuing  calibration checks.  After  initial calibration is
           successful, a  continuing calibration check is required at the
           beginning of each 8 hour period during which  analyses are
           performed.  Additional periodic calibration checks are good
           laboratory practice.

                                      11

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9.2.  Establish GC/ECD operating conditions equivalent to those indicated
      in Tables 1 and 2.  Calibrate the GC system using the external
      standard techniques or use the preferred technique, i.e., carry the
      aqueous standards through the LSE extraction procedure  (Appendix
      1), then calibrate with the  "extracted" standards.

9.3.  Prior to calibration, the GC system must be conditioned.  Column
      conditioning and injection port liner conditioning are  a
      prerequisite for stable and  reproducible analytical measurements.
      System conditioning should be done each day that analyses are to be
      performed.

      9.3.1.   The conditioning solution should be at least 100 ppb
               tributyltin  (TBT) as tin.  (Analysts may convert this
               value to reflect the intrinsic entity TBT if desired).
               Lower concentrations will prolong the length of time
               needed for conditioning (require more injections).
               Following conditioning, laboratory reagent blanks should
               be run to determine whether carry over will be a problem
               in subsequent sample analyses.

9.4.  External Standard Calibration Procedure

      9.4.1.   An external  standard is a known amount of a pure compound
               that is analyzed with the same procedures and conditions
               used to analyze samples containing that compound.  From
               measured detector responses to known amounts of the
               external standard, a concentration of that sample compound
               can be calculated from measured detector response to that
               compound in  a sample.

9.5.  Standards Carried Through the LSE Procedure

      9.5.1.   Standards carried through the LSE procedure provide an
               inherent correction for recoveries, because they are
               preconcentrated in the same manner as the samples.

               9.5.1.1.  The standards should be prepared in analyte free
                         solutions that resemble the aqueous matrix of
                         the sample as closely as possible.

               9.5.1.2.  The volume of the standard should be identical
                         to the volume of the sample(s) to be
                         extracted/concentrated.

               9.5.1.3.  The recoveries of the standards should bracket
                         the expected concentration range of the samples.
                         NOTE:  External standards may be used to check
                         the "extracted" standards' curve. (See 9.6).
                                 12

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               9.5.1.4.  The standards'  extract should be diluted to a
                         known, predetermined volume (Table 3).

               9.5.1.5.  From measured detector responses to known
                         amounts of the standards,  the concentration of a
                         sample compound can be calculated from its
                         measured detector response in the sample.

9.6.  At least three calibration standards are needed.  One should
      contain the analytes at a concentration near to, but greater than,
      the method detection limit for the compound;  the other two should
      bracket the concentration range expected in the samples, or define
      the working range of the detector.  For example, if the MDL is
      1.0 ng/L, and a sample is expected to contain approximately 5 ng/L.
      standards should be prepared at concentration of 2.0 ng/L, 5.0
      ng/L, and 10.0 ng/L.

9.7.  Preparation of Calibration Standards

      9.7.1.   To prepare an external calibration standard, add an
               appropriate volume of each secondary dilution standard to
               acidified ethyl acetate in a 10 mL volumetric flask and
               fill to the mark.  Mix by inverting  several times.

      9.7.2.   To prepare standards to be carried through the LSE
               procedure, add an appropriate volume of each secondary
               dilution standard to solutions that  closely mimic the
               sample matrix.

9.8.  Inject 2 ML of each calibration standard and tabulate peak heights
      or area response versus the concentration of  the standard.  The
      results are to be used to prepare  a calibration curve for each
      analyte by plotting the peak height or area versus the
      concentration.

9.9.  The working calibration curve must be verified on each working day
      by the measurement of one or more  calibration standards (and
      when/if the injection liner is changed between analyses).  If the
      response for the analyte varies from the response predicted by the
      calibration curve (9.8.) by more than + 10%,  the test must be
      repeated using a fresh calibration standard.   If the results still
      do not agree, i.e., the response is off by more than ± 10%,
      generate a new calibration curve  for each analyte.  (Assuming that
      the injection liner has become "activated," the analyst should
      change it before proceeding further).  Usually the liner can be
      used 3 to 4 days before its response begins to deteriorate.

