A study of the processes that termites use to break down plant cell walls could provide new enzymatic pretreatment processes for the production of biofuels. 

Termites are highly effective at degrading plant biomass including lignin but the process by which they do this is still not well understood. A study published in Biotechnology for Biofuels,

 has investigated the structural modification caused by termites in the lignin biomolecular assembly in softwood tissues crucial for cell-wall degradation. Termite-digested and native softwood tissues were compared using 13C crosspolarization magic angle spinning and nuclear magnetic resonance spectroscopy, Flash pyrolysis with gas chromatography–mass spectrometry (Py-GC–MS), and Py-GC–MS in the presence of tetramethylammonium hydroxide (Py-TMAH)-GC–MS. 

Spectroscopic analysis, confirmed by the Py-GC–MS data indicated dehydroxylation and modification of selective intermonomer side-chain linkages. Moreover, Py-TMAH-GC–MS analysis showed significant differences in the product distribution, which the researchers report strongly suggests that the structural modification in lignin could be associated with the formation of additional condensed interunit linkages. The study concluded that these results provide insight into lignin-unlocking mechanisms for understanding plant cell-wall deconstruction, which could be useful in the development of new processes mimicking the termite system for biochemical conversion of lignocellulosic biomass to fuels and chemicals.

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A study of the processes that termites use to break down plant cell walls could provide new enzymatic pretreatment processes for the production of biofuels.

Termite study

Polybrominated diphenyl ethers (PBDE) are used as flame-retardants and are widely distributed into the environment. In the first controlled study of PDBE concentrations looking at soil, grass and the milk of cows grazed on flood-prone land on industrial river catchments, it was found that even if the land itself becomes polluted these river sediments do not introduce an increased health risk in cow’s milk.

Soil and grass were collected from the same areas of fields from five flood-prone farms on the River Trent, UK, and five neighbouring flood-free farms along with milk produced on the ten farms. Samples were analysed by GC–MS, which targeted 16 PBDE congeners. Higher PBDE levels were detected in soil on flood-prone compared with control farms; median 770 vs 280 ng/kg dry weight. However these higher levels were not reflected in the grass samples, which the study suggests indicates that PBDE contamination on soils is not transferred efficiently to grass. According to the study, this observation, and the fact that cows on flood-prone farms spend time on non-flood-prone land and eat a lot of commercial food, could explain why no significant difference was seen in flood-prone and control milks.

In the first controlled study of PDBE concentrations looking at soil, grass and the milk of cows grazed on flood-prone land on industrial river catchments, it was found that even if the land itself becomes polluted these river sediments do not introduce an increased health risk in cow?s milk.

PBDEs in pasture

In 1978 50 Hawaiian monk seals died mysteriously. Scientists at the time believed that ciguatoxins were responsible but at the time lacked the tools to test for the toxins directly. A recent study has used a method designed to test human blood to confirm the presence of ciguatoxins in living seals.

Ciguatoxins are neurotoxins, produced by algae, which build up in fish that are then eaten by the critically endangered Hawaiian monk seal. In investigating the levels of seal exposure the researchers used a Neuro-2A cytotoxicity assay to quantify ciguatoxin activity, and liquid chromatography–tandem mass spectrometry to confirm the molecular structure.

According to the study, tissue analysis from dead stranded animals revealed ciguatoxin activity in brain, liver and muscle. Analysis of blood samples from 55 free-ranging seals revealed high levels of ciguatoxin activity in 19% of the animals. Samples from animals in shoreline pens had no toxin in their blood. In some cases blood samples from the exposed seals contained toxin levels as high as several picogrammes per millilitre, which is a high enough level to kill a rat. 

The study provides the first confirmation that Hawaiian monk seals are exposed to significant levels of ciguatoxins and the first evidence of transfer of ciguatoxin to marine mammals.

A recent study has used a method designed to test human blood to confirm the presence of ciguatoxins in living seals.

Seal Sickness

As a separation technique, it is claimed that sequential injection chromatography (SIC) has a number of advantages over HPLC, but also suffers from some limitations. A new study claims to have overcome these limitations, offering a method that is faster, more sensitive and uses less reagent than HPLC methods.

The joint use of sequential injection analysis and monolithic columns facilitated SIC, which claims advantages over HPLC regarding simplicity, inexpensiveness, portability, ease-of-use, maintenance requirement and operation time. Unlike HPLC, SIC applies a miniaturized discontinuous flow-based procedure, therefore it is reported to be more reagent-saving than HPLC, rendering SIC methods inexpensive, as well as providing better safety for the environment. However, SIC does suffer from a number of drawbacks; it has a limited pressure tolerance, which causes solution leakage when applying high flow-rates, adopting a mobile phase including a buffer or installing long monolithic columns. 

