Portable X-ray Fluorescence Equipment Research Articles

Calibration of portable X-ray fluorescence equipment for the geochemical analysis of carbonate matrices

A methodology was developed for the calibration of carbonate matrices using portable X-ray fluorescence equipment (pXRF), which involved the analysis of 11 solid mixtures prepared with certified reference material PACS-3 and an analytical CaCO3 reagent as diluent. Of the 31 elements detected in the solid mixtures, significant linear regressions (P < 0.001) were obtained for 20 of them (Al, As, Ca, Cu, Fe, Hg, Mn, Mo, P, Pb, S, Si, Sr, Ti, Zn, K, V, Rb, Y, Zr). The first 17 yielded the best fit with a correlation coefficient of >0.90. The elements Rb, Zr and Y could have been reliably measured with the pXRF if their certified concentrations in PACS-3 were reported, given that they showed a highly significant correlation (P < 0.001) with their respective percentages in the solid mixture. The main advantages of the calibration method include (1) its low cost resulting from the use of a single certified reference material, (2) an excellent linear fit (R = 0.924 to 1.000, for Mo and Zn, respectively), obtained in the calibration, and (3) the possibility of combination with other calibration techniques reported in the literature. The new calibration technique was used to determine the concentrations of major and trace elements in carbonate sediments of the Yucatan continental shelf. Finally, the spatial sampling resolution of the pXRF, equivalent to the diameter of the X-ray beam, was determined to be 6.25 ± 0.55 mm. This methodology allows rapid analysis, low cost and shows an excellent application to carbonate matrices.

Ethnomedical survey and safety evaluation of traditional eye medicines used in Misungwi district, Tanzania.

This study aimed at documenting products used as traditional eye medicine (TEM) in Misungwi district, Tanzania, and performing preliminary analysis on safety status. Ethnomedical study was conducted in Misungwi district. Information was sourced by face-to-face interview with traditional healers, traditional medicine vendors, and knowledgeable people guided by a well-structured questionnaire. Safety was evaluated by determining pH using pH meter and mineral analysis using the Delta, Portable X-ray fluorescence equipment, and qualitative chemical tests. A total of 23 TEM products were recorded from botanical (79%) and zoological (21%) sources including animal excreta. Liquid preparation ranked highest among dosage forms. Safety evaluation showed that only one product possessed the pH value of 7.4 as recommended for topical ophthalmic medicines. Fourteen minerals were detected and quantified in three samples; some of these minerals are known for their negative effects to the eyes, of medical interest is strontium used for the management of benign eye tumors. Information providers were unaware of health risks associated with the use of TEM. This study has revealed the common use of TEM in Misungwi district. The majority of the products are from the botanical source. Although literature provides supporting data for the application to some of the recorded TEM, safety evaluation by pH and mineral analysis in this study have indicated possible ophthalmological medical problems that could result from using such products. Extensive scientific studies including animal experiments and identification of bioactive compounds are essential to develop safe TEMs.

Analytical investigation of Mudéjar polychrome on the carpentry in the Casa de Pilatos palace in Seville using non-destructive XRF and complementary techniques

The pigments, execution technique and repainting used on the polychrome wood ceilings and doors in the Casa de Pilatos (Seville, Spain) were studied using portable X-ray fluorescence equipment. Cross-sections of small samples were also analysed by optical microscopy, SEM with EDX analysis, micro-Raman and micro-infrared spectroscopy and X-ray diffraction. These carpentry works are magnificent examples of the Mudéjar art made in Spain in the early 16th century. Portable X-ray fluorescence gave good information on the different components of the polychrome. The SEM-EDX study of the surfaces of small samples gave information on their components and also characterized the compounds that had been deposited or formed by environmental contamination or by the alteration of some pigments. The SEM-EDX study of cross-sections facilitated the characterization of all layers and pigments from the support to the most external layer. The following pigments were characterized: red (cinnabar/vermillion, lead oxide, iron oxides and orpiment/realgar), black (carbon black), white (white lead and titanium barium white), yellow-orange-red-brown (orpiment/realgar and iron oxides), green (chromium oxide), blue (indigo blue and ultramarine blue), and gilding (gold leaf on bole). False gold, bronze and brass were also found. The pigments were applied with the oil painting technique over a support layer that had been primed with animal glue. This support layer was gypsum in some cases and white lead in others. This study is essential to the polychrome conservation of the studied artwork, and it will help clarify uncertainties in the history and painting of Mudéjar art.

Analysis of Pre-Columbian objetcs from Cupisnique, one of the oldest culture from Perú, using a portable X-ray fluorescence equipment

Cupisnique (2000–200 BC) is one of the first complex societies that developed in the Jetequepeque valley in the “Formative period.” It includes several settlements: Puemape on the coast, Limoncarro in middle valley, Montegrande and Tembladera in the upper valley, and Kuntur Wasi in San Pablo. Currently the valley comprises two provinces, Pacasmayo and Chepen in the La Libertad region, north of Lima. Consideration should be given to cupisniques as premetallurgical culture, and the only used metal was gold, which is present in the native state, on the soil surface or shallow, and attracted attention because of color, brightness, weight, ductility, and inalterability. We analyzed three Cupisnique metal objects belonging to the Larco Museum of Lima designated with No. 4 (pectoral), No. 7 (pendant), and No. 12 (bracelet), using a portable energy-dispersive X-ray fluorescence equipment. Mean value for the pectoral were Au (62 %), Ag (23 %), Cu (15 %); for the pendant, Au (81 %), Ag (16.5 %), Cu (2.5 %); and for the bracelet, Au (69.1 %), Ag (20 %), and Cu (10.9 %).

Direct Determination of Sugar Cane Quality Parameters by X-ray Spectrometry and Multivariate Analysis

Current methods for quality control of sugar cane are performed in extracted juice using several methodologies, often requiring appreciable time and chemicals (eventually toxic), making the methods not green and expensive. The present study proposes the use of X-ray spectrometry together with chemometric methods as an innovative and alternative technique for determining sugar cane quality parameters, specifically sucrose concentration, POL, and fiber content. Measurements in stem, leaf, and juice were performed, and those applied directly in stem provided the best results. Prediction models for sugar cane stem determinations with a single 60 s irradiation using portable X-ray fluorescence equipment allows estimating the % sucrose, % fiber, and POL simultaneously. Average relative deviations in the prediction step of around 8% are acceptable if considering that field measurements were done. These results may indicate the best period to cut a particular crop as well as for evaluating the quality of sugar cane for the sugar and alcohol industries.

Conventional and Portable X-ray Fluorescence Determination of Ruthenium on Catalytic Surfaces

Determination of the amount of ruthenium in surface catalysts was important in predicting catalyst activity and projecting catalyst consumption rates. In order to develop a nondestructive analytical method for ruthenium, conventional and portable x-ray fluorescence equipment was used to analyze ruthenium in catalytic surfaces. The portable unit performed comparably to the conventional wavelength dispersive instrument, allowed larger samples to be measured, and provided linear calibration over a sufficiently large range to be useful for quality control. Calibration standards were prepared in matched pairs to allow analysis of one sample of each pair by atomic spectroscopy methods.