9.10. Some possible remedial actions.

      9.10.1.  Check and adjust GC operating conditions.
                                 13

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           9.10.2   Clean and/or replace the splitless injection port liner;
                    silanize injection port liner for later use.

           9.10.3.  Flush the GC column with solvent according to
                    manufacturer's instructions.

           9.10.4.  Elevate the temperature of the oven and the detector to
                    "bake-off" any residual components.

           9.10.5.  Break off a short portion (1 meter) of the column from the
                    injector end; or replace GC column.  This action will
                    cause a change in retention times.

           9.10.6.  Check the mechanical action of the GC syringe daily.
                    Clean or replace as necessary.  On occasion decreasing
                    peak height may be caused by clogging of the syringe as
                    opposed to a deteriorating injection port liner.

10.   Quality Control

     10.1.  Each laboratory using this method is required to operate a quality
            control (QC) program.  The minimum requirements of this program
            consist of the following:  an initial  demonstration of laboratory
            capability and regular analyses of laboratory reagent blanks
            (including sol vent/eluent blanks), and laboratory QC samples.
            More specifically, GC/ECD procedural blanks from commercial  C-18
            bonded silica, and C-18 polymer cartridges and C-18/C-8 Teflon
            impregnated filter disks should be obtained when new lots of
            cartridges and/or disks are used.  NOTE:  The same lot number
            should be used throughout any study.  The laboratory must maintain
            records to document the quality of the data generated.

     10.2.  Initial demonstration of low system background and acceptable
            particle size and packing.  Before any samples are analyzed, or
            upon receiving a new supply of cartridges or disks from a
            supplier, it must be demonstrated that a laboratory reagent  blank
            (LRB) is reasonably free of contamination that would prevent the
            accurate determination of the analyte of interest.  The analyst
            should obtain chromatograms of column/disk extracts prior to and
            after the conditioning phase.  From this information the analyst
            can determine if further conditioning is warranted or if other
            action should be taken.  These experiments can be used to
            demonstrate that the particle size/packing of the LSE cartridge
            are acceptable, and if the flow rate is consistent through the LSE
            column or disk.  (Stable flow rates indicate uniform particle
            distribution and homogenous packing).   Cartridges and disks  may be
            placed in series to test for breakthrough.

            10.2.1. Liquid solid extraction (LSE)  cartridges can be a major
                    source of contamination (LSE disks appear to be a more
                    attractive alternative with fewer interferences,
                    consistent reproducibility from disk to disk, and from lot

                                      14

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               to  lot, etc.)-  Cartridges may contain phthalate esters,
               silicon compounds, plastlclzers and other contaminants
               that could Interfere with and prevent the accurate
               determination of the method analyte (b).  The compounds
               may be leached from the cartridges into acidified ethyl
               acetate and produce a background of varying magnitude.   If
               the background contamination prevents accurate and precise
               analyses, the condition must be corrected before
               proceeding with the analyses.  Figure la and Ib show
               unacceptable background contamination from poor quality
               commercial LSE cartridges. By contrast, Figures 5a, 5b,
               and 5c show the lower backgrounds obtainable from LSE
               disks.  (It may be necessary for the analyst to evaluate
               LSE cartridges from several sources before an acceptable
               supply is identified.)

       10.2.2.  Additional sources of background contamination are the
               solvents, reagents, and glassware.

       10.2.3.  One hundred milliliters of water should pass through the
               100 mg silica-based cartridge of 25 mm Teflon impregnated
               filter disk in about 25 minutes @ » 10 psi.  The
               extraction time should not vary significantly among LSE
               cartridges (columns) or disks.

10.3.   Initial  demonstration of laboratory accuracy and precision.
       Analyze  at  least seven replicates of a laboratory fortified blank
       solution (laboratory QC samples) containing the analyte (see
       regulations and maximum contaminant levels for guidance on
       approximately concentrations).

