Why is Superlubricity of Diamond-Like Carbon Rare at Nanoscale?

Hydrogenated diamond-like carbon (HDLC) is a promising solid lubricant for its superlubricity which can benefit various industrial applications. While HDLC exhibits notable friction reduction in macroscale tests in inert or reducing environmental conditions, ultralow friction is rarely observed at the nanoscale. This study investigates this rather peculiar dependence of HDLC superlubricity on the contact scale. To attain superlubricity, HDLC requires i) removal of ≈2 nm-thick air-oxidized surface layer and ii) shear-induced transformation of amorphous carbon to highly graphitic and hydrogenated structure. The nanoscale wear depth exceeds the typical thickness of the air-oxidized layer, ruling out the possibility of incomplete removal of the air-oxidized layer. Raman analysis of transfer films indicates that shear-induced graphitization readily occurs at shear stresses lower than or comparable to those in the nanoscale test. Thus, the same is expected to occur at the nanoscale test. However, the graphitic transfer films are not detected in ex-situ analyses after nanoscale friction tests, indicating that the graphitic transfer films are pushed out of the nanoscale contact area due to the instability of transfer films within a small contact area. Combining all these observations, this study concludes the retention of highly graphitic transfer films is crucial to achieving HDLC superlubricity.

Simultaneous Measurement of Trace Levels of Hg, As, Sb, and Bi in Coastal Seawater with a Multichannel Chemical Vapor Generation Atomic Fluorescence Spectrometer.

Trace levels of Hg, As, Sb, and Bi in coastal seawater have been simultaneously detected by a laboratory-built multichannel chemical vapor generation coupled to an atomic fluorescence spectrometer. The system was configured with a built-in electrochemical H2 generator as the fuel supplier to replace chemical H2 produced by the oxidation of potassium borohydride under acidic conditions in traditional instruments. The electrochemical H2 generator not only isolated the atomization process from the chemical vapor injection process but also improved the stability of atomization, excitation, and fluorescence emission in the hydrogen flame, making it easier to optimize conditions for CVG while introducing evaporating multielement vapors. Calibrations were obtained using a mixed standard solution of Hg(II), As(III), Sb(III), and Bi(III). The addition of KBr to a 3% (v/v) HCl solution was selected as the preservative to ensure the stability of 0.10 µg/L Hg(II) in a multielement standard solution for at least 15 days while also preserving µg/L levels of As(III), Sb(III), and Bi(III) stable. The method detection limits (LOD, 3σ) were 0.001, 0.015, 0.010, and 0.005 µg/L for Hg, As, Sb, and Bi, respectively. The relative standard deviations (RSD, n = 7) of the standard spiked seawater samples were 3.2% (0.020 µg/L Hg), 1.2% (0.50 µg/L As), 1.0% (0.50 µg/L Sb), and 3.5% (0.050 µg/L Bi), respectively. The recoveries of seawater samples spiked with different salinities were in the range of 84.5%(Sb)-114%(Hg). The system has been successfully applied to the simultaneous analysis of the four elements in the seawater samples collected from Xiamen Bay, Southeast China.

The association between blood albumin level and cardiovascular complications and mortality risk in ICU patients with CKD.

BACKGROUND: Studies involving the association of blood albumin with prognosis in patients with chronic kidney disease (CKD) during intensive care unit (ICU) were scarce. AIM: We investigated whether reduced blood albumin level independently associated with an increased risk of cardiovascular (CV) complications and 1-year mortality risk in ICU patients with CKD. METHODS: The Medical Information Mart for Intensive Care III (MIMIC-III) database was used. Disease diagnosis and death information among a number of 925 ICU patients with CKD, who have been measured for blood biochemistry, were recorded. Here, multivariable logistic regression Models were structured to evaluate the associations between blood albumin levels (first value on admission, maximum and minimum value during ICU) and risks for CV complications and 1-year mortality among these CKD patients. RESULTS: In 925 CKD patients, the number of CV complication with heart failure (HF), myocardial infarction (MI) or stroke was 470 (50.8%). 406 (43.9%) patients were dead during the follow-up of 1 year after patients were discharged. Our smooth curve results suggested a curvilinear relation on association between blood albumin level and risk of CV complications. The "inflection point" of blood albumin level that patients were at highest risk of CV complications was 3.4 g/dL. The almost linear relationship with a downward trend was observed on the association between blood albumin level and 1-year mortality risk. We found that reduced blood albumin level contributed to lower risk for CV complications and higher risk for 1-year mortality respectively when blood albumin levels in CKD patients were below 3.4 g/dL. Additionally, albumin therapy had an obvious modifying effect on the independent association, suggesting a possible improved effect of albumin therapy on risk of CV complications and 1-year mortality risk in these CKD patients. CONCLUSIONS: Our study reported that reduced blood albumin levels in CKD patients during ICU were related to lower risk for CV complications and increased risk of 1-year mortality.

