Buck scientific model 1018




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BUCK SCIENTIFIC



Model 1018



Combination Hydride/Cold Vapor Generator

for low-level determination of Arsenic, Selenium and Mercury

INSTALLATION AND OPERATION MANUAL

6/25/2001

NOTES:


  1. When using Swagelok tube fittings it is not necessary to use pipe tape or to tighten the fittings tighter than 1 to 1 1/4 turn beyond finger tight initially to make a gas-tight seal.

-=> NOTE: Do NOT over-tighten or the brass fittings will strip or damage the tubing!!

2. Check all gas connections for leaks using a dilute soapy water solution.

3. It will be easier to connect the silicone tubing to the glassware if you first wet the fittings on the glassware before attaching the tubing to them.

4. These following instructions assume that the user is familiar with the operation of the AA instrument.

5. Once the hydride system has been plumbed (gas connected) to the AA & Quartz T-Tube / Absorption Tube, it can be left connected permanently so that you can switch between normal AA flame operation and hydride/cold vapor operation at any time.


  1. You can use the standard Air/Acetylene Flame to create the Atomic Vapor in the T-Tube for the

Hydride reactions, to avoid running an Argon/Hydrogen flame instead of Air/Acetylene.

INSTALLATION:

1. Position the Hydride unit in such a way that you can keep the length of the tubing to the Quartz flow cell (for CV-Hg) or tee tube (for Hydride) as short as possible but not so close as to interfere with the operation of the instrument. An appropriate length is 12”-20” (see step-5).

2. Use the supplied diagram (see diagram #2 for details) to make the gas connections with the appropriate gases on the back of the unit using the ¼” Nylon tubing and brass Swagelok fittings.

3. Install the desired H-C Lamp into the instrument and allow 15-20 minutes for the lamp to warm up. Optimize the instrument according to the instruction manual for your instrument. For 210/211-VGP customers, recall element files [As-Hydride_193.7] or [Se-Hydride_196.0], set conditions as noted for best results and automatic peak integration:


ELEMENT WAVELENGTH (nm) SLIT (A) HCL CURRENT (mA)

Arsenic 193.7 7 Per file setup, or 5.0

Selenium 196.0 7 “ , or 6.0

Antimony 217.6 2 “ , or 5.0

Mercury 253.7 7 “ , or 3.0

4. Install the sheet metal tee tube holder on the burner head. Next cut a 3" length of the ¼” O.D. Silicone tubing and slip it on to the Quartz flow cell or tee tube inlet. Connect the other end of the tubing to the plastic moisture trap tube. Insert the flow cell or tee tube into its holder and align the so that the lamp image is centered through the tube for maximum energy.



  1. Use a convenient length of ¼” silicone tubing to connect the moisture trap tube to the reaction outlet line of the reaction flask. The moisture trap should be filled with one or two Kim-Wipe tissues to trap any liquid aerosol coming from the reaction flask. Do NOT use any chemical dryers!

  2. Once the connections are complete turn the flame on to a lean blue condition for HYDRIDE or just proceed to the reaction for COLD VAPOR (no Flame needed).


STOPPER ASSEMBLY / Gas Line Connections:

  1. Using the ¼” Silicone tubing, connect the required Gas OUTLETS from the 1018 unit to the Gas INLET tube on Stopper Assembly for the reaction flask (see diagram #3).

  2. Use a short, but convenient length of silicone tubing (12”-20”) from the Gas OUTLET tube of the Stopper Assembly to the end of the moisture trap tube.

  3. The outlet side of the moisture trap tube should be connected to the inlet of the on to the Quartz flow cell or tee tube.

  4. You are now ready to begin the analysis of the Sample.


Running the HYDRIDE Analysis (Arsenic or Selenium):

  1. Prepare FRESH reagents as noted below. ALWAYS keep track of the AGE of your solutions!!

REDUCING AGENT = Weigh 0.5 grams of Sodium Hydroxide into a 4oz. HDPE bottle.

