Latest Blog posts from Markes.com

Chemical emissions from food packaging and the challenges ahead

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Caroline Widdowson examines the issue of chemicals in food packaging

The occasional, but very widespread and damaging, bursts of media attention focusing on the range of chemicals found in food packaging, plastic bottles, wrappings and containers has meant that ‘materials emissions’ has become something of a buzz phrase for many of those working in product manufacturing.

Hard-hitting headlines such as:

have meant that the packaging industry has had to face some major challenges.

Even in news stories where an industry spokesperson seeks to assure the public that there is no risk to human health, there still remains a difficult, and often long-lasting, public relations barrier to overcome.

Added to this, the increase in regulations and market pressure from many diverse manufacturing sectors (construction, automotive, toys, and consumer goods) has greatly increased consumer awareness of the potential health risks associated with various chemicals.

But what choice do manufacturers have to proactively and positively manage the potential problems related to the chemicals in their products? Whether you’re concerned with the effects of chemicals leaching from packaging, ink contamination, migration of mineral oils from packaging to food or the re-use of plastic water bottles, I’m sure that most people would agree that it’s not acceptable for manufacturers not to know what effect their products could have on a consumer’s health.

While any move to introduce new legislation linked to chemicals in packaging is likely to take years, the pressure from consumers and forward-thinking competitors alike are forcing the hand of many manufacturers.

There are of course numerous companies that are actively embracing these challenges, seeing them as opportunities to improve their overall product offering or brand image. Those of us working in material emissions testing have seen a growing demand from manufacturers for us to work alongside them to develop a range of simple and quick tests that enable them to fully understand the exact nature and specific chemical make-up of their products.

The use of new innovations and technology to enable effective in-house material emissions testing is already commonplace in related industries, and this trend looks certain to gather further momentum in the packaging industry over the coming years.

Fracking (Hydraulic fracturing)

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Not for the first time (see this BBC news item), there has recently been a great deal of publicity devoted to fracking, the process of using high-pressure water-based liquids to extract natural gas from underground. How can thermal desorption be of value in this field?

Hydraulic fracturing, or fracking as it has come to be known, has been around since the late 1940s as a means of increasing the yield from underground oil/gas reserves – indeed, the majority of new gas wells drilled today use fracking. However, technological developments such as horizontal drilling have meant that it is now economically feasible to apply fracking to ‘unconventional’ sources such as shale deposits. The widespread occurrence of these deposits, combined with continued demand for new gas sources, has led to a surge in fracking over the last few years, and resultant increased public concern about its effect on the environment and on public health.

The potential environmental impacts of fracking are varied, and extend beyond the obvious one of the contamination of groundwater from the chemicals used in fracking. To a large extent these impacts mirror those for extraction of petrochemicals, with the added potential for earthquakes (recently gaining coverage from the BBC and the press). These risks include:

Blowouts, leaks and spills from stored chemicals, wells, pipelines and evaporation pits
Emissions from flowback – the part of the fracking process when the fracturing fluids, water and gas return to the surface
Emissions from the wells as part of normal operation
Emissions from equipment and vehicles on-site.

Potential emissions associated with fracking are of more than just methane – other less volatile organic chemicals (VOCs) can also be released, either from the well itself or from associated activities above-ground. These include members of the groups known as ‘air toxics’ (also known as ‘hazardous air pollutants’) and ‘ozone precursors’, both of which have for many years been the subject of legislation.

To detect releases of such chemicals, gas chromatography (GC), whether used in conjunction with mass spectrometry (MS) or other detection techniques, is well-established. With thermal desorption (TD) as a pre-concentration tool, detection limits can easily be lowered to the point that enables early detection and reduction of negative impacts on the environment or human health. This makes TD–GC/MS an ideal technology to monitor concentrations of hazardous VOCs in air or liquids. However, methane itself is too volatile to be retained on the sorbents currently used with thermal desorption, so if this is to be quantified, then a dedicated methane-detecting system is needed.

With legislation and controls on fracking only now catching up with the reality on the ground, the one thing that we can be sure of is that fracking will remain in the spotlight for years to come. With this will come the need for environmental monitoring – where a range of technologies, including thermal desorption, will clearly have an important role to play.

David Barden

Further reading

The following provides an overview examining the environmental risks associated with the technologies used to extract shale gas: M. Zoback, S. Kitasei and B. Copithorne, Addressing the environmental risks from shale gas development, Worldwatch Institute, July 2010.

