Summary

Hf comes out with REE in Sr chemistry, with Tru spec, Hf and REE can be efficiently separated.

 

What to write down in the lab notebook

For wet chemistry:

1. Date for every step from crushing to dissolving and running samples on the TIMS.

2. Sample full name, abbreviations, location, weight processed, powder or glass, etc.

3. Table of procedure used on the samples from leaching to dissolution, make notes on notable differences between samples.

4. For a series of experiments with different beakers, write down what each set of beakers correspond to. For example beakers marked REE means after samples purified by Tru spec chemistry, or not.

5. The amount of water and acid used to make up chemical solutions.

6. The time it took for a certain chemistry to finish, for example how long did it take for 1 ml of solution to pass through the column? Flow rate is an important parameter in judging the functionality of the column chemistry. A time table is also good for you to keep track of time since we are confined by the bus schedule.

 

Preparing Pb columns for chemistry:

 

Resin used is AG1 X-8 100-200 mesh anion resin.

1) Turn the column over and fill it from the bottom with water.

2) Then turn the column right side up and fill the reservoir with water.  Before proceeding,

make sure that there are no bubbles in the stalk of the column.

3) If there are no bubbles, rejoice and fill the column with AG1-8X 100-200 mesh resin by

loading the resin into the reservoir with a pipette. At this point, your task is to fill the

column stalk with resin just up to the neck of the column trying not to leave excess resin

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lying in the reservoir.  If you succeed, you may commence with the separation of Pb from

your sample.

 

Pb chemistry procedures

4) Pick up all samples and blank in 1-1.5 ml 0.7 N HBr

5) Leave on hotplate for at least 2 hrs.  Overnight is better

6) Pipette off HBr and tranfer to 2 ml acid cleaned centrifuge tube. Be sure to get as much

liquid as possible.  Don’t worry if you pick up some solid in the pipet as well.  Just put it

all into the centrifuge tube

7) Centrifuge samples to drive all solid to the bottom of the centrifuge tube

8) Rinse Pb columns with 240 µl QD 3X

9) Rinse with one reservoir 6N HCl 3X

10) Rinse with 240 µl QD

11) Charge the resin with 240 µl 0.7 N HBr

12) Load sample onto the column – at this point you should begin collecting into the original

beaker ion which you dissolved your sample

13) Add 300 µl HBr 3X

14) Add 240 µl 2N HCl  - this is waste don’t collect it

15) Elute Pb – Add 0.5 ml 6N HCl 2X – collect in new beaker labeled “ sample # - Pb”

16) Dry down Pb

17) Pick up in 0.5 ml 0.7 N HBr

18) Rinse columns with 240 µl QD 3X

19) Rinse with 1 reservoir 6N HCl 2X

20) Rinse with 240 µl QD

21) Charge resin with 0.5 ml HBr

22) Load sample onto the column – this waste don’t collect

23) Add 300 µl 0.7 N HBr 3X – this is also waste

24) Add 240 µl 2N HCl – this is waste

25) Elute Pb - Add 0.5 ml 6N HCl 2X – collect in beaker labeled “sample # - Pb”

26) Dry down (add 2-3 drops of phosphoric acid before you dry down so that you can see the spot when it dries down)

 

 

Sr Spec Column Chemistry

Sr Spec columns

The Sr column is made of teflon shrink tubing.  Sr chemistry is performed using a 30 µl column volume.

The Sr columns are constructed from PTFE 4:1 H/S Clear Shrink Tubing, 3/8" diameter.

Sr chemistry is performed using a 30 µl column volume, with a ~0.5 ml reservoir volume.

To make Sr columns, use the 6 mm diameter mold, and place the 1mm diameter metal needle at

the end.  Cut 10 cm of tubing for use.  Place one end of the teflon tubing on the mold (the side

with the metal needle) and slide tubing up 14mm (to the end of the brown part of the mold).

Place the end of the mold without the tubing in a copper rod.  Preheat the oven to 500 degrees.

Stick the tubing into the back of the oven, but hold the door open and hold onto the rod.  Rotate

the rod around for even heating.  Rotate until tubing has shrunk to the mold.  Take rod out of the

oven, stick tubing and mold in deionized water, but do not bend column (because it is still soft

and this will destroy the column).  Twist tubing off the mold once it has cooled.  Make sure the

bottom of the reservoir is smooth.

