Radial basis function neural network optimization algorithm based on dynamic inertial weight particle swarm optimization for separating overlapping peaks in ion mobility spectrometry.

RATIONALE: Ion mobility spectrometry (IMS), as a promising analytical tool, has been widely employed in the structural characterization of biomolecules. Nevertheless, the inherent limitation in the structural resolution of IMS frequently results in peak overlap during the analysis of isomers exhibiting comparable structures. METHODS: The radial basis function (RBF) neural network optimization algorithm based on dynamic inertial weight particle swarm optimization (DIWPSO) was proposed for separating overlapping peaks in IMS. The RBF network structure and parameters were optimized using the DIWPSO algorithm. By extensively training using a large dataset, an adaptive model was developed to effectively separate overlapping peaks in IMS data. This approach successfully overcomes issues related to local optima, ensuring efficient and precise separation of overlapping peaks. RESULTS: The method's performance was evaluated using experimental validation and analysis of overlapping peaks in the IMS spectra of two sets of isomers: 3'/6'-sialyllactose; fructose-6-phosphate, glucose-1-phosphate, and glucose-6-phosphate. A comparative analysis was conducted using other algorithms, including the sparrow search algorithm, DIWPSO algorithm, and multi-objective dynamic teaching-learning-based optimization algorithm. The comparison results show that the DIWPSO-RBF algorithm achieved remarkably low maximum relative errors of only 0.42%, 0.092%, and 0.41% for ion height, mobility, and half peak width, respectively. These error rates are significantly lower than those obtained using the other three algorithms. CONCLUSIONS: The experimental results convincingly demonstrate that this method can adaptively, rapidly, and accurately separate overlapping peaks of multiple components, improving the structural resolution of IMS.

Urban green infrastructure features influence the type and chemical composition of soil dissolved organic matter.

In urban areas, green infrastructure (GI) has been widely developed utilizing different types of engineered soil to enhance ecosystem functions to interact with soil dissolved organic matter (DOM). However, there remains a lack of urban studies that have examined the link between GI features and soil DOM. This study, which was conducted in a typical heavily industrialized and urbanized area (Ningbo City, East China), aimed to characterize the chemical variation and composition of DOM in the engineered soil of four GI types (enhanced tree tips, ETP; street-side infiltration swales, SSIS; vegetated swales, VS; urban forests, UF). The results showed that soil organic carbon varies among the four GI types with significantly lower content in SSIS and ETP compared to VS and UF. Smaller variation was observed in the water-soluble organic carbon (WSOC) content, with UF having significantly higher content than ETP. Three humic-like substances and one protein-like substance were derived using the parallel factor analysis (PARAFAC) model. These fluorescent compositions and their spectral parameters displayed specific distributions among GI features with VS having the highest proportion of humic-like substances (C1) and the lowest proportion of protein-like substances (C4). The distribution of spectral indices indicated terrigenous sources of DOM in these GI engineered soils. Significant positive correlations were found between protein-like substances and the population density and nightlight index, while negative correlations were found between humic-like substances (C1) and these two indices. These results demonstrate significant human disturbance of the chemical composition and characteristics of GI features. Our findings suggest that the overall design and management of GI features have a fundamental influence on soil DOM that is vital for carbon cycling in urban ecosystems.

[Analysis of picric acid and picramic acid in water samples by ultra performance hydrophilic interaction chromatography-tandem mass spectrometry].

An ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/ MS) method was developed for the determination of picric acid and its reductive transformation product picramic acid in aqueous samples. A hydrophilic interaction liquid chromatography (HILIC) column (Acquity UPLC BEH HILIC; 100 mm x 2.1 mm, 1.7 microm) was used for the separation. Surface water samples could be injected into the UPLC system just after being filtered through a 0.2 microm membrane. The satisfactory recoveries of picric acid and picramic acid were in the range of 89% - 107%. Waste water samples were purified by solid phase extraction (SPE), and then were analyzed. The recoveries of picric acid and picramic acid in waste water were 72%-101%. The reproducibility of the method was good with the RSDs of 4.9% - 14.7%. The limits of detection (LODs) of picric acid and picramic acid were 0.1 microg/L and 0.3 microg/L, respectively. This proposed method is rapid, highly specific and suitable for the confirmation and quantitative determination of picric acid and picramic acid in surface water and waste water.

Levels of flame retardants HBCD, TBBPA and TBC in surface soils from an industrialized region of East China.

