Centrifuge tubes go through a lot of abuse during extractions. Because of all of this handling, your careful labeling can be lost due to rubbing off in a shaker or centrifuge, or from solvent leakage from the top of the tube. Sometimes if you squint, you can tell what was written on the destroyed labels, but an easy way to save your nerves and eyesight is to label the tops of your extraction tubes instead of the sides. For the most part, no solvent gets on the tops of the vials, and nothing rubs on them. In the picture below, I have both the sides and tops of my vials labeled, but that’s because the tops of FEP centrifuge tubes are pretty small and I couldn’t fit a full description of the sample on the top. While FEP centrifuge tubes are a must when using aggressive solvents such as hexane/acetone (as we were during this extraction), there’s more real-estate for labels on the disposable polypropylene centrifuge tubes, and you can write directly on the tops because they’re disposable. However, if you do use lab tape for labeling your vials, it’s easily transferrable to evaporation tubes or other containers so you only have to write your label information once.
Archive for the ‘Miscellaneous’ Category
You know, its sometimes funny how some things trigger the creativity of others. We started this year a campaign at Pittcon, which was focused around being a “Chromatography Mastermind”. We had a series of questions participants could answer, and when a certain score was reached, a nice T-shirt could be earned. This campaign was even specially rewarded, see http://www.restek.com/news/view/?p=693
We ran the same action during the 37th ISCC in Palm Springs, and got some very positive feedback, See: http://blog.restek.com/?p=8536
During this show I met Bill Winniford from Dow Chemical, who is a respected scientist and frequent contributor to scientific chromatography meetings. He is also a good friend for about 25 years and I gave him a “chromatography mastermind” shirt.
Bill said: “can you give it in a different size, as I like to give it to my son”. Maybe his motive was to trigger some interest with his son in chromatography. It will be a challenge as I tried it myself and none of my 2 kids have any affinity with chemistry or physics, so I lost that game.
So this week I met Bill again at the Gulf Coast Conference at Galveston and he was smiling and said: ” I have something for you, which I am sure you will appreciate”. Bill opened his laptop and started a music file. It was a song composed by his son, David Winniford. It brings up the typical issues being a “Chromatographic Mastermind”. It was composed for Bill as a birthday present.
David is 25 years and he graduated from the University of North Texas with a degree in Jazz Performance, minor in Mandarin. He lives in China. To hear the song, click here:
(If that doesn’t play, try this: Chromatography Mastermind by David Winniford)
So the T-shirt on “Chromatography Mastermind” did trigger some creativity with other people.
It also made me think of the old days at Chrompack, where we had a creative product specialist, Hans Heijmans, who made a song to train the sales engineers on the importance of gas filtration: “Gas Clean Filters Go for It” ! It triggered a lot of appreciation (and attention)!
I almost hate to admit it, but oftentimes when I am enjoying a vacation, I can’t help but think about chromatography and how it touches so many aspects of life. Last week I was in Corning, NY and went to the Corning Museum of Glass which has a fantastic display of all facets of glass. The museum started with artistic sculptures, then a historical perspective of glass making, including a display on borosilicate glass used to make scientific glassware (including the Kuderna-Danish Concentrator and the glassware used for soxhlet extractions). I’m sure my family loved hearing how all of the pieces of glassware are used! At Restek, we acquired Glastron, a manufacturer of specialized glassware, to expand our glassware products.
The final area in the museum is the Innovation Center which is an interactive science and technology exhibit that houses the optics gallery. I couldn’t ignore the connection to chromatography when the exhibit started explaining how Corning chemist J. Franklin Hyde made fused silica in 1934 from pure liquid chemicals instead of melting dry mineral ingredients like other glass products. Fused silica therefore, has a much higher melting temperature than other traditional glasses. It took another 45 years until fused silica was used for capillary GC columns by adapting a process for the manufacturing of fiber optics. The development of fused silica capillary GC columns changed the entire field of gas chromatography and continues to be the chosen platform for efficient, fast separations. It makes me wonder, what is the NEXT invention that will change the face of chromatography like fused silica capillary columns did decades ago?
Recently I talked to a couple of customers who ordered an inline gas regulator, but didn’t order any end fittings, so when the regulator arrived, they weren’t able to connect it to their gas line. As a result, I decided to write this post to remind our customers that they may need to purchase end fittings when ordering an inline gas regulator.
Because each of our inline regulators (catalog numbers 21666* or 22452*) has 1/4 inch FNPT (Female National Pipe Thread) ports on each end (input & output), you would need two fittings for each regulator. Because we sell associated fittings in ten-packs, you will have spare fittings if you order just one of the following catalog numbers:
(Note: You may also want to order some PTFE tape if needed. ResTape PTFE Tape)
If you are reading this and realize you actually need a regulator with a CGA fitting (to connect to a tank/cylinder), I have a previous post which discusses these regulators (link below).
