larry@kitty.UUCP (Larry Lippman) (11/24/90)
In article <11159.273c4346@amherst.bitnet>, tjbryce@amherst.bitnet writes: > > A colleague at another library has asked what I think is a rather > > interesting question. Her institution has a manuscript that was > > ostensibly signed in blood in the 17th century and we are trying to > > think of a way to verify whether this is the case. Does anyone know > > of a test that would identify blood (or its components) that > > > > a) requires only microsamples? > > b) might work on a sample that is 300 years old? > > You might consider testing the wavelength at which the "blood" absorbs > light. Hemoglobin absorbs light at very specific frequencies, which would > be a useful fingerprint to tell the "blood" apart from ink. I believe > this is what was done in the book you refer to. I agree with the above advice. A microspectrophotometer is an instrument which couples a traditional scanning UV/VIS/NIR spectrophotometer to a microscope, and can facilitate both transmissive and reflective measurements. In a viewing mode the microscope eyepiece is used to position the instrument to the desired location on the sample, at which point a movable mirror is operated to connect the spectrophotometer in place of the eyepiece. Since one must use a more complex optical path through a microscope, the wavelength of a microspectrophotometer is limited to not much more than 1100 nm at the high end, and not much less than 300 nm at the low end. Zeiss makes a series of microscopes called "Zonax" which offer scanning spectrophotometric capabilities. A computer with color monitor is used to process and display various types of spectrophotometric data representations. My organization had a Zeiss Zonax system for almost two years as GFE; unfortunately, we had to return it at the conclusion of the contract. :-) This particular model was really slick, although its spectral range was limited to 400 to 700 nm. Newer models have greater spectral range. Zeiss Zonax systems are rather pricey, however; the model we had sold for around $ 60 K. Getting back to the specific issue of blood, hemoglobin has two very specific absorption bands at 540 and 578 nm, with a minimum absorption at 560 nm. Not only can such spectrophotometric data be used for determination of the presence of blood, but work by Kind, Patterson et al has developed methodology for the spectrophotometric *dating* of blood. In this case, a small amount of a bloodstain is dissolved in a dilute solution of ammonium hydroxide, and a complete spectrophotometric scan is made. Analysis of the spectrophotometric curve is used to arrive at an approximate age of the bloodstain. Further details on this process is in the literature. In the particular case of authenticating the document in question, I would suggest that a spectrophotometric determination be made along with at least one *other* test. The following are general suggestions for such an additional test (explicit test details are readily found in the literature and in textbooks on forensic science). Sampling for these tests can be relatively non-destructive through scraping of a small sample of suspected blood, or through the use of moistened filter paper to absorb a sample of the suspected blood. 1. Methylated benzidine test, which can detect blood in concentrations as low as 10 ppm. 2. Kastle-Meyer phenolphthalein test, which while less sensitive than the methylated benzidine test, is surprisingly immune to interference (except for a few fruit and vegetable materials). 3. Takayama hemochromogen test, which uses pyridine to cause the reduction of hemoglobin, resulting in characteristic salmon-pink crystals of pyridine hemoglobin observable under the microscope. Unfortunately, at this point, even if we achieve affirmative results from the above tests, we are faced with another problem: is the blood *human*? With blood stains that are less than a few months old, this is not usually a problem, and various procedures exist for such determinations. A common test uses what is called anti-human precipitating antiserum. There is, however, a common interference problem with such precipitin tests resulting from tannin in wood, paper and leather. This may or may not be a problem with the document in question. The use of anti-serum tagged with fluorescent dye, and the making of observations under a microscope with UV illumination may aid in precipitin testing. Another problem, though, is that anti-human serum will not differentiate between human and primate blood - however, I would probably not lose any sleep over this remote possibility. :-) There is a gel electrophoresis procedure whereby the albumin and non-gamma globulins of the samples are made to migrate toward the gamma globulins of the selected anti-sera (usually a selection of anti-human, anti-cow, anti-pig, anti-dog, etc.). Positive results are indicated by a precipitation line. Unfortunately, it is highly doubtful that 300-year old blood stains can be species-identified (let alone ABO-typed) by *any* method. Many antigens, such as M and N factors are destroyed within several weeks. Various isoenzymes and serum proteins (like Hp, AK, PGM, EAP, etc.) are also destroyed within a few months. I have, however, heard it claimed that if blood dries quickly and *remains* dry, the A and B antigens will remain stable almost indefinitely. The oldest antigen identification that I have heard of occurred in the U.K. after a period of ten years. This specimen actually contained a dried crust of blood, as opposed to a stain - so the greater quantity may have been a factor. While I feel confident that 300-year old blood can be reliably identified *as blood*, I am highly doubtful that any species identification can be made. I don't know if that is sufficient authentication for the document in question. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
mikew@sanjuan.wrcr.unr.edu (Mike Whitbeck) (11/27/90)
I recently read an article in the newspaper that some archaeologists were using serum antigens to ID very old blood with species identification. ______________________________. | mikew@wheeler.wrc.unr.edu | |__RENO___NEVADA_______________|