An article primarily examining the issue of methane emissions from fracking can be found in: Methane: A new ‘fracking’ fiasco, Chemical and Engineering News, volume 90, issue 16 (16 April 2012), pp. 34–37.

On the same website there’s also a news article on regulations issued by the US Environmental Protection Agency (EPA) for the control of air pollution released during fracking. The US EPA regulations themselves and a summary fact-sheet issued by the EPA are also downloadable.

A short history of fracking and the current state of the technology from an industry perspective can be found in two back-to-back articles at:
C.T. Montgomery and M.B. Smith, Hydraulic fracturing – History of an enduring technology, Journal of Petroleum Technology, December 2010, pp. 26–32, and R. Beckwith, Hydraulic fracturing – The fuss, the facts, the future, Journal of Petroleum Technology, December 2010, pp. 34–41.

Reverse logic – Backflush operation for thermal desorption

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Desorbing analytes from sorbent beds in the opposite direction to which they were sampled greatly extends the analyte range of thermal desorption. Matt Bates, Thermal Desorption Product Manager at Markes, explores the reasoning behind this essential technique.

Public awareness of a healthy environment and consumer products free from harmful chemicals continues to increase. This, and the resulting legislation, means that analytical laboratories are being asked to identify and quantify a wider range of compounds than ever before, and at ever-lower levels.

As a result, manufacturers have put a lot of effort into making thermal desorbers compatible with as wide a range of compounds as possible. Modern instruments can now routinely trap and inject compounds ranging from acetylene all the way up to n-C₄₀, as well as thermally labile compounds and ‘sticky’ compounds such as phthalates, all on one system.

Having taken the trouble to make the flow-paths of thermal desorbers compatible with this range of analytes, we need to ensure that the sorbent-packed tube and trap are also up to the job – especially when compounds differing greatly in volatility and thermal stability can be present in the same sample.

Unfortunately, no one sorbent can quantitatively trap every relevant analyte. One way of getting around this is to use liquid cryogen to cool the sampling trap, so that volatile components have less chance of breaking through. However, this is not compatible with field sampling, and on-instrument use of liquid cryogen brings its own problems of logistics and cost, quite apart from the issue of ice formation.
A much better solution is to use a combination of different-strength sorbents in each tube, as this allows the widest possible range of compounds to be trapped and released in a single run. This is best done by packing the sorbents in series, separating the beds by short plugs of glass or quartz wool.

But this raises a question – as there’s now more than one sorbent in the tube, does it matter which end of the tube is used for sampling? The answer is yes it does. The overriding factor is to prevent the low-volatility analytes from coming into contact with the stronger sorbents, as if this happens, you won’t be able to quantitatively recover them (if at all). The sample therefore has to be drawn onto the weakest sorbent first, so that the high-volatility components pass through it and adsorb onto the stronger sorbents further in (see figure).

When the sample is desorbed, we still need to ensure that the low-volatility analytes don’t come into contact with the strong sorbent. Therefore the gas flow must be reversed to desorb the sample. Applying this backflush principle to both the field sampling stage and the internal refocusing trap is what allows modern thermal desorption systems to handle the wide range of analytes demanded. In addition, because the analytes leave the tube in a much narrower band of gas than when they entered, it delivers the narrow on-column peak shape we’ve all become accustomed to.

Further reading

The use of multi-sorbent tubes and backflush desorption is covered in: E. Woolfenden, Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air. Part 2: Sorbent selection and other aspects of optimizing air monitoring methods, Journal of Chromatography A, 2010, vol. 1217, pp. 2685–2694.

Backflush operation also gets a couple of pages in: E. Uhde, Application of solid sorbents for the sampling of volatile organic compounds in indoor air, in Organic Indoor Air Pollutants: Occurrence, Measurement, Evaluation, eds. T. Salthammer and E. Uhde, Wiley-VCH, 2009, chapter 1, pp. 9–10.

Technical aspects of backflush operation are covered in our Application Note TDTS 64 (Simultaneous TD–GC(MS) analysis of VOCs and SVOCs),

Launch of new building and Environmental seminar

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This blog’s been a bit quiet for the last few months, but that not because of lack of anything to talk about. On the contrary, we’ve been very busy with an office move!

Our existing building had served us well since we arrived there in 2006, but as we’ve expanded in numbers, we were increasingly finding it a bit of a squeeze. An opportunity arose to move the applications teams into a building next door to us on the business park in Llantrisant, near Cardiff, so arrangements were made late last year, and we’re now busy settling into our new Technical Resource Centre!