Source tracing and health risk assessment of phthalate esters in household tap-water: A case study of the urban area of Quanzhou, Southeast China.

The occurrence of phthalate esters (PAEs) in household tap water has been investigated via the presence of their geochemical characteristics in the pretreatment and transfer processes of water plants in the urban and suburban areas of the subtropical medium-sized city of Quanzhou, southeast China. The results for all approximately 300 tap water samples collected from 6 sampling stations at household kitchens from Nov. 30, 2017, to Dec. 6, 2018, showed that dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutylphthaate (DIBP), di-n-butyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP) could be identified and quantified among the 16 PAE congeners with the developed gas chromatographymass spectrometry method. The levels of the sum of 5 PAE congeners (Σ5PAEs) for all tap water ranged from 780.0 ng/L to 9180 ng/L, while DIBP and DEHP were the most abundant congeners, accounting for 82.2% in the dry season, 89.9% in the normal season, and 89.3% in the wet season. Factors of the transferring process, such as the spatial distance from the sampling station to the water plant, the material of pipelines, and the storage time of tap water in the pipeline, affected the levels of PAE congeners in tap water from the correlation of Σ5PAEs levels and transferring distance according to hierarchical cluster analysis. The seasonal variations in Σ5PAEs and each congener had good agreement with the temperature, suggesting that PAEs in tap water mainly come from raw water, which should be further explored in future work. Health risk assessment of PAEs in tap water with the HQ method showed that the occurrence of DEP and DBP has no noncarcinogenic risk for adults and children, while the concentration of DEHP might cause potential noncarcinogenic risk for adults and children, which should be given considerably more attention.

COMMD7 functions as molecular target in pancreatic ductal adenocarcinoma.

Our previous studies provided evidence that COMMD7 was associated with tumor progression in human solid cancer. Herein, we aimed to investigate its expression pattern, clinical significance, and biological function in pancreatic ductal adenocarcinoma (PDAC). We found that high COMMD7 expression was specifically detected in PDAC tissues and PDAC cell lines. In addition, COMMD7 overexpression positively correlated with histological differentiation and tumor node metastasis (TNM) stage. Patients with high COMMD7 expression had significantly poorer overall survival, and high COMMD7 expression was an independent predictor of poor prognosis. To further explore the regulatory mechanism of COMMD7, we used stable short hairpin RNA (shRNA)-mediated knockdown and divided the work into in vitro and in vivo experiments. In vitro, the anti-proliferation effects of COMMD7 inhibition were observed under long-time stress conditions, which correlated with cyclin D1 and Bcl-2 downregulation and Bax upregulation. We found that under short-time stress conditions, decreased COMMD7 expression also inhibited PDAC cell invasion in vitro which decreased the secretion of matrix metalloproteinase 2 (MMP-2). Moreover, extracellular signal-regulated kinase1/2 (ERK1/2) was identified as a direct target of COMMD7. The inhibition of ERK1/2 activity under short- or long-time stress conditions using specific inhibitors in COMMD7 inhibition cells all exhibited a strong tumorigenic role. In vivo, COMMD7 was sufficient to impair tumor growth. Our results suggest that COMMD7 plays an important role in the late progression of PDAC and is a potential novel target. © 2016 Wiley Periodicals, Inc.