*The difference between 21666 and 22452 is the gauge; 21666 is designed for an outlet pressure up to 50psi and 22452 for an outlet pressure up to 100psi. Maximum inlet pressure is 3000psi for both regulators. Additional information is below.
21666 Product Name: Ultra-High-Purity Line Gas Regulator
Material: Chrome-Plated Brass
Fittings: 1/4″ female NPT ports
Outlet Gauge: 30″ – 0 to 100 psig (0-689 kPa)
Outlet Pressure: 0-50 psig (0-345 kPa)
22452 Product Name: Ultra-High-Purity Line Gas Regulator
Material: Chrome-Plated Brass
Fittings: 1/4″ female NPT ports
Outlet Gauge: 30″ – 0 to 200 psig (0-1,379 kPa)
Outlet Pressure: 0-100 psig (0-689 kPa)
Occasionally we get calls from customers who are having difficulty identifying the Membrane Microfiltration Glassware item/kit they need. As a result, I decided to write this short post to help those individuals find the correct Restek item. The catalog number breakdown below shows a visual presentation of the items available. I hope you find it useful.
Below are a few additional notes
- Each kit includes one funnel (from # 1), one aluminum clamp (# 2), one integrated fritted glass support base (#’s 3 & 4), and one flask (from # 5).
- Additional items for purchase include: A Flask Cap (glass stopper for a flask), and PTFE Joint Sleeves (used as a substitute for vacuum grease). We also sell a limited variety of membrane filters.
- Each size of funnel and flask can be purchased separately.
It appears the “helium cliff” has been avoided with both the US House and Senate passing measures to keep the current US facilities from shutting down on October 7, 2013. You can read the latest developments in the links below.
Update: October 1, 2013
With the current US Government shutdown, I was wondering if the domestic supply of helium would be affected. According to the information below, it will not.
Helium Operations: The crude helium enrichment plant will continue operation to provide
critical resource meends (assuming enactment of the House and Senate passed helium
authorization bill). This function is funded through the Helium Funds and authorized by the
Helium Act of 1960 and Helium Privitization Act of 1996.
Why are Restek capillary columns tested with different components? What can I, as a user, do with this information?
We have all bought a new capillary GC column, but only a few of us have probably reviewed the QC test report. For those of you who may have reviewed a report, you might have wondered about the data presented. In this post, I hope to clarify some of the information in regards to the column’s quality/performance.
Capillary GC columns are typically tested using a mix of compounds. Since there is not one mix that will work for every column, the components of each mix vary, but generally speaking, each mix contains the same classes of compounds. The compound classes provide a quality control mechanism for the column. For demonstration purposes, excerpts from an Rtx-1 column are below.
The alkanes – Tridecane and Pentadecane – are very stable and will elute through a column without a significant loss of response. For that reason, other compounds contained in the mix can use the alkanes for comparison purposes. On the Rtx-1, all other compounds have their responses compared to Tridecane. Pentadecane is used to measure the column’s efficiency in plates per meter. Columns with high theoretical plates will exhibit peaks with short retention times and narrow widths. Pentadecane is also used to measure the capacity factor, which can confirm the film thickness of the column. Additionally, a fatty acid methyl ester, such as methyl nonoate can be used for these purposes.
Some labs may use a test mix for system suitability purposes, to evaluate a used column, or for troubleshooting purposes. If you do use a test mix in your lab and the alkanes do not chromatograph, you should check the instrument setup before blaming the column. Improper column installation or injection port issues are the likely culprits.
Acenaphthylene, which is a polycyclic aromatic hydrocarbon, is used to determine the column-to-column reproducibility via retention index. This helps ensure that all Rtx-1 columns of the same dimensions are identical. The retention time index verifies that the correct polymer was used to manufacture the column.
The alcohols – 1,6-Hexanediol and 1-Undecanol – are used to determine the presence of hydrogen bonding. Silanol sites occur on bare tubing. The deactivation process and polymer phase coating act to shield these sites. Tailing peaks and decreased alcohol response indicate the column coating was not uniform creating unwanted activity. As a column is used over time, tailing alcohols can show that the phase has been stripped exposing these active sites. Additionally, the retention index of 1-Undecanol is used in a similar manner to Acenaphthylene to measure column reproducibility.
An acid, 4-Chlorophenol, and a base, 4-Propylaniline, are used to determine the suitability of the column for these types of compounds. Acids will interact with basic active sites in a column, and bases with acidic sites. A peak’s asymmetry, which can be measured for peak tailing, is indicative of these interactions. As a note, poor performance for the acid or base compounds does not always mean the column is bad. Some columns are specifically deactivated for the analysis of basic or acidic compounds.