Make a frit for the column using the frit punch and make 1mm diameter frits from a sheet of the

X-4900 1/16" Fine Sheet UHMW frit material.  Use the frit screwdriver tool to push the frit into

the column bottom.  Calibrate the column capacity by pippetting 30uL QD into the column and

then adjusting the frit until the water hits the mouth of the column.

Place columns in 6N HNO3 overnight.

The Sr Spec resin should just be enough to slightly protrude from the neck of the column into the

reservoir.

 

Rb-Sr column procedures

Resin cleaning, 1st time use, clean with QD, pipette out fines after settling. To reuse Sr resin, careful wash with H2SO4 is necessary. Procedure suggested by Pin et al. (1994) is to wash the resin 3 times with 7ml 0.1M H2SO4 3 times and 5ml 0.05M HNO3.

 

The procedure below allows for collection of REE in the case that Nd will be analyzed from the

same split.  If not, follow the procedure without collecting the REE cuts

1) Take Sr-REE cuts from Pb chemistry or the Sr cut from Tru-Spec chemistry and dry

down.

2) Pick sample up in about 0.5 ml 3N HNO3.

4) Wash 3x reservoir with QD to clean columns to remove any Sr.

5) Add 8 drops of 3N HNO3 to equilibrate the columns.

6) Load sample in 0.5-1.0 ml 3N HNO3.

7) Wash out other elements with 8 drops 3N HNO3.  Collect for REE and Rb.

8) Continue to wash out with 8 drops 3N HNO3.  Collect for REE and Rb.

9) Continue to wash out with 8 drops 3N HNO3.  Collect for REE and Rb

10) Collect Sr by eluting with 3 reservoirs of QD water.

After finishing the chemistry, discard the resin in the resin waste bottle and clean the columns by

placing them back in their container (which should contain a mixture of QD water and

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concentrated Nitric Acid) and sonicating them for 20.  Once the sonicating is done, place the

acid-water mixture in the appropriate acid waste container and store the columns in with QD and Nitric acid.

 

Tru-Spec for REE separation

Pin et al. (1997) discovered that 0.1 mol HCl- 0.1 mol HF mixture is effective in stripping off residual LREE, thus allowing reusing Tru-spec resin. However, used resin has high blank levels for U and Th.

 

Tru-Spec chemistry (Eichrom TRU resin - TR-B25-A) is used to separates the REE from Sr, Rb, and other cations.

 

Tru-Spec columns:

Columns have a volume of 100 ul. Pb columns may be used.

1) Dry Eichrom TRU Spec resin is placed in long beaker or centrifuge tube.

2) Wash with 1N HNO3, allow to fully settle.

3) Discard floating resin.

4) Wash with QD water, allowed to settle.

5) Discard floating resin.

6) Repeat water wash 5-6 times, until no resin floats.

7) Fill column with resin to neck, or slightly overfill. If underfilled, bubble/gap may form at resin top preventing flow

 

Tru-Spec procedure:

1) Wash column with 3 times each with 8 drops reservoirs of 1 N HCl to remove contaminant REE.

2) Dissolve sample in 0.5 ml of 1 N HNO3.

3) Prime column with 8 drops of 1 N HNO3 to charge the resin.

4) Centrifuge sample for 20 min on high.

5) Load sample on column with 0.5 ml of 1 N HNO3. Pipette avoiding solids

6) Collect Rb, Sr and other cations with 4 drops of 1 N HNO3.

7) Continue to collect Sr and other cations with 8 drops of 1 N HNO3.

8) Continue to collect Sr and other cations with 8 drops of 1 N HNO3.

9) Collect REE with 8 drops of 1 N HCl.

10) Continue to collect REE with 8 drops of 1 N HCl.

11) Dry Rb-Sr cut on hotplate set at 150 C.

12) Dry REE cut on hotplate at 100 C or less.

 

Tru-spec Chemistry for REE and U-Th separation

 

The purpose of this chemical step is to separate the LREE (light rare earth elements), U and Th from the major elements like Fe etc.  The LREE must go through a final chemistry step required to separate Nd and Sm from the other REE.  The U,Th cut must pass through pre-filter resin beads before analysis on the ICPMS.

