Spectroscopy Articles

This article provides a valuable summary of the choice of sample clean-up methods available for the quantification of small molecules in body fluids. What are the key factors? Judy outlines the principal processing methods and provides practical advice on protocol development using quantification of serum testosterone in serum samples as the model compound.

Spectroscopy is widely used in forensics, but the determination of the age of documents was one application I had not considered. With a huge variety of papers and inks available, each with their own ageing profiles, and with such ageing depending on environmental factors, the determination of the age of a document is not straightforward. However, infrared spectroscopy and chemometrics may have the answer.

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.

In this work we demonstrate the suitability of confocal Raman microscopy for the characterisation of carious dental tissues. Samples of enamel and dentine, presenting carious lesions in different stages of progression, were evaluated by comparing the depolarisation ratio of the PO₄^3– symmetric stretching band at 959 cm^–1 in the different tissues. Both line and area scans were performed to gauge these variations. Moreover, the obtained results were compared with the tissues’ behaviour when interacting with ultraviolet radiation, namely the induced fluorescence in some tissues. The depolarisation ratio has proven to be a valuable tool in recognition of demineralisation of both enamel and dentine due to caries. The analyses of the collagen bands in the dentine sample turned out to be more difficult to evaluate due to high fluorescence in the carious region.

In this article the question of the certification of calibration samples for the characterisation of advanced thin film materials is addressed within the framework of reliable process control or quality management purposes. Reference measurement techniques can be used in order to address the gap in appropriate certified reference materials (CRMs) for thin film analyses. They allow for qualifying out-of-production samples originating from an operating production line as calibration samples. As a template for this procedure, CIGS [Cu(In,Ga)Se₂] layers, that are absorber layers for high efficiency thin-film solar cells, have been used for establishing and validating reference-free X-ray fluorescence (XRF) analysis and Auger-electron spectroscopy (AES) as reference measurement techniques.

Dmitry Gakamsky and Anna Gakamsky describe how fluorescence may be used to diagnose cataracts in human eye lenses. Further, it may also be able to grade cataracts and monitor the disease’s progress, which may help discover metabolic and ambient factors that influence the progress of the disease.

X-ray spectroscopy techniques have some advantages over other atomic spectroscopy techniques in the analysis of foods, for instance in not requiring significant sample preparation. Amongst these, TXRF has higher sensitivity and limits of detection in the ng range. The authors look at the analysis of a number of very different foods, including seafood, honey and vegetables.

The CAL(AI)²DOSCOPE (Cryogenic Absorption/Luminescence Alignment Independent Alternative Intermittent Detection Optical µSCOPE) is a microspectrometer that was constructed with the aim to facilitate the correlated investigation of absorption and fluorescence emission properties of nanovolumic protein samples under modulatable actinic illumination.