Add ~25ml. DI Water and swirl to dissolve. Add 5 grams of fresh Sodium Borohydride into the

100ml. bottle, swirl gently (do not cap & shake!) to dissolve. Add DI Water to ~100ml. volume,

cap and keep cool. This 5% NaBH4 solution is stable for approx. 30 days.


ACIDIFICATION SOLUTION = Mix 200ml. H2O and 100ml. H2SO4; let cool then carefully

add 150ml. HCl; swirl to mix and dilute to ~500ml. final volume. After measuring the Sample into the Reaction Flask, add 25ml. of this acid mixture and bring the total volume to ~100ml. with DI Water. This Mixed Acid solution is usable for approx. 3 months, but will pick up contamination rapidly in many cases; so discard and make fresh as your Blank value increases.




  1. Connect the Purge and Hydrogen outlet lines from the front of the 1018 unit to the small plastic Tee, and then out of the Tee into the Bubbler line of the stopper assembly [see diagram #4 for enlarged details for stopper assembly].




  1. Adjust the gas flows to the following settings as a starting point, and raise or lower as needed to optimize the analysis [see diagram #1 for details of the flowmeter front panel assembly]:

Arsenic: Purge (Argon) = 0.3-0.4 Air = 0.1-0.2

Selenium: Purge (Argon) = 0.3-0.4 Air = 0.0-0.1

Antimony: Purge (Argon) = 0.2-0.3 Air = 0.0-0.1


-=> NOTE: These are SUGGESTED settings, but the optimum gas flows will depend on the volume of the sample, the concentration of the analyte and the composition of the sample matrix (background). Please adjust to provide the most accurate and reproducible peak shape.


  1. Pipet an aliquot (5-50 ml.) of a Standard solution into the reaction flask

Suggested calibrations for a decent 2nd. Order curve-fit = 5PPB, 50PPB and 250PPB.


  1. IF NEEDED; add ~0.25gms of a Secondary Reductant (Ascorbic Acid, Potassium Iodide or Hydroxylamine) to vessel and warm to 75-80oC if possible; or use hot water for the dilution of the sample. This step is only needed if the Sample results are not consistent. Add 25ml. of the Mixed Acid to flask and dilute to ~100-150ml. Start flow of Argon to bubbler.




  1. With the gases bubbling through the reaction flask, press the A/Z key to zero the energy on the 210/211-AA. Fill a syringe with 5ml. of the 5% Sodium Borohydride Reductant solution, insert into the septum tube of the stopper assembly, press the READ key and then slowly, but steadily, inject this reductant onto the surface of the solution in the flask, allowing the Reductant to react and agitate the mixture. For best results, Introduce the Reductant on TOP of the sample solution at ~1ml/sec to control the rate of reaction, and swirl the flask gently to insure complete mixing.




  1. After the 10-20 seconds needed to record the signal, allow the reading to get back or close to zero after the integration, turn off the Argon bubbler flow and remove the reaction flask. Rinse twice with 5% HCl, and wash down the bubbler tube with 5% HCl + 3% H2O2 in a wash bottle. Reassemble and continue with next solution.




  1. Start with a Reagent Blank run to insure the quality of the materials used, followed by the appropriate Standards for calibration; then take 8-12 integrated sample readings, afterwards checking a Standard.




  1. Use the Integrated Area of the Peak to establish a Calibration Curve, and interpolate Sample Peak Areas relative to this to get the appropriate concentrations using the 210/211 Calibration option.




  1. Be sure to rinse off the Bubbler assembly and the Reaction Flask well with DI Water and 2-5% Nitric Acid when finished to remove all traces of Reagents that may affect future analyses .



Running the COLD VAPOR Analysis (Mercury):

  1. Place a mercury H-C Lamp in holder and allow to warm up for ~15 minutes. For 210/211-VGP customers recall file [Hg-CV_253.7].




