Structural Insight into Molecular Inhibitory Mechanism of InsP6 on African Swine Fever Virus mRNA-Decapping Enzyme g5Rp.

Removal of 5' cap on cellular mRNAs by the African swine fever virus (ASFV) decapping enzyme g5R protein (g5Rp) is beneficial to viral gene expression during the early stages of infection. As the only nucleoside diphosphate-linked moiety X (Nudix) decapping enzyme encoded in the ASFV genome, g5Rp works in both the degradation of cellular mRNA and the hydrolyzation of the diphosphoinositol polyphosphates. Here, we report the structures of dimeric g5Rp and its complex with inositol hexakisphosphate (InsP6). The two g5Rp protomers interact head to head to form a dimer, and the dimeric interface is formed by extensive polar and nonpolar interactions. Each protomer is composed of a unique N-terminal helical domain and a C-terminal classic Nudix domain. As g5Rp is an mRNA-decapping enzyme, we identified key residues, including K8, K94, K95, K98, K175, R221, and K243 located on the substrate RNA binding interfaces of g5Rp which are important to RNA binding and decapping enzyme activity. Furthermore, the g5Rp-mediated mRNA decapping was inhibited by InsP6. The g5Rp-InsP6 complex structure showed that the InsP6 molecules occupy the same regions that primarily mediate g5Rp-RNA interaction, elucidating the roles of InsP6 in the regulation of the viral decapping activity of g5Rp in mRNA degradation. Collectively, these results provide the structural basis of interaction between RNA and g5Rp and highlight the inhibitory mechanism of InsP6 on mRNA decapping by g5Rp. IMPORTANCE ASF is a highly contagious hemorrhagic viral disease in domestic pigs which causes high mortality. Currently, there are still no effective vaccines or specific drugs available against this particular virus. The protein g5Rp is the only viral mRNA-decapping enzyme, playing an essential role in the machinery assembly of mRNA regulation and translation initiation. In this study, we solved the crystal structures of g5Rp dimer and complex with InsP6. Structure-based mutagenesis studies revealed critical residues involved in a candidate RNA binding region, which also play pivotal roles in complex with InsP6. Notably, InsP6 can inhibit g5Rp activity by competitively blocking the binding of substrate mRNA to the enzyme. Our structure-function studies provide the basis for potential anti-ASFV inhibitor designs targeting the critical enzyme.

Downregulation of diacylglycerol kinase delta contributes to hyperglycemia-induced insulin resistance.

Type 2 (non-insulin-dependent) diabetes mellitus is a progressive metabolic disorder arising from genetic and environmental factors that impair beta cell function and insulin action in peripheral tissues. We identified reduced diacylglycerol kinase delta (DGKdelta) expression and DGK activity in skeletal muscle from type 2 diabetic patients. In diabetic animals, reduced DGKdelta protein and DGK kinase activity were restored upon correction of glycemia. DGKdelta haploinsufficiency increased diacylglycerol content, reduced peripheral insulin sensitivity, insulin signaling, and glucose transport, and led to age-dependent obesity. Metabolic flexibility, evident by the transition between lipid and carbohydrate utilization during fasted and fed conditions, was impaired in DGKdelta haploinsufficient mice. We reveal a previously unrecognized role for DGKdelta in contributing to hyperglycemia-induced peripheral insulin resistance and thereby exacerbating the severity of type 2 diabetes. DGKdelta deficiency causes peripheral insulin resistance and metabolic inflexibility. These defects in glucose and energy homeostasis contribute to mild obesity later in life.

The tetrameric assembly of 2-aminomuconic 6-semialdehyde dehydrogenase is a functional requirement of cofactor NAD+ binding.

