Hello from Tepui´s Land!

I would like get yours opinions about these two questions:

1) Could CZE and/or CEC to displacement to HPLC?

2) What's the future of CZE/CEC respect to HPLC?

Thanks in advance,

Ruben Cortez

Ruben,

That is a good general question, though I do not think you might find anyone here that will say that CZE or CEC will replace HPLC.

Although there is a potential, there are some problems associated with these electrokinetic tecniques that needs to be taken care. Furthermore, when you see CE constractors that have patented most of the possible buffers for specific applications to stop the production of these instruments it is not a very good sign. But again that was done before the rise of the CEC.

I am curious to see what the others has to say, though I believe that most of the people here might be biased in this subject.

Kostas

Ruben:

Your question is one that comes at every meeting I attend to. I do not believe that either CEC or CZE will ever displace HPLC, even more I believe that both electrophoretic techniques will only find something of a niche application in general.

Industry has been in many cases the deciding factor on the acceptance or rejection of a given analytical technique. In this regard CE seems to have found some acceptance in the biochemical area, but is still too early to say if it will stay there.

A few years ago there was a lot of excitment about CE and related areas. With time some instrument manufacturers have realized that the market is not there, and many people in industry has found that they can do very much the same with CE or HPLC.

Benjamin

Benjamin, I think if you have compounds which can be easily analysed by HPLC there is no need for CE. But if you need to analyse complexants (NTA, EDTA, DTPA) or phosphonates (ATMP, HEDP, DETAPMP,PBTC)or mixture of organic acids in very complex matrices I guess that CE can be a superior technique over any LC method (RP, IEC, IC...). I hope so, because I am about to buy a CE system for above mentioned tasks. Would be great to hear your oppinion. Thanks.

Vojtech;

Let me add a few words to my previous opinion. Our current understanding of what CE and HPLC can do is that CE has some advantages where you need extremely high efficiency or when your sample is very limited or complex. It is also true, that in many cases either technique can do the same. For these cases the obvious choice is HPLC since it is easier to operate and less expensive.

I have tried to use CE for several cases such as peptides, metabolites, and oligonucleotides. In all cases I have ended up using HPLC instead. The initial popularity of CE has decreased and some instrument manufacturers decided not to pursue their research on CE. In my opinion, CE will continue to be used in the biochemical area and to some extent in the pharmaceutical one, but it will never replace HPLC.

I remember reading and article on LC/GC some years ago where a flowchart was presented to help you decide where CE or HPLC was the better technique. If I remeber correctly, the main decision points were the presence of strong chromophores and the ionic character of the samples.

If there are no chromophores CE will be difficult to handle. If the samples are strongly ionic, then CE will probably do a better job.

Good Luck;

Benjamin

Benjamin'

Could you please explain why CE is more expensive? I thought that it is cheaper because there is no high pressure pump, no expensive organic solvent used.

Anonymus;

When I said that CE is more expensive I was referring to the equipment price. In many instances you can get a HPLC unit from anyqhere between 20-30K dollars.

It is true, solvents and other items are considerable expense in HPLC, but all the reagents and accessories for CE are also quite costly.

Benjamin

Benjamin,

Please tell us why you ended up using HPLC for peptides metabolites and oligonucleotides? What problems did you encounter when you did these by CE that pushed you back towards HPLC?

Many thanks

Anonymous;

My work was such that needed to be transferred to QC laboratories. After I concluded that all my problems could be equally solved by CE or HPLC, my decision was not to buy additional equipment, and use HPLC instead.

CE will take sometime before before is accepted in QC operations. There normally you require more rugged and simpler instrumentation.

Benjamin

It's amazing to me that 21 years after modern CE first made its appearance that people are still talking about "eventually, with a few further improvements". The reality is CE has a number of fundamental flaws relegating it to secondary status. Fundamental breakthroughs are required to change the situation and after 21 years I think the probability is quite low. The reality is that CE has the world's simplest pump (no moving parts) but it also has the world's worst reliability pump. Inject one sample with the wrong sort of components and you need a new "pump". In addition, optical detection in CE is at a severe disadvantage relative to HPLC due to the shorter optical path length. Furthermore, analyte identification is more problematic in CE since sample composition can significantly affect migration time. Ironically, CE can be better at quantitative analysis than qualitative analysis with misidentification a frequent problem. Also, fundamentally, reproducibility of CE is 5-10X worse than HPLC and there is no foreseeable avenue to correct the problem because the root cause is connected to the injection process.

Furthermore, CEC is even less likely to succeed than CE because it adds to the problems listed above the requirement that the stationary phase have a significant number of free silanol groups in order to accomplish pumping (the HPLC community has spent decades getting rid of them and now we want them back?, I don't think so). In addition, while there are some possible strategies for gradients, these are relatively impractical in CEC. Another issue with CEC is that it's difficult to implement in systems requiring high solvent content since the pumping mechanism doesn't work well under these conditions.

