ChromaBLOGraphy: Restek's Chromatography Blog

Capillary GC Column Killers – Part 1

May 11th, 2012 by Alan Sensue

Most analysts already know that at elevated temperatures, oxygen damages the stationary phase inside a capillary gas chromatography column, and so does operating a column above the recommended maximum temperature. However, there are also several lesser known capillary column killers including the pH of the sample, derivatizing reagents, samples containing elemental sulfur, and aqueous (water) injections. Over the next month or so, I will discuss these column killers in a four-part BLOG series.

Although quantitative data to support these recommendations is unavailable, the following information is based upon personal experience and the feedback provided by experienced analysts. By no means are these topics all-inclusive, but I am hoping that before you inject your next sample, you will pause to think about what exactly you are injecting into your capillary column.

Please note that these recommendations are specific to bonded (cross-linked) stationary phases. Extra care must be taken with non-bonded or partially bonded columns, as these columns are much more susceptible to damage, and generally have shorter column lifetimes and higher bleed.

Extremes in Sample pH

The pH of the sample/extract that is introduced into a GC capillary column can potentially cause damage to the stationary phase and/or the deactivation layer on the inside of the fused silica tubing if it falls outside of the pH range of 5 to 9. Levels outside this range can result in a column quickly developing high bleed and/or poor chromatography. The further a sample/extract pH level is outside this “safe” range, the faster damage will likely occur.

If you suspect that your sample/extract may fall outside this safe pH range, test the sample/extract by putting some of it onto a strip of pH paper (shown below).

Photo courtesy of VWR LabShop.
http://vwrlabshop.com/em-9590-1-colorphast-ph-test-strips-emd-chemicals/p/0011566/

If you discover that the sample/extract pH is outside of this range, you can still analyze your sample, but you should adjust it so that the pH falls within the range of 5-9. This can be accomplished several different ways, but by far the best way is to dilute the sample/extract until its pH is between 5 and 9. We do not recommend the use of buffer salts, as these may become deposited inside the column and cause damage. In addition, keep in mind that “buffering” your sample/extract may have negative effects (via chemical reactions) with your compound(s) of interest.

Hopefully this information will help save someone’s capillary column. Please stay tuned for parts 2-4 of my BLOG series on this topic.

Posted in Tips & Tricks, Troubleshooting | Add a Comment »

Petroleum Biomarkers and Tarballs at the 36th International Symposium on Capillary Chromatography and the 9th GCxGC Symposium

May 9th, 2012 by Jack Cochran

I’d like to invite my colleagues to a preliminary view of an upcoming presentation in Riva del Garda, Italy for the 36th International Symposium on Capillary Chromatography and the 9th GCxGC Symposium. We’ve been working on characterizing tarballs that could have originated from the Deepwater Horizon oil spill in the Gulf of Mexico in 2010. The key to matching a source oil and a tarball that may be highly weathered through water washing, evaporation, biodegradation, etc., is to look at compounds such as steranes and hopanes that are resistant to weathering. To get a flavor for what I’m talking about, check out the steranes and hopanes region for “unmatched” oils below that were analyzed using GCxGC-TOFMS. It’s easy to see the differences here and un-matching is easier than matching, typically, for this oil spill fingerprinting work.

Why are my acetaldehyde concentrations off… has someone been drinking? A multi-blog series on airborne carbonyls, part III.

May 8th, 2012 by Jason S. Herrington

Ask yourself the following questions: (1) Are you using 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents (i.e., U.S. Environmental Protection Agency (EPA) Compendium Method TO-11A) to measure ambient levels of airborne acetaldehyde? (2) Are you sampling for long-term (i.e., 24 hr or greater) durations? (3) Have you compared the results you generated with a DNPH-based method and another sampling method or model data? (4) Did you find a discrepancy in the acetaldehyde concentrations amongst methods/models?

