University departments traditionally divided chemistry into inorganic, organic and physical subsets, with analytical chemistry sitting somewhere in between. But this is changing...
University departments traditionally divided chemistry into inorganic, organic and physical subsets, with analytical chemistry sitting somewhere in between. But this is changing. The teaching of analytical chemistry is currently undergoing a renaissance in many universities. What has led to this increase in interest? And how are chemistry departments dealing with it?
One area of chemistry that regularly receives positive attention in the media is analytical chemistry1,2 – the measurement of chemical composition - though it is rarely recognised by the general public as being 'chemistry' at all.3,4 The Cassini space probe, which is currently orbiting Saturn is just one example. Many people will have been impressed by the detailed photographs of Saturn's rings, and a superb view of the planet Jupiter, but few will have realised that much of the data being sent back to Earth from this probe have been obtained by a wide range of analytical techniques, including IR and UV-Visible spectroscopy.
There is also an abundance of TV and radio programmes featuring scientific investigations – fictional and factual – which rely on chemical analysis to reach a conclusion. In all of these cases - from archaeology and forensics, through environmental issues, to medical matters – analytical chemists are at the forefront of identifying problems and finding solutions. Against this background it is perhaps not surprising that the teaching of analytical chemistry in universities is taking on a new importance. But there is a bit more to it.
Why a renaissance?
About 50 per cent of those who graduate with a degree in chemistry or a related discipline, and who use their degree in their work, are required to do some analytical chemistry. Thus employers often look for a high level of analytical chemistry skills when they recruit a chemistry graduate. The modularisation of degree courses has made it easier to recognise analytical chemistry within a course. Such modules are usually often a core part of a chemistry syllabus. There is also a plethora of new courses that have expanded the scope and uptake of analytical chemistry in many universities. Programmes in environmental science, natural sciences, pharmacy, scientific archaeology and forensic science will typically include some analytical chemistry, though this is often not realised by students applying for such courses. Forensic science5,6 courses illustrate this point very well. While such courses are proving to be very popular with university entrants, students do not always recognise that the fundamental skill which is most likely to gain them employment in this area is a high-level ability in chemical analysis.
Much emphasis is, quite rightly, now being made on key or transferable skills that university students acquire during their degree. These include: problem-solving, numeracy, computer skills, presentation skills and team work. Anyone working as a chemical analyst will use these skills on a daily basis alongside their more specialised skills. Analytical chemistry courses naturally provide all of these skills at a high level.
Inevitably, problems come with the expansion of a subject. For example, many chemistry departments now have to teach undergraduates outside the traditional single honours chemistry BSc or MChem. Many of these students may not have a strong background in chemistry, so examples must be chosen carefully. Some courses, for example pharmacy, have professional bodies that stipulate what should be taught, and lecturers and course designers must take account of this.
At the same time the question of what students will do after graduation must be considered. The two areas where new graduates are most likely to use their analytical chemistry skills are in further study for a PhD or MSc degree, or in employment in an analytical chemistry laboratory. PhD research students are quick to realise how useful their analytical training has been. It is becoming increasingly common for PhD students to spend some time on industrial placements, which has the added bonus of improving their employment prospects.
Feedback from employers suggests that they find it difficult to recruit graduates who have both a strong analytical background and an appreciation of the regulatory aspects of the work, including quality standards such as good laboratory practice (GLP). Some departments address this problem by assigning industrial supervisors to placement students, and mentors to new graduates. However, some universities have recently included specific modules that concentrate on quality standards in industry, as well as offering a placement year in industry.
The renaissance in analytical chemistry has been recognised and encouraged by professional bodies such as the Royal Society of Chemistry (RSC). For example, the RSC has introduced two initiatives - prizes for top analytical chemistry undergraduates, and several postgraduate studentships in analytical chemistry which are awarded in conjunction with the Engineering and Physical Sciences Research Council (EPSRC) each year. An important aspect of these initiatives is that they encourage research into analysis. While much analysis is simply a routine matter of running many samples through the appropriate apparatus and reading off the appropriate numbers, there are many areas where a genuine research input is required. New analytical methods must always be developed if the subject is to move forward. One only has to think of the advances in pharmaceutical chemistry made possible by the developments in NMR spectroscopy, mass spectrometry and X-ray crystallography, which allow synthetic or natural products to be rapidly identified. Outside chemistry the rapid advance made in DNA profiling - now perhaps the most important tool in the forensic scientists' armoury - has only been possible because of improved separation and analytical methods.
