Pyrolysis PLOT Cryoadsorption

or,

Headspace Sampling on Steroids

Thomas J. Bruno

Physical and Chemical Properties Division

National Institute of Standards and Technology

Boulder, CO
The vapor that develops above a 

condensed phase:

Food quality 

analysis

Environmental 

sample analysis

Natural 

products

IMPORTANT 

FOR:
Condensed phase and vapor phase 

composition will be different: 

Thermodynamics ensures 

that there will be a 

difference

VLE is “predictable”*, VSE is 

less predictable 

* If you have an equation of state
So, why bother with this?

• Sometimes you need to know what is in the vapor 

phase

– The vapor is all you get

– The vapor is the best way to analyze sample
The Challenge:

• The primary difficulty has always been to obtain 

enough solute (or analyte)

• Other difficulties:

• Calibration

• Matrix overload

• Stability, etc.
The Challenge:

• The primary difficulty has always been to obtain 

enough solute (or analyte)

• Other difficulties:

• Calibration

• Matrix overload

• Stability, etc.

• Purge and Trap Approach:

• Capture what you can grab

• Analyze it later

• SPME

• The sample does the walking
Getting back to pyro PLOT cryo

What’s in a Name?

• Lineage:
• Lineage:

– First, what was PLOT cryoadsorption

Getting back to pyro PLOT cryo

What’s in a Name?
What’s in a Name?

• Lineage:

– First, what was PLOT cryoadsorption

• A dynamic headspace sampling method developed at 

NIST (2009) initially for energetic materials (explosives) 
What’s in a Name?

• Lineage:

– First, what was PLOT cryoadsorption

• A dynamic headspace sampling method developed at 

NIST (2009) initially for energetic materials (explosives)

• Highly repeatable, thermodynamically consistent

– Van’t Hoff equation represents f(1/T) at 10 ppb
What’s in a Name?

• Lineage:

– First, what was PLOT cryoadsorption

• A dynamic headspace sampling method developed at 

NIST (2009) initially for energetic materials (explosives)

• Highly repeatable, thermodynamically consistent

– Van’t Hoff equation represents f(1/T) at 10 ppb

– go/no-go at < 1 ppb
What’s in a Name?

• Lineage:

– First, what was PLOT cryoadsorption

• A dynamic headspace sampling method developed at 

NIST (2009) initially for energetic materials (explosives)

• Highly repeatable, thermodynamically consistent

– Van’t Hoff equation represents f(1/T) at 10 ppb

– go/no-go at < 1 ppb

– PLOT cryo beats SPME in a walk
So what was PLOT Cryo?

PLOT capillary trap, in a cryoadsorber

A wide variety of sorbent phases can be used:

 alumina, silica, polymeric, sol-gel, clay, organoclay,...

Sorbent is porous 

throughout

0.1 to 1 meter long
PLOT Capillary Cryoadsorption*

*Bruno, T.J., Simple quantitative headspace analysis by cryoadsorption on a 

short alumina PLOT column, J. Chromatogr. Sci., 47, 569-574, 2009.
Vortex Tubes:

Compressed air

Really cold! Really hot! 

No moving parts

My Favorite Toy:

Bruno, T.J., Vortex cooling of HPLC components, Liquid Chromatography, Vol. 4, No. 2, pp. 134-136 (1985).

Bruno, T.J., Vortex cooling for low temperature gas chromatography, Anal. Chem., Vol. 58, p. 1596 (1986).

Bruno, T.J., Laboratory applications of the vortex tube, J. Chem. Educ., Vol. 64, No. 11, p. 987 (1987).

Bruno, T.J., Applications of the vortex tube in chemical analysis, Proc. Contr. and Qual., 3, 195, 1992.

Bruno, T.J., Application of the vortex tube in chemical Analysis, Part I, Am. Lab., 25(12), 15 1993

Bruno, T.J., Application of the vortex tube in chemical Analysis, Part II, Am. Lab.,, 25(14), 14 1993

Bruno, T.J., Chromatographic cryofocusing and cryotrapping with the vortex tube, J. Chromatographic Sci., 32, 112, 

1994.
PLOT Capillary Cryoadsorption*

*Bruno, T.J., Simple quantitative headspace analysis by cryoadsorption on a short alumina PLOT column, J. 

Chromatogr. Sci., 47, 569-574, 2009.

COLD!

- 40 

oC
PLOT Capillary Cryoadsorption*

*Bruno, T.J., Simple quantitative headspace analysis by cryoadsorption on a short alumina PLOT column, J. 

Chromatogr. Sci., 47, 569-574, 2009.