       10.3.1.  Prepare each replicate by adding an appropriate aliquot  of
               the primary/secondary dilution standard solution, or other
               certified quality control sample, to reagent water.
               Analyze each replicate according to the procedure
               described in Table 3 and in Section 11.

       10.3.2.  For each replicate, calculate the measured concentration
               of  analyte, and the mean accuracy (as mean percentage of
               true value) and precision  (as relative standard deviation,
               RSD) of the measurements.

       10.3.3.  For the analyte at 25 pg/L as tin, the mean accuracy,
               expressed as a percentage of the true value should be 92-
               108% and the RSD should be < 8%.

       10.3.4.  Analysts should develop and maintain a system of control
               charts to plot the precision and accuracy of analyte
               measurements over time.  For the analyte, the mean
               accuracy, expressed as a percentage of the true value
               should be   75-125% and the  RSD  should be  <  25%.


                                 15

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                    This quality control criteria is applicable to LSE
                    cartridges (Sections 7.13.1 and 10.2.1).

            10.3.5. It is recommended that the laboratory periodically
                    document and determine its detection limit capabilities
                    for the analyte of interest.

     10.4.  Laboratory Reagent Blanks (LRB).  Before processing any samples,
            the analyst must demonstrate that all glassware and reagent
            interferences are under control.  Each time a set of reagents are
            changed, new solvent bottle opened, or the injection port liner
            replaced or silanized, a LRB must be analyzed.  If within the
            retention time window of the analyte of interest the LRB produces
            a peak that would prevent the determination of the analyte,
            determine the source of the contamination and eliminate the
            interference before processing samples.

     10.5.  A single laboratory fortified blank, containing the tin analyte
            must be analyzed with each set of samples,  at a concentration as
            specified in 10.3.

     10.6.  A field reagent blank should be analyzed with each set of field
            samples.  Data/information from these analyses will be used to
            help define and determine contamination related to field sampling
            and transportation activities.

     10.7.  Each quarter, replicate laboratory fortified blanks must be
            analyzed to determine the precision of the laboratory
            measurements.  The data will be used in documenting data quality.

     10.8.  Each quarter, the laboratory must analyze a quality control sample
            obtained from an external source.  A quality control  sample should
            be analyzed each time a new set of standards are used.  The entire
            analytical procedure must be checked, if unacceptable accuracy
            data is obtained.

     10.9.  The laboratory must analyze an unknown performance evaluation
            sample (if available) at least once per year.  Results for each
            analyte must be within established acceptance limits.

     10.10. At various points in this document, quality control measures are
            incorporated to alert the analyst to potential problems.

11.   Procedure

     11.1.  Gas Chromatography

            11.1.1. Tables 1 and 2 present the recommended operating
                    conditions for splitless mode GC/ECD, i.e., conditioning,
                    calibration and sample analysis.

            11.1.2. Gas Chromatographic conditioning.

                                      16

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               11.1.2.1. The analyst must condition the analytical column
                        and the injection liner before starting any
                        tributyltin analyses.

               11.1.2.2. The recommended conditioning solution  is a 100
                        ng/mL solution of the tributyltin as tin.

               11.1.2.3. Make approximately four 2-^L injections of
                        tributyltin in acidified ethyl  acetate.

               11.1.2.4. Monitor the peak response—either area and/or
                        height.  When these parameters stabilize
                        analyses can begin.  NOTE:  If the injection
                        liner is replaced, conditioning must be
                        performed again.  Fewer injections are required
                        during this phase.  However, the analyst should
                        verify this in his/her laboratory.

11.2.   Liquid-Solid  Extraction

       11.2.1.  The liquid-solid extraction procedure is presented in
               Appendix 1.

       11.2.2.  Set up  the liquid-solid extraction column processor as
               shown in Figure 3.  Three options are shown, depending
               upon  the type of extraction device chosen.  NOTE:  This
               identical arrangement is not required, but it is
               convenient for handling small volumes of solution (< 200
               ml).

