Fast GC Theory-Data

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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
	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)
	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)

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 PDFGuide to the use of FAST GC - MEGA PDF

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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