Hexabromocyclododecanes (HBCDs) and tetrabromobisphenol A (TBBPA) are of increasing concern because of their potential environmental persistence, bioaccumulation and toxicity. Tris-(2,3-dibromopropyl)isocyanurate (TBC) is another brominated flame retardant (BFR) which has recently been found in the environment and begun to attract attention. The objective of this study is to determine the concentration of these three BFRs in surface soil samples collected from a heavily industrialized and urbanized region in East China. Levels of ∑HBCDs ranged from below detection limits (0.020 ng g(-1)) to 102.6 ng g(-1) on a dry weight basis (dw) with a median level of 15.8 ng g(-1) dw. For TBBPA, the concentration ranged from below detection limits (0.025 ng g(-1)) to 78.6 ng g(-1) dw with a median level of 9.17 ng g(-1) dw. TBC was found at relatively lower concentrations ranging from below detection limits (0.024 ng g(-1)) to 16.4 ng g(-1) dw with a median level of 0.95 ng g(-1) dw. The concentrations of these three BFRs are significantly positively correlated, indicating a common source. Variable BFRs levels were found in different types of soils, with significantly higher concentrations observed at waste dumping sites and industrial areas. The diastereoisomer profiles of HBCDs in most of the soil samples differed from those of the commercial products. The mass inventories of HBCDs, TBBPA and TBC in this region gave preliminarily estimates of 6.68, 2.67 and 0.85 kg, respectively. Therefore, the ubiquitous contamination of soils by these BFRs may well reflect their widespread usage in the study area.

Spatial distribution and inter-year variation of hexabromocyclododecane (HBCD) and tris-(2,3-dibromopropyl) isocyanurate (TBC) in farm soils at a peri-urban region.

Hexabromocyclododecane (HBCD) is a high production volume brominated flame retardant (BFR) which has been of increasing environmental and public health concern due to its potential environmental persistency, bioaccumulation and toxicity. Tris-(2,3-dibromopropyl) isocyanurate (TBC) is another BFR which has recently been found in environmental matrices near a manufacturing plant, but its production volume and environmental distribution is currently not well known. This study was conducted to investigate the presence and distribution of these two BFRs in farm soils at a region in southeast Beijing. Total HBCD levels ranged from 0.17 to 34.5 ng g(-1) on a dry weight basis (dw) with a median level of 2.97 ng g(-1)dw. The composition profile of HBCD diastereoisomers was, on average, 28%, 13% and 59% for α-, ß- and γ-HBCD, respectively. Detection frequency of TBC was only 25% in 2010 but was detected in all soil samples in 2011, and the median level was 0.19 ng g(-1)dw with the range between below detection limit to 1.62 ng g(-1) dw. There were no significant differences of HBCD and TBC levels among different irrigation sources in the region. The soil HBCD and TBC levels in samples collected in 2011 were significantly higher than in 2010. The increasing short-term temporal levels in farm soil might be due to the rapid urbanization in this region or could also reflect the increasing usage of HBCD and TBC after the phase out of other BFRs.

Simultaneous determination of hexabromocyclododecanes and tris (2,3-dibromopropyl) isocyanurate using LC-APCI-MS/MS.

Hexabromocyclododecanes (HBCDs) and tris (2,3-dibromopropyl) isocyanurate (TBC) are both brominated flame retardants, and have been used throughout the world with subsequent concern for potential environment pollution. Here we describe the development of a method for the simultaneous determination of TBC and HBCD diastereoisomers in environmental matrices by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The method recovery ranged from 81% to 93% and limits of detections (LODs) on column were 4.3 pg, 0.5 pg, 0.4 pg, 0.3 pg for TBC, α-HBCD, ß-HBCD, and γ-HBCD, respectively, which showed high sensitivity compared to previous published methods. Compared to electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) was found to be a more sensitive, effective ionization mode for determination of HBCDs. This novel method was further validated by analyzing TBC and HBCDs in biotic and abiotic samples. The concentration ranges of TBC, α, ß, γ-HBCD in sediment samples were 136.1-5884.6 ng/g, 9.0-1079.6 ng/g, 1.0-1161.7 ng/g, and 65.4-3964.2 ng/g, respectively. The concentration range for TBC, α-HBCD, ß-HBCD, and γ-HBCD in common carp samples were 51.1-1899 ng/g, 21.6-1338 ng/g,