Abstract:The precise targeting and excellent specific cleave capability of CRISPR/Cas (clustered regularly inters-paced short palindromic repeats-associated proteins) have gained much research interest. In addition to nucleic acid detection, researchers exploring the potential of this system for detecting various other targets. Herein, we proposed a novel CRISPR/Cas biosensing based Tobramycin (TOB) detection method. Combining with the aptamer recognition and element labeling strategy, highly sensitive and specific detection of TOB is realized. Due to the powerful elemental analysis capabilities of inductively coupled plasma mass spectrometry (ICP-MS) and the excellent signal amplification effect of CRISPR/Cas, the linear concentration range for TOB was 2.8-100 nM in this method, whereas the detection limit was 0.83 nM. The proposed method has been successfully applied in the analysis of actual water samples.

Abstract:Zircon, a common U-rich accessory mineral occurring in terrestrial and extraterrestrial rocks, serves as a crucial tool for unraveling the temporal and geochemical clues on geologic events that have taken place on Earth and other planetary bodies. Zircon water content analysis has been advanced in the past three years via a novel sample preparation method using Sn-Bi alloy as a mounting material. Here, we present an improved Pb-free Sn-Bi alloy material for mounting samples and investigate whether the alloy mounts are suitable for in situ U-Pb dating. The secondary ion mass spectrometry (SIMS) U-Pb dating results show that the count rates of 204Pb for zircon standards in the alloy mount are less than 0.01 cps/nA, and the calculated U-Pb and Pb-Pb ages of zircon standards are consistent with the recommended values within analytical uncertainties. Our results indicate that the alloy material used in this study is a good mounting material for U-Pb dating. Therefore, we recommend that this Pb-free Sn-Bi alloy material can be applied to mount geological samples for water abundance and U-Pb systematic analyses.

Abstract:High-precision and accurate Fe isotopic analyses are essential for various geological processes. In this study, Fe isotopic measurements were optimized on a large-geometry, high-resolution Nu Plasma 1700 MC-ICP-MS instrument, which can distinguish Ar-related interferences completely as opposed to other general-sized MC-ICP-MS instruments. Under the conditions of high mass resolution, complete separation of Ar-related interference can be achieved. We evaluated the type and intensity of all Ar-related interferences. The effects of the acid molarity, concentration mismatch, residual HCl, and matrix elements were also evaluated. The results demonstrate that the molarity of the acid, residual HCl, and Cr significantly affected the precision of the Fe isotopic measurements. Fe was purified by one-step column anion-exchange separation using the anion resin AG-MP-1M. The long-term external precisions of δ56Fe and δ57Fe were greater than ± 0.03‰ (2SD) and ± 0.06‰ (2SD), respectively. The Fe isotopic compositions of the five geological reference materials measured in this study agreed with previously published data, within uncertainties.

Abstract:NanoSIMS features a capability of high spatial resolution, which allows for Pb/Pb and U/Pb dating at the submicron scale, using a recently established radio-frequency (RF) oxygen ion source. However, the secondary ion yield of Pb+ is relatively low when using 16O- as the primary beam species compared to that obtained using large-geometry secondary ion mass spectrometry (LG-SIMS), which limits the precision of Pb/Pb and U/Pb dating. In this study, using 16O2- as the primary species with an RF oxygen source on a CAMEA NanoSIMS 50L ion probe, we acquired Pb sensitivity in zircon of approximately 12 cps/nA/ppm. Analyses of the zircon reference materials M257 and OG1 resulted in Pb isotopic compositions consistent with their reference values and Pb/Pb age with an uncertainty of ~3 % for the target region of interest (ROI) smaller than an area of 2 μm × 2 μm. Pb/U age with an uncertainty < 2.2% was acquired via Pb/U correction based on the Pb/U vs. UO2/U power relationship or the Pb/UO vs. UO2/UO one. The adoption of 16O2- as the primary species for NanoSIMS using the RF ion source is promising as a possible approach for accurate U/Pb age determination. It significantly improves the precision of Pb/Pb dating of minerals at the submicron scale, especially those with low Pb content in precious extraterrestrial samples.