Column bleed is also measured. This is normally done at the maximum isothermal temperature for the column. Low bleed values lead to better signal-to-noise ratios (lower detection limits).
As mentioned, not all column test mixes are the same. There are some that contain additional fatty acid methyl ester, which are used to monitor column efficiency. Some mixes contain an aldehyde to look for non-hydrogen bonding activity. There are also mixes that are method specific because the column was designed for that particular methodology.
I hope that provides a little insight in regards to a column’s test report. Next time you purchase a column, check it out.
Sometimes we get calls from customers who ask us if we have any application data on the analysis of highly toxic gases. Unfortunately, in most cases, the answer is “no”. We typically do not have on-site samples/standards of any dangerous gases except those (at low concentrations) which can be found on our website under the section Gas Calibration Standards.
Photo above from the MSA website
We do realize that some of our customers need to perform analysis on these types of gases, so we try and help as much as we can. Unfortunately, in many cases, we just don’t have the answer, so we need to use other resources. For those of you who need to perform toxic gas analysis and are looking for a method, I would recommend searching for the compound’s name in each of the three links below.
NIOSH (NIOSH Publications and Products)
If a method is not found in any of the links above, Google the “compound name” along with the word “method” to see if any online methods are available. If not, your best bet is to ask your customer for one; otherwise, you are going to need to do some research & development.
If you plan do the analysis via gas chromatography and are trying to select a column (and detector), maybe my blog post series (links below) will help narrow down possible column/detector choices.
Hopefully this post will help you get started with your analysis. Above all, be careful. Thanks for reading.
There are a variety of techniques for making sure your GC system is leak tight. Senior Technical Service Specialist Tom Bloom discusses different approaches for leak checking using leak detectors or a pressure decay test 1. Scott Grossman’s article, “How Much Sensitivity is Needed in a Leak Detector?” demonstrates the sensitivity of the Restek Leak Detector may negate the need for pressure decay 2. While both opinions are correct the approach we’ll take here incorporates both leak detector and pressure decay and is a bomb-proof method of leak checking.
Follow these simple steps:
- Set inlet pressure to 50 psig*
- Cut column 10cm from injection port and seal with a septum cat#27142 (fig 1)
- Seal column to detector using a septum cat#27142 (fig 1)
- Seal split vent and septum purge vent using 1/8’’ brass plug cat#21816 (fig 2)
- Shut gas off from back of instrument
- If connected directly to a tank shut the gas off at the dual stage regulator
- For other configurations make sure the gas can be turned off, for instance use a 2-way plug valve cat#21586
- Pressure shown on instrument display should not drop by more than 0.5 psig over 5 minutes.
- If the pressure drops use a leak detector cat#22655 to find the leak 3
Using a pressure decay at higher pressures (50 psig) exaggerates any small leak in the system and makes them easy to find; even difficult to access areas will produce a signal on the leak detector. Restek’s chemists and engineers have developed a way to prevent leaks using the Dual Vespel inlet seal at the bottom of the GC inlet. This patented technology provides a leak tight seal between the bottom of the inlet and inlet seal 4. This leak check procedure is a quick and easy way to guarantee a leak tight system and assure maximize column lifetime.
*For older instruments with 30 PSI maximum pressure set to 25 PSI.
The diagnostic technology available to physicians has changed a great deal over the centuries, to the benefit of their patients and often making their own jobs more pleasant as well.
From medieval times up through the nineteenth century, doctors relied on their own senses — notably the sense of taste — to assess urine samples. The technique was highly developed and held to be useful in diagnosing an array of ailments. In fact, the very name of diabetes mellitus, from the Latin “mel” meaning “honey,” is attributable to the characteristic flavor it confers to patients’ urine.
Other traits of the sample were crucial as well for proper diagnosis. Color, turbidity, viscosity, aroma, particulates, and bubbles all were referenced, their collective interpretation being the practice of uroscopy. Charts like the one shown here guided interpretation — note the groupings according to color, making this a chromatographic approach of sorts. Uroscopy, in viewing urine as a humor, belongs with leeches in the spectrum of medical technology. Contact of any sort with bodily wastes strikes us as barbaric. Yet at the same time, as a methodical form of inquiry with demonstrated value in identifying numerous ailments, it presages the modern medical laboratory.
Today, clinical tools such as GC and HPLC make urinalysis a far more palatable chore. (Sorry, I just couldn’t resist.) Search restek.com for “urine” and check out the Resources tab for dozens of technical articles, blog posts, and chromatograms.