On-site monitoring of dissolved Sb species in natural waters by an automatic system using flow injection coupled with hydride generation atomic fluorescence spectrometer.

Antimony (Sb) is a toxic and potentially carcinogenic element in the environment. The toxicity of Sb(III) is ten times that of Sb(V). Therefore, on-site monitoring technique for dissolved Sb species is crucial for the study of Sb environmental processes. In this study, an automated, portable, and cost-effective system was developed for field simultaneous analysis of Sb(III) and Sb(III + V) in natural waters. The system comprised a portable atomic fluorescence spectrometer equipped with a built-in electrochemical H2 generator to reduce the consumption of acid/borohydride solution and make the atomizer more stable for on-site analysis. Flow injection technique was also used to achieve on-line pretreatment of water samples, including filtration, acidification, pre-reduction, and hydride generation procedures. Under the optimal conditions, the limits of detection (3σ, n = 11) of the developed method were 0.015 µg/L and the linear ranges were 0.05-5.0 µg/L for both Sb(III) and Sb(III + V). The relative standard deviations (n = 11) of the spiked samples of Sb(V) were 3.2% (0.05 µg/L), 3.3% (0.2 µg/L), and 1.7% (0.5 µg/L), respectively. The spiked recoveries of lake water, treated wastewater, and seawater ranged from 97.0% to 108.5%. The novel system of flow injection coupled with hydride generation atomic fluorescence spectrometer (FI-HG-AFS) was applied to carry out an 18-h fixed-point monitoring at a secondary settling tank of a wastewater treatment facility in Xiamen University, and a 6-h real-time underway analysis in the surface seawater of Dongshan Bay, China, proving that the system was capable of long-term monitoring in the field.

Mesenchymal stem cells may alleviate angiotensin II-induced myocardial fibrosis and hypertrophy by upregulating SFRS3 expression.

INTRODUCTION AND OBJECTIVES: The development of cardiac fibrosis (CF) and hypertrophy (CH) can lead to heart failure. Mesenchymal stem cells (MSCs) have shown promise in treating cardiac diseases. However, the relationship between MSCs and splicing factor arginine/serine rich-3 (SFRS3) remains unclear. In this study, our objectives are to investigate the effect of MSCs on SFRS3 expression, and their impact on CF and CH. Additionally, we aim to explore the function of the overexpression of SFRS3 in angiotensin II (Ang II)-treated cardiac fibroblasts (CFBs) and cardiac myocytes (CMCs). METHODS: Rat cardiac fibroblasts (rCFBs) or rat cardiac myocytes (rCMCs) were co-cultured with rat MSCs (rMSCs). The function of SFRS3 in Ang II-induced rCFBs and rCMCs was studied by overexpressing SFRS3 in these cells, both with and without the presence of rMSCs. We assessed the expression of SFRS3 and evaluated the cell cycle, proliferation and apoptosis of rCFBs and rCMCs. We also measured the levels of interleukin (IL)-ß, IL-6 and tumor necrosis factor (TNF)-α and assessed the degree of fibrosis in rCFBs and hypertrophy in rCMCs. RESULTS: rMSCs induced SFRS3 expression and promoted cell cycle, proliferation, while reducing apoptosis of Ang II-treated rCFBs and rCMCs. Co-culture of rMSCs with these cells also repressed cytokine production and mitigated the fibrosis of rCFBs, as well as hypertrophy of rCMCs triggered by Ang II. Overexpression of SFRS3 in the rCFBs and rCMCs yielded identical effects to rMSC co-culture. CONCLUSION: MSCs may alleviate Ang II-induced cardiac fibrosis and cardiomyocyte hypertrophy by increasing SFRS3 expression in vitro.

Unveiling the tribological potential of MXenes-current understanding and future perspectives.

