Chemistry Department Blog

- Article by Kathryn Ashe

This week’s CPS saw the return of Hasok Chang to UCL.  Prof Chang currently works with the Department of History and Philosophy of Science at Cambridge University, but has spent 16 years of his career working at UCL and has been the speaker at CPS meetings many times.  This time he covered a new topic: how did we work out the molecular structure of water?  And is a theory less important because it is not true?

This topic took us on a tour of the changing philosophies in Chemistry throughout the 19^th Century.  We started with Dalton, who left school at the age of eleven but whose perseverance in studying science lead to his realisation that the molecular formula of water is HO: as there was no method of directly observing molecules, Dalton believed the simplest possible solution must apply.  Around the same time, Avogadro’s work led him to believe that the molecular formula of water was H₂O – although he only achieved this by adding caveats to his original hypothesis when it didn’t work when applied to all compounds.  This theory, however, violated the basic laws of physics known at the time: positively charged hydrogen and negatively charged oxygen could obviously form a compound, but two atoms of hydrogen would surely repel each other.  These opposing ideas lead to two different philosophies in science: realism (good theories should truthfully explain even unobservable things) and positivism (science should only deal with the observable).  Unfortunately, the latter theory was adopted by some of the eminent scientists of the day: Dumas in France claimed that atoms cannot exist because we have no experience of them, and consequently all references to atoms and atomic theory was removed from French textbooks.

The answer to this conundrum came from organic chemistry.  At that time, many new compounds were being synthesised and discovered – but there was no system for classifying them or for discovering how they fitted together.  Modelling was used in organic chemistry to try to understand these problems; whether the model related to the truth or not was unimportant.  Related to this was substitution theory: hydrogen and chlorine could be substituted for each other in different compounds, but like before this contravened what was known at the time about the charges of atoms.  Type theory, developed by Williamson (at UCL!), provided a model which fitted with his observations of etherification (aka the ‘inverse Jesus’ reaction of turning alcohol into water).  Water, ethanol and diethyl ether all belong to the same ‘type’, with each hydrogen attached to the oxygen being consecutively replaced with an ethyl group.

Physical molecular models were created soon afterwards: Hofmann created the first ball and stick models out of croquet balls (albeit in only two dimensions).  Meanwhile Kekulé, despite realising the structure of benzene, was not consistent in the accuracy of his beliefs.  He used sausage-shaped molecular models, as he thought that well-formed molecules should stack up nicely; he also said that the existence of atoms should not concern chemists.

After this tour of chemical philosophy through history, we were left pondering two important questions: is success a sign of truth? And if not, what is?  As always, the evening ended with wine and refreshments in the Nyholm Room, which we could enjoy with our new knowledge of the importance of wine in chemistry: optical isomers were discovered when Pasteur realised there were two types of tartaric acid in his wine, whilst etherification was first recorded in 1275 by Ramon Llull who probably discovered it by seeing what happened when he added acid to wine.

- Article by Jack Humphrey

The human brain is the most complicated and enigmatic structure that we know of and neuroscience hopes to understand how it is wired together, how it functions and (importantly for this talk), how it changes over time. You can approach the problems of the brain from any level you like; from individual neurons (the constitutive cells of the brain), to small neuronal networks and farther out still to observing the behaviour that emerges.  Sarah Jayne Blakemore is a Professor of Cognitive Neuroscience at UCL. After working on schizophrenia, a mental illness that appears during puberty, Professor Blakemore moved her interests towards the study of how the brain changes during adolescence. Adolescence can clearly be defined as starting with the onset of puberty but it is harder to define when it ends and this differs between cultures. Thanks to modern technology we can investigate the changing biology of the teenage brain whilst developing sophisticated tests to examine behaviour.

