XRF - Laboratory for X-ray fluorescence spectrometry

Jožef Stefan Institute,
Jamova 39,
SI-1000 Ljubljana,
Slovenia

T:+3861477368

Leader: Dr Marijan NečemerCoworkers: Prof. Dr Katarina Vogel-Mikuš, Dr Peter Kump

Activities

•   we carry out studies, monitoring, non-destructive characterization of materials, control of the origin of various materials, authenticity within current domestic and international projects, as well as for external clients, administrative and inspection bodies
•   conduction of various studies on the effects of contaminated areas on vegetation, research of responses and establishment of defence and tolerance mechanisms of plants on the accumulation of heavy metals (phytoremediation, hyperaccumulators)
•   development of statistical models for tracing the geographical origin of food of plant and animal origin

Determination of elemental content is performed on various samples and objects from the natural and working environment:
•   aerosols
•   surface and ground waters
•   soils
•   sediments
•   plant and animal materials
•   objects of cultural heritage and archaeological excavations
•   metallic materials, stainless and special steels, alloys, precious metals and alloys
•   scrap metals and alloys
•   building materials
•   geological materials
•   industrial and municipal sewage
•   industrial raw materials
•   materials from the chemical, pharmaceutical processing industry
•   materials from landfills, mine tailings

A special feature of XRF analysis in our laboratory is the platform for quantitative XRF analysis of the elemental composition of the sample (Figure 1), developed by Dr. Peter Kump

Figure 1. Software platform for quantitative XRF analysis of the elemental composition of the samples, developed in our laboratory The platform allows easy and transparent measurements and quantitative analysis of the XRF spectrum of the measured sample, all in one place.

Projects

Methods

In the XRF laboratory we have several systems:

X-ray fluorescence spectrometers with the radioisotope sources Fe-55, Cd-109, Am-241. The excitation is monochromatic, the background during the measurement is small, so that the detection limit for single elements is down to 0.1 µg/g. The technique is particularly suitable for measurements of environmental, biological, food, pharmaceutical, industrial and cultural heritage samples. The Fe-55 system operates in a vacuum. It is possible to measure solid samples in the form of a pellet (d = 2.5 cm). The Cd-109 and Am-241 systems work under room conditions. Measurements in the form of a pellet (d = 2.5 cm) as well as larger industrial or heritage samples can be performed.
The portable XRF spectrometer (Peduzo T01) with Rh anode is the result of our own development and construction (P. Kump, Z. Rupnik, D. Ponikvar). It is equipped with an SDD detector (Amptek) and the software is developed in a Labview environment. The excitation is polychromatic. The spectrometer is portable and useful for field measurements and for measurements of bigger samples from industry and cultural heritage. Measurements can also be performed on pelleted samples (d = 1 cm, 1.3 cm and 2.5 cm).

Figure 2: Portable XRF spectrometer designed and assembled in our laboratory

Laboratory XRF with Mo anode. The excitation is polychromatic. The spectrometer is suitable for the measurements of samples in the form of pellets (d = 1 cm, 1.3 cm and 2.5 cm) and larger industrial and cultural heritage samples.
TXRF system with Mo anode. The excitation is monochromatic. The technique is suitable for the measurement of special samples where only a small amount of sample (a few mg) is available (e.g. biological samples such as isolated proteins, gametes, expensive active pharmaceutical ingredients) and therefore analysis by ICP-MS is not possible. The sensitivity of the system is 10⁻⁹ g of the element in the sample. The TXRF system is based on a module which is a result of our own development (Dr. P. Kump). The system is equipped with a SiLi detector. The sample preparation is based on the application of a small amount of liquid (10 µL) on quartz glass slides with subsequent drying. In the module the sample is irradiated at an extremely small angle (less than 0.1 rad).

Figure 3 a) Sample preparation for TXRF, b) TXRF module

Samples of analysis

Programs and projects

International projects:

COST CA18130 European Network for Chemical Elemental Analysis by Total Reflection X-Ray Fluorescence (2019-2022)
Europe Regional (International Atomic Energy Agency, IAEA) TC Project (RER7009) on Enhancing Coastal Management in the Adriatic and the Black Sea by using Nuclear Analytical Techniques, under the framework of TC Project RER7009, (2018-2019).
REALmed (No. 9104) REALMed Pursuing authenticity and valorization of Mediterranean traditional products – Contract No: 3330-17-500186 (2017-2019)
ERA Chair ISO-FOOD ERA CHAIR for isotope techniques in food quality, safety and traceability (2014-2019)
IAEA Project under Contract No. 17897 entitled “The use of stable isotopes and elemental composition for determination of authenticity and geographical origin of milk and dairy products” as part of CRP D5.20.38 “Accessible technologies for the verification of origin of dairy products as an example control system to enhance global trade and food safety” (2014-2016)
IAEA’s Coordinated Research Project (CRP); Applications of synchrotron radiation techniques with particular emphasis on interdisciplinary sciences; Studies of localization and chemical speciation of trace elements in crop plants using synchrotron micro-spectroscopy techniques for improving food quality and safety (2010-2013).
IAEA’s Coordinated Research Project (CRP); IAEA 1576; Micro-analytical Techniques Based on Nuclear Spectrometry for Environmental Monitoring and Material studies; Complementing the X-ray spectrometry activities with micro-beam facility for different applications ((2011-2013)
Bilateral project Slovenia Belgium Ion distribution and heavy metal tolerance: a comprehensive approach toward the use of plants for soil decontamination (2010-2012)
SPIRIT, Support of public and industrial research using ion beam technology, analysis of plant materials at Microanalitical center at IJS (2009-2012).
Slovenian-Greece bilateral project; Analysis of Slovenian and Greece wines and waters by TXRF, 2002-2005.
EU Copernicus project (CIPA-CT94-0210) Validation of Instrumental Trace Element Analysis for Quality Monitoring in the Drinking and Mineral Water Industry, 1995-1996.

