Potential of total-reflection X-ray spectrometry for multielement analysis of biological samples using dilution or suspension sample preparation techniques

In most clinical and nutritional studies, it is of significance to know information about the multielemental composition of biological samples. Conventional analysis of biological samples relies upon sample digestion followed by atomic spectrometry detection. This approach is essential for the quantification of ultratrace elements in biological samples. While in other applications it could be of interest to have simpler analytical methods with multielemental capability but involving a minimum sample treatment, reduce the amount of sample and a more cost-effective analysis. In the present contribution, the possibilities and drawbacks of simple sample treatments (i.e., dilution and suspension) in combination with total reflection X-ray fluorescence spectrometry (TXRF) for the analysis of different types of biological samples have been critically evaluated. For that, a set of reference materials or well-characterized biological human fluids (blood, serum, plasma and seminal plasma) and animal/vegetal tissues have been used to estimate the analytical capabilities in terms of limits of detection, trueness and precision of the proposed TXRF methods. The results are based on the authors' experience in analysing biological samples using TXRF, and it is expected that they can be useful for new TXRF users in this field and they can provide a good basis for further application of this technique in clinical studies and other applications dealing with the analysis of biological samples in the future.     

Direct analysis of essential oils by means of TXRF spectrometry

Direct analysis of essential oil has been performed for estimation of the elemental content in five different extracted essential oils from the leaves of different plants, namely, Mentha longifolia, Rosmarinus officinalis, Ocimum basilicum, Elletaria cardamomum, and Lavandula hybrida. A benchtop total reflection X-ray fluorescence spectrometer with a maximum power of 40 W was used for this purpose. Fourteen elements have been quantified in most of the extracted essential oil samples, and their limits of detection were determined. The detected elements are P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Ni, and Hf. The validity of the present method was demonstrated using a standard reference material of organometallic oil sample. Two extraction methods of essential oils from leaves of the mentioned plants are evaluated, namely, classical hydro-distillation and microwave-assisted hydro-distillation. The quantitative elemental analysis of the extracted essential oils using the two extracted methods was studied and compared.     

Structural Changes of Hierarchically Nanoporous Organosilica/Silica Hybrid Materials by Pseudomorphic Transformation

Herein, it is reported how pseudomorphic transformation of divinylbenzene (DVB)-bridged organosilica@controlled pore glasses (CPG) offers the possibility to generate hierarchically porous organosilica/silica hybrid materials. CPG is utilized to provide granular shape/size and macroporosity and the macropores of the CPG is impregnated with organosilica phase, forming hybrid system. By subsequent pseudomorphic transformation, an ordered mesopore phase is generated while maintaining the granular shape and macroporosity of the CPG. Surface areas and mesopore sizes in the hierarchical structure are tunable by the choice of the surfactant and transformation time. Two-dimensional magic angle spinning (MAS) NMR spectroscopy demonstrated that micellar-templating affects both organosilica and silica phases and pseudomorphic transformation induces phase transition. A double-layer structure of separate organosilica and silica layers is established for the impregnated material, while a single monophase consisting of randomly distributed T and Q silicon species at the molecular level is identified for the pseudomorphic transformed materials.