The bacterium Pseudomonas sp. AP-3 is able to use the environmental pollutant 2-aminophenol as its sole source of carbon, nitrogen, and energy. Eight genes (amnA, B, C, D, E, F, G, and H) encoding 2-aminophenol metabolizing enzymes are clustered into a single operon. 2-Aminomuconic 6-semialdehyde dehydrogenase (AmnC), a member of the aldehyde dehydrogenase (ALDH) superfamily, is responsible for oxidizing 2-aminomuconic 6-semialdehyde to 2-aminomuconate. In contrast to many other members of the ALDH superfamily, the structural basis of the catalytic activity of AmnC remains elusive. Here, we present the crystal structure of AmnC, which displays a homotetrameric quaternary assembly that is directly involved in its enzymatic activity. The tetrameric state of AmnC in solution was also presented using small-angle X-ray scattering. The tetramerization of AmnC is mediated by the assembly of a protruding hydrophobic beta-strand motif and residues V121 and S123 located in the NAD+ -binding domain of each subunit. Dimeric mutants of AmnC dramatically lose NAD+ binding affinity and failed to oxidize the substrate analogue 2-hydroxymuconate-6-semialdehyde to α-hydroxymuconic acid, indicating that tetrameric assembly of AmnC is functional requirement.

Effects of repeated drug administration on behaviors in normal mice and fluoxetine efficacy in chronic unpredictable mild stress mice.

Mental disorders are characterized by high incidence and high recurrence rates, and only part of patients responded to drug medication. In this case, substantial preclinical investigations are needed. Most antipsychotics taken daily orally in clinics are administered through injection, oral gavage, or minipum implant in rodents, which may induce stress and affect the results of behavioral tests. How drug administrations on behaviors and drug efficacy remains an unsolved problem. In this study, we compared the intraperitoneal injection (IP), intragastric administration (IG), and tail vein injection (TVI) on behaviors, as well as the difference between administration-induced stress and chronic unpredictable mild stress (CUMS). Next, we studied the effects of IG on CUMS model and drug efficacy. We found that IP, IG, and TVI, especially IG, induced a behavior-like phenotype of depression and anxiety, which we call the "CUMS-like behaviors". However, such behaviors were not equal to depression. When treated CUMS mice with saline by gavage, they didn't show any aggravated phenotype compared with CUMS alone. We observed that fluoxetine by intraperitoneal injection was more effective than intragastric administration. Our study confirmed that repeated administrations lead to CUMS-like behaviors. Although these behaviors are not depression, they have adverse effects on drug efficacy.

Peritumoral abnormalities on dynamic-enhanced CT after brachytherapy for hepatic malignancies: local progression or benign changes?

OBJECTIVES: To determine if dynamic CT can differentiate local progression from radioactive seed-induced peritumoral reaction (RSIPR) after brachytherapy with iodine-125 radioactive seeds (BIRS) for advanced hepatic malignancies. METHODS: Enhanced CT images of seed-implanted lesions between 2006 and 2018 were retrospectively evaluated. Hounsfield units of peritumoral parenchyma were measured and assessed quantitatively. The classification, conversion, consequences, and serological indicators during follow-up were recorded and quantified. Statistical differences were analyzed using a Pearson χ2 test. RESULTS: RSIPR was observed in 201 of 290 (69.3%) lesions (161 patients; median age, 55 years; range, 26-79 years), while local progression occurred in 53 lesions. The low density of local progression was much lower than that of RSIPR (p < 0.001), and the former did not exhibit iso-/high density in the portal or equilibrium phase. Ring-like enhancement in progressive lesions was also quite different from RSIPR. Local progression rate was lower for lesions with RSIPR than for those without RSIPR (14.9% vs 25.8%; p = 0.03), and their doses were different (397.2 Gy vs 120.3 Gy, p < 0.001). CONCLUSIONS: Radioactive seed-induced peritumoral reaction has characteristic manifestations on CT images, which is associated with a higher dose of lesions and lower local progression rate. Notably, the enhancement pattern of local progression was distinct from RSIPR and was clearly distinguishable on dynamic-enhanced CT. KEY POINTS: • Radioactive seed-induced peritumoral reaction after brachytherapy with 125I seeds for liver malignancies has characteristic manifestations on CT images, which is associated with a higher dose of lesions (397.2 Gy vs 120.3 Gy, p < 0.001), as a focal radiation injury. • Lesions with RSIPR were less likely to develop local progression, while those without RSIPR had a higher rate of local progression (14.9% vs 25.8%; p = 0.03). • The enhancement pattern of local progression after brachytherapy was distinct from radioactive seed-induced peritumoral reaction and was clearly distinguishable on dynamic-enhanced CT.

