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>> The title of this presentation is the Use of PSPME
for Particle Sampling of Surfaces,
and that's what we're going to do
in the laboratory later this morning.
And part of the afternoon is we're going
to do several exercises on removing particles
from surfaces, which is primarily the way
that illicit substances are detected in,
in terms of the trace amounts.
So, the outline for this talk, we're going to talk
about the principles of contact sampling,
so far the PSPME applications we did
in the laboratory yesterday have been noncontact, okay?
So we've been sampling volatiles, either static
or dynamic, noncontact, and it's a lot of interest
in noncontact sampling, but primarily what's done currently
out in the field is contact sampling, so we,
we felt we needed to cover this.
And the other thing you heard from Patty earlier this,
this morning was that the substrate mattered quite a bit.
So, the force for lifting particles did not matter as much
as the composition, the texture of the substrate,
so there's been a lot of work,
people developing different materials
for removing particles, so now we have the ability
to do noncontact sampling with PSPME, and the possibility
for particle removal using contact sampling.
So we're going to do, we're going to use PSPME
in the laboratory for that function.
So, we're actually going to cover particle sampling
of surfaces, and then we're going to talk
about alternative sampling modalities besides static,
headspace, volatiles, and dynamic volatile sampling
and besides direct contact sampling on surfaces.
There are others and we'll cover a few of those,
and that will lead us into some of the exercises
that we'll cover later this morning,
immediately after this presentation.
So, let's, let's talk a little bit about the big picture,
so you take 30,000 foot view of detection.
Well, if you, if you can't collect it, you can't detect it,
so that's the first step.
And if you go back even further, if the samples not there,
then you can't collect it.
So, first the canine handler yesterday said, the odor has
to be available in order to, to be able to detect it.
If it's there, then the canine can detect it.
Well, same thing with particles, they have to be there,
number one, and we have to collect it
from wherever they are.
So, unlike volatiles, if you, if you have a scent source
in the corner of a room and you've got circulation going on,
well, the dog will eventually be exposed to some of those,
some of those compounds,
even though they're in minute quantities.
They'll, they'll get to the dog's nose.
That's different with particles.
You actually have to swab or swipe the arrow
where the particles are present.
So you have to collect them, and then you have
to expose them to the instrument.
So, we go from -- we would like to do is improve this front end,
which is collection, sampling,
because if we do a good job here,
we can enhance our ability to detect it.
We enhance the sensitivity,
we might even enhance the selectivity,
that means we don't want
to collect all those dust particles, they're not going
to lead to a detection, and may even overload the instrument
and interfere with the particles we want to detect.
So we want to collect in the right spots.
This is applicable to many different systems,
and if you look at the big picture for odors,
as well as for surfaces, we want to sample large volumes.
When you have a swab when you're just picking
up particles off the surface, it's very difficult to,
to do a whole table, or a whole bag, so you're going to have
to limit yourself to where you're going to collect,
but ideally you want to collect from high volumes,
that's the first step.
You're, you have to get the particles
into your system somehow.
Then what we do SPME is selective pre-concentration,
we're going to concentrate those odors, they're going
to be important for us to detect,
and particle swabbing is, is similar to that.
The instrumentation, IMS, provides a separation,
so we'll get peaks at different migration times,
that will separate the components
so that we can then detect them and the numbers
that you quote this morning, those times are indicative
of different compounds, Okay?
Then we have a detector that's very sensitive in IMS.
We have an exquisitely sensitive detector, less than a nanogram
of mass of material can be detected.
Now, then after you have a signal from the instrument,
you have to interpret that signal.
We could automate some of that and turn it into a green light,
red light situation, that's the analysis and the fusion,
and then that goes to the decision maker.
What happens next?
What's the policy when you have this green light,
red light, what does it mean?
Do you go back and do some more work?
Normally that's, that's the analytical process is a,
is a feedback loop.
Once you have a signal, go back and take more sample,
for example, do further investigation.
So that's, that's what the big picture.
But you need to get the sample,
otherwise it's not going to work.
So, very -- there's been a lot of work here -- let me just --
there's been a lot of work here in the amount of force
and the way that people remove samples from surfaces
and here's a little cartoon of having particles on surfaces,
you get the particles onto the substrate,
and Patty already said that the composition
of the substrate is an important role in how much,
how well you remove the particles, okay?
So we're talking about particles,
but we're also interested in these volatiles.
So, PSPME offers the opportunity to do both.
We have a mechanical removal of these particles
onto the surface, and Patty's already talked
about the particle sampling using surface wipes
of different composition, different material,
and she said the material is more significant
than the pressure.
Now, to assist us with training
and evaluating particle sampling systems,
NIST came up with a standard reference material
which is 2905.
2905 can be purchased from NIST,
it contains approximately .1% RDX and .01% TNT,
and also has some HMX composition,
and it simulates the composition of C4.
And these are micron size particles,
you cannot see the actual particles.
And they come in a little vial,
and I'll show you what it looks like, and they make them
so that it simulates explosive particles.
Explosive particles stick to the surfaces,
and that's an advantage, so if you have a bomb maker
that is handling the explosive device and then packaging it,
well, the explosives will get onto their fingers
and then transfer, secondary transfer from the fingers
onto the outside packaging.
We're going to simulate some of that and then try
to remove particles
after simulated handling of explosives.
So, the reason why this standard reference material was created,
2905, was to evaluate the performance of these TEDs.
These trace explosive detectors for both calibration, detection,
collection efficiency, and allowing people
to make purchasing decisions,
looking at a standard reference material doing the same thing
with the same material with a lot of different instruments,
and as well developing standard operating procedures
for collecting particles.