There are fundamental changes that occur in the brain during this adolescence. Looking at the brain as whole the ratio of grey matter (the cell bodies of neurons and synapses – the local connections between them) to white matter (the axons – long wires connecting different brain areas) shifts dramatically in favour of the former during childhood before dropping off after puberty. This is not due to increased birth or death of neurons themselves, in fact our number of brain cells stays relatively constant throughout life. The changes are due to the increase in synapses (synaptogenesis) following birth as our brains wire themselves up. Following puberty, synapses start to reduce (synaptic pruning) as useful connections are maintained whereas underused ones are cut off. This raising and lowering of synaptic strengths is known as plasticity and is believed to be the mechanism of long term memory and learning. This is greatly shaped by our environment. Professor Blakemore used the example of Japanese speakers. Because the Japanese language does not differentiate between “R” and “L” sounds, Japanese children not exposed to languages that do lose this ability after nine months of age. However, Professor Blakemore stressed that plasticity is a constant feature of the brain all throughout life and the idea of “critical periods” for learning is falling out of favour.

Social cognition is the brain’s ability to emphasise with other brains. The “theory of mind” idea is that social cognition develops in childhood. This can be observed from specific tests of toddlers’ ability to understand other people’s viewpoints. A ceiling effect is observed where after four years of age nearly all children can grasp this whereas autistic children take much longer. This is not set in stone as it appears that different tasks have different ages of onset. But does social cognition change during adolescence? Professor Blakemore’s lab have applied theory of mind experiments to adolescents to investigate changes in social cognition. Their task involves picking objects either from a different person’s perspective or simply by recognising a pattern. They showed that even adults still make mistakes on the shifted perspective task 50% of the time. Adolescents were shown to be the same at the pattern recognition version but significantly worse at the perspective shift. It is not surprising that adolescence ushers in an improvement in social cognition. People change schools, make new friends and widen their social environments.

Both small and large-scale approaches can be combined in investigating the prefrontal cortex (PFC).  Located just behind the forehead, the PFC is believed to be the seat of complicated decision making and self control. In line with previous findings, the PFC increases in size during adolescence and decreases afterwards. Brain imaging studies have shown the PFC is activated during theory of mind tasks along with several other brain regions in a possible social brain matrix, but this activation decreases after puberty. Is this because the brain possibly adopts new, more efficient strategies? As always in neuroscience there is much more work to do, which makes it so exciting.

PC: If you weren’t able to make it to the talk, you can see Professor Sarah-Jayne Blake’s ‘The mysterious workings of the adolescent brain” on the TED talks series here.

Article by Jack Humphrey

- Article by Abigail Mountain

Silicones have had a lot of media attention in the last year owing to the PIP implant scandal. We’ll return to this issue later but first let’s talk about the other uses of silicones and why they’re cropping up everywhere. As I’m a chemist, my mum thought it was apt to supply me with loads of silicone baking ware in the past few years, hoping to rumble my inner-geek. She was successful. Indeed, many kitchen utensils are now being made of the stuff. But why? And where else can we find silicones? Mike Southon from Basildon Chemicals gave this week’s CPS lecture, which gave a welcome and interesting insight into these versatile compounds.

Of course, the multitude of uses of silicones is related to their structures and properties. The most basic silicone has trimethylsilyl end-groups and a repeating middle unit consisting of a (…Si-O-Si-O…) backbone with methyl constituents attached to the Si atoms. The way in which these are units are put together governs their chemical and physical properties, and thus their uses. Silicone oils – long chains of middle units – are so-called due to their hydrophobic and lubricating characteristics. They are very commonly found in conditioners and cosmetics due to these properties. The reason they have these properties are as follows: there is lots of space along the zigzagging backbone, allowing the hydrophobic methyl group to orientate themselves on one side, leaving the hydrophilic Si-O chain atoms on the other. When the chains coil up the methyl groups remain on the outside, resulting in a hydrophobic oily molecule. The Si-O bonds have a very low energy barrier to rotation, meaning the molecule is easily deformed and allows it to be a fantastic lubricant.