The new study has overcome some of the limitations with a new SIC assembly and method. By installing a valve with a higher pressure tolerance and additional ports the system avoided the problem of solution leakage. The SIC method was reported to offer advantages over the HPLC methods with respect to rapidity, reagent consumption and safety for the environment, besides the other benefits of the instrumentation of SIC over HPLC. 

As a separation technique, it is claimed that sequential injection chromatography (SIC) has a number of advantages over HPLC, but also suffers from some limitations.

SIC vs HPLC

A plastic-wrapped bundle of herbs packaged and sent halfway around the world. A cardboard box filled with blister-packaged counterfeit tablets. A bag of coffee. One‑half tablet, either cut or bitten. A single open capsule with only a residue of powder remaining. These are just a few of the samples that have been seized by law enforcement agencies, analysed by forensic chemists and identified as containing illegally‑distributed sildenafil, the active ingredient in Viagra.

The illegal use and abuse of prescription drugs has surged in recent years and poses a challenge to forensic laboratories around the world. The Internet, along with an increasingly complex global supply chain, has led to their widespread illegal distribution. This is especially true for so-called “lifestyle” drugs such as Viagra, Levitra and Cialis, all of which are phosphodisesterase-5 (PDE-5) inhibitors used to treat erectile dysfunction (ED). These medications and the Internet became increasingly popular in the late 1990s and have been linked ever since. In October 2008, an Internet search engine found 13 million hits for “Buy Viagra.” In March 2011, the same search resulted in 33 million hits. 

Whether it is due to convenience, expedience or embarrassment, men who suffer from ED often choose Internet pharmacies to purchase these medications without a prescription. Others buy them online not for therapeutic purposes, but for recreational use, including dangerous combinations of the PDE-5 inhibitor with 3,4-methylenedioxymethamphetamine (more commonly known as MDMA or ecstasy) in a club drug known by such colourful names as “sextasy,” “trail mix“ or “hammerheading” (so-called due to its headache-inducing side effects). As early as 1999, one year after Viagra’s market introduction, use of the drug in combination with ecstasy was reported in Canada, the US and the UK. Some products advertised as “all-natural” have been found to be mixed with sildenafil, thus unknowingly exposing the customer to the PDE-5 inhibitor — a serious public health problem, as this class of drugs is contraindicated for a number of other prescription medications. In 2009, 900 boxes of coffee laced with sildenafil were confiscated in Malaysia. That same year, herbal supplements sold in stores throughout the UK were pulled from the shelves after the country’s Medications and Healthcare Regulatory Agency (MHRA) found the capsules not only contained tadalafil but that the drug was present at more than twice the maximum allowable dose for a prescribed tablet.

Forensic Determination of Sildenafil and Vardenafil in Seized Evidence

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The GPC/SEC column is the key component for the separation of macromolecules by size. The column enables a conventional HPLC instrument to be used for GPC/SEC analysis. GPC/SEC columns, in general are mechanically and chemically very stable. They are packed with either porous highly cross-linked polymer particles or porous silica particles. 

GPC/SEC columns, like all LC columns, have a finite life span, and to get the best performance and a long life the columns have to be treated properly. However, there are many ways to damage or destroy a column, or influence the column properties and column performance. The polymer network can break down, the pores can partly or totally collapse, the polarity of the column surface can be modified, the column hardware, for example, the metal of the column body, can be damaged or oxidized and the frits can be damaged or blocked.

To run a sample in a pure GPC/SEC mode, a balanced system of solvent, stationary phase and sample is required. The column performance can also be described by the plate count, the separation power and the resolution. The pore volume and the pore size distribution influence the separation power and the resolution. The plate count depends mainly on the particle size, the packed bed density and the interstitial volume. The better the value of these three parameters, the better the overall column performance. 

Column back pressure is important too. The back pressure is mainly affected by the particle size and the solvent viscosity. As the particle size decreases and the solvent viscosity increases the higher the detected back pressure for a column. 

The major question is how to operate a column correctly?

The GPC/SEC column is the key component for the separation of macromolecules by size. It enables a conventional HPLC instrument to be used for GPC/SEC analysis.

Tips & Tricks: GPC/SEC Columns - Dos and Don'ts

Thin layer chromatography (TLC) is a planar chromatographic technique introduced in the 1950s as a fast, easy and inexpensive method for qualitative analysis. Just as with column chromatography, the chemistry and size of the particles (as well as the thickness of the layer) affects the speed and nature of the separations that are possible. After the sample is applied near one edge, the plate is developed by dipping the edge into solvent and allowing the separation to take place. Once the process nears completion, the plate is dried and various methods can be used to derive qualitative and quantitative measurements from the plate. These methods include densitometry, fluorometry and even mass spectrometry.

Thin Layer Chromatography industrial distribution

The Column-07-01-2011