Ruptured brain aneurysm-induced subarachnoid hemorrhage with concurrent myocardial infarction in a rhesus monkey (Macaca mulatta).

Brain aneurysm ruptured subarachnoid hemorrhages (SAH) are extremely rare except in humans. This study described a SAH caused by a ruptured anterior communication artery aneurysm and concurrent myocardial infarction, along with pneumonia and intestinal obstruction in a rhesus monkey, which is rather rare in animal experiments.

Redox-Triggered Chirality Switching and Guest-Capture/Release with a Pillar[6]arene-Based Molecular Universal Joint.

A chiral electrochemically responsive molecular universal joint (EMUJ) was synthesized by fusing a macrocyclic pillar[6]arene (P[6]) to a ferrocene-based side ring. A single crystal of an enantiopure EMUJ was successfully obtained, which allowed, for the first time, the definitive correlation between the absolute configuration and the circular dichroism spectrum of a P[6] derivative to be determined. The self-inclusion and self-exclusion conformational change of the EMUJ led to a chiroptical inversion of the P[6] moiety, which could be manipulated by both solvents and changes in temperature. The EMUJ also displayed a unique redox-triggered reversible in/out conformational switching, corresponding to an occupation/voidance switching of the P[6] cavity, respectively. This phenomenon is an unprecedented electrochemical manipulation of the capture and release of guest molecules by supramolecular hosts.

Leptin rs2167270 G > A (G19A) polymorphism may decrease the risk of cancer: A case-control study and meta-analysis involving 19 989 subjects.

Accumulating evidence has suggested that leptin (LEP) is very important for the development of cancer. Recently, a number of case-control studies about the relationship of the rs2167270 G > A (G19A) variants in the LEP gene with the risk of cancer have yielded inconsistent results. In this study, we have carried out a case-control study [1063 esophagogastric junction adenocarcinoma (EGJA) cases and 1677 controls] in a Chinese population. Furthermore, we carried out a pooled-analysis of 13 studies involving 8059 cancer patients and 11 930 controls to assess whether the LEP G19A locus was associated with overall cancer susceptibility. Odds ratios (ORs) with the corresponding 95% confidence intervals (CIs) were harnessed to evaluate the potential association. In our case-control study, we found an association between the carriers of LEP 19A allele and EGJA risk. In addition, the results of meta-analysis also suggested significant associations with cancer risk (A vs G: OR = 0.92, 95% CI = 0.88-0.97, P = 0.001; AA vs GG: OR = 0.83, 95% CI = 0.74-0.93, P = 0.001, GA/AA vs GG: OR = 0.93, 95% CI = 0.88-0.99, P = 0.023 and AA vs GG/GA: OR = 0.83, 95% CI = 0.74-0.92, P < 0.001). Upon conducting a stratified analysis, we found that LEP 19A allele might decrease the susceptibility of non-Hodgkin lymphoma (NHL) and colorectal cancer (CRC). In a stratified-by-ethnicity analysis, significant associations were also found in Asians, Caucasians, and mixed populations. We can conclude that the LEP G19A polymorphism constitutes a decreased risk of cancer.

Association of metabolism-related genes polymorphisms with adenocarcinoma of the oesophagogastric junction: Evidence from 2261 subjects.

