These days gas chromatography (GC) is one of the primary analytical techniques used in every forensic laboratory. GC is widely used by forensic scientists - from analysis of body fluids for the presence of illegal substances, to testing of fiber and blood from a crime scene, and to detect residue from explosives. Yet scientists from Ohio University explored another application of gas chromatography with differential mobility spectrometry as a low cost, onsite detection method for ignitable liquids.

Read More on… Forensic Application of Gas Chromatography

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Scientists have measured heat conduction through a monolayer of hydrocarbon chains using a novel technique. Researchers understand heat transfer on the scales of individual molecules and in solids, but there is still much to learn about the physics of heat transfer in just a few molecules that will be used in nanometer-scale electronics.

Zhaohui Wang and coauthors used a laser pulse to heat a gold substrate onto which a self-assembled monolayer of long-chain hydrocarbon molecules had been formed. The researchers used coherent vibrational spectroscopy to measure the heat conduction as it traveled through the chain of molecules via distinct vibrations. The heat flowed through the chains at about 1 kilometer per second in agreement with theoretical predictions.

_{References:
“Ultrafast Flash Thermal Conductance of Molecular Chains,” by Z. Wang, J.A. et al., Science, 317, pp 787-90, DOI:10.1126/science.1145220
“Molecules Take the Heat,” by A. Nitzan, Science, 317 pp.759-60, DOI: 10.1126/science.1147011}

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In theory, the analyte sensitivity increases on decreasing the column inner diameter; however, because of the very low sample volumes injected - 20-60 nL, nano liquid chromatography cannot be considered as an analytical method of high sensitivity.

There are several research studies that focused on the improvement of sensitivity by using techniques such as on-column focusing[1] and 2-D separation[2].

_{1. “Trace Level Determination of Organophosphorus Pesticides in Water with the New Direct-Electron Ionization LC/MS Interface”, Achille Cappiello et al., Analytical Chemistry, 2002 vol. 74 pp. 3547-54}

_{2. “Fully automated micro- and nanoscale one- or two-dimensional high-performance liquid chromatography system for liquid chromatography-mass spectrometry compatible with non-volatile salts for ion exchange chromatography” by Masuda, J. et al., Journal of Chromatography A 2005, 1063, pp. 57–69.}

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Research scientists from Schering-Plough Research Institute developed a rapid high-performance liquid chromatography (HPLC) technique that allows for efficient separation and analysis of pharmaceutical compounds.

The method uses a short column packed with 2.7μm “fused-core” silica particles that are made by fusing a 0.5μm layer of porous silica onto a solid silica particle[1]. These unique particles enable very rapid chromatographic separation at a relatively low backpressure.

Ultra-high-pressure liquid chromatography (UHPLC) is another chromatographic technique that allows the system to handle the high backpressure resulting from the stationary phase with sub-2μm particles. UHPLC offers advantages in chromatographic resolution, speed, and sensitivity over conventional HPLC systems.

Read More on… “Fast” HPLC better than UHPLC

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Folks from India extracted 99.6% pure eicosapentaenoic acid (EPA) using silver ion (argentation) column chromatography from hydrolyzed sardine oil^[1].

EPA and DHA (docosahexaenoic acid) are the two main long-chain polyunsaturated fatty acids, also frequently referred to as “omega-3″. These lipids are primarily found in oily fish and shellfish. Some researches theorized that the consumption of the aquatic creatures and, hence, DHA/EPA is a key to the brain development of our prehistoric ancestors some 150,000 years ago^[2]. Omega-3s also have been found to reduce the risk of heart disease and stroke.

Chakraborty and Raj concentrated EPA from chemically hydrolyzed sardine oil using urea fractionation with methanol at different temperatures and urea/lipids ratios followed by argentation neutral alumina column chromatography. The urea-fatty acid complexes were analyzed by gas-liquid chromatography and gas chromatography-mass spectroscopy that revealed the highest EPA concentration of 48% was at 4 C and 4:1 urea/fatty acid ratio.

Lipid chemists heavily employ argentation chromatography - a technique that dependents on polar complexes that reversibly form between the silver ions and double bonds of the fatty acyl residues of lipids.

I get the science behind the silver ion chromatography, but what about the smell in the lab? You can only imaging that fish stench that permeates everything in its path and comes home with you on your clothes.