So what’s in the new building? The best thing is undoubtedly a nice new lab that houses instruments for visitors to get hands-on with, as well as for our all-important customer application work. We’ve been busy equipping the lab with as much of our TD equipment as possible, alongside BenchTOF-dx, the time-of-flight mass spectrometer produced by our ALMSCO division.

We also have a conference room for seminars and customer training (providing plenty of space to entertain visitors), meeting rooms, and extra office space too.

To launch the new building, we held an Environmental seminar on 8th March, with a couple of very interesting speakers – Heidi Hayes from Eurofins Air Toxics (CA, USA), and Alastair Lewis from the University of York (UK). Their talks demonstrated how thermal desorption equipment can provide answers to tricky problems across a range of applications, from the soil beneath our feet (vapour intrusion in basements) to air 6 miles above our heads (in-flight monitoring of VOCs on a research aircraft).

Simon Stevens, the organiser of the event, said that ‘As this was the first event to be held in our new Technical Resource Centre, we were keen to set the bar as high as possible, so we were really pleased to welcome two such high-profile speakers.’

Also as part of the day, we had talks by four of our applications/instrument specialists, and a tour of the lab, with demonstrations of our TD and mass spec equipment, and group discussions about topics of interest.

Simon added that ‘speaking to the delegates, it was clear that the day was a resounding success, with a clear request for more of the same!’

As a result, we’ll definitely be holding more events like this in the future. If you think you might be interested to hear about future seminars and workshops, please sign up to our email list here, and we’ll let you know when the next one is planned.

David Barden

In the news – Trichloroethylene linked to Parkinson's Disease

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Over the last day or so, the attention of the global media has been attracted by a study concluding that occupational exposure to a once-common chlorinated solvent substantially raises the chance of acquiring Parkinson’s Disease.

The study, published on 14 November in Annals of Neurology, found that long-term exposure to trichloroethylene (aka TCE or trichloroethene) was found to raise the risk of Parkinson’s Disease by more than a factor of 6. Two other ‘air toxics’, perchloroethylene (aka tetrachloroethene) and carbon tetrachloride, were also found to be risk factors.

Trichloroethylene of continued interest to analysts

Although the cohort of twins studied are likely to have been exposed to the solvents before modern working practices and exposure limits came into force, the study is nevertheless of interest to analysts. For example, trichloroethylene remains in use for industrial degreasing and is widespread in groundwater, although it has long been banned for use as a general anaesthetic, skin disinfectant, and coffee decaffeinating agent.

Advice on detecting chlorinated solvents

Chlorinated solvents such as those mentioned in this study are easily detected by thermal desorption–GC/MS, and Markes offers a range of solutions for detecting these chemicals. Examples can be found in the following documents:

Analysts interested in detecting components in workplace air may find the first in our series of Applications Guides a useful starting point: Thermal Desorption: A Practical Applications Guide. I. Environmental Monitoring & Exposure to Chemicals at Work (Contact Markes for your personal copy)

Application Note TDTS 86 describes the detection of ‘air toxic’ compounds in compliance with a standard method (US EPA Method TO-17)

Application Note TDTS 78 describes how headspace–thermal desorption can be used to detect volatile compounds in water

Application Note TDTS 13 describes how the Bio-VOC can be used to detect compounds in breath. The UK’s Health & Safety Laboratory also offers guidance on breath sampling

If you’d like any more information on detecting trichloroethylene or other volatile organic chemicals, please contact our specialists directly for impartial advice.

David Barden

The Peltier effect – a ‘cool technology’ for thermal desorption

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David Barden, Media Officer at Markes International, dusts off his physics books and gets to grips with Peltier cooling, one of the key technologies behind Markes’ thermal desorption instrumentation.

The Peltier effect, despite being first noticed by Jean Peltier in 1834, remained a backwater of physics for over a century. However, in the last few decades, the technology has experienced a revival, leading to its incorporation into a number of commercial systems, our thermal desorption instrumentation being one. To understand why we use it, let’s first take a look at what the effect is.

How Peltier cooling works

The Peltier effect is the heat exchange that results when electricity is passed across a junction of two conductors, and is a close relative of the Seebeck effect (effectively the same phenomenon in reverse, used in thermocouples used to measure temperature), and the Thomson effect (generation of electricity along a conductor with a temperature gradient). Sparing ourselves the maths, conduction electrons have different energies in different materials, and so when they are forced to move from one conductor to another, they either gain or lose energy. This difference is either released as heat, or absorbed from the surroundings.

