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Daynotes
Journal
Week of 18 August 2008
Latest
Update: Saturday, 23 August 2008 11:52 -0500 |
08:22
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This weekend, I had an idea that could revolutionize home science and
science education, not to mention a lot of other endeavors.
What we need are inexpensive, and I mean really
inexpensive, laboratory instruments. Things like gas chromatographs,
high-performance liquid chromatographs, atomic-absorption
chromatographs, visible/UV/IR spectophotometers, mass spectrometers,
Fourier-transform infrared spectrometers, nuclear magnetic resonance
spectrometers, and so on.
I don't see any reason why basic
versions of most such instruments couldn't be mass-produced and sold
for the price of a decent microscope, or less. They wouldn't have to
have any smarts. PCs are ubiquitous, so the instruments would need only
USB ports to connect to a lab PC. The guts of most of these instruments
are surprisingly simple. Things like glass, plastic, and stainless
steel tubing, vacuum pumps, diffraction gratings and slits,
photodetectors and CCDs, lamps and LEDs, heating elements, and so on.
Here, for example, is a visible light spectrometer
that sells for $1,600. If it were mass-produced, there's no reason
it couldn't sell for $100 or less. Other types of spectrographs and
chromatographs could also be produced to sell for very low prices.
Sure, the resolution, precision, sensitivity, and range of such
inexpensive instruments would be lower than that of a $25,000
instrument, let alone a $250,000 instrument, but they'd be no less
useful for that.
So
who'd buy a $100 visible/UV/IR spectrometer or a $200 gas
chromatograph? I would, for a start, and so would a lot of hobbyists.
Not to mention middle-schools, high-schools, and even universities. For
that matter, a lot of corporate and government labs would probably buy
such instruments.
When it comes to instrumental analysis
equipment, we're still back in the dark ages. I'm old enough to
remember when the mainframe was the holy-of-holies, and we acolytes
stood attendance on it, waiting patiently in line with our card decks
for the few seconds of machine time we needed. Let me tell you,
compiling and debugging a program back in those days wasn't much fun.
And I remember in college and graduate school waiting for a
time slot on an IR or NMR instrument. I doubt things have changed much.
In many cases, the instrument is still the bottleneck.
People queue up for time on $250,000 instruments, or even $25,000 instruments. In
many labs, time on those instruments is booked for days, weeks, sometimes even
months in advance. That's one reason forensics work is so notoriously slow.
The staff aren't the bottleneck. They do what they can in a timely
manner. But they often have to wait for free time slots on expensive GC
or AA or MS instruments.
That's why wet-chemistry presumptive
tests are still so commonly used in forensics labs. A positive
presumptive test doesn't prove anything in a legal sense--it can't be
used for court testimony--but what it does do is let the forensics
scientists use the expensive equipment only for definitive confirmatory
tests that are admissable in court.
But what if inexpensive
versions of these expensive instruments were available? It'd be the
equivalent of putting a PC on everyone's desk. But instead, you'd put a
$200 GC or whatever on the lab bench of anyone who needed one
regularly, or even once a week. The lower sensitivity, resolution,
precision, and range of the inexpensive instrument would often suffice.
Better is often the enemy of good enough. If I'm testing for gunshot residue
or the presence of an accelerant, all I care about is whether it's
present or absent and, if present, some idea of the level. If necessary, I can schedule time on the expensive
hardware to get better data, but quite often the data provided by an
inexpensive instrument would be all that was necessary.
Public
schools, even those in poor areas, could afford at least some
such instruments, which'd allow them to expose students to modern
instrumental analysis techniques without busting the budget. College
and university science departments could have ten or twenty of each
instrument where they now have one or two, as could corporate and government
labs.
I think the only reason this hasn't happened already is
that no one with the ability to make it happen has seriously considered
doing it. Obviously, Perkin-Elmer and other instrument suppliers aren't
going to do it. They'd rightly assume that inexpensive analytical
instruments would cannabalize sales of their expensive instruments.
