On the effect of using collision/reaction cell (CRC) technology in single-particle ICP-mass spectrometry (SP-ICP-MS)

In this work, the effects of using collision/reaction cell (CRC) technology in quadrupole-based ICP-MS (ICP-QMS) instrumentation operated in single-particle (SP) mode have been assessed. The influence of (i) various CRC gases, (ii) gas flow rates, (iii) nanoparticle (NP) sizes and (iv) NP types was evaluated using Ag, Au and Pt NPs with both a traditional ICP-QMS instrument and a tandem ICP-mass spectrometer. It has been shown that using CRC technology brings about a significant increase in the NP signal peak width (from 0.5 up to 6¿ms). This effect is more prominent for a heavier gas (e.g., NH3) than for a lighter one (e.g., H2 or He). At a higher gas flow rate and/or for larger particle sizes >100¿nm), the NP signal duration was prolonged to a larger extent. This effect of using CRC technology has been further demonstrated by characterizing custom-made 50 and 200¿nm Fe3O4 NPs (originally strongly affected by the occurrence of spectral overlap) using different CRC approaches (H2 on-mass and NH3 mass-shift). The use of NH3 (monitoring of Fe as the Fe(NH3)2+ reaction product ion at m/z¿=¿90 amu) induces a significant peak broadening compared to that observed when using H2 (6.10¿±¿1.60 vs. 0.94¿±¿0.49¿ms). This extension of transit time can most likely be attributed to the collisions/interactions of the ion cloud generated by a single NP event with the CRC gas and it even precludes 50¿nm Fe3O4 NPs to be detected when using the NH3 mass-shift approach. Based on these results, the influence of a longer peak width on the accuracy of SP-ICP-MS measurement data (NP size, particle number density and mass concentration) must be taken into account when using CRC technology as a means to overcome spectral overlap. To mitigate the potential detrimental effect of using CRC technology in the characterization of NPs via SP-ICP-MS(/MS), the use of light gases and low gas flow rates is recommended

Non-destructive characterisation of the Elephant Moraine 83227 meteorite using confocal Raman, micro-energy-dispersive X-ray fluorescence and Raman-scanning electron microscope-energy-dispersive X-ray microscopies

The application of a non-destructive analytical procedure to characterise the mineral phases in meteorites is a key issue in order to preserve this type of scarce materials. In the present work, the Elephant Moraine 83227 meteorite, found in Antarctica in 1983 and originated from 4 Vesta asteroid, was analysed by micro-Raman spectroscopy, micro-energy-dispersive X-ray fluorescence and the structural and chemical analyser (Raman spectroscopy coupled with scanning electron microscopy-energy-dispersive spectroscopy) working in both point-by-point and image modes. The combination of all these techniques allows the extraction of, at the same time, elemental, molecular and structural data of the studied microscopic area of the meteorite. The most relevant results of the Elephant Moraine 83227 were the finding of tridymite for the first time in a 4 Vesta meteorite, along with quartz, which means that the meteorite suffered high temperatures at a certain point. Moreover, both feldspar and pyroxenewere found as the main mineral phases in the sample. Ilmenite, apatite, chromite and elemental sulphur were also detected as secondary minerals. Finally, calcite was found as a weathering product, which was probably formed in terrestrial weathering processes of the pyroxene present in the sample. Besides, Raman spectroscopy provided information about the conditions that the meteorite experienced; the displacements in some feldspar Raman bands were used to estimate the temperature and pressure conditions to which the Elephant Moraine 83227 was subjected, because we obtained both low and high formation temperature feldspar.Proyecto MINECO Retos de la Sociedad. Ref. ESP2014-56138-C3-2-

Mineral concentrations in hair of Belgian elementary school girls : reference values and relationship with food consumption frequencies

Although evidence suggests that hair elements may reflect dietary habits and/or mineral intake, this topic remains controversial. This study therefore presents age-specific reference values for hair concentrations of Ca, Cu, Fe, Na, Mg, P and Zn using the LMS method of Cole, and investigates the relationship between dietary habits (i.e. food consumption frequencies) and hair mineral concentrations in 218 Belgian elementary school girls by reduced rank regression (RRR). Hair minerals were quantitatively determined via inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion of 6-cm long vertex posterior hair samples. The Children's Eating Habits Questionnaire-Food Frequency Questionnaire was used to obtain information on food consumption frequency of 43 food items in the month preceding hair collection. The established reference ranges were in line with data for other childhood or adolescent populations. The retained RRR factors explained 40, 50, 45, 46, 44 and 48 % of the variation of Ca, Cu, Fe, Mg, P and Zn concentrations in hair, respectively. Although this study demonstrated that a large proportion of hair mineral variation may be influenced by food consumption frequencies in elementary school girls, a number of food groups known to be rich sources of minerals did not show a relation with certain hair minerals. Future research should focus on mechanisms and processes involved in mineral incorporation and accumulation in scalp hair, in order to fully understand the importance and influence of diet on hair minerals

Cross-sectional relationship between chronic stress and mineral concentrations in hair of elementary school girls

Chronic stress exposure is associated with diverse negative health outcomes. It has been hypothesised that stress may also negatively affect the body's mineral status. This study investigates the association between chronic stress and long-term mineral concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P) and zinc (Zn) in scalp hair among elementary school girls. Complete information on child-reported stress estimates (Coddington Life Events Scale (CLES)), hair cortisone and hair mineral concentrations, and predefined confounders in the stress-mineral relationship (i.e. age, body mass index, physical activity, diet, hair colour and parental education) was provided cross-sectionally for 140 girls (5-10 years old). The relationship between childhood stress measures (predictor) and hair minerals (outcome) was studied using linear regression analysis, adjusted for the abovementioned confounders. Hair cortisone concentrations were inversely associated with hair mineral concentrations of Ca, Mg, Zn and the Ca/P ratio. Children at risk by life events (CLES) presented an elevated Ca/Mg ratio. These findings were persistent after adjustment for confounders. This study demonstrated an independent association between chronic stress measures and hair mineral levels in young girls, indicating the importance of physiological stress-mineral pathways independently from individual or behavioural factors. Findings need to be confirmed in a more heterogeneous population and on longitudinal basis. The precise mechanisms by which stress alters hair mineral levels should be further elucidated