Application of Multi-energy Calibration for Determination of Chromium and Nickel in Nickeliferous Ores by Laser-induced Breakdown Spectroscopy.

A multi-energy calibration method was applied for the determination of chromium and nickel in nickeliferous ores by laser-induced breakdown spectroscopy. For the optimization of the laser-induced breakdown spectroscopy parameters, such as laser fluence and delay time, an experimental study was conducted. The best results in terms of trueness were observed using a laser fluence and a delay time of 2500 J/cm2 and 1.1 µs, respectively. A study of sample matrix effects and the determination of emission lines for calibration and normalization of the spectra were undertaken, and appropriate values of those variables were selected for each analyte. The trueness values for chromium and nickel varied from 89 to 114% when certified reference samples (nickeliferous laterite, rock phosphate and contaminated soil) were analyzed.

Assessment of sediment pollution by metals. A case study from Cienfuegos Bay, Cuba.

Sediments were grouped in three zones of the bay: two in the northern basin with higher metal contamination; and another in the southern basin, where lithogenic metals were predominant. Sediment pollution classification made using Index of geoaccumulation and Enrichment factor was consistent, indicating higher accumulation of Cd and Pb in the northern basin. The negative influence of activities linked to petrol was predicted by V/Ni and V/(Ni+V) ratios. Cd and Pb did not represent a potential risk; while Cu and Ni could be risky for biota in most sediment, according to Screening Quick Reference Tables (SQuiRTs). Comparison of bioavailable fraction of metals with references in SQuiRTs corroborated the low potential damage on the biota due to As, Cd, Pb, Cr, Zn; and a higher potential damage due to Cu; while an attenuation of the risk due to Ni predicted by SQuiRTs could be expected.

Multielemental inductively coupled plasma optical emission spectrometry analysis of nickeliferous minerals.

An inductively coupled plasma optical emission spectrometry method for the quantitative simultaneous determination of Al, Ca, Co, Cu, Cr, Fe, K, Mg, Mn, Na, Ni, P and Zn in Cuban laterite and serpentine minerals has been developed. Additionally, V and Ti can be quantitatively determined in laterite mineral; Li, Sr, and Zr can be detected in both mineral types and Pb can be detected just in laterite mineral. The microwave-assisted total acid digestion of samples was achieved with HCl+HNO3+HF and HNO3+HClO4+HF acid mixtures for laterite and serpentine samples, respectively. In non-robust plasma operating conditions, the matrix effect characteristics of the laterite sample were dictated by the principal component Fe; while the character of the Mg principal component matrix effect was some how modified by the concomitants Fe and Ni in serpentine sample. The selection of robust conditions decreased the matrix effect. Additionally, the simulation of the matrix samples by introducing the principal component Fe or Mg, correspondingly, in calibration dissolutions was needed to overcome completely the matrix effect over the analysis accuracy. Precision of analysis was very near or lower than 10% for most elements, except Sr (15%) in L-1; and K (15%) and Li (15%) in SNi sample. Accuracy of analysis was around or lowers than 10% for most elements, except K (15%), Na (19%), P (19%) and V (19%) in L-1 sample; and Ca (14%) and P (20%) in SNi sample.