Cyclic silicones have low boiling points and are therefore used in many deodorants and suncreams. They’re still oily, so still feel nice to slather on, but quickly evaporate without feeling cold to leave just the active ingredients. This is the only difference between the cyclic and oils, the rest of the following properties are shared. Their high water repellency lets them be used in waterproof jacket coatings, rising damp preventatives, medicine bottle coatings, and many many more. Their antifoaming ability was very nicely demonstrated by dropping a tiny amount of one such silicone into a large beaker of bright yellow foam which almost instantaneously dropped down to just a meniscus. This is down to the spreading properties of the silicone once it has entered into the bubble film. Such antifoams are used in the beer industry, antibiotic delivery systems and in vegetable processing.

But those are just the basic silicones. Functional silicones can have anything you like added to the backbone. Platinum is the catalyst used to functionalise the building blocks. Polyethers make them hydrophilic, leading to personal care applications; amino groups make them stick to surfaces; alkyl groups let them be overpainted. Taking the functional silicone and your regular basic silicone, you can equilibrate them, giving you a silicone with properties tunable to how much of each you add. Another great demo showed two colourless functional silicones reacting before our eyes to give a thick yellowy (Pt catalyst changing oxidation state) rubber. Pretty cool. Silicone rubbers, of baking ware fame, are cross-linked functional silicones. Non-stick and a thermal stability up to around 200°C make them perfect for such uses. A plethora of other functional compounds exist with a wide range of uses, too many to go in to here.

It’s fair to say that silicones are a very interesting and widely used groups of materials that I think will only become utilised in more and more applications in the future. They are highly biocompatible, which brings me back to the PIP implants. This story has probably given silicones a bad name. And fair enough, it’s put a lot of women through a horrible experience. It must be clear,  however, that it was the way in which the silicones used in the PIP implants were made that made them so dangerous, not the silicone gel itself. They consisted of industrial grade silicone which still contains many impurities, including the transition metal catalyst and organic side-products. It is these which pose a serious risk to the women’s health if the implant casing were to rupture. So no hating on silicones please. I think they’re pretty cool.

-Article by Abigail Mountain

For many, Professor Andrea Sella’s lectures are the highlight of the CPS calendar. And with good reason too! Renowned for his explosive (literally) demonstrations and electric charisma, there’s no wonder he’s the media maverick of the chemistry department. Last year he wowed us with “Spooklights”, a talk which I found incredible. So no pressure…

“Strange Ice” – coinciding with the centenary of X-ray diffraction – guided us through the weird and wonderful properties of ice. The most bizarre, but so taken for granted on a day-to-day basis, is the phenomenon that ice floats on water. But almost every other solid phase of a compound is denser than its liquid counterpart. In fact it is such an oddity that Professor Sella challenged the audience to name another material exhibiting this property (our resident “iceman” Dr Christoph Salzmann was exempt from the challenge, however). He made the amusing observation that society actually views the normal behaviour between solid and liquid phases of a substance as alien, with warning labels of olive oil-bergs as an example.

Dripping away at the front of the auditorium was an enormous block of crystal clear ice which had been cut through by a wire over the course of the day. You could see where the wire had sliced a seam through the block but also that the ice had healed itself, resealing behind the wire. It isn’t the pressure underneath the wire which causes the cutting, however. A process called pre-melting is the culprit – also the reason we’re able to ice-skate and ski.

Moving on to the structure of ice, Sella posed the question “why are snowflakes six-sided?”. This must be related to the way in which ice is built up. What about other crystals? Calcite – or fondly called Iceland spar – is a beautifully clear mineral that is easily split into rhombs and is birefringent, creating a double image of anything underneath it. The fact that it splits so perfectly into identically angled rhombs illustrates the concept of the unit cell, something which fascinated René Just Haüy. If you keep splitting the crystal you’ll eventually get down to the smallest reproducible building block.