The etiology of adenocarcinoma of the esophagogastric junction (AEG) remains unclear. It is believed that the increasing of AEG may be correlated with the elevated ratio of obesity and overweight. Thus, metabolism-related genes and variants may play important roles in the occurrence and progress of AEG. The current investigation involved 720 patients with AEG and 1541 healthy controls. We selected transcription factor 7-like 2 (TCF7L2) rs7903146 and rs290481, INS rs689 and INSR rs1799817 single-nucleotide polymorphisms (SNPs), and explored the association of these SNPs with lymph node status and risk of AEG. The polymerase chain reaction was harnessed to identify the genotyping of four polymorphisms. We found that TCF7L2 rs290481 (T > C) and INSR rs1799817 (G > A) polymorphisms were associated with the increased susceptibility of AEG (P = .007 and 0.004 for TCF7L2 rs290481 in TC vs TT and TC/CC vs TT models, and P = .040 for INSR rs1799817 in GA/AA vs GG model). We also conducted a subgroup analysis by different cancer stage. We identified that TCF7L2 rs290481, INS rs689, and INSR rs1799817 SNPs increased the susceptibility of AEG in different cancer stage subgroups. In addition, we found that rs290481 SNP in TCF7L2 gene increased the risk of lymph node metastasis in drinking patients with AEG. However, the association of INSR rs1799817 SNP with a decreased risk of lymph node metastasis in smoking patients with AEG was found. Our findings highlight that TCF7L2 rs290481, INS rs689, and INSR rs1799817 polymorphisms may increase the risk of AEG. In addition, TCF7L2 rs290481 and INSR rs1799817 SNPs may influence the lymph node metastasis in patients with AEG.

The structural basis of human Spt16 N-terminal domain interaction with histone (H3-H4)2 tetramer.

FACT (Facilitates Chromatin Transactions) is a heterodimeric protein complex involved in RNA polymerase II transcription elongation, playing essential roles in chromatin remodeling during transcription, replication, and DNA damage repair. The FACT subunit hSpt16 is essential for nucleosome reorganization. The N-terminal domain of hSpt16 (hSpt16-NTD) was recently described as a histone (H3-H4)2-binding domain; however, its mode of interaction remains unknown. In this study, we solved the structure of hSpt16-NTD437 at 2.19 Šand found that a long-disordered region (hSpt16-LDR), after the main body of hSpt16-NTD, is a novel histone-binding motif. Furthermore, hSpt16-LDR interaction with (H3-H4)2 is H3 N-terminal tail-independent. Therefore, Spt16-NTD is a histone H3-H4-specific binding domain with a distinct mechanism of interaction between histones and histone chaperones.

Precise Manipulation of Temperature-Driven Chirality Switching of Molecular Universal Joints through Solvent Mixing.

Three chiral bicyclic pillar[5]arene derivatives termed as molecular universal joints (MUJs), were synthesized and separated enantiomerically. These MUJs showed temperature-driven chirality switching in certain solvents. Herein, it is demonstrated that temperature-driven chirality switching could also be realized by mixing two miscible organic solvents, in each of which chirality inversion is not accomplishable. Additionally, solvent mixing drastically varied the inversion temperature of the MUJs, for example, from far below zero to room temperature. Moreover, the temperature-driven Sp /Rp to Rp /Sp chirality switching direction could be reversed by the solvent mixing and it was critically controlled by the mixing ratios of the two solvents. These observations allowed precise manipulation of the chirality switching behavior of the MUJs. Such a chirality switching was ascribed to the influences of solvent and temperature on the in-out equilibrium of the side rings, which is delicately controlled by several processes, including the solvation/desolvation and the inclusion/exclusion of the side rings and solvent molecules. Crucially, the solvent mixing introduced new supramolecular processes, in particular the desolvation of solvent molecules from the mixed solvent system and the solvation of the side ring by the mixed solvent, which significantly disturbed the original in-out equilibrium of MUJs and drastically switched the entropy and enthalpy changes of conformational interconversion.

Supramolecular Assembly-Improved Triplet-Triplet Annihilation Upconversion in Aqueous Solution.