Therefore, when two conductors are arranged in a circuit (see diagram), they form a heat pump, able to move heat from one junction to the other. Unfortunately, though, it’s not always this simple, as the Peltier effect is always up against the Joule effect – the ‘frictional’ heating that results from electrons bouncing off the atoms. In most systems, this swamps the Peltier effect, and means that all that you get is a bit more heating at one junction, and a bit less heating at the other.

Such problems hindered the development of practical Peltier coolers, and it took the development of suitable materials for the technology to really take off. In modern devices, semiconductors are normally used, with many ‘couples’ like those in the diagram being formed into an array. Linking them together is a thin metal film, while ceramics are used for the cold and hot ‘plates’.

Why use Peltier cooling in thermal desorption instrumentation?

The most obvious benefit is that Peltier coolers don’t use liquid cryogen. This is a big advantage for thermal desorption technology, sparing the analyst from the cost and trouble of keeping the instrument topped up with liquid cryogen, and making it much easier to run automated cycles.

In addition, Peltier units are small, and because they have no moving parts, they also have a long lifetime. In our UNITY thermal desorber, we use two Peltier units stacked on top of one another to get down to the low temperatures needed to quantitatively trap the most volatile analytes like acetylene.

So why aren’t they used more widely in consumer products? The main reason is their relative inefficiency – typically only 0.5 J of cooling is achieved for every 1 J of electricity used, making them roughly an eighth as efficient as a modern refrigerator. In the case of the UNITY thermal desorber, this doesn’t really matter because we’re only cooling a 6 cm length of a focusing trap. However, the energy consumption becomes significant when cooling larger objects, and that’s why Peltier cooling is not yet routinely used for refrigerators or freezers.

Looking to the future, improvements in the materials used to make Peltier coolers are starting to make the technology more appealing, and already they can be found incorporated into portable devices for cooling drinks and the like. It’s possible that with further advances, the efficiencies of Peltier coolers may start to approach that of modern refrigeration systems, and this intriguing aspect of physics may start to feature more in our everyday lives!

Material emissions legislation in the EU – is your company ready?

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Caroline Widdowson, Material Emissions Specialist at Markes International, examines what the upcoming EU Construction Products Regulation will mean for materials manufacturers, testing laboratories, and the GC(MS) industry.

Concerns about air quality used to be associated just with outdoor air, but as this has got cleaner, attention has shifted to the quality of indoor air. Clearly, the most troublesome VOCs from indoor materials are those that are both toxic and widespread, and manufacturers are already under pressure to reduce or eliminate such chemicals from their products.

In the EU, this pressure is about to increase substantially, due to the implementation of the Construction Product Regulation (CPR). The upshot of this is that, from 1st July 2013, manufacturers wishing to CE-mark their construction products for sale in the EU will need to have their products tested by accredited third-party test labs using the harmonised methods. Significantly, they’ll also need to carry out in-house checks and controls to demonstrate ongoing conformity of their products – something that may well come as a bit of a shock to the system!

The implications for manufacturers of construction products in the EU and elsewhere are clear – unless they adapt to the new regulations, they will not be able to obtain the necessary labels to sell their products. It would be wrong of manufacturers to view this in a negative light, however – on the contrary, it is an excellent opportunity for product improvement and innovation. Even now, some companies are making low chemical emissions a key selling point of their products, and this is something that we can expect to see a lot more of in the future.

So what does this mean for those involved in chemical emissions testing and supply of TD–GC(MS) equipment? The effects will be twofold – small producers will be looking to third-party laboratories to provide a quick, simple and affordable screening service to evaluate prototype products and raw materials, while larger manufacturers will be more likely to invest in test equipment for routine in-house checks. Clearly, then, those involved in all areas of TD–GC(MS) would be well-advised to consider how the requirement for increased testing will affect their business. The methodology and tools for meeting the requirements of the incoming regulations already exist – the challenge will be in making sure that they’re available to the people who need it.

Notes

This blog post is an abridged version of an article that appeared in Separation Science in August 2011. For the full version, which also includes a discussion of the latest developments in the US, please see http://www.sepscience.com/emails/SepSci0811EU.pdf#page=2

What’s in the air I breathe?

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Matt Bates, Thermal Desorption Product Manager at Markes International, gets a handle on the amounts of volatile organic compounds present in the air

Speaking as an analytical chemist, I quite happily use ‘parts per billion volume’ (ppbv) to describe concentrations of volatile organic compounds (VOCs) in the ambient atmosphere – but it’s easy to lose sight of what these values actually represent in real life.

The air we breathe is made up predominantly of permanent gases, along with a variable amount of water vapour. The VOCs too vary substantially from place to place, but the most concentrated is methane (1.8 ppmv), with all the other organic compounds being in the low ppbv range. To get an idea of just how little these amounts are, see the accompanying graphic.