If you answered “yes” to all four of these questions, then you may have said “why are my acetaldehyde concentrations off… has someone been drinking?” WHY? For starters… Method TO-11A is clearly titled “Determination of FORMALDEHYDE in Ambient Air Using Adsorbent Cartridge Followed by …” The method is not titled “Determination of ACETALDEHYDE…” OR Determination of CARBONYLS…”, because the method was originally developed in the early 80’s for formaldehyde only, not acetaldehyde and other carbonyls. However, over the past three decades researchers found that the formaldehyde-DNPH chemistry was applicable to other carbonyls, and therefore the method was expanded to include additional carbonyls.

BUT (recall from my last blog (http://blog.restek.com/?author=22), this is another big BUT)… there were some assumptions (you know what happens when we ASS-U-ME) and some inadequate/inappropriate method validations made over the past three decades. This is where you may find yourself asking “has someone been drinking?”, because the oversight I am about to point out to you is gross enough to make you think some booze was involved along the way. Speaking of booze… before we delve into the aforementioned oversights, if your acetaldehyde concentrations have been off, you might also ask if someone has been drinking based on the information found in the following story:

So my “friend” in graduate school just so happened to be doing his Ph.D. dissertation on VOCs, in particular, carbonyl sampling with derivatizing agents like DNPH. Well, one Friday evening he may have indulged a little too much on the libation during a card game with his fellow graduate students. However, despite his irresponsible behavior Friday evening, he was diligently working in the lab early Saturday morning preparing a fresh batch of DNPH cartridges for an upcoming experiment. Well… it turned out that when he went to test the blanks for that batch of cartridges the acetaldehyde concentrations were inordinately high. See… when booze (ethanol) is metabolized, the first metabolite along the metabolic pathway is acetaldehyde. So… apparently my friend consumed enough alcohol Friday night and late enough in the evening, that when he was preparing the cartridges Saturday morning, he was still off-gassing enough acetaldehyde to contaminate his blanks.

Now back to the oversights… Back in 2007, for reasons that I do not have the time nor space to get into, I conducted an exhaustive search that failed to produce any documentation from the body of readily available literature that appropriately evaluated the long-term sampling collection efficiencies (CEs) of DNPH-coated solid sorbent sampling methods for carbonyls other than formaldehyde. So I set out to evaluate the CEs of DNPH-coated solid sorbents for acetaldehyde. I built and used a dynamic atmosphere generation system (Figure 1) to generate controlled atmospheres of formaldehyde and acetaldehyde gas standards with permeation devices (VICI Metronics, WA, USA).

Figure 1: Dynamic atmosphere generation system.

With the use of the dynamic atmosphere generation system, the long-term sampling CEs were determined for four different DNPH-coated solid sorbents. The following commercially available DNPH-coated cartridges were used in this study: SUPELCO’s (Bellefonte, PA, USA) LpDNPH Air Monitoring Cartridge (referenced as SUPELCO); Waters (Milford, MA, USA) Sep-Pak DNPH-Silica Cartridge (referenced as WATERS); and Waters Sep-Pak XPoSure™ Aldehyde Sampler (referenced as XPOSURE). These cartridges were selected based on their ubiquitous citation in the literature. In addition to the commercially available DNPH-coated cartridges, an “in house” cartridge (referenced as HOUSE) was evaluated. The long-term CEs were determined for 24- and 48-hour sampling durations at 30 and 60% RH. The results from these CE experiments (Table 1) indicated that DNPH-coated solid sorbent sampling methods consistently underestimate acetaldehyde concentrations for long-term sampling durations.

Table 1: Collection efficiency, ratio of concentration measured to concentration generated in the dynamic atmosphere generation system, reported as mean ± sd, parentheses represent sample number. a Temperature = 30°C b Sample flow rate = 150 mL min-1 c Only determined with WATERS cartridge d Sample flow rate = 75 mL min-1

The aforementioned study and results are discussed at great length in Herrington et al., 2007 (http://pubs.acs.org/doi/abs/10.1021/es061247k) with all the supporting references. In addition, this work has been backed and cited in more recent manuscripts, such as Mason et al., 2011 (http://pubs.acs.org/doi/abs/10.1021/es102500v).

