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CHROMTECH :  Specialists in Chromatography
- Fluid Transfer Products : & FOR All Your Laboratory Needs !
- Importers & Distributors in AUSTRALIA


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Tips > for Capillay GC “Bunnies”


The “intricacies” really requires a “multi-disciplinary learning curve”  involving chemistry, physics, fluid dynamics separation techniques but superficially is a magic and asy to use in principle . . . experience helps !

Knowledge of electronics, chemistry, physics, pneumatics and of course computers(PC)
and always the essential “ bit of common sense”
By rote the methodology is fairly well sorted out but not quite to the perfected “push-button” technology
> expected > hoped for !
In a “perfect” World maybe but the in depth complexity of GC “Systems” can be somewhat “daunting” for beginners . . . when things start to go wrong . . . that’s ineviitable ! without attention to detail and the need for pre-emptive maintenance
Often left up to in-house “experts” to troubleshoot “after the event” the various specialty technologies required . . .often with out the case “history” sequence of events and “lack of memory” > accountability of GC operators often multi-users and the need to keep relevant “cause & effect” records

the “Difficulty” WE as 3rd party often remote  /phone consultants also experience > plagued by lack of details, even so-called “secrecy of THE project”

equally the lack of general confidence in sales / marketing people exacerbates this hesitancy often shown by end-users
not unique to GC > chemistry in general inadequate communication skills?

RARELY these people have the overview / knowledege required ! ?
& GOOGLE Wikiipedia useful as they are ! . . .  only go far !

The Internet “diluted” somewhat by ALL the “crap” and often needs interpretation / translation” can be useful

that’s if you can wade through “False Fact” even “Fake Science” > mischief
particularly some of the “technical” chromatography forums> intended mischief
- often fed by maybe well-intentioned but naive inexperience GC Users looking for help feedback etc but often ves “ need some “sorting out“
some “real” experts do seem to be secretive” of giving away their “treasured” ideas / experiences

Buy via E-Bay Amazon and you get barely what you pay for . . . if your lucky !

Trouble-shoot via (in your) FaceBook, Twitter and the like ! . . . r even Chromatography Forum it’s really “buyer” BE-a-WARE !

At the GC Bench level  the GC operator needs to “saavy” to be aware !
whether deliberately perhaps, mismanaged or micro-consonstrued

TIPs !

New GC or installing a new column

These Fused Silica ( and Siltek/MXT capillary columns > nowadays after some 4-5 decades   have evolved ( > perfected  ?) in terms of coating technology to be virtually a perfected technique and column performance NEW from authenticated OEM Suppliers are guaranteed to meet almost 100% theoretical performance in terms of column efficiency ( Theoretical Plates per metre ) and inertness ( perfected deactivation techniques in production ).
But In terms of minimial column bleed ( liquid phase cross-bonding to fused silica column surface and /or metal deactivation like Siltek )
The better “surviving” Column OEM always test individual columns and supply the test chromatogram with every new columns
However some OEMs do tend to “cut corners” and do just “batch testing” foe expedience ONLY ! but  BE a WARE!

Always test in YO . .if only as a “yardstickUR GC New column immediately to verify “the initial performance”
any life(-time) can inevitably Only deteriorate

whether IT IS STILL useful > that’s YOUR decision . . . Wise or Not ! maybe your “bosses”

(a) to verify your GC is performing at optimum performance

re-install a similar column of proven performance from a preferably from a different GC
RE-install the New and re-test > it’s very unlikely the New column is bad ! . . . but it can Happen !

IF you can’t verify and reproduce the test chromatogram > same GC conditions and same or similar component
“Test Sample” ( sometimes NOT supplied with the New column due to Dangerous Goods stupidity regulations etc )

The GROB Test mixture is Universally used by “savvy” operators

& designed to really be “useful” to test column efficiency ans test for columns activity ( acid / base) with probe “polar” moleculels

Any tailing ( even loss of such peaks ) indicates column problems from New ( bad QC from column OEM ? ) or column deterioration ( by attrition ! ) > oxidation of column liquid phase or from sample contamination / residues or injection liner problems or “other”

(b)  Do NOT proceed with actual samples until you have verified GC performance with a synthetic ”clean” sample of typical
or expected sample components in an ideal solvent & at same concentration / sample size etc )
Never”initially”  inject real samples / matrix eg water, ambient air, crude sample extracts etc

(c)   test regularly ( daily, perhaps weekly) with GROB
Tailing loss of peaks does mean your sample is GOOD even if it by wishful thinking it appears to meet QC specifications ( the engineers fallacy and hopeful expectations and pressure to prove product acceptability > ethics etc )

(d) first sign od ANY adnormality in GROB > THen immediatelu ASK Questions

The veracity of your whole work > project ultimately depends on this !

problems do tend to escalate and make diagnosis even more difficult ! . . . if not rectified ! > ASAP !

Ultimately the problems may need to be replaced . . .more likely it’s a GC instrumentation problem !
Obvious issues

phase stripping sample matrix too large sample sizes contamination > cut short piece ( ~ 5cm off column front THEN the column end ; particles of graphite ferrules (if used) can lodge or even partially block columns’ inlet/ outlet fitting_

Polar phases eg PEG are notorious susceptible to oxidation > drift of retention and completed destruction over time due to impure (O2) carrier gas or leaks in any part or the carrier gas / columns stream
( Air can diffuse in via micro-cracks And against positive pressure

DO NOT Relay on Gas OEM Suppliers for their HighPurity 4 9’s gases
ALWAYS use an Oxytrpap particularly with sensitive columns Use an indicating OxyTral as close to the GC as possible

Do NOT trust / rely on metal or “closed systems” particularly in back/remote a gas manifolds > somewhere else !

If GC is to be on STANDBY ( Overnight perhaps ) preferably leave the GC carrier gas flowing at a reduced column ”safe” temperature

If on re-Start-up ALWAYS allow sufficient GC system/ Column purge time before proceeding with sample

or elevating column temperatures certainly NOT above the limit set by the OEM relevant to the column ( liquid p
Preserve column life by minimising use at high temperatures

Use an Isolation Valve on GC Inlet and also on Gas cylinder regulator to minimise “slugs“ of Air inevitable during bottle changes for example.

othewise OxyTraps will quickly and dramatically become deactivated > columns will be destroyed > otherwise > eventually > inevitably > precationary > U need to replace ALL traps in the system certainly track and fix / minimise those “leaks”
NEVER Use Sopa solion Or “Goop” to leaktest > use an electronic Leak Detector” and/or PRESSURE TEST the whole GC & Column flow system.

H2 Carrier is relatively safe if leak tested properly

Use a Mass Flow Controller on the GC I Carrier inlet as a limiting factor !
An EPC ( Electronic Pressure Controller ) or Pressure Regulator produces virtually “unlimited” flow in case of of a major leak FS column break ( possible but still unlikely ? ) even if hidden in a “bundled” column configuration > goes un-noticed !

OR use a H2 Generator normally of limited by design to a MAX flow rate capacity
anything < 50cc/min quickly gets diffused > lost within the columns oven

explosion are virtually impossible except in case of extreme negligence / oversight eg conditioning columns disconnected from the detector > stupid as this might be !
                                                 of course ! . . . All “common sense”  BUT often overlooked !

above NO Guarantees > Our Disclaimer Applies !
above > by NO means complete Nor an “exhaustive” analysis > YOUR feedback is welcome to expand on ALL this !

GROB Test > Typical PDF results > troubleshooting Guides( Restek & others )

& > as a product preview to / from
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