               11.2.2.1. Sample water is added to the reservoir and
                        drains from it through the LSE column or disks
                        into blunt stainless steel syringe needles
                        (LUER-LOK HUB) permanently mounted in the
                        manifold cover.  The sample passes into waste
                        collection containers placed in the stainless
                        steel basin (6.7.1.).

               11.2.2.2. A slight vacuum of « 10 mm Hg is used  during
                        the course of sample extraction.  The  sample
                        flow rate is about 5mL/min.  The pressure and
                        flow rate are critical.  Variations during
                        operations may result in poor precision.
                        Approximately 20 minutes is required to pass 100
                        ml of sample solution through the system. This
                        however, is extraction device dependent.

               11.2.2.3. Depending on the volume of water extracted, the
                        vacuum may have to be released in order to dump
                        the waste from the collection containers.  The


                                17

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                              vacuum control valve should be closed slowly
                              followed by gently lifting one of the vacuum
                              manifold luer plugs.  Releasing the vacuum too
                              quickly will cause splashing Inside the basin
                              and may result in solution getting into the
                              vacuum gauge.  The analyst should be aware of
                              the volume of solution that has been added to
                              the column processor to prevent solution
                              overflow inside the vacuum manifold basin.

                    11.2.2.4. During sample application the solution should
                              never drop below the top edge of the packing in
                              the LSE column.  Likewise, the LSE disk should
                              be immersed in solution at all times.

            11.2.3. Following sample application the extraction device  is air-
                    dried on the vacuum manifold for approximately 20 minutes,
                    then placed in a desiccator.

            11.2.4. The analyte is eluted with two 250 ML portions of
                    acidified ethyl acetate into a GC vial mounted inside the
                    vacuum manifold basin.

            11.2.5. The final volume of the eluate is adjusted to 0.5 mL with
                    a few drops of acidified ethyl acetate.

            11.2.6. The extract is refrigerated overnight (4°C)

     11.3.   GC-ECD

            11.3.1. Inject a 2 ML aliquot with the GC-ECD system under  the
                    conditions shown in Tables 1 and 2 and section 9.8.

12.   Calculations

     12.1.   Calculate analyte concentrations (in the sample) by utilizing the
            calibration curve generated from the relative responses of the
            standard (analyte) solution.
            (a)   The calibration curve is generated from the analyte response
                  produced from the "external standard" curves and/or
                  "extracted standard" curve, i.e., analyte standards taken
                  through the LSE procedure.

     12.2.   Data should be rounded to one decimal  place and reported in M9/L
            or pg/L.

     12.3.   The data should show which calibration technique is used.  The
            enhancement (or recovery) factor should be reported.
                                      18

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13.   Precision and Accuracy

     13.1.   In a single laboratory  the  method  detection limit (MDL) (17) was
            determined for the  tin  analyte.  Seven  aliquots of the fortified
            sample are measured and the results  used  to calculate the MDL at
            the 99% confidence  level.    The  MDL  is  calculated using the
            formula:

                MDL=t  (n-l.l-alpha =» 0.99)(S)

                where:
                      (n-l.l-alpha = 0.99)
                           Students t value  for  the 99%
                                 confidence level with  n-1 degrees
                                 of freedom,  where n =  number of
                                 replicates,  and S = standard
                                 deviation of replicate analyses.

The reported MDL can be lowered substantially by extracting a
larger volume of sample and/or concentrating  to a lower
known/constant volume.  NOTE:  The analyst should compensate for
the increased sample volume or smaller extract volume by lowering
the relative concentration of the analyte in  the reagent water.
Analyte detection at the regulatory level should be achievable.

     The MDL was difficult to determine for several reasons:
     (a) unstable non-reproducible backgrounds which may
     be attributed to low quality commercial  LSE cartridges
     (Section (10.2).  Please see figures la  and Ib.  (b)
     TBT is thermally unstable and therefore  quantitative
     measurements are difficult.   However, an MDL limit of
     6.7 parts-per-trillion of the analyte as tributyltin
     was determined.  For the MDL determination,  seven
     replicate measurements were  made  on solutions fortified
     with the tin analyte at 0.025
                                      19

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14.   References

      1.   Junk, G.A.,  and Richard,  J.G.,  "Solid Phase Extraction,  GC
          Separation and EC Detection of Tributyltin Chloride,"  Chemosphere,
          1987,16,61.