However, the take away message is that assuming (there is that ASS-U-ME again) DNPH-coated solid sorbent methods have 100% acetaldehyde CEs for long-term sampling durations (as many researchers are currently doing) will result in a substantial under-estimation of acetaldehyde concentrations. This is likely to be the case for other carbonyls as well. Evaluations of long-term sampling CEs, using DNPH-coated solid sorbents, need to be extended to other commonly measured carbonyls in future studies. AND… until said studies are conducted, you must have been drinking to think it is safe to continue using DNPH-coated solid sorbent methods for any carbonyl other than formaldehyde.

More importantly, the issues I raised in my last two blogs (http://blog.restek.com/?p=4664 and http://blog.restek.com/?p=4738) and in the current blog need to be addressed in the most commonly used standardized methods (i.e., EPA Method TO-11A) to accurately reflect these shortcomings, so that end-users are aware of them. However… the part about my graduate school “friend” can probably be omitted from any such amendments.

Posted in Air | Add a Comment »

Looking back to a Successful Series of GC Seminar in the UK

May 3rd, 2012 by Jaap de Zeeuw

In the week of April 24-24 a series of GC seminars were presented throughout the UK. The seminars were organized by Thames Restek and were taking place in London, Edinburg and Bradford.(fig.1)

Fig. 1 Announcement

Main theme was learning backgrounds and principles of every day GC lab practices from injection, optimization, speed of analysis and recognizing troubles.

The day started with Injection techniques where the focus was to get a narrow injection band. For most techniques a focusing mechanism was essential which was delivered via temperature, using solvent focusing or retention gaps. We learned that retention gaps have the power to correct poor injections and can be applied for any injection technique where excessive solvent condensation can occur.

Also liner selection and purpose was discussed in detail.

Fig. 2 Participants in London seminar

The second session was targeted as trace analysis and optimization of the system for producing highest signal to noise. Here it was shown that many parameters impact sensitivity and many can be optimized while operating a GC. Next generation column technology, like developed for the Rxi-line, helps also to reach our goals.

Third topic was reducing analysis time. Depending on the separations, one can choose for offering plates in favor of analysis time. If that’s not possible, the choice of hydrogen or smaller ID columns is there.

Whatever change we initiate, in order to get the same chromatogram, the oven temperature programming needs to be adjusted to get the same elution temperatures during the “faster” run. Guidelines were shared how this is done and several examples were shared.

Last topic was troubleshooting GC discussing several of the main issues that happen in every lab. Here real customer chromatograms were shared and discussed.

After the seminar all participants obtained an official certificate, fig.3

Fig. 3 All participants received a certificate

Without exception, the reactions from participating customers were very encouraging.

Posted in Conferences | 2 Comments »

Nitrogen Carrier Gas for GC – Reduced Response Because of Slower Oven Program Rate

May 1st, 2012 by Jack Cochran

When you get into a discussion with Jaap de Zeeuw about gas chromatography, you better have the data to back your position. In fact, that is one of the best things about working with Jaap. He challenges you to get in the lab and prove your point (or his). Not that I have to be pushed to the lab, as anyone who knows me knows that GCs are my best friends.

Jaap mentions in his comment on my blog Nitrogen Carrier Gas for GC – Is it Feasible? – Is it Practical? that you can lose a factor of 2 in response by going to nitrogen carrier gas because of the slower program rate we use to maintain the same separation as we would get with helium and hydrogen, which are “faster” GC carrier gases. In the case of the previous blog, the GC oven program rates were 3.5, 9, and 13.5°C/min for nitrogen, helium, and hydrogen carrier gases, respectively. This gives factors of 2.6 and 3.9 for helium/nitrogen and hydrogen/nitrogen.

