A green and facile direct ink writing technique for preparation calibration standards in laser ablation inductively coupled plasma mass spectrometry analysis.

BACKGROUND: Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful tool for microanalysis of solid materials. Nevertheless, one limitation of the method is the lack of well-characterized homogeneous reference materials (RMs), such as BaF2 crystal and BaCO3 ceramics samples, making direct quantification difficult. This work presents a novel Direct Ink Writing (DIW) method to produce RMs for microanalysis. The Mg, Cr, Fe, Co, Ni, Cu, Y, Mo, Pr, Gd, Dy, Ho, Er, Tm, Yb, and Lu solutions were gravimetrically doped into BaCO3 by mixing with the dispersant and then cured with DIW techniques. (94) RESULTS: BaCO3 powder was combined with a dopant analyte to produce a printable slurry, aided by the use of a dispersant and cellulose. The resulting mixture was then printed using DIW equipment. The retention rates of the doped elements were investigated by internal and external standard method, and the results showed that they were completely dispersed in the solid material. After further optimization, it was found that there was no significant heterogeneity among the printed samples. LA-ICP-MS was used to analyze printed samples, to evaluate micro-scale homogeneity. The mass concentration of the doped element was determined by ICP-MS, verify its move closer to nominal value. Compared with the traditional reference materials preparation methods, the DIW technology greatly increased the sample homogeneity and the accuracy of the desired concentration. (132) SIGNIFICANCE: As far as we know, there are few reports on the application of DIW method to prepare calibration standards. In brief, it is proved that the proposed method of preparing calibration standard by DIW technique to quantify analytes is valid and robust. This procedure provides great potential for LA-ICP-MS in-situ analysis in the field of well-prepared products, such as ceramic and crystal samples.(63).

Lead retention in a calcareous soil influenced by calcium and phosphate amendments.

Phosphate amendments in calcareous lead (Pb)-contaminated soils to immobilize Pb may be hindered due to competition of Pb with calcium (Ca) that may inhibit the retention of Pb as a precipitation mechanism. This study explored the retention of Pb in a calcareous soil spiked and aged with 500 mg kg(-1) Pb(2+) and amended with H2PO4(-). In addition, Ca(2+) was added immediately or three days before or after phosphate, after which ryegrass (Lolium perenne) was planted. Diethylene triamine pentaacetic acid (DTPA)-extractable Pb of the soils in which Ca was added immediately after phosphate was lower than those only amended with phosphate or when Ca was added three days before or after phosphate. The addition of Ca immediately after phosphate resulted in the greatest reduction of ammonia acetate-exchangeable Ca concentration, Olsen-P concentration, and carbonate phase Pb. Higher plant biomass yields were observed for the simultaneous P and Ca treatment. The results of the study demonstrate that co-added Ca and P may help reduce Pb availability by forming fresh Ca-P sorbent phases to retain Pb through an adsorption-substitution mechanism, which may play an important role in the sequestration of Pb in calcareous soils with soluble phosphate in addition to the mechanism of the direct precipitation as pyromorphite.