      2.   Matthias, C.L., Bellama,  J.M.,  and Brinckman,  F.E.,  "Determination
          of Tributyltin in Estuarine Water Using Bonded C-18  Silica  Solid
          Phase Extraction, Hydride Derivatization and GC-FPD,  "Proceedings.
          Oceans 87 Conference,  Marine Technology Society,  TEEE  Ocean
          Engineering  Society,  Halifax, Nova Scotia, Canada (1987).

      3.   Junk, G.A.,  and Richard J.J., "Organics in Water:  Solid Phase
          Extraction on a Small  Scale," Anal.  Chem., 1988,60,451.

     4.    Junk, G.A. and Richard, J.J., "Solid Phase Extraction  on a  Small
          Scale," Jo.  of Res.  of the National  Bureau of Standards, 1988,93,
          274.

      5.   Junk, G.A.,  and Richard,  J.J.,  "Solid Phase Versus Solvent
          Extraction of Pesticides  from Water," Mikrochim,  Acta  [Wien],  1986,
          1,387.

      6.   Junk, G.A.,  Avery, M.J.,  and Richard, J.J., "Interferences  in  Solid-
          Phase Extraction Using C-18 Bonded Porous Silica  Cartridges,"  Anal.
          Chem., 1988,60,1347.

      7.   Rodriguez-Vazquez, J.A.,  "Gas-Chromatographic Determination of
          Organomercury, (II)  Compounds," Talanta, 1978,25,299.

      8.   Silvis, P.H., "Optimizing Injection  into 0.53-mm  i.d.  Capillary
          Columns," in GC Troubleshooting, LC'GC,  1989,7,562.

      9.   "Carcinogens-Working  With Carcinogens", Department of  Health,
          Education and Welfare, Public Health Service,  Center  for Disease
          Control, National Institute for Occupational Safety  and  Health,
          Publication  No. 77-206, Aug. 1977.

     10.   "OSHA Safety and Health Standards, General Industry,"  29 CFR 1910,
          Occupational Safety and Health Administration, OSHA  2206,  (Revised,
          January, 1976).

     11.   "Safety in Academic Chemistry Laboratories", American  Chemical
          Society Publication,  Committee on Chemical Safety, 3rd Edition,
          1979.

     12.   Saxena, A.K., "Organotin  Compounds:  Toxicology and Biomedical
          Applications", Applied Organometallic Chemistry,  1987,1,139.

     13.   Muller, B.,  M.D., Renberg, L.,  Rippen, G. "Tributyltin in the
          Environment—Sources,  Fate and Determination an Assessment  of
          Present Status and Research Needs,"  Chemosphere,  1989,18,2015.

                                      20

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14.   Carter,  R.J.,  Turoczy,  N.J.,  and Bond, A.M.,  "Container Adsorption
     of Tributyltin (TBT)  Compounds: Implications  for  Environmental
     Analysis,"  Environ. Sci. Technol.,  1989,23,615.

15.   Maguire,  R.J., Carey, J.H., and Hale, E.J., "Degradation of the Tri-
     n-butyltin  Species  in Water."  J. Agric.  Food. Chem.,  1983,31,1060.

16.   Valkirs,  A.O., Seligman, P.P., Olson, G.J., Brinkman,  F.E.,
     Matthias, C.L. and  Bellana, J.M., "Di-and Tributyltin  species in
     Marine  and Estuarine Waters.  Inter-laboratory Comparison of Two
     Ultratrace  Analytical Methods  Employing Hydride Generation and
     Atomic Absorption or  Flame  Photometric Detection,"  August, 1987,
     112,17.