Modern analytical chemistry
So what can a student starting a course in analytical chemistry expect to be doing?
To a large extent 'wet' chemical methods, which formed a large part of laboratory classes up to about 10 years ago, have been superseded by instrumental techniques. No longer are metals determined by sulphide precipitation, or organic functional groups determined by the Lassaigne sodium test (halogens, sulphur or nitrogen), precipitation of hydrazones (aldehydes and ketones) or the 'silver mirror' test (to distinguish aldehydes from ketones). Nowadays metals are determined by one of various methods available for elemental analysis: inductively coupled plasma-mass spectrometry (ICP-MS), X-ray fluorescence (XRF), energy dispersive X-ray analysis (EDXA) or atomic absorption spectroscopy (AAS); while functional groups in organics are characterised by NMR and IR spectroscopy.
However, techniques of volumetric and gravimetric analysis are typically still taught in the first year of many courses. These are considered to be valuable in training a student in accurate and precise analytical methodology. In the later years of a course instrumental methods are introduced. While not every student will have access to all methods, many will use a wide range - especially in their final-year project work. Some students also get the opportunity of using national facilities such as the synchrotron source at Daresbury. Types of work in which undergraduate project students have had an input are discussed in Boxes 1-3.7-11
By way of example we describe how the subject is taught at two institutions, the universities of Reading and Hull. At both universities analytical chemistry is a core part of all chemistry courses and is offered to students on other degree programmes.
University of Reading
At Reading a core of compulsory analytical chemistry modules is taken by all chemistry students in their second and third years. These include an introduction to analytical methodology and a basic range of spectroscopic and chromatographic techniques. Parts of these modules are taken by students outside the school of chemistry, including pharmacy students. Transferable skills are taught within these modules.
We encourage students to take an additional module, Further analytical chemistry, which focuses on 'professional' aspects such as quality assurance and control, method validation and data handling. A range of more advanced analytical methods are also addressed here. Much of the material in this module is taught by an outside lecturer with experience in industry. Specialised modules are provided in the second and third years for students taking the BSc chemistry with forensic analysis programme. In these modules outside lecturers who have worked in the Forensic Science Service come in to discuss the application of analytical methods used to solve specific problems in forensic analysis. Students on the MChem in chemistry with analytical sciences spend one year working in the analytical chemistry industry.
University of Hull
At the University of Hull there is a strong tradition of teaching analytical chemistry, with specialist degrees in analytical and in forensic science available. In recent years there has been a move away from teaching analytical, inorganic, organic and physical chemistry separately to reflect the more holistic way in which chemical research is now done. In the first and second years students study modules that include concepts from all the different branches. For example, they learn the theory behind the spectroscopy, how the measurements are made and spectral interpretation in one module. In the third year students may complete their studies (BSc course), spend a year in industry or spend the year at Hull, before completing a fourth year, with the two MChem degree options being carefully balanced to ensure similar coverage of academic work.
The specialised third- and fourth-year modules take advantage of the research interests at the University of Hull. One of these is the miniaturisation of instrumentation into lab-on-chip devices that can be used for measurements in doctor's surgeries, at the scene of crimes or in the environment. Topics of importance to industrial employers are also covered such as process analysis, where chemical reactions are monitored as they progress so that the process can be adjusted during production. This approach can save millions of pounds, compared with analysing the final product and finding that it is out of specification. These topics are delivered and assessed by a variety of methods to ensure the students gain transferable skills, and the analytical modules are available as options to all students.
The future looks analytical
A continuing supply of high quality graduates for the chemical industry remains a priority, and schemes involving industrial training assume great importance. There is more to a well-qualified analytical chemist than an understanding of the techniques used and efforts by universities to include training in areas related to quality standards are to be applauded in this respect. We anticipate a continuing revival and healthy future for this branch of chemistry.
We thank Gillian Greenway for her useful contributions and for writing the section on analytical chemistry at the University of Hull, and Elizabeth Page for her helpful comments on this article.
Matthew Almond is a senior lecturer in chemistry in the school of chemistry at the University of Reading, UK; Lisa Marshall is a PhD student in the same school; and Samantha Atkinson is a senior scientist and study director at York Bioanalytical Solutions,York, UK.
Box 1 – Investigating a seventh century BC Greek helmet7,8
The seventh century BC Greek helmet is in the collection of the Manchester Museum. Archaeologist, Dr Alastar Jackson suspected, on the grounds of appearance and position, that the nose guard had been added in Victorian times when the helmet was discovered. Two X-ray methods - X-ray diffraction and X-ray fluorescence - were used to investigate this.