Reducing energy consumption and CO2 emissions by improving the tribological performance of mechanical systems relies on the development of new lubrication concepts. Two-dimensional (2D) materials have been the subject of extensive tribological research due to their unique physical and chemical properties. 2D transition metal carbides, nitrides, and carbonitrides (MXenes), with their tuneable chemistry and structure, are a relatively new addition to the family of 2D materials. MXenes' good strength and stiffness, easy-to-shear ability, capability to form wear-resistant tribofilms, and the possibility to control their surface chemistry make them appealing candidates to be explored for tribological purposes. This review provides a comprehensive overview of MXenes' tribology, covering their structure-property relationship, synthesis approaches, deposition methods to generate MXene coatings for tribological purposes, and their fundamental tribological mechanisms. Furthermore, detailed insights into studies exploring MXenes' tribological performance from the nano- to the macro-scale are presented with special emphasis on their use as self-lubricating solid lubricants, lubricant additives, and reinforcement phases in composites.

[Advances in On-site Analytical Methods for Inorganic Arsenic in Environmental Water].

Arsenic is a ubiquitous metalloid element in the environment. Arsenic is classified as a group A carcinogen and has caused serious impacts on human health. For example, chronic poisoning caused by arsenic in groundwater is a global health problem. The forms of arsenic in environmental water are diverse, which can easily be transformed into each other during the sampling process and transportation, resulting in errors in laboratory analysis results. Therefore, developing on-site analytical methods for arsenic and acquiring accurate data are the basis for the study of the morphological transformation and bio-absorption process of arsenic and accurately evaluating its toxicity. In the past few decades, laboratory-based analytical methods for arsenic have developed rapidly, but there are still huge challenges in the on-site analysis of arsenic. This review summarized the relevant reviews on analytical methods of arsenic in environmental water in the past decade (2011-2022); discussed the advances in on-site analytical methods such as colorimetric methods, luminescence-based methods, and electrochemical methods of arsenic; anticipated the future development of on-site analytical methods for arsenic in environmental waters; and provided references for the development and applications of new methods.

Qualitative analysis of trace quinolone antibiotics by SERS with fine structure dependent sensitivity.

Antibiotics are widely used in daily life, which has created a global scenario where many pathogenic organisms have become effectively resistant to antibiotics. The abuse or overuse of antibiotics causes significant environmental pollution and even endangers human health. It is well-known that antibiotics' efficacy (toxicity) is determined by molecular structure. Therefore, structure-level qualitative analysis with high sensitivity and accuracy is vitally important. Characterized by fingerprinting recognition, Raman spectroscopy, especially surface-enhanced Raman spectroscopy (SERS), has become an essential qualitative analysis tool in various fields, such as environmental monitoring and food safety. With the exception of chirality, this study completed the qualitative trace analysis of 16 quinolone antibiotics (QNs) with fine molecular structure differences using SERS. The sensitivity was tuned in by one order of magnitude through the different electronegativity and steric hindrances of the slightly changed functional groups in the specific antibiotics. The fine structure dependent sensitivity enables SERS to be a powerful on-site monitoring tool to control the abuse of antibiotics with high toxicity; thus, decreasing the subsequent risk to the environmental ecology and human society.

Toward a versatile flow technique: Development and application of reverse flow dual-injection analysis (rFDIA) for determining dissolved iron redox species and soluble reactive phosphorus in seawater.

A versatile flow analyzer that extended the features of reverse flow injection analysis (rFIA) was developed in this study and named reverse flow dual-injection analysis (rFDIA). Compared with typical rFIA, the analyzer requires less reagent and is more environmentally friendly, which has two injection valves and two reagent loops for the accurate and successive injection of two reagents. With a 2-m long liquid waveguide capillary cell (LWCC) and a spectrophotometer, the analyzer was applied to underway determination of dissolved iron redox species in estuarine and coastal waters. Detection limits of 0.18 and 0.20 nmol L-1 were achieved for Fe(II) and Fe(II + III), respectively and a linear dynamic range of 0.5-450 nmol L-1 was obtained for both Fe(II) and Fe(II + III). The sample throughput for the simultaneous measurement of Fe(II) and Fe(II + III) was 12 h-1, and each analysis consumed only 8 mL sample, 520 µL ferrozine solution, and 260 µL ascorbic acid solution. The analyzer was also used to measure nanomolar amounts of soluble reactive phosphorus (SRP) in seawater. The detection limit and the linear dynamic range for the SRP assay were 0.5 nmol L-1 and 1.5-850 nmol L-1. For SRP determination, the sample throughput was 20 h-1, and each analysis required 9 mL of sample, 130 µL of mixed reagent solution and 260 µL of ascorbic acid. The analytical results were reproducible, with a relative standard deviation of 1.4% (2.5 nmol L-1, n = 10), 2.1% (2.5 nmol L-1, n = 10), and 2.1% (10 nmol L-1, n = 11) for Fe(II), Fe(II + III), and SRP, respectively.