National projects:

(2010- ) P6-0282), Objects and prestige: taste, status, and power (Researches of the material culture in Slovenia), Dr. Tomaž Lazar
(2019-2022) N1-0105, Spatial localization of elements and metabolites in plants, Prof.Dr. Katarina Vogel Mikuš
(2018-2021) J7-9418, Ionom of crop plants for safe and quality food production, Prof.Dr. Katarina Vogel Mikuš
(2018-2021) L4-9305, Localy grown buckwheat grain for production of high quality food products, Dr. Kušar Anita
(2014–2017) J7-6857, Vegetation and hydrology of Ljubljansko barje in the past, present and future - a consequence of succession, human impact or climatic fluctuations?, Dr. Maja Andrič
(2014-2016) V4-1408, Evaluation of quality and safety parameters of vegetables produced on different systems in Slovenia and abroad with aim to establish national quality scheme for vegetables, Prof.Dr. Rajko Vidrih
(2011-2014) V4-1108, The use of specific methods for determination and prevention of adulteration of milk and dairy products, Prof. Dr. Nives Ogrinc
(2011-2013) L2-4072, Complex hyperspectral system for automatic analysis and control of pharmaceutical pellet coating processes, Prof.Dr. Boštjan Likar
(2011-2013) J6-4085, Archaeologies of hunter-gatherers, farmers and metallurgists: Cultures, populations, palaeoeconomies and climate, Prof.Dr. Mihael Budja
(2011-2013) Research Ionic homeostasis in plants with the help of map elements in the tissues by laser ablation-Inductively coupled plasma mass spectrometry, Dr. Johannes Van Elteren
(2011-2013) J1-4117 Research of the ionome of selected mycorrhizal plants, Prof. Dr. Marjana Regvar.
(2010-2012) V4-1047, Slovenian Nutrition Tables - Foods of Vegetable origin, Prof.Dr. Terezija Golob
(2008-2010) V4-0516 Authenticity and quality of honey at the slovenian market, Dr. Marijan Nečemer
(2005-2008) V4-0416: Determination og geographical and botanical origin of slovenian honey, Dr. Marijan Nečemer
(2005-2008) L1-7060, Use of X-ray analytical techniques, Dr. Peter Kump
(2005-2008) L1-7001, Cartography of the Sečovlje salt-pans flora and the cultivation of native glasswort species, Dr Marijan Nečemer
(2003-2005) L1-5146, Tolerance of organisms in stressed ecosystems and potential for remediation, Prof.Dr. Marjana Regvar
(1999-2001) L4-1475, Chemical composition and nutritive value of slovenian beef meat, Dr. Božidar Žlender
(1998-2001) L1-0583, Analytical techniques based on X-ray fluorescence, Dr. Peter Kump
(1998-2001) T6-0388, Investigation of technology of medieval glass objects production, Dr. Mateja Kos Zabel

The XRF Laboratory was established in 1992 at Jožef Stefan Institute by dr. Peter Kump with the aim of providing users with fast, non-destructive multi-element characterization of a wide range of materials from the fields of environment, biology, food, pharmaceuticals, metals, industry and semi-finished products, cultural heritage and of archaeological origin. XRF provides a fast, easy and non-invasive insight into the elemental composition of samples that are either solid (e.g. metals, environmental, biological and chemical samples) or (semi-)liquid (e.g. viscous substances such as paints, honey, body fluids).

We can determine a wide range of elements from Al to U (also S, P, Cl, Se, Br, I, rare earth elements Sc, Y, Nd, La, Ce, Pr, Pm, Sm etc.). We have several energy dispersive spectrometers (EDXRF) with excitation by radioactive sources (Fe-55, Cd-109, Am-241) or X-ray tubes (Mo, Rh anode) and TXRF (X-ray spectrometry with total reflection).

The analysis of solid samples is performed directly or with minimal preparation, which includes drying, grinding, milling and compression of the pellets. (Semi-)liquid samples can also be analysed directly by TXRF.

XRF is a complementary method to AAS, OES and ICP-MS, with the advantage that the XRF analysis is relatively simple, with low costs for sample preparation, as chemical degradation by acids and microwave-assisted digestion is not required. It is not necessary to dilute the samples, and with XRF analysis we can also detect elements that were not expected in the sample after only a few minutes of measurement. Taking into account the measurement and the quantitative analysis of the spectrum, the analysis takes some 10 minutes, with TXRF 3 minutes. The detection limit of EDXRF ranges from 1 to few 10 µg/g, and 0.1 to 1 µg/g in the case of TXRF, depending on the material and the individual element.

A special feature of the XRF analysis in our laboratory is the software package for quantitative XRF analysis of the elemental composition of the samples, based on fundamental parameters, developed by dr. Peter Kump. The problem with quantitative XRF analysis is that some elements do not response on the detection system. These are mainly C, N and O, which are the components of the so called "dark matrix". With the help of an innovative approach of the measurement of the total absorption on the sample, it is possible to determine the "dark matrix" of the sample experimentally, which then serves as the basis for calculating the final concentrations of the elements in the sample.