In an experiment done for my GC training course, I looked at the effect of various program rates on the signal-to-noise values for representative organochlorine pesticides, and indeed, a decrease in response by a factor of up to 2.5 could be seen when going from 40°C/min to 5°C/min (see slide below). Is that fatal for all analyses? Of course not, but if we’re doing trace residue work, it is undesirable.

I had previously addressed this GC oven program rate – peak signal-to-noise issue in Run Faster and Jump Higher in your GC Lab!

Posted in Detection Techniques, Enviro, Faster Analyses, Optimizing Applications, Pesticides, Tips & Tricks | Add a Comment »

Nitrogen Carrier Gas for GC – Is it Feasible? – Is it Practical?

May 1st, 2012 by Jack Cochran

Jaap de Zeeuw and I discussed nitrogen carrier gas for GC today, its potential benefits, its drawbacks, and how it might be used “successfully” in more laboratories given the finite supply of helium and helium’s higher costs than nitrogen or hydrogen. As sometimes happens, we don’t always agree on the finer points, so maybe we can get our blog readers to comment, too.

I start with a slide I have for my GC training course that indicates some general points about helium, hydrogen, and nitrogen carrier gases, followed by a dimensionless van Deemter plot that demonstrates the performance of those carrier gases in a graphical way. We want minimum H for the highest efficiency (the best chromatographic separation), which makes nitrogen the most efficient gas, but we also want the highest average linear velocity for the carrier gas while not sacrificing efficiency, which gives the edge to hydrogen. The other thing we’d like, but has become less critical given that we can operate in constant flow or constant linear velocity mode these days due to electronic flow control, is a relatively flat van Deemter curve. This allows us to stray outside of the optimum linear velocity and not lose too much of the separation, important, especially if we’re going with a higher linear velocity for faster analyses. Hydrogen has the edge in this criterion.

Next, I show three organochlorine pesticides separations for helium, hydrogen, and nitrogen on a 20m x 0.18mm x 0.18µm Rtx-CLPesticides column where the carrier gas linear velocities and oven programming rates are close to optimum for maximizing peak capacity. The peaks from left to right are: heptachlor epoxide, trans-chlordane, endosulfan I, DDE (4,4’), dieldrin, endrin, DDD (4,4’), endosulfan II, DDT (4,4’), endrin aldehyde. Generally speaking, our expectations are met where we see a faster analysis for hydrogen versus helium, and a much slower analysis for nitrogen. However, we do get a better separation for endosulfan I and DDE when using nitrogen. Surprised?

Finally, I had blogged on this subject a few years back and showed that even with nitrogen carrier gas you don’t always have to settle for slow analyses, as long as you have a highly selective GC column like the Rtx-CLPesticides.

12 min GC-ECD analysis of EPA Method 8081 organochlorine pesticides using nitrogen carrier gas

Posted in Enviro, Faster Analyses, Optimizing Applications, Pesticides, Tips & Tricks | 5 Comments »

Put some backbone into it, man! Improving GC separations for chlorinated dioxins and furans by modification of the backbone of the siloxane polymer stationary phase

April 26th, 2012 by Jack Cochran

For a long time now we’ve had backbone modifications of the siloxane polymers we use in gas chromatography to help us reduce bleed. By insertion of a bulky modifier group (e.g. phenyl, biphenyl, carborane, etc.), we make the polymer more rigid and reduce its tendency to “back-bite” and break off cyclic siloxanes that are detected as bleed. In addition, we often get a higher maximum operating temperature for a backbone-modified GC stationary phase. Somewhat surprisingly though, many gas chromatographers do not even know this is done and what effect it can have on their separations. For more reading on the effect that a phenyl insertion can have on the selectivity of a 5% phenyl type column:

Maybe a rose is a rose is a rose, but a “5” is not a “5”, when it comes to pesticide analysis…