  1. Prepare FRESH reagents as noted below. ALWAYS keep track of the AGE of your solutions!!


REDUCING AGENT = Place 10 grams of FRESH Stannous Chloride (looks yellow, not chalky) into an empty, acid-cleaned 100 ml. plastic (HDPE) bottle, and 30 ml. concentrated HCl, ~1 gms Tin metal (foil, shot, mossy; NOT powder) and swirl/stir to dissolve the SnCl2. When dissolved (some solutions will be milky due to some SnO2 oxide present, this does not present a problem), add ~75 ml. good quality DI water. Swirl gently to mix. This 10% solution is stable and usable for ~30 days.
ACIDIFICATION SOLUTION = Mix 200ml. H2O and 100ml. H2SO4; let cool then carefully add 150ml. HCl; swirl to mix and dilute to ~500ml. final volume. After measuring the Sample into the Reaction Flask, add 25ml. of this acid mixture and bring the total volume to ~100ml. with DI Water. This Mixed Acid solution is usable for approx. 3 months, but will pick up contamination rapidly in many cases; so discard and make fresh as your Blank value increases.


  1. Connect the Purge outlet line from the front of the 1018 unit directly into the Bubbler line of the stopper assembly [see diagram #4 for enlarged details for stopper assembly].




  1. Adjust the gas flows to the following settings as a starting point, and raise or lower as needed to optimize the analysis [see diagram #1 for details of the flowmeter front panel assembly]:

Mercury: Purge (Argon) = 0.2-0.5 Air = [not used]
-=> NOTE: These are SUGGESTED settings, but the optimum gas flows will depend on the volume of the sample, the concentration of the analyte and the composition of the sample matrix (background). Please adjust to provide the most accurate and reproducible peak shape.


  1. Pipet an aliquot (5-50 ml.) of a Standard solution into the reaction flask.

Suggested calibrations for a decent 2nd. Order curve-fit = 1.0PPB, 10PPB and 25PPB.


  1. With the Air or Argon gas bubbling through the reaction flask, press the A/Z key to zero the energy on the 210/211-AA. Fill a syringe with 5ml. of the 10% Stannous Chloride Reductant solution, insert into the septum tube of the stopper assembly, press the READ key and then slowly, but steadily, inject reductant onto the surface of the solution, allowing the Reductant to react with the mixture. For best results, Introduce the Reductant on TOP of the sample solution at ~1ml/sec to control the rate of reaction, and swirl the flask gently to insure complete mixing.




  1. After the 10-20 seconds needed to record the signal, allow the reading to get back or close to zero after the integration, turn off the Argon bubbler flow and remove the reaction flask. Rinse twice with 5% HCl, and wash down the bubbler tube with 5% HCl + 3% H2O2 in a wash bottle. Reassemble and continue with next solution.



  1. Start with a Reagent Blank run to insure the quality of the materials used, followed by the appropriate Standards for calibration; then take 8-12 integrated sample readings, afterwards checking a Standard.




  1. Use the Integrated Area of the Peak to establish a Calibration Curve, and interpolate Sample Peak Areas relative to this to get the appropriate concentrations using the 210/211 Calibration option.




  1. Be sure to rinse off the Bubbler assembly and the Reaction Flask well with DI Water and 2-5% Nitric Acid when finished to remove all traces of Reagents that may affect future analyses.



MODEL 1018 PACKING LIST:
*1 Hydride Unit box

*1 Mercury flow cell holder

1 Tee tube holder

*1 250ml reaction vessel

*1 Adapter and bubbler assembly

*1 150mm flow cell

*1 Quartz Tee tube

*1 Moisture trap

*1 10', 1/4" O.D. black nycoil nylon tubing

*1 10', 1/4" O.D. red nycoil nylon tubing

*1 10', 1/4" O.D. silicon tubing

*6 1/4" nuts with ferrules



*10 10cc syringes






58 Fort Point Street  East Norwalk, CT 06855  Tel. 800-562-5566 / (203) 853-9444

Fax (203) 853-0569  E-mail: quality@bucksci.com Web Site: www.bucksci.com


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