X-ray diffraction of crystals, discovered by Max von Laue, allowed us to probe their internal structure and observe these building blocks. The ice we use everyday (ice Ih) has a hexagonal arrangement, containing large empty channels that explain its low density. Although the oxygen arrangement throughout the crystal is fixed, the placements of the hydrogen atoms need only satisfy two rules: each oxygen must be covalently bonded to two of them and hydrogen bonded to two others; only one H atom can be found between each pair of O atoms. This allows for a plethora of hydrogen arrangements and leads to a highly disordered internal structure, despite the highly ordered long range crystal. There are in fact fifteen polymorphs of ice, many of which have been discovered by the aforementioned department iceman.

Andrea then told us about the amazing ways we can observe ice in the sky. A 22°-halo can be seen at the end of your little finger when you put your arm out at arm’s length and, holding you hand open, hold your thumb over the sun. These and other beautiful optical phenomena are due to sunlight being refracted by hexagonal ice crystals in the atmosphere. For more information and to see some incredible images visit http://www.atoptics.co.uk

I can’t possibly fit everything that we learnt into such a short post. As always, Professor Sella impresses the audience with his polymathic knowledge and entertaining delivery. I hope I’ll still be around next year to see his talk, otherwise I’ll be making a special trip. If you missed it, details of when he’ll be doing it again can be found on his blog: http://solarsaddle.wordpress.com

-Article by Abigail Mountain

The reason we’re all here, be it learning, researching or teaching science, is probably due to someone or something inspiring our thirst for knowledge. If we want to continue to get youngsters enthusiastic about our subject we need to get out there ourselves and show them why they should love it too.

STEMNET is doing just that and are encouraging us to join up and become a STEM ambassador. It’s a national program with around 25,000 ambassadors currently volunteering in schools. Activities you would be doing range from giving careers advice to hands on activities with students; from skype lessons to helping out at national events such as the BBC Bang Goes the Theory road show. You can get more information at www.stemnet.org.uk or email directly at ambassadorslondon@stemnet.org.uk.

To give us some idea of what to expect when becoming an ambassador, we had four speakers give their first-hand experiences. Steve Plumridge, a professional engineer, was full of enthusiasm about the benefits he and the children get from him helping judge engineering competitions at some of his local schools. The kids get so involved in the competitions and the results are really promising for the future of our engineering community. Dr Jasbir Singh Lota, head of STEM at Parmiter’s School in Hertfordshire, showed us some greats snaps of STEM events held at his school, along with updates on where some of the one who became inspired are now.

Dr. Laura Fenner, a past PhD student of Andrew Wills, told us of how being an ambassador was not only beneficial to the students she came across, but also to her progress throughout her research degree. She designed an hourlong lecture on her favourite subject – magnetism – to give to schoolchildren. Before doing this Laura absolutely dreaded public speaking (I can really empathise) but this experience gained her great confidence and she doesn’t recommend it highly enough, especially if you are considering becoming a teacher.

Adrian Fenton also spoke to us about the CREST program, part of the British Science Association. It provides STEM activities for youngsters and also runs the CREST Awards, which is endorsed by UCAS. These awards can be undertaken by 11-19 year olds and are a bit like the Duke of Edinburgh Awards but for science. I kind of wish this was around when I was at school – sounds way more fun that trekking through a muddy field. I think it’s great that universities now recognise commitment to STEM. What we would be able to do as part of CREST is volunteer as judges for events or help out at national events held in the Excel centre. For more information about joining up visit www.britishscienceassociation.org/crest

So if you want to capture the attention of the next Nobel Prize winner become a STEM ambassador. Passing on our expertise and passion should come easily to most of us, and if that’s not a good enough reason to want to it I reckon it’ll look great on a CV too.

-Article by Abigail Mountain

Firstly, I think this is an opportune moment to wish everyone a happy new year! Hopefully the chocolate oranges have been forgotten and ground-breaking research is well under way.

We had rather a special first lecture of our second session. The legend that is Professor Alwyn Davies spoke about the history of our very own department – he should know it out of anyone, he’s been at UCL since 1944! Many of us who are/were undergraduates here will remember his lecture about William Ramsay’s discovery of the noble gases from our first year, so it was a pleasure to hear from him once again.