Abstract:Polymeric tungstates exhibit different toxicities and mobilities when compared to those of monomeric tungstates. However, there is limited information on the occurrence of polytungstates in natural waters due to the lack of a reliable analytical approach for the determination of aqueous polytungstates. In this study, we conducted a simultaneous analysis of monomeric and polymeric tungsten species in natural water using reverse-phase ion pair chromatography coupled with inductively coupled plasma mass spectrometry (RP-IPC-ICP-MS). Polytungstates and five monotungstates, including tungstate as well as mono, di, tri, and tetrathiotungstate, were chromatographically separated within 35 min of using ethanol (12 - 48% gradient) as the mobile phase. The detection limit of polytungstates was 1.50 μg/L. Although common for the analsis of metals, experimental studies based on electrospray ionization - high resolution mass spectrometry (ESI-HRMS) have indicated that samples containing polytungstates should not be acidified, as it could result in the transformation of monotungstates to artifact polytungstates. Overall, our study offers an effective method for the analysis of various tungsten species, especially polytungstates, at environmentally relevant concentrations.

Abstract:In recent years, the stable isotope composition of barium has emerged as a powerful tracer for understanding crucial geo-social processes; therefore, it is necessary to develop an efficient method for Ba isotopic ratios. Herein, we describe a rapid method for determining the isotopic ratios of Ba using a multi-collector inductively coupled plasma mass spectrometer in the low-resolution mode (Neptune Plus). In this method, the exact amount of the resin and the low eluted volume of the acid used in column purification significantly reduce the time required for Ba separation. Instrumental mass bias calibrations were performed for both standard-sample bracketing (SSB) and double-spike methods. The results show that the double-spike method provided Ba isotopic ratios with higher precision than the SSB technique. The effects of acid molarity and concentration mismatch, as well as the potential matrix effect, were investigated in the wet plasma mode. We evaluated the Ba isotopic compositions of ten geological reference materials, namely, BCR-2, BHVO-2, AGV-2, GSP-2, RGM-2, G-2, GSR-3, GSR-5, GSR-8, and GSR-11. Results indicated that these compositions were highly accurate with respect to the international Ba isotope standard, NIST SRM 3104a. Furthermore, the Ba isotopic compositions of most geological reference materials examined in this study agreed well with previously published data within the quoted analytical uncertainties. The long-term reproducibility analyses of all standards indicated that the obtained isotopic ratios were highly reproducible for δ138/134Ba, with precisions of ≤±0.05‰ (2SD). Compared to previous reports, we optimized the process of chemical purification, separated Ba samples faster, and improved the efficiency of the analyses employed in this study.

Abstract:In this study, a deep eutectic solvent (DES)-based rapid synergistic cloud point extraction (RS-CPE) was coupled with inductively coupled plasma optical emission spectrometry (ICP-OES). This unprecedented method was used for the simultaneous determination of Cd and Ni in the medicinal plant Salvia yunnanensis C. H. Wright (S. yunnanensis). Compared with traditional CPE, RS-CPE was accomplished rapidly at room temperature. In this study, DES was used as an environmentally friendly cloud point and synergic reagent to decrease the cloud point temperature (CPT) of Triton X-114 (TX-114) and assist the subsequent rapid extraction process, thereby replacing toxic organic reagents. The experimental parameters affecting extraction efficiency were investigated and optimized. Using this combined extraction method and analytical technique, the analytical performance of ICP-OES was notably improved. Under the optimal conditions, the limits of detection (LOD) of Cd and Ni were 0.01 and 0.05 μg L-1, and the limits of quantification (LOQ) were 0.04 and 0.16 μg L-1, respectively. The enhancement factors (EFs) of Cd and Ni were 33 and 30; the spiked recoveries were 96.1–105% and 90.3–106%, respectively. The established method was applied to analyze S. yunnanensis samples with satisfactory results and provided a simple, rapid, sensitive, and green method for the determination of potentially toxic elements in medicinal herbs.

Abstract:As an emerging interdisciplinary science, metallomics aims to integrate research fields related to metals and metalloids in biological systems from a systematic perspective. Inductively coupled plasma mass spectrometry (ICP-MS) is considered one of the most versatile tools for metallomics research. This review presents a brief overview of ICP-MS and describes recent advances in ICP-MS instrumentation. Then, ICP-MS-based methods and applications are discussed, focusing on single particle analysis, single cell analysis, and spatial metallomics. With the rapid developments in instrumentation and methodology, ICP-MS-based methodologies will evolve further and play a dominant role in metallomics research.