Water-soluble 9,10-diphenylanthracene-modified γ-cyclodextrin derivatives A1 and A2, in which the γ-cyclodextrin unit serves as a molecular host for a binding sensitizer, and the 9,10-diphenylanthracene moiety plays a role as an emitter/annihilator, were synthesized to investigate the supramolecular triplet-triplet annihilation (TTA) upconversion in aqueous solution. Both A1 and A2 readily aggregate and form nanoscale assemblies in water as a combined result of host-guest complexation and π-π stacking among the 9,10-diphenylanthracenes. The aggregation behavior of the supramolecular emitters was fully characterized by using a diversity of methods, including dynamic light scattering (DLS), SEM, NMR, fluorescence, and circular dichroism studies. Fluorescence spectroscopic analysis reveals that the emitters have high fluorescence quantum yields in water (82 and 90 % for A1 and A2, respectively), thus demonstrating that aggregation does not quench the fluorescence. By using a coordinated ruthenium sensitizer, a high TTA upconversion quantum yield of up to 6.9 % was observed for this supramolecular TTA system, which is significantly higher than the value (<0.5 %) obtained with nonassembled emitters in organic solvent and in contrast to the fact that TTA upconversion emission in aqueous solution is usually low or negligible. We ascribe the strong TTA upconversion emission in the present supramolecular assembly system to an efficient TTA process, which is facilitated along the stacked emitters by triplet energy migration and improved triplet-triplet energy transfer through host-guest complexation.

Feasibility and clinical value of CT-guided 125I brachytherapy for metastatic soft tissue sarcoma after first-line chemotherapy failure.

PURPOSE: To evaluate the feasibility and usefulness of computed tomography (CT)-guided iodine125 (125I) brachytherapy for patients with metastatic soft tissue sarcoma (STS) after first-line chemotherapy failure. METHODS: We recruited 93 patients with metastatic STS who had received first-line chemotherapy 4-6 times but developed progressive disease, from January 2010 to July 2015; 45 patients who had combined 125I brachytherapy and second-line chemotherapy (Group A), and 48 patients who received second-line CT only (Group B). RESULT: In Group A, 49 125I seed implantation procedures were performed in 45 patients with 116 metastatic lesions; the primary success rate was 91.1% (41/45), without life-threatening complications. Local control rates at 3, 6, 12, 24 and 36 months were 71.1%, 62.2%, 46.7%, 28.9% and 11.1% for Group A, and 72.9%, 54.2%, 18.8%, 6.3% and 0% for Group B. Mean progression-free survival differed significantly (Group A: 7.1±1.3 months; Group B: 3.6 ±1.1 months; P<0.001; Cox proportional hazards regression analysis), but overall survival did not significantly differ (Group A: 16.9 ±5.1 months; Group B: 12.1 ± 4.8 months). Group A showed better symptom relief and quality of life than Group B. CONCLUSION: CT-guided 125I brachytherapy is a feasible and valuable treatment for patients with metastatic STS. KEY POINTS: • 125 I brachytherapy is feasible and valuable for treating metastatic soft tissue sarcoma. • 125 I brachytherapy represents a prominent activity in disease control. • 125 I brachytherapy can achieve better symptom relief and quality of life.

Feasibility and Efficacy of Microwave Ablation Combined with Iodine-125 Seed Implantation in Local Control of Recurrent Retroperitoneal Liposarcomas: Initial Clinical Experience.