Of course, I can’t just recount the whole lecture here. That would be too much like reading a history student’s class notes. Instead I’ll briefly re-live some of the key points and giggle-worthy anecdotes.

Well we wouldn’t have a chemistry department without a university. This is where Jeremy Bentham rears his stolen head. UCL, founded in 1826, was the first university to accept students irrespective of their religion, or lack thereof. This is how we gained the nickname “that godless college in Gower Street” from our best friends down at King’s. We were also the first college in England to have a chemistry department, as well as others such as zoology and geology.

Our first Professor was Edward Turner and during his time there were no laboratories for undergraduates. This may sound appealing to some first and second years right about now but his examination papers could put you off. His first had 35 questions, from which you had to get two thirds of 1100 marks, set over 6 hours. Ours don’t seem so bad now… The questions were pretty peculiar too, for example “What is the taste of white arsenic?” (I can think of maybe one professor from our current department who would ask such a question nowadays, but otherwise, a little bizarre!)

Following Turner was Thomas Graham in in 1836, who set up the first undergraduate laboratories with help from George Birkbeck. There were still only male students at this time, it wasn’t until the 1860’s that females could study at UCL, and even then the sexes were kept separate by lectures for men and women on and half past the hour, respectively.  Then Williamson, of our favourite ether synthesis fame, took over, who in turn was succeeded by the Nobel laureate Sir William Ramsay. He of course won the Nobel prize in 1904 for his discovery of the noble gases, original samples of which Alwyn masterfully lit up with a discharge. We also got the see duplicates of the medal itself (the real gold ones were melted down by Ramsay and their proceeds given to charity) which were far bigger and impressive than expected.

The next famous name on the list of heads of departments is Sir Christopher Ingold. Not only did he have our beautiful (?!) department named after him – it did come second in the London Borough of Camden “Best Builiding of 1970” list – he also put forward the electronic theory of organic chemistry. These are the principles we now learn even as early as at A-level. The idea that reactions involve the transfer of electrons as well as the pushing of those little arrows around a conjugated system all stemmed from Ingold. Everyday vocabulary such as mesomeric effect, SN1, SN2, E1 and E2 all came from him too. Without any of these concepts organic chemistry would be even more of a nightmare (no bias here, I swear).

Professor Davies captured and held the attention of a very good turnout with his enthusiasm and spirit. He raised the question of will we see another famous head of department? One problem may be due to the length of time the more recent heads have acted for. 6 or 7 years compared with tens must surely make a difference. Also, in times gone by the head would have put most of the departments effort and money into his own research whereas today we see a much wider spread. Either way, Prof Parkin won’t let us forget about Pilkington TM, that’s for sure.

-Article by Abigail Mountain

All term people have been asking if there was a typo on the talk list, but at last on Tuesday night it was confirmed that it is not our own Andrew Wills who has a secret passion for odour. Will Andrews from P&G was the man who wowed the Ramsay lecture theatre this week, bringing a crowd so big that people were sitting on the stairs – rather reminiscent of a second year Inorganic class.

Not being a chemist, he explained that he wasn’t on the early development side of the industry, his trained nose is instead used to evaluate odours in the fragrance design team. With ten different bottles for us to smell he began the interactive lecture by passing around a manly aftershave odour. He asked the audience to describe the smell using the other four senses. Would it be soft? Cold? Sweet? Bitter? What colour would it be? Was it high-pitched? A plethora of contradicting descriptions were given, except when asked what it smelled of… We all fell silent. He had used this exercise to demonstrate that there is no universal vocabulary for odours. Indeed, companies in the fragrance industry use all of the senses to describe smells.

The room was divided about whether or not what we were smelling was actually nice. This introduced us to the idea that perfumes are trying to evoke a memory or character to a product. We will like an odour if we have a positive memory associated with it and this was proven to me when a pot of something that I’ve not smelled in nearly twenty years brought an overwhelming comforting  feeling over me; play-dough. Again, some people just did not enjoy it, showing that fragrances are incredibly subjective.