17.   Glaser,  J.A.,  Foerst, D.L., McKee,  G.O.,  Quave, S.A.,  and Budde,
     W.L.,  "Trace Analyses for Wastewaters," Environ.  Sci.  Technol,  1981,
     15,1426.
                                 21

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TABLE 1.  LIQUID-SOLID EXTRACTION
          AND GAS CHROMATOGRAPHY
          EXPERIMENTAL CONDITIONS
                22

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                                TIN SPECIATION
                                 (TRIBUTYLTIN)

                         Liquid-Solid  Extraction (LSE)
                           with  Gas  Chromatography -
                      Electron Capture Detection  (GC/ECD
Liquid-Solid Extraction:
Sample Volume
Sample pH
Extraction Devices:
     Columns/Disks

Eluting Solvent
100 mL (50, 200, 250 mL)
4.5

1 mL, 100 mg silica or polymer-based
(C-18); Teflon enmeshed extraction disks  (C-18)
Acidified ethyl acetate (HCl)-15/xL
of 20% HC1/50 mL of solvent
Gas Chromatography:
Column

Detector
Retention Time
Injection Volume
Injector
Carrier Gas
Make-up Gas
Linear Velocity
Fused Silica Capillary (DB-1, 30 mx 0.32  mm i.d.,
0.25 tun film)
Electron Capture
=14.6 min (TBT)
2 /iL
Splitless
Helium (3.86 mL-min'1)
Argon-Methane (30 mL-min"1)
20.8 cm/sec 0 160°C (measured isothermally)
            23

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               TABLE 2.   TEMPERATURE PROGRAM
          Initial Value ° 80°C
          Initial Time =» 1.00 Min

          Level  1

              Program Rate = 15.00°C/min.
              Final Value  = 160°C
              Final Time   = 10.00 Min

          Level  2

              Program Rate = 20.00°C/min
              Final Value  = 230°C
              Final Time   = 8.00 Min

Injector Temp =  200°C, Oven Temp. = 80°C to 230°C,
Detector Temp =  260°C, Splitless injection with 30s delay
                             24

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Table 3.   Accuracy and Precision  Data  for  Eighteen Determinations  of the
          Method Analyte at  0.025 ng/L (100 uL)  with  Liquid-Solid  Extraction
          and GC/ECO Using  a C-18 Silica-Based Column  100 mg.
Volume of Sample
 Conc'n after Extraction
	(uQ/L)	
                      Expected     Mean
                                Observed
                          Std.    Rel.     . Mean
                          Dev.     Std.    Method
                                   Dev.    Accuracy
       (ml)
            (M9/L)
                        (%)      (% True
                                Conc'n)
       200
       250
  10
  12.5
10.3
12.0
0.8
1.4
 7.7
11.7
102.9
 96.1
                                      25

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Table 4.  Accuracy and Precision Data for Thirteen Determinations of the
          Method Analyte at 0.1 /ig/L  (100 ml) with Liquid-Solid-Extraction.
          Using a C-18 Polymer-Based Column (Polystyrene-100 mg).
         Concentration After Extraction
(ua/L
Mean
Expected Observed
(M9/L) (Mg/L)

Std.
Dev.

(M9/L)

Rel.
Std.
Dev.
(*)

Mean
Method
Accuracy
(% True
Conc'n)
             20
18.8
1.01
5.4
93.8
          200 ml sample volume, standards taken through the LSE procedure.
                                      26

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Table 5.   Accuracy and Precision  Data for Eight Determinations of the Method
          Analyte Using a 25 mm C-18  Teflon  Enmeshed  Extraction (Filter) Disk.

          True Conc'n      Mean        Std.     Rel.       Mean Method
           (ng/L)        Observed     Dev.      Std.        Accuracy
                          Cone.                Dev.      (% True Conc'n)
                          (ng/L)       (ng/L)    (%)

            50             52.7        3.79     7.2             105.

          200 ml sample volume, standards taken through  the LSE procedure.
                                      27

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                APPENDIX  1.   LIQUID-SOLID EXTRACTION  PROCEDURE

(a)  Adjust a typical  100 mL  sample volume to pH 4.5, containing 1-2% (V/V)
     methanol.  (Add  1-2 mL of methanol/100 mL of sample).