Hot 

 160 

oC 
Analyte Elution

N2(inert)

Acetone (solvent)

vent

 Solvent 

(with analyte)
The Payoff:

Multiple PLOT Capillaries:

 -tailor the sorbent to the analyte

only headspace method that

makes this possible

 

alumina

polymeric

clay
Application and Impact:

• Vapor composition of explosives

– Lovestead, T. M., Bruno, T. J., Trace Headspace Sampling for Quantitative Analysis of 

Explosives with Cryoadsorption on Short Alumina Porous Layer Open Tubular Columns. 

Anal. Chem. 2010, 82, 5621-5627

• Early detection of food spoilage

– Lovestead, T. M., Bruno, T. J., Detection of poultry spoilage markers from headspace 

analysis with cryoadsorption on a short alumina PLOT column. Food Chemistry 2010, 

121, 1274-1282.

• Finding illegally buried corpses

– Lovestead, T. M., Bruno, T. J., Detecting gravesoil from headspace analysis with 

adsorption on short porous layer open tubular (PLOT) columns. Forensic Science 

International, 204 156–161, 2011.

• Fire retardantsin auto interiors, histamine in shrimp, 

COS in imported drywall, arson fire debris,...
Now, add the pyro!

• Combine an in situ pyrolyzer platform with 

PLOT cryo

Modes of Operation:

 -Enhanced vaporization

 -True pyrolysis

 -Combined
Now, add the pyro!

• Combine an in situ pyrolyzer platform with 

PLOT cryo

A headspace analysis 

method that makes 

it’s own headspace!
PTFE/silicone 

sandwich septum

22 ga PTFE insulated Cu wire

Blob of ceramic 

resistance cement

Hooks
Shove platform into the autosampler vial cap with a ball burnisher
Wrap 15 winds of 0.002 in 

OD resistance wire around 

hooks; form a basket

Different wires have been used:

304 SS 541 Ω/ft

NiCr 650 Ω/ft

NiCr 675 Ω/ft

0.001 in W has also been used, but it is too 

small to bother with.

304 SS works fine.
A custom made 

bobbin winder 

makes quick work!
Pin vise

Ceramic tube

Wire

Magnetic holdfast

Spool
Ready 

for 

Action
Regulated DC 

Power Supply

Pyro PLOT Cryo 

Platform

Firing Circuit

Couldn’t be simpler, a spot welder!
Regulated DC 

Power Supply

Pyro PLOT Cryo 

Platform

Firing Circuit

Couldn’t be simpler, a spot welder!

100 Ω, to protect 

power supply 
Regulated DC 

Power Supply

Pyro PLOT Cryo 

Platform

Firing Circuit

Couldn’t be simpler, a spot welder!

100 Ω, to protect 

power supply 

40,000 to 1,900,000 μF 
Ready 

for 

Action
Ready 

for 

Action

Some Interesting Examples

• From: forensics, explosives, fuels, polymers, 

reactions, bioproducts

• All samples were collected by Pyro PLOT cryo, 

30 second sweeps

• Vials at room temperature

• Analyses were done by 1 mL acetone elution, 

then GC-MS
Analysis of Cosmetics

A Forensic Science Measurement Challenge

• Two aspects

– DNA recovery in lip cosmetics

– Cosmetics transfer to clothing and persons

Base

 oils, siloxanes, surfactants, 

Additives

coloring agents, bases, bulking 

agents, sunscreens, and additives
Analysis of Cosmetics

A Forensic Science Measurement Challenge

• Two aspects

– DNA recovery in lip cosmetics

– Cosmetics transfer to clothing and persons

Base

 oils, siloxanes, surfactants, 

Additives

coloring agents, bases, bulking 

agents, sunscreens, and additives
0.06 mg (a mere smear)

Collection was for 30 sec

Nothing to clean up

Lip Gloss
Blush

0.1 mg (another mere smear)

Collection was for 30 sec

Nothing to clean up
Vapor composition of explosives:

• TSA required the ability to measure and predict the 

vapor composition above explosives

• For the certification of in-the-field equipment

 Lovestead, T. M., Bruno, T. J., Trace Headspace Sampling for Quantitative Analysis 

of Explosives with Cryoadsorption on Short Alumina Porous Layer Open Tubular 

Columns, Anal. Chem. 2010, 82, 5621-5627.
With PLOT Cryo:

• 100 - 200 mg samples

• Collection for 2.5 to 6 hrs

• At 50 to 150 oC
N+

O

-O N+

O

OO

O

O

O

Recovered mass (grams per liter x 109) from 

tagged C-4

0

2

4

6

8

10

12

14

16

0.0024 0.0026 0.0028 0.003 0.0032 0.0034

1/T, K-1 ln( g/L x 10

9 ) 

taggent - 2,3-dimethyl-2,3-dinitrobutane plasticizer - bis(2-ethylhexyl) adipate
Tagged C4 