  1. Prepare work surfaces.
    • Wipe down counter, shelf and column stands with de-ionized water
    • Cover counter and shelf with plastic wrap
    • Cover column stands with parafilm
  2. Prepare columns
    • Rinse columns from bottom and top with QD water
    • Fill with QD, making sure there are no air bubbles, and load with Tru-Spec resin
  3. Clean resin
    • 3 reservoirs QD H2O
    • 2 reservoirs 3 N HCl
    • 2 reservoirs 0.2 N HCl
    • 2 reservoirs 0.1 N HCl / 0.3 N HF
    • 2 reservoirs QD H2O
    • 2 reservoirs 1.6 N HNO3
  4. Load samples (re-dissolved in 1.6 N HNO3).  To re-dissolve add 200ml 1.6 N HNO3.  You may stir with pipetter tip (sample specific), sonicate, or gently heat to facilitate dissolution if necessary.  Centrifuge samples to make sure you are only adding liquid.
  5. Pass 2 or 3 reservoirs of 1.6 N HNO3 through columns letting each flow completely through before proceeding to next step. Save this cut in bullets labeled with sample name and “TRU-spec wash”.
  6. Elute the LREEs with 2 reservoirs of 3N HCl.  This cut will need to be dried down, and it will go through the Alpha Hiba chemistry procedure.
  7. Elute Th with 3 reservoirs of 0.2 N HCl.  This will need to go through pre-filter resin before it is dried down.
  8. Elute U with 3 reservoirs of 0.1 N HCl / 0.3 N HF.
  9. Clean up
    • Clean columns, squirting water through frit several times and rinsing reservoir. Return to container.
    • Remove parafilm and plastic wrap, wipe down counters with tap water

 

Eichrom Pre-filter Procedure

 

The purpose of this step is to remove any resin that might have made its way into your sample.  The Eichrom Pre-filter is made up of resin substrate (beads) without any of the organic compound that coats the other Eichrom resins.  When your samples are passed through the pre-filter beads, the organic resin compounds will stick to the beads.  The HClO4/HF step is to break down any remaining organic compounds that managed to pass through the columns.

 

  1. Prepare columns
    • Rinse columns from bottom and top with QD water
    • Fill columns with 1 ml Eichrom Pre-filter in QD or MQ water
  1. Clean resin
    • 2 QD washes
    • 2 0.1 N HCl / 0.3 N HF washes (500 ml each)
  1. Load samples
    • Place clean, labeled Teflon beakers under columns.
    • Load samples in 0.1 N HCl / 0.3 N HF. 
    • Add 500 ml 0.1 N HCl / 0.3 N HF to each bullet.  Load onto columns.
  1. Pass 2-3 reservoirs (500 ml each) of 0.1 N HCl / 0.3 N HF through columns.
  2. Dry down
    • Place beakers on hot plate to dry down
    • Turn heat up to 250ºC.  Add 100ml HClO4 and wait for it to fume. 
    • After the HClO4 has been fuming several minutes, add 50 ml HF. 
    • If necessary, repeat the HClO4 and HF additions.
    • Dry down, re-dissolve in 1%HNO3/ .1%HF and transfer back into bullets.
  1. Clean up
    • Dump used resin in proper waste container.
    • Clean columns with tap water and then QD water.

 

Procedure – LN Nd Column Chemistry

 

1) Dry down the REE clean cut to incipient dryness on a hotplate at ~100°C for ~2-3 hours.

2) Pipette 100 µL of 0.22 N HNO3 into the original beakers (there should be no bubbles on the bottom).

3) Sonicate the samples for ~20 minutes to dissolve the samples. 

4) Concurrently prepare LN Nd columns:

            a) Prepare column stand by rinsing with DI water and putting parafilm across the top of the stand.  Cut holes in parafilm for columns.

b) If setting up columns for the first time, fill column reservoir with QD water and loosen the bottom to get all of the air bubbles out of the column.  Plug the bottom of the column and pipette clean resin into the column.  Reduce the volume of resin in the column (once the resin has settled) to the top of the neck.

c) After the resin level is properly adjusted, tighten the bottom of the column and allow the QD water to pass through the column.

            d) Add one full reservoir of QD water.

5) If the samples have not dissolved completely, heat on hotplate at 100°C for ~30 minutes and then sonicate for ~20 minutes.  Note:  If samples are still not dissolved, dry down the samples, then add 2 µL of conc. (15.0 N) HNO3, sonicate, and then dilute with 140 µL of QD water.

6) To clean the resin: 

a) Add 0.5 mL of QD water.

b) Add 0.5 mL of 6 N HCl (3 times) to wash out the REE, especially the HREE.

c) Add 0.5 mL of QD water.

d) Add one full reservoir of 3 N HNO3.

e) Add 0.5 mL of QD water (2 times).