_{[1] “Eicosapentaenoic Acid Enrichment from Sardine Oil by Argentation Chromatography”, Kajal Chakraborty and R. Paul Raj J. Agric. Food Chem., ASAP Article DOI: 10.1021/jf071407r
[2] “The possible role of long-chain, omega-3 fatty acids in human brain phylogeny”, J G Chamberlain, Perspect Biol Med, 1996 vol. 39 pp. 436-45
“Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain”, M A Crawford et la., Lipids, 1999 vol. 34 Suppl pp. S39-47}

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Choosing the right column is key in Gas Chromatography. “Columns for Gas Chromatography: Performance and Selection” is a new hands-on reference for scientists and technicians working with packed column and capillary column gas chromatography.

The authors Eugene F. Barry (University of Massachusetts Lowell) and Robert L. Grob (Villanova University) discuss the development, performance, selection, and technology of columns for gas chromatography and include a handy list of packed column separations and guidelines for column selection in Appendices A and B. A subject index completes the book.

Book Description

Gas Chromatography (GC) is the most widely used method for separating and analyzing a wide variety of organic compounds and gases. There have been many recent advancements in both packed column and capillary column GC. With numerous options and considerations, selecting the right column can be complicated. This resource provides essential guidance for scientists and technicians, including:

• Methods of choosing both capillary and packed columns
• Selection of dimensions (column length, I.D., film thickness, etc.) and type of column
• Guidelines for proper connections of the column to the injector and detector
• United States Pharmacopeia and National Formulary chromatographic methods
• ASTM, EPA, NIOSH, and OSHA column selection specifications
• Information on the advantages of computer assistance in GC and multidimensional GC
• Comprehensive information on column oven temperature control

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The biological cell is basically a miniature factory, which contains a large collection of dedicated protein machines. In a Review, Martin van den Heuvel and Cees Dekker look at recent progress in using some of these proteins to move, manipulate or power artificial, nanoscale devices.

Read More on… Motor Proteins in Nanotechnology

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I am continuing the series dedicated to the chromatography’s founder Mikhail Tsvet. So, in 1897 he moves to Russia from Switzerland, and here is his first impression of Russia:

“…during the first six months that I have been in Russia, in vain, I have been trying to force myself to feel that I have a Russian heart beating in my chest! I traveled throughout Russia. I visited Moscow, the holly city, and my eyes and ears were widely opened… Nothing moved, nothing responded in me. In my homeland I felt like a foreigner. And this feeling deeply and desperately is weighing on my mind… Now I regret that I left Europe…”

Read More on… The Little Botanists

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Today I studied my blog’s statistics to see what keywords people use to search in Google and Yahoo! to get to the pages of my site.

Here is what I found based on the last 60 days of statistics:

1. People used 1966 various search terms
2. The top 20 keywords are:

Top 20

Then I looked at the correlation between the search keyphrase and the landing page and discovered that very frequently people end up on the wrong pages.

For example, someone searched for “principles of chromatography” and Yahoo! took him/her to my home page where I may have talked about “principles of chromatography” a month ago but this post is no longer on the front page.

Here is another one. The search term was “soy milk bad reactions” and Google presented the person with “Soy Milk, Good or Bad? HPLC vs CZE - Part 2” - the post about a study that compares HPLC and CZE methods for QC of soy beverages.

Alas, because of my choice of the words for the title, this post attracts visitors that google with the keywords such as “soy milk is it bad or good”, “soy milk bad”, “bad reaction from soy milk”, “soy milk versus cow milk”, “soy milk good vs bad”, “soy milk is it bad for health” and etc. Obviously, these poor souls won’t find the answers to their questions from my comparison of HPLC to CZE, sorry!

So I decided to go through some of the unanswered questions and answer them one post at time, so next time someone searches for “types of hplc detectors” they won’t be staring at the post on “Iodized Table Salt“.

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Researchers have developed a new method for producing tandem solar cells, in which two solar cells working together to use a wider range of the solar spectrum.

The physical properties of the semiconductor materials in each cell allow one to absorb light at longer wavelengths and the other to absorb light at shorter wavelengths. Researchers have made tandem solar cells before, but the vapor-deposition methods used to produce the multilayer structure have made the cells relatively expensive.

Jin Young Kim and colleagues now describe a cheaper method for making a tandem semiconducting polymer cell, in which all of the layers, including the electrode connecting the two units, are processed from solution. They used bulk heterojunction materials made from semiconducting polymers and fullerene derivatives.

The cell’s efficiency exceeds 6 percent at illumination of 200 milliwatts per cm2, which is quite good for cells produced via an all-solution method.

Reference: “Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing,” by J.Y. Kim et al.
DOI: 10.1126/science.1141711

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