So in summary, I think it's safe to say that neither of these techniques will ever play a replacement role relative to HPLC. They might find uses in some special niches but generally they will never be serious competitors to HPLC.

CE is too complicated. All this electrical stuff. HPLC is simple. All mechanical. Higher flow rate, higher pressure, faster peaks. CEC puts just these electrical complications into a simple mechanical device. Not a good idea!

Anybody have a thought on HPLC vs CE if nanotechnology (HPLC on a chip, etc) gets going?

Athought I have no experinece with CE I believe it is more expensive, more difficult to operate and less reliable. I agree that CE will not displace HPLC but probably will become an alternative in specific areas and sometime it will provide results faster and with lees effort than LC.
(If you need to analyze volatiles you'll use GC but probably LC may also work. And nobody talks about GC displacing LC...).

I checked installed base of CE in the Czech Rep. and I wonder why a new nuclear power plant recently bougt three CEs? Propably not to generate problems have less reliable results and more work.

For example: I need to analyse phosphonates. I know that Dionex has a columnn for this task. But I do not have Dionex system... Maybe I can try some alternative from other supplier. Maybe I won't be lucky for first time and I'll have try again and again... Spending a lots of money on columns I won't use any more. That's propably why my supplier of phosphonates is about to buy second CE system.

vojtech,

In the first place, regarding your question about a nuclear power plant which bought 3 CEs: the fact that they bought three instruments for power applications is by no means validation of the utility of CE for this application (assuming they got the instruments for determination of ions in high purity water). You may not be aware of it but nearly a decade ago Waters tried marketing CE for power applications using what they called CIA. However, Waters abandoned this and stopped selling any instrumentation because of inadequate performance for this application (among another's). Probably the three sales in the Czech Republic reflect not the validity of the methodology but rather the persuasiveness of some salesperson. I'll wager that they switch to Ion Chromatography before the end of the year. The attraction for this technique in high purity water analysis is the supposedly ability to utilize simple concentration methods without expensive consumables. Unfortunately, while the method works under controlled experimental conditions, the process biases the analysis in a way that's dependent upon the composition of the sample. While appealing in concept, it is of very little practical utility.

Also, it is true that Dionex sells a column specifically for analysis of phosphonates and other chelating agents (the IonPac AS7 column). However, it's not necessary to own a Dionex system to purchase this column. It's readily available to all and can be purchased at https://www.dionex.com/app/login.taf?NextURL=/jsp/index.jsp?pathid=eHomePage_FS.htm&template=dstore

Dionex + others tried CE and pulled out too.
We all make mistakes.
I do not think Waters will go into the IC market.
Too much competition from Metrohm + Shimadzu + others

I think we all agree that CE/CEC will never replace hplc. Certainly not for sample prep and not even for the majority (rplc) of lc analytical applications. Depending on how fancy one wants to get, all you need is a HV power supply ($2k), a platinum wire and some capillary. Injection reproducibility will always be a problem unless you go with the old gravity injection. I've done lc and ce and found that with a little practice the gravity injection can be very reproducible. Not very practicle though.
I think whats been missing here is to note the lack of gradient and requilibration time as well as the speed of analysis (all you need to do is crank up the voltage. better N too) that ce offers. it has some good bio applications, but it'll never out do hplc. I think a big part of that is partially people not wanting to change. There are better designs than the combustion engine for driving your car, but every mechanic knows how to fix the engine. too difficult to change.
just my 2 bits
mike

Chris,
you can be sure that sales people are very active when they hear we want to spend some money.
About the power plant: to my knowlege they already have some IC systems.

Again I have to say: in lots of labs there are both GC and LC systems and nobody talks about one competing each other. If you do routine work with robust HPLC methods there is no reason to try anything new or less developed. We do some routine work and we do not want to switch it to CE. But we have a lots of samples coming from RD department and many problems we cannot solve with LC/GC or IC.
So I thing there is reason to think about different separation mechanism even if it is less robust and more diffcult to operate. Vojtech

Vojtech;

I work at a very large (actually, the largest) chemical company in the US. We receive many types of samples, perhaps more than you, and we very rarely (almost never) have the need for CE or related techniques.

Perhaps what you need is better or more people knowledgeable on LC and GC in all their variations.

Benjamin

Benjamin,
Thanks for input. We are not decided yet.
We are a producer of chemicals for electroplating industry and market is rather small and everybody is very secretive about methods of analysis.

I sent some difficult samples to lab which would do CE analysis and I think they will provide the info which we need for decision.

I talk to industry and academic people, trying to find solutions. We do contract GC/MS and LC MS. But sometimes we cannot get what we need. Vojtech

Hi;

I have been using CE for 3 years now and I see the future of this equipment because of its effeciecy, low cost, simple sample extraction and others.

I also agree on what kostas said that "people here might be biased in this subject".