Complexity/Cost of ownership - LC vs GC?

Off-topic conversations and chit-chat.

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Hi everyone,

Just wanted to get people's perspective on the cost of ownership in operating a basic (ie. non coupled) HPLC vs GC in a basic lab environment. I've operated both instruments in the past, but as a "lab owner/operator" would you agree that LC is more expensive/complicated than say GC?

Overall I've found that LC systems are: (1) significantly more expensive than GC (even used), (2) more expensive in terms of consumables, that is, HPLC grade solvents (eg. methanol, ACN, etc) are $$$, (3) LC are more complex systems to operate in general than GC, (4) have a higher "fail" rate due to more systems involved (ie. high pressure pumps, degassers, etc).

These of course are my own personal opinions, I fully understand the differences between both systems and their respective applications. But Im simply posing this question to get a basic sense from a "owner/operator" perspective, I know there are a million variables to consider.

Any input would be great.
Overall I've found that LC systems are: (1) significantly more expensive than GC (even used), (2) more expensive in terms of consumables, that is, HPLC grade solvents (eg. methanol, ACN, etc) are $$$, (3) LC are more complex systems to operate in general than GC, (4) have a higher "fail" rate due to more systems involved (ie. high pressure pumps, degassers, etc).
Agreed. And mass spectrometers are more expensive, more complex, and more service intensive than either. And pH meters are less expensive, simpler, and more robust than either.

I know there are a million variables to consider.
The chief of which is what you want to do. There is very little overlap in applications where either GC or LC would be equally useful/convenient/appropriate.

Just out of curiosity, why are you trying to make that particular comparison?
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
I've used GC, GCMS, and HPLC for over 3 decades. GC and HPLC both have great value, cannot really say one is better if you have to make a choice, except that GC requires analytes to be volatile or derivatized to be volatile under GC conditions like up to 450 C.

HPLC does not require analytes to be volatile, so somewhat more versatile.

Now, if your application or need is specific, then that takes high priority. I wouldn't choose HPLC for butane assay.....
Hi Tom, thanks for the input and the sarcasm. But if you read my post properly I specifically said "non-coupled" instruments, so Im not sure why you mentioned MS. Also, you would of also noticed that I repeated the term "owner/operator" in the post as well - with reason. We will be purchasing a GC or HPLC system in the next 3 months and I simply wanted to get a sense of which instrument was more expensive to maintain, that's all.

My intent was not to see if GC is "better or worse" than LC, I know the diff and applications. But in the past I've used these systems only as a "user" , but now that I will be come a "owner" - I simply wanted to get some input on the total cost of ownership/maintenance/consumables, etc. that's all.
Hi Lespaul

It is an interesting question and as you said there are a lot of variables to consider. You almost answered the question yourself.

However, with regard to Tom's reply, it was very positive and I can not see any trace of sarcasm in it. He was also , to me, illustrating the extreme range of costs/servicing

What is governing your choice of purchase in the next 3 months apart from running costs?

Regards

Ralph
Regards

Ralph

www.itsjustabox.com
I specifically said "non-coupled" instruments, so I'm not sure why you mentioned MS
I know; that's why I specifically said "MS", not "LC-MS" or "GC-MS". :wink:

I *have* been in the lab owner/operator business (the lab portion of LC Resources was sold a dozen or so years ago) so I see where you are coming from; the point I was trying to make (and which has been elaborated by subsequent posters) is that the cost of operation takes a back seat to the application. A pH meter is cheap and easy to use, but it won't quantitate in a complex mixture. A mass spec is expensive and complex, but it won't tell you the pH. An LC is more complex and expensive than a GC, but would not work to analyze for butane, and a GC would be a poor choice for a therapeutic protein.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
Also worth noting: disposal costs are non-negligible with HPLC. The cost of reagents as eluent waste going out for disposal is approximately that of them coming in as chrom-grade solvents.
They're so different. It's hard to compare even the purchase cost, because the price of either a basic GC or a basic LC can vary nearly 2-fold depending on how very basic it is. The LC person has to decide whether they want UPLC, which will make the purchase cost higher, but it's still "basic" in that it won't do anything a normal HPLC can't do - it just does it faster - and that means that although the purchase cost is higher, the cost per sample can be quite a bit lower. You can't write UPLC off as an expensive luxury. The LC person also has to decide what detectors are necessary. Meanwhile the GC person needs to think about what inlet(s) to order. LC and GC people both need to decide what detectors are necessary, although FID for GC and PDA for LC are the default options, and both very versatile. In effect, saying that GC is cheaper than LC is like saying women are shorter than men. In general, yes, but the standard deviations are so high that there are sufficient exceptions for it to be unsafe to assume it's true when making a decision.

