Category: science kits

09:06 – Thirty days and counting to the deadline on the forensics book. As always, we’ll make the deadline, but we’ll be using every minute available before then to get the book ready to roll.

I finished work on the glass and plastic analysis group of lab sessions yesterday, and I’m well into the group on revealing latent fingerprints. I am going to drop one of the lab sessions that covers developing latent prints with silver nitrate. When I wrote the original draft, silver nitrate was selling for $0.70 to $0.80 per gram. Right now, it’s more like $3.50 to $4.00 per gram, and who knows where it’ll be a year or two from now. Given the amount needed, that’s simply too expensive to include in a kit. It’d be one thing if it was really needed, but silver nitrate development of latent prints is similar enough to other development methods that it’s an easy decision to leave it out.

13:30 – I just ordered 100 grams of ninhydrin crystals for $70. That’s enough ninhydrin to make up 15 to 20 liters of working solution, which is probably a year’s supply for a typical forensics lab, and enough for 150 or more forensics kits.

07:35 – We’d be ready to build more chemistry kits, except for one thing. Each kit includes a 30 mL bottle of 0.1 M IKI (iodine/potassium iodide) solution. I’m now waiting for iodine to dissolve.

Iodine is very poorly soluble in water, something like 300 mg/L at room temperature. That changes if iodide ions are present in the water. Molecular iodine–a neutral molecule made up of two iodine atoms–reacts with an iodide ion to form a triodide ion, which is extremely soluble in water. IKI solutions contain iodine and iodide ions in water, with the iodide ions typically in at least small excess. The solution we supply is 0.1 molar with respect to both iodine and iodide, which means there’s no excess iodide. That solution is made up of 12.69 grams of iodine and 16.60 grams of potassium iodide per liter.

The problem is, iodine is tightly controlled by the DEA because it’s used by illegal methamphetamine labs. I do have some on hand, but I try to reserve it for situations where I really need elemental iodine. Accordingly, I’ve been buying an IKI solution from one of my vendors that contains 22 grams of iodine and 40 grams of potassium iodide per liter, then adding iodine crystals to bring it up to equimolar, and then diluting to give an IKI solution that’s 1.26% iodine and 1.66% potassium iodide. But iodine dissolves very, very slowly in that 2.2%/4% solution. By “slowly” I mean a week or two with frequent swirling. So, right now, there’s a one-liter volumetric flask sitting on my lab bench with a few grams of undissolved iodine sitting in the bottom. Fortunately, I already had some of the IKI solution made up, but not enough for 30 kits. So I’ll probably bottle that and make up how ever many kits that IKI solution will cover.

The really annoying thing is that although iodine dissolves very slowly in a dilute KI solution, it dissolves quickly in a concentrated KI solution. If I were making up this solution from scratch, I’d dissolve 16.60 grams of potassium iodide in about 20 mL of distilled water and add 12.69 grams of crystal iodine. The iodine would go into solution within a few minutes.

In fact, I think that’s what I’ll do. The stuff in the volumetric flask, when it finally dissolves, can be used for the next batch of kits. It’s not like anything is going to be growing in a 1.26% solution of iodine. And as to my supply of crystal iodine, I may just do what someone suggested a week or so ago. Order it on eBay. I see that there are several vendors offering ACS Reagent grade iodine crystals in 250 g or 500 g bottles for reasonable prices.

08:22 – Barbara got quite a bit done on the chemistry kits yesterday. Today we should finish up the rest of the items we need to assemble 30 more of those. While Barbara works on those, I’ll continue work on the forensic science book.

07:58 – Inventory of the chemistry kits is getting critically low, so while I work on the forensics book this weekend Barbara will be working on chemistry kits. We’ll put together another couple dozen of those. I also need to create and issue purchase orders for more components for the chemistry and biology kits, not to mention some initial orders for the forensic science kits.

09:06 – I’m getting emails from a lot of people who’ve received their copies of the biology book. Kit orders are also coming in, and I’m getting a bit concerned. It’s only 9:00 a.m. and I’ve already received two kit orders so far this morning, with the book barely available. We built and boxed 30 biology kits as our initial stock, and have the components on-hand to build 30 more. Once those run out, it’ll take at least two weeks to get the components in and make up and bottle the chemicals needed to build a new batch. Meanwhile, stock on the chemistry kits is getting dangerously low. And I have a 31 May deadline on the re-write of the forensics book. Things are going to be busy around here.

07:55 – Work on the forensics book continues. I think we’re going to end up having two kits for this book, one kit that includes the special equipment and chemicals to do all of the lab sessions in that book, and a second kit that includes a subset, with the materials for doing only a selected group of the lab sessions.

Speaking of science kits, we shipped two chemistry kits yesterday, which took our inventory down below a half dozen. We’ll assemble another batch of those this weekend.

16:06 – Sad news. Levon Helm has died. Although younger people may not recognize his name, to my generation he was well-known as the drummer of The Band, and the voice of many classic tracks like The Night They Drove Old Dixie Down.