Frankly,
I'm surprised that the Chinese haven't done it, and I'm very surprised
that MAKE hasn't published articles about building your own instruments
from readily available parts. I'd do it myself, except I'm no
instrument maker and I'm pretty hopeless at building things. But I may
give it a try. If it works, perhaps I'll sell kits.
What I really want is a $100 tricorder. I wonder how long it'll be before I can buy one.
I
actually wrote this yesterday and sent the text to some friends for a
sanity check. Brian Jepson, my editor at O'Reilly, commented that MAKE
actually has run an article on building an inexpensive spectrometer.
As you might expect, that instrument has limited flexibility (for
example, it uses five LEDs to test at only five specific wavelengths),
but it shows what can be breadboarded with $100 worth of parts. And
something that can be assembled as a one-off with $100 worth of parts
can probably be manufactured in volume for $10 or $20.
07:45
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I know I'm strange, but some things bother me although other people
don't give them a second thought. Or even a first one. Minor errors in
TV programs, for example.
The other night Barbara and I watched
S1D1 of the Showtime series Weeds. The sixth and final episode on that
disc opens with the main character, played by Mary-Louise Parker,
having an erotic dream featuring her and her husband before his
untimely death. She awakens to find herself in bed, alone except
for a talking stuffed animal, realizes that she'd been having a
dream, and, after a moment's consideration, opens the drawer in her
nightstand, from which she extracts a vibrator.
She
turns on the vibrator and it twitches a couple of times before
dying. So she looks around for a source of replacement AA cells. She
spots the TV remote, opens it, pulls out the cells, and puts them
in the vibrator. The vibrator comes to life, buzzing nicely, but it
soon dies. Hmmm. So she continues looking around the room, until her
gaze falls on the smoke detector. Cut to the next scene, with the smoke
detector hanging open, batteryless, and her vibrator buzzing merrily
away.
The problem is, I've never seen a smoke detector that
uses anything but AC power or a 9V transistor battery. It's obvious in
the video that her smoke detector in fact uses a 9V battery. So, for
the next minute or so, I missed most of what was going on in the
program because I was still wondering exactly how she shoe-horned that
9V battery into that vibrator. And, in a vibrator designed to use 3V
(or perhaps 4.5V; it wasn't clear in the video), exactly what would
happen if you delivered 9V to it? That made me think of Tim the Toolman
Taylor and More Power. The scene with him clearing a clog in the
kitchen sink with a gasoline-powered roto-rooter popped into my head
and I started laughing.
Yes, sometimes it's not easy being me.
The good thing is that my very odd thought processes are seldom obvious
to others. If we'd been watching that scene with a group of friends,
everyone--except possibly Barbara and Mary, who know me too well--would
probably have assumed that I was laughing at her frustration when in
fact I was laughing at the thought of the gasoline-powered roto-rooter.
Perhaps it's just as well that few people know what I'm thinking.
Wednesday, 20 August 2008
08:38
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I finished up the chapter on Forensic Drug Testing yesterday, and got
started on the chapter on Forensic Toxicology. I found myself again
wishing for that $100 visual/IR/UV spectrometer and the $200 gas
chromatograph. Without them, I'll just have to do the best I can.
I'm
working right now on the lab session about determining salicylate
concentration by visual colorimetry. Deaths from aspirin (salicylate)
toxicity are relatively common (although less common than deaths
from acetaminophen, which is really nasty stuff). Most salicylate
poisonings are accidents or suicides, but forensic aspirin poisonings
(murder) are not unheard of.
Salicylate ions form an
intensely-colored violet complex with iron(III) ions. If I had that
$100 spectrometer, I'd plot absorption of various known concentrations
at a green wavelength, produce a linear graph, and match the absorption
of the unknown against that graph to determine its concentration. I
don't have the spectrometer, so I'll modify the procedure to substitute
comparisons via the Mark I human eyeball, which is surprisingly
accurate.