The second smell passed around was that of rose. This one odour contains over three hundred different aromatic compounds and yet most of us would instantly recognise the smell. It’s still not known for sure how we do this, but what is clear is that our noses are very powerful tools. It’s believed that some smell recognition is genetic, for example being able to smell burning, and that we use it to detect danger.

We moved on to smelling different types of natural products used in building up a complex fragrance. Orange/lime, cinnamon, and vanillin were top-notes, heart-notes and bass-notes, respectively.  Top-notes have the lowest molecular weight and are therefore most easily evaporated from the skin, typically lasting only half an hour. So if you thought your citrusy expensive perfume was a rip-off because it wasn’t lasting all day, don’t worry – it’s just physical chemistry in action! Smelling all three together was surprisingly familiar but no-one could put their finger on it. When it was revealed to be Coca-Cola the whole room erupted in amazement.

After sniffing natural vanilla and star anise we moved on to synthetic smells, the last of which was that sickly sweet strawberry smell used in bubblegum and shampoo. Perfumers need to make synthetic products because we’re not able to extract the odour of natural strawberry, for example, due to the processes involved. Steaming or hot solvent extraction would simply turn the strawberries into a mush; similarly with any soft fruit. Other natural products are just too scarce to be able to make any decent volume of extract. In these cases we can capture the smell and analyse the odour compounds using gas chromatography-mass spectrometry (GC-MS). Theoretically we can capture any smell, it’s getting the mixture of the compounds right when reproducing it that is the tricky part.

Will Andrews did a great job of waking everybody up after a long day at work with discussions, nostalgia and a thoroughly interesting lecture. Certainly everyone I spoke to after the lecture had decided that they wanted to become a perfumer.

- Article by Belle Taylor

Last week’s CPS talk was given by UCL’s very own Dr. Daren Caruana whose research interests lie in the field of gas phase electrochemistry. We were eased into the talk with a demonstration showing that when two electrodes were placed in a flame (butane was used as an example) a potential can be measured, similar in magnitude to that over a salt solution electrolyte. Using this knowledge there are huge implications in using a flame as the electrolyte in electrochemistry experiments.

A brief history of flames was then given. Did you know that a flame is hollow? (It blew my mind!) This is because all the reactions occur where O₂ meets the fuel. Of course, no one is able to see the inside of a flame, (although we later learned that Dr. Caruana has tried…) Flames are dynamic and extremely complex. The simplest H₂ flame can be described by 11 reactions but different flames are much more complicated in character. A hydrocarbon flame for example, is thought to be made up of around 150 trace species /ions formed through thermal collisions and subsequent transfer of energy. Although not involved in the main combustion reactions, their presence is enough to change the properties of the flame. If a flame is made entirely of ions it is electrically conducting and is termed a plasma. These conductive properties mean that a plasma is considered analogous to a salt dissolved in liquid, the electrolyte medium used in liquid phase electrochemistry.

The gas phase is of huge interest in electrochemistry; and not just because it can provide a mechanistic understanding of the solid/gas interface. Reactions can be looked at without the restrictions of the potential window defined by solution phase, with boundaries coinciding with the oxidation and reduction of water.  A larger potential window means that a much wider breadth of redox reactions can be studied. Previous studies have involved doping a flame with different oxide additives. It was found that the different oxides produced different fingerprints and showed a concentration dependence. This method of detecting different species is currently being taken further (as below).

Dr. Caruana talked about some of his current research in the field; that of bio-detection. This involves using gas phase electrochemistry to detect the presence of (and to distinguish between) biological species present in a gas. It was found that burning pollen spores in an H₂ flame led to the formation of plumes (amplification) which could be detected with electrodes positioned in the gas. The voltage of plumes passing the electrolytes varied significantly between different pollen spores and so the species were able to be distinguished. The addition of more electrodes meant that a 3D picture of the plumes was able to be formed, giving a more complete view of the electrochemistry.

