Combination of Total-Reflection X-Ray Fluorescence Method and Chemometric Techniques for Provenance Study of Archaeological Ceramics.

The provenance study of archaeological materials is an important step in understanding the cultural and economic life of ancient human communities. One of the most popular approaches in provenance studies is to obtain the chemical composition of material and process it with chemometric methods. In this paper, we describe a combination of the total-reflection X-ray fluorescence (TXRF) method and chemometric techniques (PCA, k-means cluster analysis, and SVM) to study Neolithic ceramic samples from eastern Siberia (Baikal region). A database of ceramic samples was created and included 10 elements/indicators for classification by geographical origin and ornamentation type. This study shows that PCA cannot be used as the primary method for provenance purposes, but can show some patterns in the data. SVM and k-means cluster analysis classified most of the ceramic samples by archaeological site and type with high accuracy. The application of chemometric techniques also showed the similarity of some samples found at sites located close to each other. A database created and processed by SVM or k-means cluster analysis methods can be supplemented with new samples and automatically classified.

Multielement analysis of continental and lacustrine ferromanganese nodules by WDXRF, TXRF, and ICP-MS methods. Intercomparison study and accuracy assessment.

Specific elemental and mineral composition of lacustrine and continental nodules differ substantially from silicate sedimentary rock, oceanic nodules, and crusts. The examination of this rock type requires study of the applicability of analytical methods to get accurate data on the elemental composition due to the lack of matrix-matched certified reference materials. In this study, multielement analysis of continental and lacustrine ferromanganese nodules was performed using various analytical methods. Samples were prepared as fused glasses and pressed pellets for wavelength-dispersive X-ray fluorescence, suspensions for total reflection X-ray fluorescence, and solutions after fusion for inductively coupled plasma mass spectrometry measurements. An intercomparison test was carried out to study the results using several analytical methods.

Features of sample preparation techniques in the total-reflection X-ray fluorescence analysis of tea leaves.

Tea is a popular drink around the world and contains essential minerals and trace elements for human health. In this study, the analytical capabilities of the total-reflection X-ray fluorescence method (TXRF) were considered for the analysis of tea. Different sample preparation techniques, e.g. suspension, open vessel acid digestion, and microwave acid digestion were examined. The influence of particle size was investigated in the analysis of the suspension of tea samples. Mass-absorption coefficients for the tea matrix and the critical surface density of the specimen were calculated. The data obtained explain the presence of absorption effects in the determination of P, S, Cl, and K in suspensions. The digestion procedure is chosen as an optimal sample preparation technique for the TXRF analysis of tea. Nineteen real tea samples were analyzed using TXRF. The advantages of TXRF have been presented through the comparison of results with the wavelength-dispersive X-ray fluorescence spectrometry method.

Development and validation of a method for multielement analysis of apatite by total-reflection X-ray fluorescence spectrometry.

Apatite group of minerals incorporates a large range of trace metals such as Sr, Y, U, Th, as well as the rare earth elements, that allows obtaining useful information on their genesis and could be used in several applications in geology and geochemistry. In this study, a new method for the multielement analysis of apatite using total-reflection X-ray fluorescence spectrometry (TXRF) was developed. The acid digestion procedure was chosen as an optimal sample preparation with the capability to analyze a low sample amount (~5-10 mg). The validation of the method passed through the combination of procedures: analysis of Durango and Otter Lake well-known apatite samples; using inductively coupled plasma mass spectrometry and wavelength-dispersive X-ray fluorescence spectrometry as reference analytical methods; assessment of the measurement uncertainty. The proposed TXRF method is advantageous in being fast, cheap and simple for the multielement analysis of apatite with high accuracy.

Wavelength dispersive X-ray fluorescence determination of major oxides in bottom and peat sediments for paleoclimatic studies.

The wavelength dispersive X-ray fluorescence method was applied to identify the distribution of major oxides within bottom and peat sediments containing organic matter of up to 70 wt.%. Samples were prepared as glass beads by fusing with lithium metaborate. The accuracy of results was assessed by flame photometry, spectrophotometry, and flame atomic absorption techniques. The proposed technique requires a sample weighing only 110 mg, which allows to analyze each centimeter of core collected at high-mountainous sites with undisturbed environment and eventually achieve uniquely high resolution of paleoclimatic reconstructions of global and regional climatic and environmental changes.

Analytical approaches for determination of bromine in sediment core samples by X-ray fluorescence spectrometry.

Bromine has been recognized as a valuable indicator for paleoclimatic studies. Wavelength dispersive X-ray fluorescence (WDXRF) and total reflection X-ray fluorescence (TXRF) methods were applied to study the bromine distributions in lake sediment cores. Conventional WDXRF technique usually requires relatively large mass of a sediment sample and a set of calibration samples. Some analytical approaches were developed to apply WDXRF to small sediment core samples in the absence of adequate calibration samples with a known Br content. The mass of a sample to be analyzed was reduced up to 200-300mg and the internal standard method with correction using fundamental parameters was developed for Br quantification. TXRF technique based on the direct analysis of a solid suspension using 20mg of sediment sample by internal standard method was additionally tested. The accuracy of the WDXRF and TXRF techniques was assessed by the comparative analysis of reference materials of sediments, soil and biological samples. In general, good agreement was achieved between the reference values and the measured values. The detection limits of Br were 1mg/kg and 0.4mg/kg for WDXRF and TXRF respectively. The results of the Br determination obtained with different XRF techniques were comparable to each other and used for paleoclimatic reconstructions.