The VU laboratory for element and isotope analysis offers the following facilities:
XRF – X-ray fluorescence
PANalytical Axios mAX
X-Ray fluorescence is a widely used analytical technique to determine the major and trace element composition of solid and liquid samples. Geologists use XRFs as a tool to determine major elements on glass beads and trace elements on pressed powdered tablets. In an XRF instrument these beads or pellets are bombarded with primary X-rays derived from a Rh X-ray tube. These x-rays push electrons out of the inner orbitals of an atom. The vacancy in the orbitals is filled up by electrons from outer orbitals, that send out element specific secondary X-rays. These elemental specific X-rays are analysed by selecting the specific wavelength, and after correction for the matrix and/or interferences permits the identification and quantification of the elements present in the sample. The advantages of XRF analysis are that is fast, non-destructive, cheap and very stable compared to ICP-OES and ICP-MS analysis. The disadvantages are that the detection limit for trace elements is at best 1 ppm.
Quadrupole ICP-MS – Inductively coupled plasma mass spectrometry
Thermo Scientific X-Series II
Our ICP-MS is used for rapid, precise and accurate analyses of trace elements (<1000 ppm). Routinely, we analyse >40 elements from Li to U quasi-simultaneously in a couple of minutes per sample. Samples are mainly introduced as solution via a quartz dual cyclonic spray chamber, but analyses of solid samples by laser ablation is possible (MicroLas GeoLas Q plus 193 nm ArF excimer laser). Limits of quantification for liquid samples are generally, depending on the element, between 0.1 ppt and 0.1 ppb.
ICP-OES – Inductively coupled plasma optical emission spectroscopy
The ICP-OES is used for analyses of major and trace elements. It allows for large sample throughput due to short analysis time (< 5 min per sample). Samples are usually introduced as solution. Limits of quantification are typically in the range of 0.05 to 10 ppb, depending on the element.
(LA)-MC-ICP-MS – (Laser ablation) Multi-collector inductively coupled plasma mass spectrometry
Thermo Scientific Neptune Plus
Our Neptune with Plus upgrade is equipped with 9 Faraday cups, which can be connected to 9 standard 1011 Ω and one 1013 Ω amplifier. In addition, it is equipped with 6 ion counters (one with a Retarding Potential Quadrupole (RPQ)). High resolution (mass resolving power up to ~12000) allows for resolving molecular isobaric interferences (e.g., 40Ar16O+ on 56Fe+). Samples are introduced as solution via a quartz dual cyclonic spray chamber (‘wet plasma’) or an Aridus II desolvator (‘dry plasma’) or as aerosols by laser ablation (MicroLas GeoLas Q plus 193 nm ArF excimer laser). We routinely analyse radiogenic isotopes (Pb, Lu/Hf, Sm/Nd, U/Th) as well as non-traditional stable isotopes (Si, Fe, Cu, Zn, Ba, Ti).
TIMS - Thermal Ionisation Mass spectrometry
Thermo Finnigan MAT-262 RPQ plus
The MAT-262 has 8 Faraday cups equipped with standard 1011 Ω amplifiers and a central secondary electron multiplier (SEM) equipped with an RPQ. The instrument is primarily used for (automatic) triple jump Strontium (Sr) isotope analysis of large (>100ng Sr) geological or archeological samples. Rubidium (Rb) concentration analysis (Isotope dilution) of small samples are run statically on the MAT-262.
Thermo Scientific Triton Plus
The Triton Plus has nine Faraday cups, three SEMs (one with RPQ) and three compact discrete dynodes (CDD). The Faraday cups can be connected to 10 different amplifiers using a ‘Virtual Amplifier’ relay matrix. The amplifiers are equipped with two types of resistors; 1011 and 1013 Ω used for analysis of conventional and small beam sizes, respectively. The 1013 Ω have 100 times higher signal output whereas they have relatively lower noise levels, resulting in increased precision when analysing small beams. We have six conventional 1011 Ω amplifiers installed, and four 1013 Ω and specialise in analysing Sr, Nd, Sm and Pb isotopes in small samples. The set-up, in combination with ultra-low blank chemical separation allow precise analyses of samples as small as 2 ng Sr and 30 pg Nd and 250 pg Pb. We also routinely automatically analyse the isotopic composition of larger amounts of Sr, Nd, Sm, Pb and in addition have the option to run elements as oxides and/or in negative mode (e.g. Os).
Dr. Pieter Vroon
+31(0)20 59 87404