This work has been built on by examining the presence of amino acids in gas. It is hoped that systematic addition of functional groups to an amino acid will allow similarities and differences in the cyclic voltammetry scan to be seen. Although in the early stages, it is looking promising that certain peaks may correspond to certain breakdown products of the amino acids (which attach to the electrode allowing detection). Spectroscopic techniques will soon be brought in to identify the breakdown products and thus make more concrete assignments of peaks. This work has application in industries where air purity is of importance; for example the medical industry, where the detection of biological species (e.g. viruses) in air could ultimately save lives.

Questions were answered regarding the potential window (it can be extended as far as the instruments will allow), the sun (electrochemistry on the surface of interstellar particles can drive redox reactions), the prospects of detection in ‘normal’ air (filtering out the rubbish and introducing a trickle of sample allows for readings – improvements needed for detection of non-introduced samples) and thermally stable coatings on the electrode (could use a zeolitic material)

All in all, it was an extremely interesting and well-presented talk (Dr. Caruana is a phenomenal public speaker). It was great to hear current research being discussed in an exciting field that most of us have been taught the basics of (so it wasn’t completely over our heads..!) It was made all the better as the research is taking place in our own department!

- Article by Abigail Mountain

Having attended every one of this year’s CPS lectures so far, I have to say that all of them have brought up issues often unthought-of yet so important to our day-to-day lives. Continuing this trend, last night we saw Dr John Shaw from Tyco telling us about Detecting fire, Smoke but not just smoke. Being such a vital piece of equipment, we’d be foolish to overlook the complexity that goes into designing that little white box, and forgive it for occasionally interrupting our morning toast.

False alarms, delayed reaction times and the ability to detect any type of fire are all factors that must be taken into account. Aside from our usual Bunsen burner-type flaming, there is also smouldering and pyrolysis to consider, each of which produce different gases and types of smoke. After introducing the most common forms of smoke detection (ionisation chambers, optical scattering), the focus of the lecture move to gas detection. Most real fires generate lots of CO₂, water vapour and CO; the first two already being in the air in variable concentrations over time. On the other hand, the amount of CO around us is very minimal and particularly constant. This makes it a very good gas for fire detection – typically 30ppm being the safe threshold for alarms. But is there anything else we can detect? Well, our noses can sniff out a fire extremely quickly. Personally, I love the smell of burning wood, but is there a specific gas or two that we can pick up faster than it takes for CO detector to alert us of the danger?

Dr Shaw and his team found some research that showed for your usual pyrolysis we get a load of different gases produced, and at varying amounts as the temperature is increased. But mostly not a lot of any particular thing. However these tests were not proper fire tests and there may be something else we could look at for early stage nuisance fire detection. IR/FTIR analysis would not be adequate simply because the C-H and C-C peaks don’t reach any intensity high enough to detect. Ion mobility spectroscopy was able to distinguish between different types of fires, but how useful that is is questionable, because in the end we just want to be able to tell the difference between any type of fire and cooking or steam. Tyco looked at the gas chromatography-mass spectroscopy (GC-MS) of controlled reproducible fires and although they were able to identify specific molecules, they found that the data collected wasn’t as reproducible as the fire… Nothing was found to be in any appreciable concentration for every single fire and so it was concluded that new gas sensors for fire detection are not an advisable route to go down. Of course, the big negative result of the study is actually a good result for the industry as it was prevent any more time being wasted on research in this area.

I suppose this shows just how sensitive our noses are to small changes in concentrations of gases, but we mustn’t rely on them – we can’t have a man sitting in every room 24/7 waiting for that familiar charring smell. Instead, the devices we see on the ceilings around us at work and in the labs are often complex pieces of equipment. More than one sensing technique are often combined, utilising complicated algorithms to determine when the alarm should sound. The goal for companies such as Tyco is still to be able detect fires at very early stages and to have as few false alarms as possible. The sheer number of different things that can ignite makes this a very difficult puzzle.

Well I hope this has rekindled your fire awareness. Perhaps a little check of your alarm at home isn’t the worst idea in the World. Next week we have Dr Christoph Salzmann from our very own department giving us an insight into the material chemistry of ice!