I have several other lab sessions planned for this
chapter, including the Marsh Test and presumptive tests for alkaloids
using the wonderfully-named Dragendorff Reagent. This is going to be a
fun chapter.
08:47
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I'm still working on the lab session for salicylate determination by
visual colorimetry. Trying to keep things affordable and accessible
often complicates matters. I'm constantly trying to strike a balance
between affordability and the amount of time and effort that readers
would have to expend to save a few bucks.
For example, I need a
standardized salicylate solution. The easy way to make up a
500 mg/dL solution would be to tell the reader to dissolve 0.584 grams
of sodium salicylate (14.36% of the gram molecular mass of sodium
salicylate is sodium, so you need 584 mg to get 500 mg of salicylate
ion) and make up the solution to 100.0 mL. But that presupposes the
reader has an accurate balance and a supply of sodium salicylate, which
I don't want to assume.
So, the obvious source of salicylate
ions is aspirin, acetylsalicylic acid, which is cheap, readily
available, and comes in conveniently pre-measured masses called
tablets. But dissolving aspirin doesn't yield salicylate ions directly.
We have to cleave the aspirin by reacting it with two equivalents of a
base like sodium carbonate, sodium bicarbonate, or sodium hydroxide,
which produces sodium salicylate in solution, along with only water and
carbon dioxide as byproducts. So the obvious answer seems to be to have
readers produce their own sodium salicylate from aspirin.
But
there's a problem with that. In order to make sure that all of the
aspirin reacts to form salicylate ions, we have to start with an excess
of sodium carbonate, bicarbonate, or hydroxide. Unfortunately, if we do
that, there'll be excess carbonate, bicarbonate, or hydroxide ions in
the salicylate solution. And we're going to react that solution with a
solution of iron(III) ions to produce the nice violet color. But
iron(III) ions react with those excess ions to produce insoluble
iron(III) carbonate or iron(III) hydroxide, which would skew our
results. So, we have to make sure there aren't any excess carbonate,
bicarbonate, or hydroxide ions present in the salicylate solution. That
means we'd need to neutralize those ions by, say, adding hydrochloric
acid dropwise until the solution tests as acid to litmus paper. And, of
course, that 500 mg aspirin tablet doesn't yield 500 mg of sodium
salicylate, so the actual concentration would need to be calculated and
taken into account.
On balance, in this case, I decided it was
better to assume that the reader has a balance and can order a small
bottle of sodium salicylate for a couple bucks. So that's the way I'll
write up the lab.
08:24
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So now Jerry Seinfeld is going to be featured in a new $300 million
series of ads for Microsoft Vista. Incredibly, the new catchphrase is
apparently "Vista is really better than you think", which should
probably make the Top Ten list of all-time pathetic advertising
slogans. That barely beat the second choice, "Vista. It's not
as bad as everyone thinks it is." I think they should have gone with
Charlie Demerjian's suggestion: "Vista. A chrome-plated turd."
Microsoft
is running scared. Vista is a dead product, and they know it. OS X is
starting to make inroads even in corporations, which for more than two
decades have been Microsoft's stronghold. And, horror of horrors,
corporations are actually starting to install Linux on desktop systems
in significant numbers.
Windows 7, far from Microsoft's
description of it as a major release, will actually be a dot release.
In effect, Windows 7 will simply be the next Vista service pack, but
it'll be a service pack that people have to pay good money for. The
future of Windows looks bleaker every day. Midori, Microsoft's real new
operating system, probably won't see the light of day until 2015, if
then.
Anyway, the LAMP stack and web-based apps are increasingly
making the choice of desktop OS immaterial. Office, which is even
more important than Windows in maintaining the Microsoft monopoly, is
under threat, with Microsoft's failed attempt to force the proprietary
OOXML format down all our throats.
Microsoft can't win for losing. They're right to be running scared.