0.2 mg

30 sec collection time

Nothing to clean up

Before, it took 200 mg, 2.5 hrs, at 150 oC

butyrolactone
Detaflex

0.2 mg

Collection for 30 sec
Semtex, the choice of the discriminating terrorist 

Very difficult to detect, on purpose
Clipper Maid of the Seas – Departs Heathrow on Dec. 21, 

1988, operating as Pan Am 103
With:
0.2 mg

Collection for 30 sec

Earlier, it took 200 mg, 6 hrs at 150 

oC to collect and characterize vapor

Semtex H
Pyrolysis of polystyrene

• Start with a packing peanut

• Mash it into a disk with a dental amalgam 

carrier

• Place in pyro basket, and FIRE!
Literature:

Styrene and toluene are the two major 

pyrolysis products of polystyrene

0.08 mg

Collection for 30 sec
Antiknock Additive in Gasoline

• TEL is out, but others are in

– Ferrocene is one

RMM = 186.04

Tmelt = 174 °C

Tboil = 249 °C

“therapeutic” dose: 20 mg/L
Antiknock Additive in Gasoline

• TEL is out, but others are in

– Ferrocene is one

RMM = 186.04

Tmelt = 174 °C

Tboil = 249 °C

Analysis* of fuels with this additive take 30 min

*Bruno, T.J., Baibourine, E., Analysis of organometallic gasoline 

additives with the composition-explicit distillation curve method, 

Energy & Fuels, 24, 5508-5513, 2010.
1 drop, gasoline with 20 mg/L

Evaporate to dryness

0.03 mg

30 sec collection

Residual gasoline heavies
Pharma:
0.2 mg

Collect for 30 sec

Nothing to clean up
Microscale Reaction Platform

Chapter 18, Carbanions 

page 231
Microscale Reaction Platform

Cyclization Reaction (carbanions and α,β-unsaturated carbonyls)

Ba(OH)2

Δ

+ CO2 + H2O

 adipic acid cyclopentanone 
Microscale Reaction Platform

Cyclization Reaction (carbanions and α,β-unsaturated carbonyls)

Ba(OH)2

Δ

+ CO2 + H2O

 adipic acid cyclopentanone 

21.8 g adipic acid, 1.5 g Ba(OH)2, put into distillation flask, attach condenser

Insert a 400 oC Hg/glass thermometer

Heat until solids melt (295 oC) 
Ask the DSRs:

21.8 g adipic acid, 1.5 g Ba(OH)2, put into 

distillation flask, attach condenser

Insert a 400 oC Hg/glass thermometer

Heat until solids melt (295 oC) 
Microscale Reaction Platform

Cyclization Reaction (carbanions and α,β-unsaturated carbonyls)

Ba(OH)2

Δ

+ CO2 + H2O

 adipic acid cyclopentanone 

21.8 g adipic acid, 1.5 g Ba(OH)2, put into distillation flask

Insert a 400 oC thermometer

Heat until solids melt (295 oC) 
Microscale Reaction Platform

Cyclization Reaction (carbanions and α,β-unsaturated carbonyls)

Ba(OH)2

Δ

+ CO2 + H2O

 adipic acid cyclopentanone 

21.8 g adipic acid, 1.5 g Ba(OH)2, put into distillation flask

Insert a 400 oC thermometer

Heat until solids melt (295 oC) 
Microscale Reaction Platform

Cyclization Reaction (carbanions and α,β-unsaturated carbonyls)

Ba(OH)2

Δ

+ CO2 + H2O

0.2 mg of total reagent

Collection was for 30 sec.

All products and side products are present

Nothing to clean up

Nobody got hurt or screamed
$ Bottom Line $

$ 0.16 + 0.10 + 0.20 = $ 0.46

Use it once, then toss

$10, use over and over

Circuit, one time cost, $ 100
Next Steps:

• Provisional patent has been filed

• NIST-PRC recommended full filing

• Commercial Partners have been identified

• ACS Regional Meeting

• Extend capabilities

– Wick stick for liquids

– KBr for FTIR; Krytox® for FTIR; C3D8O3 for NMR

• Optimize resistance and capacitance
Acknowledgements

• Jessica Nichols, NIST SURF student 

Summer, 2012
• Other Methods that might appear 

similar:

– Pyrolysis GC

• Larger samples, complex chromatograms, the injector is 

perpetually dirty, you’re stuck with GC.

– Pyrolysis MS

• Larger samples, the ion source is perpetually dirty, very 

unreliable*, you’re stuck with MS

*I had one as an MS retrofit; it came with 12 fused silica 

crucibles, I used it a few times and excessed it, and I still have 

some crucibles in the drawer.