The Science of Fiction Q&A

Long-term Blood Storage for L. Ebba Harder

Question: In my book 'The Blood Queen' the main character keeps the blood of people she's killed inside of hour glass shaped vials. I've written it so that none of the blood seems dried up; what conditons would the area where the blood is kept would make it not dry up. I'm sorry if this question dosen't make sense.

This question has layers to it. I like it. I needed to consult with a mad scientist friend for help. She was distressingly informative.

The answer depends a lot on how much effort your killer is willing to put into preparing her samples, and what technology she has available. From what I can tell, your book is set in feudal Europe, so that might get tricky.

Preventing it from drying out should be pretty easy. Blood is mostly water. Just keep it in an airtight container and it won't evaporate. It will continue to be more or less liquid forever. However, drying out isn't your only issue.

First off, blood isn't a stable solution; It's a mixture of several things. The primary components are plasma, platelets, leukocytes (white blood cells), and erythrocytes (red blood cells). Blood left sitting will start to separate quite quickly. The red blood cells will sink to the bottom and the plasma will float to the top. With some encouragement from a centrifuge you can get a clean layer between them of the platelets and white blood cells.

Also, blood clots. Platelets and red blood cells will start to clump together pretty quickly creating a lumpy sludge. If you've ever given blood, you'll have noticed that they blood bags are kept in constant motion to prevent clotting and separation. 

To add more problems, blood is alive. The cells are active living things with complex chemical processes. Those chemical processes will continue for a while, but the cells will eventually run out of the chemicals they need, die, and break apart. If any bacteria enter into your container, that could make that process more complicated and super gross. That is, your blood could easily rot. Any of this could change the color and texture of your blood. 

So at your most basic level of souvenir blood, if you just put it in a sealed mason jar on your shelf, by the end of a day it would look like lumpy, separated salad dressing. By the end of the week it would probably be a brown sludge that would stink horribly if opened.

Let's speculate about some solutions.

First, use sterile procedures. Bleach your container and never leave it open to the air. Better yet, autoclave it. Make sure there's nothing alive in there that will turn your lovely blood sample into gross beer. Also, get the cleanest blood you can. Don't just scoop up runoff from your victim. Draw it straight out of an artery. That will help with the rotting problem. If you have access to them, the vacutainers used by doctors for collecting blood samples are great for this.

Next, spin it. Run it through a centrifuge and siphon off just the red blood cells. That's the bloodiest looking part of the blood anyway. Without the platelets it won't clot so badly, and without the plasma it won't separate. You'll have a relatively stable and homogeneous red goop.

Third, dope it. There are a variety of stabilizers available medically that will help prevent coagulation and slow the breakdown of cells. Given that your setting appears to be pre-industrial, glycerol might be useful. It can be obtained and refined from some plants relatively easily. It can be used when freezing red blood cells for transfusion.

Fourth, fridge it. Keeping your blood cool is going to be critical. With the above steps you could probably keep your samples relatively stable and looking like liquid blood for months in a normal fridge. If you want it to be stable for years, you will need to freeze it. Ideally, very frozen (-80°C, -110°F). 

I hope that helps your horrible monster of a character with her hemophilic hobby.