Determination of trace and major elemental profiles in street dust samples by fast miniaturized ultrasonic probe extraction and ICP-MS

Optimization and validation test of a sonoreactor-assisted methodology for fast and miniaturized extraction of trace elements from soils

We have proven the overall applicability of the novel sonoreactor VialTweeter as a tool for a fast, miniaturized and economical extraction of trace elements, namely Cu, Zn, As, Cd, Pb, from soil samples, followed by ICP-MS. The proposed analytical approach applicable in the context of environmental monitoring of elemental soil pollutants, since the selected analytes are relevant pollutants whose presence in soils produces significant effects on their quality affecting animals, plants and humans. The optimum conditions for the extraction of trace metals assisted by the sonoreactor, selected by a Box-Behnken (BBD) experiment design along combined with a response surface methodology were 93% sonication amplitude, 450 s sonication time, 80% HNO₃ and a solvent/sample ratio of 0.18 mL/mg. The proposed sonoreactor-assisted extraction methodology provides several advantages of respect to the standard acid digestion taken as comparison term for validation, including a shorter pretreatment time and use of less sample and reagents amounts. However, mixed validation results against the standard acid digestion (taken as a model providing accurate results) were obtained depending on the analyte, with the best results in the case of cadmium that could be measured after US extraction without systematic error respect to the standard acid digestion. Copper and lead can be determined by the proposed US extraction plus ICP-MS only after applying a correction factor based on the slope of the correlation with the standard acid digestion. US treatment for As determination can be only useable by applying a constant correction factor based on the intercept of the correlation line, whereas Zn determination requires a correction based both in the slope and intercept of the correlation line.

A feasible strategy based on high ultrasound frequency and mass spectrometry for discriminating individuals diagnosed with bipolar disorder and schizophrenia through ionomic profile

RATIONALE

A viable and accurate method based on high-power ultrasound-assisted microextraction and inductively coupled plasma mass spectrometry was developed to determine metals in human serum from patients with bipolar disorder and schizophrenia.

METHODS

A simple and rapid sample preparation method using a cup-horn sonoreactor was developed. The acid concentration of HNO₃ (10, 20, and 40% v/v) and HCl (1, 5, 15, and 30% v/v) of the extraction solution, the sonication time (1, 3, 6, and 10 min), and the sonication amplitude (20, 40, 60, and 80%) were evaluated. Cd, Cu, Fe, Li, Pb, and Zn were determined in serum samples from patients with bipolar disorder and schizophrenia, and from healthy controls. Quantitative metal recoveries using the proposed method were compared under the same conditions using an ultrasonic bath, magnetic stirring, and microwave-assisted digestion.

RESULTS

Optimum extraction conditions were obtained using HNO₃ (40% v/v) + HCl (30% v/v) as the extraction solution with 3 min sonication time and 60% sonication amplitude. Significant differences were observed among the methods compared. On application of the sample preparation method based on high-power ultrasound-assisted microextraction coupled with inductively coupled plasma mass spectrometry, Pb and Cd in all the studied samples were below the limit of detection of our method. Compared with healthy controls, the concentration of Cu, Li, Fe, and Zn was found to be significantly higher for the bipolar disorder group, while these metals and Li were found at a lower level for the group diagnosed with schizophrenia.

CONCLUSIONS

Principal component analysis showed a significant separation for the groups studied based on their ionomic profiles after the application of high-power ultrasound-assisted microextraction as a sample preparation strategy.

A Portable Smart-Phone Readout Device for the Detection of Mercury Contamination Based on an Aptamer-Assay Nanosensor

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg²⁺ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-phone), which is composed of a simple light source and a miniaturized assay platform. The colorimetric readout of the aptamer nanosensor is based on a specific interaction between the selected aptamer and Hg²⁺, which leads to a color change in the reaction solution due to an aggregation of gold nanoparticles (AuNPs). The MR S-phone-based AuNPs-aptamer colorimetric sensor system could reliably detect Hg²⁺ in both tap water and Pearl River water samples and produced a linear colorimetric readout of Hg²⁺ concentration in the range of 1 ng/mL-32 ng/mL with a correlation of 0.991, and a limit of detection (LOD) of 0.28 ng/mL for Hg²⁺. The detection could be quickly completed in only 20 min. Our novel mercury detection assay is simple, rapid, and sensitive, and it provides new strategies for the on-site detection of mercury contamination in any environment.