In a crystalline solid the atoms (or ions) lie on regular planes with a particular spacing (d). During X-ray diffraction a fine beam of monochromatic X-rays (of wavelength λ) are shone on the sample. Families of lattice planes within the sample diffract the beam by an angle θ whenever the conditions of the Bragg equation are met, ie
nλ = 2dsinθ
Thus individual crystalline compounds give particular patterns of peaks at specific 2θ values and with particular intensities. This approach allowed invisible traces, present on the helmet, but absent from the nose guard, to be identified as a mixture of quartz, calcite, gypsum and feldspar. These traces had come from the burial place of the helmet.
In X-ray fluorescence spectroscopy x-rays are shone onto a sample. The x-rays must have sufficient energy to promote core electrons of atoms within the sample to vacant valence orbitals. As the electrons decay back to the ground levels, x-rays are emitted by fluorescence and the energy of the emitted x-rays will be specific for a particular element because the orbitals of each element have specific energies (note: the technique only works for heavier elements). Thus the elemental composition of a sample may be obtained. In the case of the Greek helmet the researchers confirmed that the nose guard was composed of a 19th century mixture of copper and zinc, quite different from the rest of the helmet, which was forged from an alloy of copper and tin with traces of lead and iron.
Box 2 – Infrared spectroscopy in the detection of cancer9
Infrared radiation is absorbed by a sample as a result of molecular vibrations. Different groups of atoms give rise to absorption at different frequencies. The technique of infrared microscopy has been used to identify cancerous cells in biological samples, providing a back-up for current methods based upon visual identification under an optical microscope.
In a cancerous cell the increased rate of replication of DNA produces higher levels of phosphate and hydrogen-bonded OH groups. Other changes involve the tertiary structure of the proteins (α-helix or β-sheet) and the ratio of CH3 and CH2 groups. These can be detected by infrared spectroscopy and allow cancerous and normal cells to be distinguished. Although inappropriate for screening large numbers of samples, the technique is very useful when visual inspection is ambiguous.
Box 3 – Chromatography and mass spectrometry analysis10,1
Chromatography is used for separating chemical compounds. Most modern methods rely on a column containing an active solid or liquid adsorbed onto an inert solid (stationary phase) through which a mobile phase, including the compounds to be separated, is passed. The compounds are eluted at different speeds depending on their interaction with the mobile and stationary phases. The mobile phase may be gaseous (gas chromatography) or liquid. High performance methods may also be used (HPLC).
Of particular use are the so-called 'hyphenated' methods where an eluted compound from a chromatography column is passed into a mass spectrometer (GC/LC-MS). Thus the molecular weight and fragmentation pattern of the eluted compound may be determined, aiding identification. High resolution mass-selected mass spectrometry (MS-MS) is used to distinguish between ions of very similar masses, eg CH3NH2+ and CH3O+.
One use of such methods is in the analysis of pesticide residues, where foodstuffs, soils, plant material and indeed workers' clothing are monitored to search for minute residues of pesticides and their degradation products. Determination of exact isotopic ratios11 is also an important application of such methods. Here a compound eluted from a column is combusted, then reduced to yield CO2, H2O and N2. Precise mass spectrometers are used to detect the ratio of H216O to H218O, 12CO2 to 13CO2 and 14N2 to 14N15N and 15N2. Such methods have been applied to the topical issue of palaeoclimate - where climate change in the past may be related to current climate changes - and palaeodiet - where the lifestyle of prehistoric people may be better understood by considering their diet. Very small variations in 16O:18O ratios in ice may be related to small variations in climatic temperature; likewise variations in 12C:13C ratios in bone may be related to differences in diet.
1. S. J. Higson, Analytical chemistry. Oxford: OUP, 2003.
2. G. D. Christian, Analytical chemistry, 5th edn. New York: Wiley, 1994.
5. P. White (ed), Crime scene to court: the essentials of forensic science. Cambridge: RSC, 1998.
6. A. R. W. Jackson and J. M. Jackson, Forensic science. Harlow: Pearson-Prentice Hall, 2004.
9. M. Tobin et al, Investigating the potential for infrared microanalysis in cancer screening, European Clinical Laboratory, August 2002.
10. See, for example, A. Zazzo et al, Paleobiology, 2000, 26, 294.