ELECTRONIC COPY OF THE ORIGINAL
Dear Dr. McManamon:
Given below is a copy of the report concerning your
Kennewick bone sample which I sent to you on 13 December, 1999. We have
labeled the sample AA34818. Under separate cover is also a report of
carbon-isotope measurements made on the sample.
Results of measurements to date on the Kennewick bone.
The following equipment was used to perform various stages of sample preparation: 1) a Mettler H54AR scale; 2) a drying oven; 3) a Dremel tool; 4) aluminum foil; 5) cutting blade; 6) acetone; 7) distilled water; 8) autoclave; 9) two-ended stainless steel spatula; 10) stainless steel tweezers; 11) chem wipes; 12) VWR 4x4 weighing paper; 13) agate mortar and pestle; 14) glass scintillation vials; 15) 50 ml test tubes with lids; 16) Erlenmeyer filtration flask with rubber stopper; 17) water bath; 18) exacto knife; 19) stainless steel wood carving tools.
The following were cleaned with acetone, rinsed with distilled water, and loaded into the drying oven for ~30 minutes: 1) aluminum foil; 2) spatula; 3) tweezers; 4) mortar and pestle; 5) exacto knife and new blade 6) wood carving tools.
After the tools had dried they were placed in a cleaned (acetone and DI-H2O rinsed) plastic tray with lid.
The following were cleaned in the autoclave: 1) spatula; 2) tweezers; 3) 50 ml test tube; 4) filtration flask.
After the implements were removed from the autoclave they were placed in a plastic tray with lid. After the glassware was removed it was sealed with aluminum foil and kept in zip lock bags until it was directly used.
Dr. Tim Jull cut the submitted sample, labeled AA34818, and with initial mass = 6.2 grams, into 4 individual pieces for processing. Dr. Jull wore non-powdered latex gloves and safety glasses and used a cleaned Dremel tool with diamond blade to slice the sample into 4 sub-samples. These were each placed into individual glass vials labeled A, B, C, and D. Small fragments and powder remaining from the sawing were also saved and placed into a glass vial labeled E. The masses of the samples were: Sample A, 1.29g; Sample B, 1.27g; Sample C, 1.34g; Sample D, 1.79g; Sample E, 0.5g.
Of these 4 sub-samples, Jeanette O'Malley selected sample "A" with Dr. Donahue and Mitzi DeMartino watching. Ms. O'Malley also selected a portion of material from Sample E for nitrogen analysis.
From sample "E ", Ms. O'Malley, wearing non-powdered latex gloves, picked out clean white flakes from scrap material on weighing paper, using cleaned tweezers. These flakes were weighed on the scale until a weight of 5.79mg of material was obtained. These flakes were then poured from the weighing paper into an agate mortar and crushed to fine powder. This powder was then placed on new weighing paper and had a total mass of 5.58mg. It was then poured into a clean glass vial with lid, labeled only with the AA number. This sample was then taken off site for nitrogen analysis at an independent, private lab, where it was determined that the sample contained 0.07% nitrogen. This is approximately a factor of ten below the nitrogen content of a bone for which we would expect to make a successful radiocarbon measurement.
From sample "A", Ms. O'Malley, wearing non-powdered latex gloves and dust mask, selected the largest fragment. This piece had one surface area that had been directly exposed to the environment. Thus the opposite portion of the fragment, from the interior of the bone shaft, was used for sampling. Using an exacto knife, fine flakes and powder were scraped from this interior surface. A final total of 0.63 grams was extracted.
The Pretreatment Procedure
These 0.63 grams were placed in a covered test tube with 20ml of 0.25N HCl. There was a strong reaction of effervescence observed. The sample was then sonicated for 20 minutes, in 0.25N HCl, at room temperature. The solution was decanted and fresh DI water added. This rinsing process was repeated until a neutral pH was achieved. The sample appeared to be mostly fluffy powder, with a little gel.
This hydrolyzed sample was then put in 20ml of 0.01N HCl in a 60 degree C waterbath overnight. The sample had little visible change the next day, so the sample was then placed in a 60 degree C sonicator bath for 2 hours. The result of this treatment was an opaque suspension.
The suspension was then filtered through fiberglass filter paper and the resulting solution was decanted into a 50ml beaker and frozen.This beaker, containing the frozen liquid, was then placed on a freeze-dry apparatus overnight. The resulting solid material was a white chalky granule residue that was a bit sticky, which is NOT characteristic of collagen and indicated that a poor result would be obtained from the radiocarbon measurement.
The sample was weighed, and had a mass of 21.8 milligrams. This material was then combusted in an oxygen atmosphere. The combusted sample yielded 0.42 milligrams of carbon, or a 1.9 % combustion yield. This low combustion yield (the combustion yield from collagen should be 35-40%) indicates that the product of the freeze-dry step contained considerable non-carbonaceous mineral material.
To summarize, the overall yield,
Y = carbon yield/initial bone mass = 0.42mg/0.63 grams = 0.07 percent.
The entire procedure was repeated with a second portion
of sample A. This portion had an initial mass of 0.38 grams, and the
carbon extracted from this sample gave a yield,
We can make a measurement of the radiocarbon content of either of these samples, but because of the very low yields, we are hesitant to do so. We are continuing to work with Sample B, and will keep you informed of our progress.
/s/ Douglas Donahue