09:45
- Barbara and I have been doing a Weeds
marathon. The three series three discs are due to arrive today from
Netflix, so we should be caught up by the time I return them on Monday,
at least until series four releases on DVD.
One of the striking
things about the series, at least to me, is the amount of science
involved in growing good marijuana. I mean, they're not just talking
about hydroponics and proper fertilizers and so on, but they're
creating hybrids and clones and doing genetic engineering. Although
they talk about the science only in passing, what they do talk about is
good science rather than the bogus stuff that usually passes for
science on TV.
I never had any interest in mind-altering drugs.
Heck, I was in high-school and college in the late 60's and early 70's,
the height of sex, drugs, and rock-and-roll, and I never got high.
To me, the idea of altering my mind was profoundly distasteful. I liked
my mind exactly as it was. I wasn't all that interested in
rock-and-roll, either.
But if I had been interested in drugs, I'd like to think that I would have approached the matter scientifically.
Barbara
is off to Wal*Mart this morning. Although we prefer not to shop there,
they're the only place locally that carries Alpo Snaps in large
boxes. Our dogs go through a lot of Alpo Snaps, so Barbara goes to
Wal*Mart occasionally and grabs as many boxes as they have on the
shelves, usually half a dozen or so.
Since she's going to
Wal*Mart anyway, she's going to do the grocery shopping while she's
there. I asked her to pick up some quinine water for me. I'm going to
use it in the lab session on quantitative analysis of alkaloids.
When I mentioned it to her, the subject of pronunciation of chemical
names came up. I called it kwih-neen' water. Barbara pronounces it
kweye'-nine water.
Same thing with other chemical names. I
pronounce "iodine" correctly as eye-oh-deen, analogously with fluorine,
chlorine, and bromine. Barbara (and just about everyone else)
pronounces it eye-oh-dyne. Too many vowels in the word, I guess. In
chemistry, the "ine" ending is prounced "een", as in amine, quinine,
and all of the other alkaloids. In fact, the original spelling of
benzene was benzine, a spelling that is still used in some parts of the
world.
Which reminds me of one sure test to determine if someone
is a chemist. Write down a group of words at least vaguely related to
science including "unionized" and ask him to read the list of
words. Everyone else will pronounce it you-yun-eyezd. The chemist will
pronounce it un-eye-un-eyezd.
11:52
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For the first time, I used one the chemicals in my lab for a household
purpose. Actually, it was intended for household use, so I didn't break
any laws or violate any regulations.
While Barbara was out
running errands, I decided to take a shower. I started the shower
running to warm it up. As I was standing at the sink brushing my teeth,
I noticed a strange odor. When I looked over to the shower stall, the
bottom of it was covered in standing water with a bunch of dirt and
crap floating in it.
I got dressed, and looked under the kitchen
sink for some Liquid-Plumr, which is actually pretty much laundry
bleach with a bit of extra sodium hydroxide (lye) and a surfactant. We
didn't have any of that, so I decided to use the nuclear option. I went
into my lab, poured out a fair amount of Roebec Crystal Drain Opener
(100% sodium hydroxide), and took it up to our bathroom. The label says
to use 2 tablespoons to unclog a drain, so I figured two or three (or
four or five) times that much for a shower drain.
When I popped
over the drain cover, a huge clump of hair came with it. Aha. At that
point, the drain seemed to be running, but I dumped the sodium
hydroxide down it anyway, along with a couple pints of water. The
instructions said to let it work for something like 20 minutes, but I
decided five or ten minutes was probably enough. That's long enough for
a saturated solution of sodium hydroxide to convert fats to soap and
make a good start on dissolving keratin (hair). I was concerned because
the trap is PVC and I didn't want to risk melting it. So, after five or
ten minutes, I turned on the cold tap and let it run for 15 minutes or
so. That should be long enough to flush out the trap completely and
make a good start on flushing out the main drain line.
The drain runs fine now, but I never did take my shower.
00:00
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Copyright
© 1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Robert
Bruce
Thompson. All
Rights Reserved.