Surface mapping by laser assisted plasma spectrometry


                                        Kateřina Štěpánková

    Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno,
                                          Czech Republic


This study is focused on urinary stones. The distribution of major, minor and trace elements in
urinary stones can provide information on their formation. Therefore, analytical methods, which can
map the distribution of these elements, should be used. The most common methods include
Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass
Spectrometry (LA-ICP-MS).

Investigated urinary stones were cut, sealed into a resin and the cross-section of the sample was
polished and was mapped by laser-ablation based analytical methods. On the base of these
measurements the correlation between calcium and carbon distribution for samples containing
whewellite or weddellite (or both of these minerals) was confirmed. The correlation between
magnesium and phosphorus can be attributed to the presence of struvite. The correlation between
calcium and phosphorus distribution indicates the presence of apatite. Quantification of laser
ablation based methods is still very problematic and these methods are often used only for
qualitative elemental mapping. There are no commercially available standards, which would
correspond to urinary calculi matrix. Internal standardization is also difficult, mainly due to
different crystalline phases in one kidney stone. For this study the calibration pellets were
prepared from human urinary calculi with phosphate, oxalate and urate matrix. For this comparative
study the most frequently used laser-ablation based analytical techniques were chosen, such as LIBS
and LA-ICP-MS. Moreover some unconventional techniques such as simultaneous LIBS – LA-ICP-OES and
laser ablation (LA) – LIBS were also utilized.