I. Carbonate Removal
A. Place 50-100g of sediment into 1000ml beaker.
B. Label beaker with sample number.
C. Add approximately 200ml of 10%HCl.
D. Let react for at least 4 hours.
E. Decant off HCl, careful not to include sediment.
F. Transfer sediment to centrifuge tubes and centrifuge for 1-3 minutes; pour off a clear supernatant.
G. Wash sediment with distilled water, centrifuge and decant a clear supernatant. Soak in reagent grade H2O2 overnight to remove organics.
H. Repeat step G two more times. In final washing use dispersant.
II. Separation of 4-11 micron fraction.
A. Wash sample from centrifuge tubes through 63 micron mesh with dispersant, collecting the <63 micron fraction in a 1000ml beaker. Label beaker with sample number.
B. >63 micron fraction remaining on mesh should be dried at ca. 40 C and transferred to labeled vial and stored.
C. Make certain that the <63 micron fraction in the beaker is well dispersed. Ultrasonication may be necessary, or soak in dispersant for 24 hours.
D. Transfer <63 micron fraction from 1000ml beaker to 1000ml graduated cylinder; wash out beaker with dispersant.
E. Fill up graduated cylinder to 600ml with dispersant.
F. Place stopper on cylinder and turn over twice, to suspend all particle sizes.
G. Let stand for 30 minutes to separate the <11 micron fraction.
H. Decant the supernatant (<11 microns) into a clean 1000ml beaker, leaving the >11 micron fraction that has settled to the bottom of the cylinder. Wash >11 micron fraction from bottom of cylinder into beaker; dry at ca. 40C and store in labeled vial.
I. Repeat steps E, F, G, and H if necessary.
J. Transfer <11 micron solution to clean centrifuge tubes. Fill to the level of the black line on the tube.
K. Load tubes into centrifuge in an opposite, balanced configuration.
L. Centrifuge for 5 minutes and 30 seconds at 400RPM. Periodically check speed of centrifuge with calibration meter.
M. Carefully decant the supernatant (the clay fraction) from centrifuge tube into the sink, making certain not to disturb the sediment (4-11 micron fraction) collected at the bottom of the tube.
N. Rinse 4-11 micron fraction in tubes with methanol. Centrifuge for 1-3 minutes and then decant methanol. Centrifuge for 1-3 minutes and then decant off a clear supernatant. Repeat procedure three times.
III. Deposition of 4-11 micron fraction onto aluminum discs.
A. Wash with methanol the 4-11 micron fraction from centrifuge tubes into a “medicine” bottle.
B. Dilute mixture in medicine bottle with methanol until one’s finger is barely visible viewed through the bottle, when held up to a red light (Place finger on back of bottle, not in the bottle!).
C. Place aluminum discs in glass “shell” vials with a forceps, making certain that they are lying flat at the base of the vials. Also be sure that the discs are clean, not bent, or have burrs.
D. Add a small volume (0.1ml) of methanol to vials containing discs. Tap down discs to bottom of vials with a glass stirring rod, making certain that there is not any methanol or air bubbles between the disc and the vial.
E. Place clean plastic tip on 1 ml automatic pipettor.
F. Shake or sonicate medicine bottle containing 4-11 micron mixture to insure suspension of mixture.
G. Insert pipettor into medicine bottle and draw off 1 ml of 4-11 micron solution. Discharge aliquot into shell vial containing aluminum disc. Repeat this step for subsequent vials. Re-shake or re-sonicate every fifth draw.
H. Examine vials to make certain that discs are flat lying within vials. If not, tap down with glass rod.
I. Place vials with disc and mixture into ca. 40C oven overnight or until methanol has completely evaporated and sediment is plated onto discs.
J. Remove discs from vials by turning over and tapping vial sides. Place in storage box with forceps.