Articles

Nick Polfer gives an excellent introduction to the recent technique of infrared ion spectroscopy. Ions held in the ion trap of a mass spectrometer can be probed with a tuneable light source, and its photodissociation studied as a function of the photon frequency. Nick believes that the technique will make an impact in small molecule analysis, such as metabolites, drugs and classes of molecules containing many isomers.

Different spectroscopic techniques have been combined to provide additional and complementary information for decades. Increasingly, this is being expanded beyond just two techniques and may include spatial/imaging information as well. All of which bring their own challenges. In “Multimodal imaging of cells and tissues: all photons are welcome”, David Perez-Guaita, Kamila Kochana Anja Rüther, Phillip Heraud, Guillermo Quintas and Bayden Wood report an example of these new approaches. They look at the use of infrared, Raman and X-ray fluorescence spectroscopies to obtain combined imaging data of whole algal cells and discuss how to overcome the challenges.

We all know how spectroscopy and other analytical technologies have played important roles in detecting fraud and in authentication. Paper collages, or photomontages, are part of the art market that is seeing much interest amongst collectors. It is difficult to detect forgeries just through expertise. The use of NIR imaging offers a number of ways to identify forgeries or authenticate the collage non-destructively; from determining the glue used to the revealing of printing on the back of the pieces or paper, which often have been taken from books and magazines.

It is not every issue that one of our articles starts with a quotation in medieval English, and it is appropriate as two of our articles cover the use of spectroscopy in cultural heritage. This is yet another field where the rich information provided by spectroscopy, along with its non-destructive nature (for many techniques), portability and ability to generate chemical images make it the answer to many questions. Kate Nicholson, Andrew Beeby and Richard Gameson are responsible for the medieval English at the start of their article “Shedding light on medieval manuscripts”. They describe the general use of Raman spectroscopy for the analysis of historical artefacts, and, in particular, their work on medieval European manuscripts and 18th century watercolour pigments. They stess the importance of checking the actual laser power density to avoid damage to priceless artefacts.

Benchtop mid-IR and NIR as well as portable NIR instruments are used for quick and non-invasive quality control of this traditional Chinese medicine. Adulterations could be detected, as well as the raw herbs and different sources of the Si-Wu-Tang. The success of the mobile NIR instrument is particularly interesting due to the growing interest in such technology for its ease-of-use and cost.

Much of the exterior surface of plants is covered by the cuticle. This plays a vital role in protecting the plant from water loss, attack by pests and pathogens and damage from UV radiation. Infrared spectroscopy is very useful in characterising cuticles, as we learn in “Infrared spectroscopy as a tool to study plant cuticles” by José Heredia-Guerrero, José Benítez, Eva Domínguez, Ilker Bayer, Roberto Cingolani, Athanassia Athanassioua and Antonio Heredia. The authors point out that, whilst still in its early stages, infrared spectroscopy has provided valuable information about the functional groups, chemical structure and arrangement and interactions of plant cuticle components.

In this Tony Davies Column, we learn about “Automated detection of counterfeit drugs using multimodal spectroscopy and advanced web-based software platforms”. The German authorities have commissioned the development of a multi-modal, transportable inspection system, including intelligent data processing and evaluation, for fast spectroscopic recognition of illicit drugs and counterfeit medicines. This is described in the column.

The authors describe “Infrared mapping spectroscopic ellipsometry”. Recent developments in fundamental and materials research have increased the value of mapping techniques such as ellipsometry. IR ellipsometry, since it operates in the mid-IR fingerprint region, provides complementary information on composition, structural properties and interactions

“Optical spectroscopy in therapy response monitoring: an awakening giant” by Arja Kullaa, Surya Singh, Jopi Mikkonen and Arto Koistinen looks at the important advances made by optical spectroscopy techniques, such as diffuse optical spectroscopic imaging (DOSI), Raman, diffuse reflectance and fluorescence spectroscopy, in changing how cancer is managed in patients. The ability to repeatedly monitor tumour dynamics to see how effective a particular treatment has been has enormous potential for us all.