So, here's what it looks like.
Under, under regular fluorescent lighting, you take a picture,
this is what the little vial looks like,
you see it's a 2905, trace particles.
It's got .1% TNT.
If you eradiate it with blue light, so it's got a wavelength
of 420 to 470 nanometers, this blue light,
this is what it looks like if you take a picture,
on the blue light eradiation.
If you look at the container through amber lenses,
the orange lenses, then it looks like this.
And if you combine eradiation of blue light and looking at the,
looking at it through amber lenses,
which is what you're going to do,
you get what we call fluorescence.
So that combination of,
of adding the amber lense increases the contrast,
so you're able to see the fluorescence better.
So, if you eradiate it with blue light, we have some amber lenses
for each of you, we're going to see this fluorescence,
bright light being emitted, which is a different wavelength
than the light that's being used to eradiate the sample,
that's the definition of fluorescence.
'Kay? We have a different light.
This light happens to be yellow light, which is 589 nanometers,
so it's a sodium line, and that's what you see.
The eye perceives this particular wavelength really
well, so that's by design.
So what if we take a little drop of these particles and put it
out to a surface, it's going to look something like this.
These particles are microscopic, but you can see a bunch
of them agglomerated together.
If you disturb that drop with your finger, you're going
to distribute it on a surface.
We're going to try to visualize these in the laboratory.
Normally, you want to do this under, you know,
dark lighting conditions.
Now this is not something you do in the field
as a trace detector exercise.
We want to do this to kind of illustrate the steps
in capabilities for collecting particles.
So we're going to deposit some particles.
You can't see them, unless you use UV eradiation, amber light,
visualization, it's the only way to see them.
So we're going to ask you to collect the particles
with the PSPME swab with and without this aid
of visualization, see how you do, Okay?
So we have some exercises planned for you, and I'm going
to show a video right now on how ETDs are normally used
for collecting particles off of people's hands, for example.
This one doesn't have any volume, but you can see
that we're swabbing the surface across the hands, trying to get
as much surface area as possible with the swab,
and then you can't see the reading here,
but that's a negative, and this person's allowed to go through.
Very, very quick, fairly straightforward, and maybe some
of you have had that happen to you at a airport
or some other point of entry.
So, that's how they're trained to use this.
Now there are other ways to do particle sampling
that involves non -- no contact,
and I'll show you one way here is to produce an airflow,
high flow of air onto a surface, disturbing that surface,
and then sucking in any, any kind of particles that are,
that are coming off the surface.
So, this is called a vortex, a mini tornado that's created
onto the surface, then the particles are sucked
into the IMS, and then ionized and detected as normal
by the IMS, so this is, instead of just normal air samplings,
like what we're doing dynamic, a low volume,
this is fairly high volume of air,
plus they are disturbing the surface.
The reason for disturbing the surface is
to dislodge these sticky particles.
'Kay? And we no longer us these at airports,
but in the past we've had these noncontact particle sampling
alternatives where the air puffers,
the puffs of air dislodge the particles trapped on hair, body,
clothing, and we also have a video here.
Somebody goes into this device, the air puffers are on,
dislodging the particles and then the particles are sucked
up at very high volume onto an IMS.
[ Silence ]
>> So, there are alternatives to noncontact sampling.
We want to sample simultaneously volatiles and particles.
We want to get everything that's going to be relevant to us,
while at the same time, allowing any kind of interference,
any kind of material that's not related to illicit substances go
through so the ideal, the ideal material will be one
that collects the particles we want,
collects the volatiles we want, and let's, let's through
and does not collect the sample.
So we're not there yet.
This material does not exist, okay?
But there's an awful lot of work being devoted
to this ideal material so that then we can introduce it
into an instrument.
And what's the instrument of the future?
Probably mass spectrometry.
Probably mass spectrometry.
So we've got to get ready for great collection technique,
that's -- a lot of research is being spent there,
but also unambiguous identification of compounds
in the field, quickly, without the need for a GC separation
that takes, you know, 15 minutes.
We've got to do this in seconds.
So that's the future.
We think PSPME has a role in there somewhere.
So, we're going to apply PSPME for particle sampling.
We have other substrates that are provided
by the manufacturers of the IMS instruments right now
for particle sampling,
you'll have an opportunity to use those.
And then we're going to give you an exercise,
a series of exercises for both surface sampling
in the laboratory, and then we're going to take you
out to the warehouse where we have some vehicles
where you're going to be do some surface sampling of the vehicle.
And here's where we want you to focus, the steering wheel,
the door handle, and the gear shift.
Why? That's where the hands are, that's where the hands go.
So, if you've got secondary transfer
from somebody who's just handled some illicit material,
they're going to transfer that with their hands
to the door handle, the steering wheel, the gear shift.
And so that's where, that's where the focus should be.
There is a handout for this exercise before we get up
and move to the laboratory,
I want you to take a few minutes and, and read that,
and then we'll, we can proceed.
So, in summary, particle sampling has these advantages,
low cost, these materials are fairly inexpensive,
very easy, very fast.
They're designed to use with existing IMS systems,
and because of this secondary transfer, they're an indication
of relatively recent contact with material,
which is a big advantage and plays into your policies
as to what, what to do next when you do see a positive response.
Here's an interesting paper by Michael Verkouteren at NIST
who has been working for several years now
on removing particles using swipe sampling, and I recommend
that if you're interested
in measurement science and technology.
Are there any questions
about particle sampling before we move to the lab?
No? All right.