7) Condition the resin with 0.5 mL of 0.22 N HNO3.

8) While collecting in the original beakers, load the samples from the Teflon beakers into the appropriate columns.

9) Add 200 µL of 0.22 N HNO3 (2 times).  Note:  If the samples were dried down and diluted with 158 µL of QD water, then add 150 µL and then 200 µL of 0.22 N HNO3.

10) Add 2 mL of 0.22 N HNO3 to wash out the HREE.

11) Collecting in clean Teflon beakers, add 6 mL of 0.22 N HNO3 to elute Nd.

12) To clean the LN resin:

            a) Add 0.5 mL of QD water.

            b) Add 0.5 mL of 6 N HCl (3 times).

            c) Add 0.5 mL of QD water.

            d) Add one full reservoir of 3 N HNO3.

            e) Add 0.5 mL of QD water (2 times).

            f) Store columns with resin in QD water up to the neck of the column.

13) Dry samples down to a spot (incipient dryness).

14) Add 600 µL of 3% HNO3 and warm on a hotplate until completely dissolved.

15) Transfer to a clean 2 mL centrifuge tube with name clearly marked.

 

Hf chemistry

Hf chemistry (Merry’s recipe edited from Munker et al 2001 G3)

400ng minimum for two measurements, 200 ng for one measurement

 

Dissolution

Dissolve volcanic chips/powder in 3:1 HNO3:HF (6 and 2ml or depends on sample size)

Volcanic samples were dissolved from powder form with 3:1 concentrated HNO3:HF in Savilex beakers on lamina flow hotplate at 120°C overnight. For glass samples or chips, sonicate a few times till no residual can be observed in the beakers. The mixture is then opened up and evaporated to dryness. Afterwards it is redissolved and dried down with 2 times of 1ml concentrated HNO3 and 2 times of 1ml concentrated HCL.

 

If Pb, Sr and Nd are measured prior to Hf chemistry, remember to collect and combine the residual from all the chemistry to avoid losing Hf along the way.

 

Sample dissolution and chemistry preparation

  1. After the final HCL dry down step, take up samples in 5ml 6NHCL-0.06NHF (1L 6N HCL titrated + 2.18ml conc HF) and let equilibrate for 1 hour at 100°C before drying down again. (This step is to ensure conversion of Hf into fluoride form)
  2. Dry down samples and pick up in 5 ml 3N HCL.
  3. Transfer samples to centrifuge tubes and centrifuge for 10 min.
  4. Prepare 1M ascorbic acid (atomic weight 176g/mol, therefore 1.76g per 10ml). Sonicate the ascorbic acid for better dissolution. Prepare it right before chemistry.
  5. Centrifuge samples and add less than 0.5ml ascorbic acid to each centrifuge tube, agitate the sample solution and wait till the yellow color fade away, ~5min.

Column chemistry

  1. Fill columns with 2N HF (1liter solution needs 73ml HF 27.4N),
  2. Fill columns with 6N HCL,
  3. 5+5ml QD water rinse the side of the columns,
  4. Shake down drops,
  5. Precondition resin with 5ml 3N HCL,
  6. Load sample in 3N HCL and 0.1 ascorbic acid mixture
  7. Wash column twice with 10 ml 3N HCL (collect Lu if needed),
  8. Wash column 3~4 times with 10ml 6N HCL, depending on Yb content
  9. Rinse out HCL with 5ml+5ml QD, (shake down the drops)
  10. Wash column with 2~4 times 10ml 0.09NHcit-1wt%H2O2-0.45NHNO3 (15ml HNO3, 17ml H2O2, 45ml Hcit, 423ml QD water) until resin become white,
  11. Rinse column with 5+5ml QD (use plenty of water and shake down drops),
  12. Elute Hf with 12ml 6NHCL-0.2NHF (1L 6NHCL titrated + 7.27ml conc HF),
  13. Clean columns with 10ml 2N HF,
  14. Clean columns with 10ml QD water,
  15. Store columns in QD water.

Hf could be lost if HCL and HNO3 are both present in the resin. Also, Hcit is crucial in the nitric and H2O2 mixture in order to hold Hf in solution. In the original recipe, H2O2 is washed out by Hcit-HNO3 mixture without H2O2. But I find water wash to be sufficient.

 

HCit-H2O2 HNO3 solution: 400 ml water, 45ml HCit, 12ml HNO3, 17ml H2O2

 

2N HF, 27.5N HF 72.73ml + 927.2ml H2O