The pivotal role of oxygen in establishing superlow friction by inducing the in situ formation of a robust MoS2 transfer film.

The achievement of superlow friction is vital for the engineering application of hydrogenated diamond-like carbon (H-DLC), but it always fails in an oxygen atmosphere. In this paper, robust superlow friction was achieved by MoS2 flakes and H-DLC composite films in a large range of atmospheres, especially in oxygen. The results showed that the composite structure could only retain the superlow friction for an short time in pure argon, nitrogen and carbon dioxide; surprisingly, oxygen was capable of remaining in the near frictionless state with a friction coefficient as low as 0.002, and the duration was prolonged significantly by the introduction of oxygen in those other gases. The stability of the transfer film that induced the near frictionless state was also studied comprehensively. The experimental results and first-principle calculations demonstrated that oxygen could bond with the molybdenum, sulfur and aluminum atoms to form bridge bonds that fixed the MoS2 transfer film on the counterface; this led to the formation of incommensurate contact between the MoS2 tribo-layer and H-DLC film, which enabled robust superlow friction. This finding supports a simple strategy to resolve the challenge of superlubric failure and opens a path for the actual application of H-DLC in oxygen-rich environments.

Preparation of a novel monolith-based adsorbent for solid-phase microextraction of sulfonamides in complex samples prior to HPLC-MS/MS analysis.

Effective extraction is an essential step in the sensitive and accurate analysis of sulfonamides (SAs) in complex samples. In this study, based on the chemical properties of SAs, a novel monolith-based adsorbent using 4-vinylbenzoic acid and 4-vinylphenylboronic acid as dual-functional monomers was tailored and employed as efficient extraction phase of solid-phase microextraction. Various characterized techniques were applied to investigate the structure and morphology of the obtained adsorbent. Due to the abundant functional groups, the synthetic adsorbent displayed satisfying extraction performance for target SAs through multiple interactions including ion-exchange, B-N coordination, π-π and hydrophobic interactions. Following elution with the desorption solution of methanol/formic acid (98.5/1.5, v/v), the extractive SAs were measured by HPLC-MS/MS. Under the optimized conditions, the proposed approach exhibited wide linear ranges (0.005-10.0 µg/L for most of analytes), low limits of detection (in the range of 0.31-2.3 ng/L) and good precision (RSDs were lower than 8.0%). In the analysis of target SAs in environment waters and honey samples, the recoveries at low, medium and high spiked concentrations were in the range of 83.5-119%, and the RSDs (n = 3) varied from 0.6% to 9.6%. Compared with existing approaches, the current method presents some merits such as high sensitivity, good reproducibility, low consumptions of sample and organic solvent.

Distribution characteristics of total mercury and methylmercury in the topsoil and dust of Xiamen, China.

The levels and distribution of mercury (Hg) species, including total mercury (THg) and methylmercury (MeHg) in the topsoil and dust collected from twenty sampling stations located in different land function areas of Xiamen, China, were investigated. The THg concentrations in topsoil ranged from 0.071 to 1.2 mg/kg, and in dust ranged from of 0.034 to 1.4 mg/kg. For stations where the THg of dust was less than 0.31 mg/kg, THg concentrations in the topsoil were significantly correlated to those in the corresponding dust (r = 0.597, n = 16, P = 0.014). The MeHg concentrations in topsoil were varied between 0.14 and 5.7 microg/kg. The ratios of MeHg/THg in the topsoil ranged from 0.069% to 0.74%. The range of MeHg concentration in the dust were 0.092-2.3 microg/kg. The ratios of MeHg/THg in the dust were at the same level as those in the topsoil. The MeHg concentrations in both topsoil and dust were linked to corresponding THg concentrations and soil organic matter. Neither THg nor MeHg concentration in the topsoil and dust was obviously linked to the land function.