Selectivity differences in arylene GC phases…pesticides and zebras

Where this backbone-modifier often has the biggest effect is for the analysis of compounds that can assume planar configurations. Chlorinated dioxins and furans that are 2,3,7,8- substituted are prime examples. We recently looked at the effect of changing the backbone modifier percentage for the Rtx-Dioxin2 polymer. While the Dioxin2 is an excellent confirmatory column for EPA Methods 1613 and 8290a since it has 2,3,7,8-tetrachlorodibenzofuran (2378 TCDF) and 2,3,4,7,8-pentachlorodibenzofuran (23478 PeCDF) isomer specificity and 340°C thermal stability, we’re looking to make it the Holy Grail of dioxin/furan columns, i.e. separate all 17 2378 toxic congeners. And to do that we would have to alter the selectivity to achieve separation for 1,2,3,7,8-pentachlorodibenzodioxin (12378 PeCDD), a very important congener that has the same TEF as 2,3,7,8-tetrachlorodibenzodioxin (2378 TCDD).

Every “top” chromatogram below for the four figures shows a separation for the off-the-shelf Rtx-Dioxin2 polymer. The middle chromatograms in each figure are increased siloxane polymer backbone modifier, and the bottom chromatograms are increasing that modifier percentage even higher. As you can see from the first figure, we start to pull apart 1,2,3,6,7-pentachlorodibenzodioxin from 12378 PeCDD (hooray!) as we increase backbone concentration in the polymer. And in the second figure, we note a change in the selectivity for many of the TCDFs (yellow box), including in the general elution area for 2378 TCDF (red box). Unfortunately, as you can see in the third figure, 2378 TCDF is now coeluting with another TCDF (boo, hiss!) when the backbone modifier percentage is at its highest. This is because, in general, an increase in the backbone modifier results in more retention of the planar compounds, which moves 2378 TCDF into the succeeding congener. Finally, on the fourth figure you can see that the backbone modification helped the separation of 2,3,4,6,7,8-hexachlorodibenzofuran (middle chromatogram).

So where does this leave us? Well, one answer is we’re still short of our Holy Grail dioxin/furan column. The good news is that we’re determined to find the solution and we’ve got great polymer chemists like Shawn Reese to help us do it. More later…

Posted in Enviro, GC/MS, New GC Columns, Optimizing Applications | Add a Comment »

DB-225, SP-2330, SP-2331 GC Columns Not Needed for 2,3,7,8-Tetrachlorodibenzofuran Isomer Specificity in EPA Methods 1613 and 8290a

April 23rd, 2012 by Jack Cochran

I’ve started to wonder if some analysts are taking the language in EPA Methods 1613 and 8290a for high resolution GC – high resolution mass spectrometry of chlorinated dioxins and furans too literally when it comes to confirmatory analysis for 2,3,7,8-tetrachlorodibenzofuran (2378 TCDF), which cannot be done on the DB-5 (5% diphenyl – 95% dimethyl polysiloxane) column suggested for primary analysis. I’ve copied the language for the methods below, but in summary they recommend either 50% cyanopropyl methyl – 50% phenyl methyl or 90% biscyanopropyl – 10% phenyl cyanopropyl stationary phases that have very low maximum operating temperatures (240-275°C), not good for chlorinated dioxin/furan analysis, especially if you want to keep them in the same GC oven as the 5% phenyl primary column that has a maximum operating temperature of 350°C.

By “too literally”, I’m specifically talking about the “or equivalent” language. I can easily provide isomer specificity for 2378 TCDF on our Rtx-Dioxin2, as well as 2,3,4,7,8-pentachlorodibenzofuran specificity, but as regards being totally “equivalent”, well, the Rtx-Dioxin2 with its 340°C maximum operating temperature is way better than some old high-bleed, thermally unstable cyano column.

