Evaluation of Pyro Cube for Deuterium

Report
EVALUATION OF
PYRO CUBE FOR
DEUTERIUM OF
HAIR
By Paul Middlestead and Michelle Chartrand
Ottawa University , G.G. Hatch Lab
At the request of Paul Brooks, thanks big guy
Calgary, Asita 2013, 19th edition and still going…
WHAT IS A PYROCUBE ?
From elementar: vario PYRO cube
Note:
No endorsement from this guy. All
manufacturers make products that
(usually) deliver.
In this case, the PYRO is an alternative
to the TC/EA in our lab. Both systems
are fine and well supported.
The PYRO is newer on the market and
this is a preliminary evaluation
• Ceramic and Glassy carbon tubes :
30mm and 18mm
• Glassy carbon chips packing + soot
• Bottom feeder
• Purge and trap separation
• Crucible: 2,0 cm3+ (400 samples)
• TCD + software + computer
• 120/80 samples heated caroussel
(open, large holes)
• 125ml/min flow
• Furnace on steroids + brain
• Can be upgraded to CNS
• Sleep mode
• Ceramic and Glassy carbon tubes :
18mm and 12mm
• Glassy carbon chips packing
• Bottom feeder
• GC column separation 5A
• Crucible: 0,75 cm3 (200 samples)
• No TCD, no software, no computer
• 30/50/100 samples caroussel
(close, small holes)
• 80ml/min flow
• Furnace on steroids
IRMS
IRMS
100 ml/min
TCD
•
•
•
•
•
•
2-3 mm
He
25 ml/min
IRMS
Bottom feeder independant flush, 130ml/min
More space between glassy carbon and ceramic
Fresh He for CO desorption on chemical trap
Bypass for Hydrogen mode
TCD for % of H2 and Oxygen
Carrier flow of 125ml/min
Different modes, different packings
• O mode: CO column in line, H is
ignored
• H-O mode: CO column in line
• H mode: No CO column in line
H mode reactor
No CO column
We found Hmode packing
to work well in
all modes
Crucible
Glassy carbon
chips
Ag wool
Qtz wool
Bottom connector
H-O mode reactor
CO column
Crucible
Carbon black
Graphite felt
Glassy carbon
chips
Spacer
Qtz wool
Bottom connector
O mode reactor
CO column
Crucible
Carbon black
Glassy carbon
chips
Graphite felt
Spacer
Qtz wool
Bottom connector
Bigger is better ?
•
•
•
•
Larger tubes = more surface = less repacking
Larger crucible = more area = less cruciblication
Larger tubes = more surface = smaller peaks
Larger tubes = more $$$$ but last longer…
Wake up!
Have you noticed the major difference
with the PYRO in H mode?
• Something unthinkable
• Something not usually seen or used
• Something unnatural for analytical
reason
• Hint: no divorce
IRMS
Bypass of CO column…
No separation between CO and H2
Typical TC/EA run
Flow: 95ml/min
GC temp: 90C
Peak width: 80s
Peak height: 10,6V
Peak area: 93,5
Typical Pyro run O-H mode
WHY SMALLER?
Flow: 125ml/min
Peak width: 78s (80)
Peak height: 4,6V (10,6)
Peak area: 51,5 (93.5)
LARGER VOLUME + FASTER CARRIER FLOW (i.e.dilution)
ADDITION OF SOOT: MAGICAL….without fractionation
Typical Pyro run O-H mode, TCD
Typical Pyro run H mode
Flow: 125ml/min
Peak width: 88s (80)
Peak height: 7,0V (10,6)
Peak area: 76 (93.5)
No CO column!
No soot
Typical Pyro run H mode, TCD
USELESS
OMG, this is so cool !
For fun, O-mode only, TCD
IGNORED !
Pyro linearity
-60
0
5000
10000
15000
20000
25000
-65
-70
-75
-80
Series1
-85
-90
-95
-100
Hair, 0,051 to 1,000 mg
TC/EA linearity
-92
0
5000
10000
15000
20000
25000
30000
35000
-94
-96
-98
-100
-102
-104
Series1
For Deuterium , what standards?
First:
It is imperative to normalise
using a decent spread of values
for Deuterium analysis, best to
bracket the samples with
standards of similar matrix.
For Deuterium , what standards?
•
•
•
•
•
•
•
Polyethylene foil IAEA-CH-7 -100.3
YES
Oil NBS-22
-117
(?)
Biotite NBS-30
-66
(?)
Some hair now available from USGS:
USGS 42: -78,5
USGS 43: -50,3
Water stds in Silver capillaries (thanks Ty)
Sweet nothing
KAOLINITE Kga-1: -58
Methodology for hair (or exchangeable
material)
-212
16
AUTOSAMPLER
Light water (vsmow)
Heavy water (vsmow) Difference
-212
16
228
Hair
Water
Measured
(vsmow)
%= diff value*100
diff water
John
Light
-86,6
John
Heavy
-58,6
= (-86,6+58,6)*100/228
= 12,3% or 0,123
Hair – water
exchanged
True = measured-(percent * water)
1 - percent
Final
John Light
True light = -86,6 - (0,123 * -212)
1 – 0,123
69,0
John Heavy
True heavy = -58,6 – (0,123 * 16)
1 - 0,123
69,0
First, check the standards!
Standard
Deuterium values (raw)
PEF
Light (-212)
336,0
PEF
Heavy (-16)
335,6
PEF
Off Bench
336,4
Kga-1
Light (-212)
398.1
Kga-1
Heavy (-16)
400,5
Kga-1
Off Bench
399,0
NO EXCHANGE !!!!!
Raw Deuterium values
0
200
-20
250
300
350
400
450
y = 0.6689x - 325.07
R² = 0.9965
-40
-60
Y-Values
Linear (Y-Values)
-80
-100
-120
This PYRO curve is exactly as all others
curves done on TC/EA
Just for fun
NBS-30 Biotite test: -61,4 -63 (-66)
Not bad, this is a tough cookie!
Lets not split hairs!
Real hair test
Hair
Percent
exchanged
TC/EA
Percent
exchanged
Pyro
Diff with
real value
TC/EA
Diff with
real value
Pyro
John
12,3%
6,1%
2,6
-9,7
Paul
12,9%
7,4%
2,4
-7,1
Ringo
11,2%
7,3%
0,6
-7,3
George
12,9%
5,9%
2,3
-8,4
Samples back-exchanged
with air in auto sampler
Conclusion
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•
•
•
•
Pyro peak, in H mode, is about 80% of TC/EA
Run time of Pyro is about 50% shorter (H-mode)
Same calibration equations
Pyro appears to be less linear, but better in low range
Very comparable instruments
• Higher output: faster running, less down time
• No zero blank auto sampler: back exchange of H
We would like to thank:
Paul Brooks, Wendy Abdy,
Patricia Wickham, Gilles
St-Jean, Scott Hughes,
Robin Sutka and the Gods
of Pyrolisis.

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