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re Important Site UPGRADES

some Perspective : FAST GC has been around in priinciple since 1962 but tends to have become a “bad name” for practical chemists . . . disillusionment perhaps.
There is much obfuscation over the years by GC H’ware OEMs and Columns OEMs in a catch up “see saw” vs commercial interests in what is currently achievable and. . .  what’s worthwhile pursuing
Now (2012) column technology exceeds capabilities of the H/ware to match the  FAST GC Potential - Compromises still exist !
But tremendous advances are still being made . . . even towards commercialisation of 2D-GC
- It’s really FAST becoming a matter of whether Chemists and management can think fast enough and sample collection & data processing times are the drag on a lab - data analysis being relatively minor compared to actually analysing and interpretation of
“ the meaning of the results” AND the necessity in the first place

FAST Screening of samples in the field - GC portability AND decent Column resolution . . .
over a wide temperature range . . .  are ALL important !

Process Control GC - has always lagged analytical GC - by definition the requirements are relatively Simple -often stifled by ”engineers mentality”
FAST analysis speed - means cost saving in lost raw materials based on huge product throughputs, operator time and even in maintenance
- simplifying old column technology (multiple column / complex switching valves) . . . and often absurd, expensive h’ware limitations where STILL isothermal / hotplate oven designs exist

Calidus has some ANSWERS !

THE compromise are still there
AND FalconAnalytical are working on them

the TECHNLOGY IS HERE - for significantly upgrading GC to getting FASTER Separations . . . and at decent resolution
but . . . some of the “bullshit” still has to be weeded out !
AND patents is but one them! . . .  the basic ideas have been around for 40 to 50 years

some Theory Re UltraFAST GC - Increasing GC Speed some Tips PDF
The Rise and Fall of Expertise in Gas Chromatography(LCGC) PDF
Pivotal Article JofC 2004 195-267PDF

Resolution

for isothermal GC Nt=5.54(Tr/W50)^2; Neff=5.54((Tr-Ta)/W50)^2 k=(Tr-Ta(/Ta
Neff=N t x (k/k+1)
So. . .  R=1/4SqRt(Neff)

TZ-eqn

for Temp Prog GC

some Fast GC Data - “evidence” suggest 5m 0.1mm needs >300Hz Data System
Calidus GC  perhaps  “compromised” by 100Hz and  to peaks ~0.5-1s fastest ???

still . . . it’s Your value judgement

Characteristic

0.10mm

0.15mm

0.18mm

0.25mm

0.32mm

0.53mm ID

Helium Flow (@20cm/sec)

0.16

0.3

0.3

0.7

1.2

2.6

H2 Flow @40cm/csec

0.32

0.6

0.6

1.4

2.4

5.2

Sample Capacity

<10ng

<40

<50

50-100

400-500

1000-2000

Theoretical Plates.metre

8000

4000

3500

3200

2500

1800

 

Calidus(Max)
4m=32,000

 

 

10m=32000

15m=37500

 

TZ

 (5m 0.1mm)
24(0.35s/300Hz 15degC/min
10((0.11s) 150degC/min

 

 

20

 

 

 

depends on heat rate ,w50 and Hz

 

 

 

 

 

A consensus appears to be . . .
For method transference from Conventional Capillary GC to FASTGC
AND maintaining equivalent
peak resolution and separation selectivity
PT rates  propl to 10(degC/min) / (Ta)

FastGC-Compromise
VD-PLOT-CarrierGas VD-PLOT-ColumnID

the “jury is still out” . . .
evidence suggest VD Curve flattens out as IDs are reduced from
0.25>0.1 > 50micron
 . . . moreso for H2 than He
evidence also shows that GC H’ware A/D speeds are a factor; 300Hz  is suggested as a MIN . . .  if you can get IT !
NOTE : N2 is also quite useless for FAST GC

some practical examples of FAST GC PDFacrobat-butGuide to the use of FAST GC - MEGA PDF acrobat-but

FASTGC Flow vsPressvsID Table

*

for optimum resolution and assuming 10/ta = k
even assuming linear velocity with H2 can be
 increased by x 50% for a MAX temp prog rate of 100degC/min (. . . even for 50micron columns )
Any higher rates would appear to suffer from loss of resolution - but THAT’s OK for simple(r) separations
MY Ideal 10m 0.1mm MXT at ~max of 60deg/min to max of 400Cmax in 5 to 10 mins **
but could potentially be 1/2 that with 50micron columns
BUT Injection speed and A/D speeds then become increasingly siginificant / limiting factor in degrading the “potential” column performance
** there are few commercial GCs that can achieve that oven temperatures at over 200DegC
Calidus is one of the few !
- the max of 300degC/min max would appear
to be a bit superfluous
as separations in 40 seconds are JUST not obtained
without severe loss in peak resolution

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