Check out the chromatograms below where both 2,3,7,8- tetrachlorodibenzodioxin (2378 TCDD) and 2378 TCDF are easily separated from potentially interfering congeners on Rtx-Dioxin2. Compare this to the (very confusing) chromatogram taken from EPA Method 1613 where I believe they are trying to show 2378 TCDF on a DB-225 column, not a DB-5 column as labeled in the chromatogram. Also take note of the fact that the chromatogram was generated in 1988! Can we please get some recent technology for these methods?!

EPA Method 1613, 16.5

Confirmatory Analysis—Isomer specificity for 2,3,7,8-TCDF cannot be achieved on the DB-5 column. Therefore, any sample in which 2,3,7,8-TCDF is identified by analysis on a DB-5 column must have a confirmatory analysis performed on a DB-225, SP-2330, or equivalent GC column. The operating conditions in Section 10.1.1 may be adjusted to optimize the analysis on the second GC column, but the GC/MS must meet the mass resolution and calibration specifications in Section 10.

EPA Method 8290a, 3.4

A high-resolution capillary column (60-m DB-5, J&W Scientific, or equivalent) is used in this method. However, no single column is known to resolve all isomers. The 60-m DB-5 GC column is capable of 2,3,7,8-TCDD isomer specificity (Sec. 8.1.1). In order to determine the concentration of the 2,3,7,8-TCDF (if detected on the DB-5 column), the sample extract must be reanalyzed on a column capable of 2,3,7,8-TCDF isomer specificity (e.g., DB-225, SP-2330, SP-2331, or equivalent).

2378 TCDD and 2378 TCDF are easily separated from other potentially coeluting congeners on Rtx-Dioxin2, which gives the isomer specificity required in EPA Methods 1613 and 8290 for GC-HRMS analysis of chlorinated dioxins and furans.

The separation of what is assumed to be 2378 TCDF on a DB-225 GC column (Figure 7 from EPA Method 1613) is not as good as what is seen on the Rtx-Dioxin2.

Posted in Enviro, New GC Columns, Optimizing Applications, Tips & Tricks | 1 Comment »

Why Do We Chromatographers Persist in Delivering Inaccurate Data to Our Clients? The Case of the Indicator PCB 138 and its Coeluting Congeners 163 and 164

April 22nd, 2012 by Jack Cochran

I had some good discussions with chlorinated dioxin and furan scientists, who also analyze other POPs (Persistent Organic Pollutants), at the recent 7^th International Symposium on Recent Advances in POPs Analysis sponsored by Thermo Scientific, on why analytical chemists, gas chromatographers in the following case, persist on delivering the “wrong” answers to people requesting data. Yes, that’s what I said, the wrong answers, inaccurate results, quantification that is high-biased, however you want to put it. A classic example exists for polychlorinated biphenyls (PCBs) where PCB 138 (2,2’,3,4,4’,5’-hexachlorobiphenyl), one of the so-called European indicator PCBs, has known coelution with PCBs 163 (2,3,3’,4’,5,6-hexachlorobiphenyl) and 164 (2,3,3’,4’,5’,6-hexachlorobiphenyl) on many GC stationary phases. Mass spectrometry, even high resolution mass spectrometry, cannot distinguish these isomers unequivocally, so you’d think it would be mandatory to chromatographically separate them for both qualitative and quantitative purposes. But you’d be wrong, because it isn’t. Given that 163 and 164 together can range from about 25 to almost 50% the concentration of 138 in particular Aroclors, the bias for coelution can be quite high for some samples.

Strangely, I often get asked for a GC column that will separate PCBs 28 (2,4,4’-trichlorobiphenyl ) and 31 (2,4’,5-trichlorobiphenyl) because they coelute on “typical” GC columns and 28 is a marker PCB. My answer is the Rtx-PCB, a highly selective, high maximum operating temperature, low-bleed GC column, which easily resolves 28 and 31, while also separating 138, 163, and 164. In fact, it separates other isobaric interferences for ALL seven indicator PCBs: 28, 52, 101, 118, 138, 153, and 180 in a 60m x 0.18mm x 0.18µm format. The most important separations are shown below, including for PCBs 153 and 132, two hexachlorobiphenyls that coelute on 5% phenyl columns. PCB 132 ranges from about 45 to 60% of the concentration of 153, so the potential for an erroneous quantification is very high.