Spatial distribution and seasonal variation of phthalate esters in the Jiulong River estuary, Southeast China.

The spatial distribution and seasonal variation of 16 phthalate esters (PAEs) in water, suspended particulate matter (SPM) and sediment were investigated in the Jiulong River estuary, Fujian, Southeast China. Of the 16 PAE congeners analyzed, only six PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP), were identified and quantified. The total concentrations of the six PAEs (∑6PAEs) detected for all seasons ranged from 3.01 to 26.4µg/L in water, 1.56 to 48.7mg/kg in SPM, and 0.037 to 0.443µg/kg in sediment. DEHP, DIBP and DBP were the most abundant PAE congeners in all of the water, SPM and sediment phases. The spatial distributions of PAEs in the estuary were controlled not only by the riverine runoff, seasons, hydrodynamic condition and human activities but also the physicochemical properties of PAEs.

Occurrence, spatial distribution, historical trend and ecological risk of phthalate esters in the Jiulong River, Southeast China.

The occurrence and spatial distribution of phthalate esters (PAEs) in the Jiulong River of southeast China were investigated in water and sediment samples collected from 35 stations along the river in Mar. 2014. The historical trend of the past 26years was reconstructed with a sediment core collected in Dec. 2012 via a 210Pb dating technique. The potential ecological risk of PAEs was assessed using the risk quotient (RQ) method. Of the 16 PAE congeners analyzed, only 6 PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP), were identified and quantified; the remaining 10 PAEs were below their respective limits of quantification (LOQs) for the analytical methods used here. The cumulative concentration of 6 PAEs (∑6PAEs) found in the samples spanned a range of 3.48-17.7µg/L in water and 0.046-1.65mg/kg in sediment. The most abundant PAEs in the water-phase were DEHP and DIBP, together accounting for 84.9% of ∑6PAEs in the North River, 82.8% of ∑6PAEs in the West River and 91.6% of ∑6PAEs in the estuary. DEHP and DINP were the richest congeners in the sediment-phase, with proportions of 84.9% in the North River, 81.0% in the West River and 65.4% in the estuary. The spatial distribution of ∑6PAEs in water and sediment phases showed that the riverside environment had influence on the distribution pattern. The reconstruction profile of the PAE congeners and the ∑6PAEs vs the depth of the sediment core indicated that PAEs became increasingly present pollutants around 2006 in the Jiulong River. The results of the potential ecological risk assessment of the RQ method revealed that DIBP and DEHP posed a high risk because of their relatively higher concentrations, while DBP and DINP posed a medium risk to the aquatic system. The baseline data of PAEs in this river will be benefits to the regulatory attention and future strategies of the pollutants control along the river network.

[High current microsecond pulsed hollow cathode lamp excited ionic fluorescence spectrometry of alkaline earth elements in inductively coupled plasma with a Fassel-torch].

High current microsecond pulsed hollow cathode lamp (HCMP-HCL) excited ionic fluorescence spectrometry (IFS) of alkaline earth elements in inductively coupled plasma (ICP) with a Fassel-torch has been investigated. In wide condition ranges only IFS was observed, whilst atomic fluorescence spectrometry (AFS) was not detectable. More intense ionic fluorescence signal was observed at lower observation heights and at lower incident RF powers. Without introduction of any reduction organic gases into the ICP, the limit of detection (LOD, 3sigma) of Ba was improved by 50-fold over that of a conventional pulsed (CP) HCL with the Baird sleeve-extended torch. For Ca and Sr, the LODs by HCMP-HCL-ICP-IFS and CP-HCL-ICP-AFS show no significant difference. Relative standard deviations were 0.6%-1.4% (0.1-0.2 microg x mL(-1), n = 10) for 5 ionic fluorescence lines. Preliminary studies showed that the intensity of ionic fluorescence could be depressed in the presence of K, Al and P.