Outdoor air is one thing, but indoor air is quite another. With emissions of VOCs from indoor furnishings an area of concern at the moment, it’s worth taking a closer look at these. A pretty well-known one is styrene (the monomer that goes to make polystyrene). Widely acknowledged to be a ubiquitous component of indoor air, it’s released from a variety of materials used in interior furnishings, and is the subject of lots of regulations due to its suspected health effects. But how much might you actually breathe in over the course of a day?

Let’s say you’re in a new office, and it’s a cold day, so the heating’s on and the windows are closed, with not much fresh air circulating. A browse around the Web suggests that the indoor styrene concentration might be 2 ppbv, so let’s start with that. Given that you breathe in 10 litres of air per minute when at rest, that’s 4200 litres in a 7-hour working day. Multiplying that by 2 × 10–9 gives 8.4 µL of pure styrene vapour every day, which is equivalent to 0.34 µmol, or 36 µg (using the the molar volume of an ideal gas of 24.4 L to get a rough idea). It’s not very much really – less than the weight of a grain of table salt – and certainly much less than you get in the lab if you open a solvent bottle outside the fumehood!

OK, so that was a relatively high-concentration component – what about something at the opposite end of the spectrum? CFC-113 (or Freon^® 113) first appeared in the atmosphere in 1961, and underwent a sharp rise in concentration following widespread use as a refrigerant and solvent. However, following the Montreal Protocol, its concentration levelled off in the late 1990s, at about 84 ppt. Because its principal decomposition route is by the action of light in the stratosphere, its concentration is falling at only 1 ppt a year. Incidentally, the worldwide concentration is pretty uniform too (now that production is essentially zero, it’s had time to ‘equilibrate’), making it a useful ‘internal standard’ for air measurements.

Working through the maths again, and using its current concentration of 74 ppt, we find that, at today’s concentrations, you would inhale just 23 mg of CFC-113 over the course of an 80-year lifetime – about the mass of a grain of rice. Using another analogy, 74 ppt equates to just 0.2 mL out of an Olympic-sized swimming pool (2.5 million litres). And yet modern thermal desorption technologies wouldn’t have much trouble in detecting such low levels. That’s pretty amazing really.

However, low as those levels are, Nature’s inevitably got one up on us – at least as far as 1-p-menth-1-ene-8-thiol is concerned. This C₁₀ compound (a monoterpene thiol) is responsible for the fresh juicy smell of grapefruit, and can be detected by humans at levels as low as 0.1 ppt. Now there’s a challenge for the gas chromatographer!

A blog about thermal desorption?

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David Barden, media officer at Markes International, introduces the Markes blog and explains why, if you’re interested in thermal desorption or the wider world of air analysis, you ought to take a look.

What did you think when you saw the ‘blog’ tab on our homepage? Curiosity? Surprise? Incredulity?

Whatever your thoughts, you might legitimately question whether there’s anything worth blogging about on the subject of thermal desorption equipment.

What we hope to prove by writing this blog is that there is – and we hope it makes interesting reading.

First off, why have a blog at all? Well, at Markes, we’ve always been interested in helping customers solve their problems. Not about simply producing equipment, but about understanding what our customers want, and developing solutions that help them. In times gone by, you did that at tradeshows, or by visting customers on-site. With the rise of new media, however, this has changed for many technology companies, and we believe that it shouldn’t be any different for manufacturers of thermal desorption equipment.

So the aim of this blog is to engage more directly with you, the scientist. Perhaps you’re a Markes customer, and want to keep up to date with what’s going on in the world of thermal desorption? Maybe you’re new to the technology, and want advice about making the most of it? Or perhaps you’re just interested in the world of air analysis? If so, then this is the place to come and hear some thoughts on the industry, and have your own say on them. We’ll welcome any comments, and will happily start a conversation with you.

So what can you expect from this blog? Primarily, insight from seasoned specialists at Markes about what’s happening in the world of thermal desorption and related technologies, along with the myriad of applications. We’ll also be examining some of the underlying science, and drawing together some of the latest news on regulations, with commentary on what this might mean for you.

One thing that we’re not going to be doing is giving you the hard-sell on our equipment, as you can read all about that on the other pages on our website. We hope, though, you’ll excuse us if we just mention our products occasionally!

So whatever your interest in thermal desorption or air analysis, visit us from time to time (or follow us on Twitter), and see what we’ve got to say... and let us know what you think.