I have answers on why we stick with outdated methods and columns, and record inaccurate data, and will share them in another post (or another rant, as some of my colleagues would say), but let me hear your reasons, too.

Posted in Conferences, Enviro, GC/MS, New GC Columns | Comments Off

Restek made big impression at Analytica , Germany

April 22nd, 2012 by Jaap de Zeeuw

Analytica, one of the biggest analytical exhibition that is organized every second year in Munich, Germany, looks back on another highly successful meeting. Compared with Pittcon US, the differences are huge in nr. of exhibitors, the quality if the exhibits and especially, the number of people that participate. Especially if taken in account this exhibit is visited by >80% local (German)customers, it cannot be seen as an “European” show.

Restek Germany was present with an impressive booth (see pic.1) and had an interesting slogan: Freude in Kromatografie”, meaning: “have fun with chromatography”. That was something that was no problem as all Restek representatives were highly motivated to help customers the best they can, and you could see they liked it. (pic.2).

Pic. 1 Restek booth at Analitica 2012. Very open and inviting

Pic. 2 There was a lot of good communication and everybody really enjoyed. Have "fun" with chromatography was clearly easy to do

Besides discussing chromatography there was some special candy available (pic.3) and also a little lottery where visitors could win a nice prize. (pic.4)

Pic. 3 Suger fiber candy was available

Pic. 4 Participants could win some nice prizes

During the 4 days Restek presented 4 main technologies that are important for helping customers improve their analysis:

Pic. 5 Sky liners were a perfect fit completing the "blue" image of this booth

Rxi – technology, basically a new generation of GC capillary columns that combine low bleed with high inertness. This was designed for getting best signal and reproducibility in trace analysis, using sensitive detection techniques like the mass spectrometers. For details, see: http://www.restek.com/Landing-Pages/Content/gen_B003

Sky- deactivation technology, used for deactivation of the Sky-Liners. These liners are equipped with quartz-wool, and all is deactivated using an in-situ process. Most trouble is experienced in the injection system, using the Sky liner greatly reduces the risk for adsorption and discrimination effects. The liners also showed to interesting as a nice accessory for the ears, see pic..5. For details on Sky see: http://www.restek.com/pdfs/gnfl1323a.pdf

SulfInert /Siltek deactivation converts active metal and glass surfaces into highly inert surfaces that can be used for many applications in chromatography. Cylinders, sample lines, connections, sample loops and also MXT columns are passivated to a degree that is comparable with deactivated fused silica. This technique is also used for the high temperature metal columns like SimDist and Biodiesel, making these columns stable up to 450 C. http://www.restek.com/pdfs/PCFL1201A.pdf

USLC or Ultra Selective Liquid Chromatography, is a systematical approach for selecting the best possible column for the application. Most users try to make separations happen using a C18 column, manipulating mobile phase, while separations can be obtained much easier if the correct stationary phase is chosen first. This is often NOT a C18 phase. Four highly selective stationary phases are used in USLC, to make the above happen. For details see: http://www.restek.com/pdfs/PHFL1396-UNV.pdf

The Analitika show lasted 4 days and we welcomed many, many customers who shared their appreciation for doing business with Restek.

We also met with some great German chromatographers that worked the roots of chromatography. On pic. 6 we see Dr. Werner Engewald and Dr. Rudi Kaiser.

Pic. 6 Famous German chromatographers: Dr Engewald (left)and Dr. Rudi Kaiser

Special thanks to Restek’s German Sales team, pic.7, that did a fantastic job.

Pic. 7 Restek Germany Sales Team

Posted in Conferences, Optimizing Applications | Add a Comment »