Removal of high-salinity matrices through polymer-complexation-ultrafiltration for the detection of trace levels of REEs using inductively coupled plasma mass spectrometry.

The polymer-complexation-ultrafiltration (PCUF) technique was applied to separate trace levels of rare earth elements (REEs), including scandium, yttrium and the lanthanides, from high-salinity matrices prior to their determination by inductively coupled plasma mass spectrometry (ICP-MS). The REEs were converted into REE-polymer complexes using the water-soluble polymer polyacrylic acid (PAA) at a specified pH, retained on the ultrafiltration membrane of centrifugal filter units, and finally eluted using diluted nitric acid to achieve separation from matrices with relatively high levels of various inorganic ions, such as sodium, potassium, calcium, magnesium, and chlorine ions. Numerous factors affecting the PCUF efficiency were optimized. The optimal conditions included the addition of 30 mg L(-1) of PAA, a pH of 7.5, a reaction time of 40 min at room temperature, and 5.0 mL of 3% nitric acid (v/v) eluent. Under these conditions, the analytes were quantitatively separated and recovered, with a resulting relative standard deviation (RSD) of less than 4.0% (0.05 µg L(-1), n=5) and standard addition recoveries between 89.2% (La) and 95.8% (Sm) for matrices of various salinities. The blank samples for the method ranged from 0.0003 µg L(-1) (Dy) to 0.0031 µg L(-1) (Sc), and the limits of quantification (LOQs, 10σ) were between 0.0006 µg L(-1) (Dy) and 0.0026 µg L(-1) (Sc). Furthermore, the salinity of the sample exhibited no effect on the REE-polymer complex formation process. Finally, the method was successfully applied for the determination of trace levels of dissolved Sc, Y, and lanthanides in coastal and estuarine seawater samples.

[Atomic/ionic fluorescence in microwave plasma torch discharge with excitation of high current and microsecond pulsed hollow cathode lamp: Ca atomic/ionic fluorescence spectrometry].

A system of atomic and ionic fluorescence spectrometry in microwave plasma torch (MPT) discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL) has been developed. The operation conditions for Ca atomic and ionic fluorescence spectrometry have been optimized. Compared with atomic fluorescence spectrometry (AFS) in argon microwave induced plasma (MIP) and MPT with the excitation of direct current and conventional pulsed HCL, the system with HCMP HCL excitation can improve AFS and ionic fluorescence spectrometry (IFS) detection limits in MPT atomizer and ionizer. Detection limits (3 sigma) with HCMP HCL-MPT-AFS/IFS are 10.1 ng.mL-1 for Ca I 422.7 nm, 14.6 ng.mL-1 for Ca II 393.4 nm, and 37.4 ng.mL-1 for Ca II 396.8 nm, respectively.

[Determination of N-nitrosamines in rubber products by solid phase extraction purification and ultra high performance liquid chromatography-tandem mass spectrometry].

A method using C18 solid phase extraction (SPE) for purification and ultra high performance liquid chromatography (UHPLC) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS) for detection was developed to simultaneously determine 13 N-nitrosamines in rubber products. The analytes were extracted with methanol (60 degrees C, 30 min) with the aid of ultrasonic technique and then purified by a C18 SPE cartridge. The analytes were separated on a C18 chromatographic column and qualitatively and quantitatively detected by a mass spectrometer with positive ESI at multiple reaction monitoring (MRM) mode. The operating parameters for UHPLC separation and ESI-MS/MS detection were also optimized. Under optimum operating conditions, the relative standard deviations (RSDs, n = 7) were less than 10% at spiked level of 50 microg/kg for all analytes except N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) which were spiked at 500 microg/kg. The recoveries spiked in real from 70.7% to 117.0%. The limits of detection (LODs, 10 times of standard deviation) were in the range of 0.5 - 500 microg/kg. The method has been successfully applied to the simultaneous determination of the 13 N-nitrosamines in rubber products.