Also, the unreliabilities are different. I'd agree that a GC probably has a longer time between failures, but the most frequent failures of LC systems are often fairly trivial failures, like check-valve problems, which can be solved by a lab technician fairly easily. GC failures, although rare, tend to be fairly catastrophic events that need an engineer visit.

As you know, also, the methods are going to be radically different, and this affects the cost of use. There are so many small molecules that can be run directly by LC, but require derivatisation for GC. The cost of analysis therefore has to take into consideration the technician time (or automated equipment) necessary to carry out derivatisation, as well as the cost of derivatising reagents (and the cost of re-runs when it all goes wrong).

My feeling is that it's impossible to compare the cost of ownership unless you mean it literally: the cost of having an instrument sitting on a bench (and this is rather meaningless). It's better to compare the cost of analysing things, and there I have to agree with everyone so far: the important question is what things you need to analyse.
tom jupille wrote:
A pH meter is cheap and easy to use, but it won't quantitate in a complex mixture. A mass spec is expensive and complex, but it won't tell you the pH.



I do love this quote.

For me, I have access to various instruments. For example, if a customer asks for methyl paraben level, I would most likely use HPLC with UV detector at 280 nm. If matrix was complex or would take additional separation studies by HPLC, I would likely instead use GC or GCMS after trimethylsilyl derivatization.

If such analysis was extremely critical, like for a legal issue, I would likely assay by two independent techniques.

Tell your boss that you MUST have HPLC and GC. After that, go after RID, ELSD, conductivity detectors for the HPLC, they all have their place. Then go after fluorescence detector and MSD for the GC.
I am going to stick my neck out here. IF an assay can be done by GC it will ALWAYS be cheaper. IF it requires that you jump through major hoops to get to that point, then it may not be worth doing it that way but the cost of actual run (analysis) by GC is going to be less with less maintenance, less consumable cost, and lower user skill threshold.

If you can do the analysis by GC and there are no follow on issues, then GC will be less expensive.

Best regards,

AICMM
If you don't need extremely high sensitivity a CE instrument can do a lot of the analyses that an HPLC can do and GC cannot. I run a very budget tight lab for a small flavor company. I use GC and GC/MS for everything volatile or can be reasonably made volatile and CE for the rest.
really interesting to hear a mention of CE. It seems to scare the living daylights out of everyone in the UK, including vendors.
Another point about the GC/LC comparison is that LC systems capable of 3-6min runs are now fairly common, whereas GC runs are likely to be 30-40min. This means that if you have enough samples to keep your instrument running for long periods, the cost per assay (as opposed to the cost per hour), can start to look much more reasonable in UPLC, despite the higher cost of owning and running the instrument. I still find the two techniques basically complement one another, and it's hard to envisage a world without both.
As an owner/operator I side with Tom; I find the question a bit odd.

I normally buy instruments only if I have a defined need for them. If you are looking to buy a HPLC then as an owner you should have a defined need, and then be able to calculate a true ROI. If you can't define the need or calculate the ROI then it is a luxury purchase. I have done that, as well, but normally I only do so if it adds complementary capabilities to the lab. For example, I bought a FT-IR last year as a luxury purchase, and have paid for it twice over since getting it due to the complementary capabilities it brings to the lab.

I don't know the size of your lab. Mine is very small, so we have to be careful with our capital dollars. I honestly cannot fathom buying an uncoupled HPLC or GC given what the MS adds to both techniques, unless you have a significant, dedicated work stream for a specific detector (say vitamins by HPLC/UV or something similar). I can't think of any reason to buy a GC without a MS, and few reasons to buy the HPLC without the MS.

As far as cost of operation goes it can be a push. While solvent usage is significant you can minimize it by running 2.1 mm columns. Gases are more expensive than you initially think given cylinder demurrage. Maintenance costs in my experience run roughly the same. A lot of it depends on your sample load, and if your sample load is high then you'd better be making enough money such that the operating costs become an insignificant part of the overall analytical cost.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
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