(b)  Use 1 mL,  100 mg  silica  or  polymer-based (C-18)  column or Teflon enmeshed
     extraction disk  (C-18, C-8)

(c)  Add 3 column volumes* (3 mL) of non-acidified ethyl acetate (do not allow
     the column to become dry during additions of column conditioners and
     before the sample is added).  Note:  After pre-conditioning the Teflon
     enmeshed filter disk with ethyl acetate, maintain  vacuum to pull air
     through for 5 minutes (air-dry the disk).  The disk is not allowed to go
     dry with subsequent conditioning and sample application.

(d)  Add 4 column volumes* (4 mL) of methanol, 2 column volumes (2 mL)  of
     deionized water,  and 2 column volumes of pH 4.5  deionized water.

(e)  Attach sample reservoir  to  coluinn.  (If the LSE  disk is used the
     reservoir  is attached prior to step C).

(f)  Add sample solution and  adjust the flow rate to  approximately 5 mL/min.

(g)  Following sample  application, the LSE column and/or disk is air-dried
     (room air) (@ 10 mm Hg)  for at least 20 minutes.
(h)  Place the LSE column and/or disk in a desiccator for at least one hour.

Note:  Polymer-based LSE columns mustjremain in the desiccator overnight to
affect removal of all  residual water."

(i)  The analyte (TBT) is eluted with two 250 ML portions of ethyl acetate
     (HC1) into calibrated GC screw cap glass sample  vials. (Each portion of
     ethyl acetate (HC1) remains in contact with the  column for at least 30
     seconds).  Note:  TBT is eluted (under vacuum) from polymer-based LSE
     columns with three 250 /xL portions of ethyl acetate (HC1).

(j)  The final volume of eluate  (column extract) is adjusted to 0.5 mL with a
     few drops of ethyl acetate  (HC1).

(k)  The sample vial  is refrigerated overnight (4°C)  to allow the  extract
     solution to equilibrate.  NOTE:  We obtained higher recoveries and
     consistent reproducibility after refrigeration.

       Column volumes  are estimated/approximate.  Solutions  are dispensed
        with a squeeze bottle.

        It is essential that all residual water be removed from LSE columns
        and disks prior to elution of TBT with acidified ethyl acetate.   This
        is an absolute necessity when using splitless injection.
                                      28

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Figure 1.   GC/ECD Chromatograms from Commercial  C-18 Bonded
                        Porous Silica Columns:
           (a),(b)  Extracts from Two Pre-Conditioned Columns,
                 100 mg,  1 ml (Different Manufacturers)

           Computer Imaging by Steven Wai trip and  James  Dryer
                                      29

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O

CO
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LU
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                 14
                   28
              TIME  (min.)
                 30

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      FIGURE 2.  SCHEMATIC DIAGRAM OF SAMPLE FILTRATION APPARATUS
Stainless Steel
Screen and
Teflon Gasket
Rubber Stopper
To Vacuum
                                         250 ml Reservoir
                                             Clamp
                                             1 Liter
                                             Vacuum Flask
                             31

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Figure 3.   Photographs of LSE Column Processor

           (a)   Vacuum Manifold Displaying the arrangement for
                 Column (Cartridge) and Disk Extractions

           (b)   Display of the Component Parts for Disk Extractions
                 Using Glass Filter Holder

                Photos by James O'Oell
                            32

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(CO
cb)

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Figure 4.  Photograph of Stainless Steel Filter Holder for 25 mm
           Extraction (Filter) Disks

           Photo by James O'Oell
                            34

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'hoto by James O'Dell

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Figure 5.  GC/ECD Chromatograms of LSE Solutions from C-18 Disks

           (a)  Extract from Pre-conditioned Disk
           (b)  Extract from Laboratory Reagent Blank
           (c)  Extract from Seawater Containing 0.05 /ig/L
                Tributyltin Chloride

           Computer Imaging by Steven Wai trip and James Dryer
                                 36

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CO
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o
                     14
                 TIME  (min.)
28
                      37

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