INTRODUCTION: The objective of the present study was to evaluate the feasibility, safety, and short-term efficacy of microwave ablation (MWA) combined with iodine-125 (125I) seed implantation in recurrent retroperitoneal liposarcomas (rRPLs). MATERIALS AND METHODS: From September 2012 to March 2015, 11 patients were enrolled in this prospective study. Eleven tumors (median, 9 cm; range, 5.5-12.5 cm) were treated with computerized tomography-guided MWA for 11 sessions and 125I seed implantation for 18 sessions. 125I seed implantation was performed 4 weeks after MWA. RESULTS: There were no procedure-related deaths. Post-MWA pain (grade ≥2) was the most common complication (6 of 11 patients, 54.5%), and fever (grade ≥2) was observed in two patients. Reversible nerve injury, defined as transient limb paresthesia or leg weakness, was observed in one patient. There were fewer complications associated with the 125I seed implantation procedure compared with the MWA procedure. All 11 patients who underwent the MWA procedure achieved a partial response (PR), according to the modified Response Evaluation Criteria in Solid Tumors, 1 month post-ablation; after 125I seed implantation was performed, a complete response was observed in three, five, and six target tumors in 3, 6, and 12 months, respectively. CONCLUSION: In selected patients with rRPLs, MWA combined with 125I seed implantation is feasible and safe with favorable local control efficacy. IMPLICATIONS FOR PRACTICE: This study evaluated the feasibility, safety, and short-term efficacy of microwave ablation (MWA) combined with iodine-125 (125I) seed implantation in recurrent retroperitoneal liposarcomas (rRPLs). Results suggest that a single session of MWA may be not sufficient in large-volume rRPLs and that as a supplement treatment, 125I seed implantation is safe and easy accessible. MWA combined with 125I seed has excellent local control effectiveness, and long-term efficacy and survival benefit still need to be more comprehensively evaluated.

Blood-spinal cord barrier disruption contributes to early motor-neuron degeneration in ALS-model mice.

Humans with ALS and transgenic rodents expressing ALS-associated superoxide dismutase (SOD1) mutations develop spontaneous blood-spinal cord barrier (BSCB) breakdown, causing microvascular spinal-cord lesions. The role of BSCB breakdown in ALS disease pathogenesis in humans and mice remains, however, unclear, although chronic blood-brain barrier opening has been shown to facilitate accumulation of toxic blood-derived products in the central nervous system, resulting in secondary neurodegenerative changes. By repairing the BSCB and/or removing the BSCB-derived injurious stimuli, we now identify that accumulation of blood-derived neurotoxic hemoglobin and iron in the spinal cord leads to early motor-neuron degeneration in SOD1(G93A) mice at least in part through iron-dependent oxidant stress. Using spontaneous or warfarin-accelerated microvascular lesions, motor-neuron dysfunction and injury were found to be proportional to the degree of BSCB disruption at early disease stages in SOD1(G93A) mice. Early treatment with an activated protein C analog restored BSCB integrity that developed from spontaneous or warfarin-accelerated microvascular lesions in SOD1(G93A) mice and eliminated neurotoxic hemoglobin and iron deposits. Restoration of BSCB integrity delayed onset of motor-neuron impairment and degeneration. Early chelation of blood-derived iron and antioxidant treatment mitigated early motor-neuronal injury. Our data suggest that BSCB breakdown contributes to early motor-neuron degeneration in ALS mice and that restoring BSCB integrity during an early disease phase retards the disease process.

Feasibility and Clinical Value of CT-guided (125)I Brachytherapy for Bilateral Lung Recurrences from Colorectal Carcinoma.

PURPOSE: To prospectively evaluate the feasibility and clinical value of computed tomography (CT)-guided iodine 125 ((125)I) brachytherapy to treat bilateral lung recurrences from colorectal carcinoma. MATERIALS AND METHODS: This study was approved by Sun Yat-sen University Cancer Center Institutional Review Board and all patients provided informed written consent. Seventy-two patients with bilateral lung recurrences from colorectal carcinoma were enrolled and randomly divided into two groups. Thirty-three were percutaneously treated with CT-guided (125)I brachytherapy (group A) and the other 39 were only given symptomatic and supportive treatments (group B). Follow-up contrast agent-enhanced CT scans were reviewed and efficacy of treatment was evaluated. (125)I brachytherapy was considered a success if it achieved the computerized treatment planning system criteria 1 month after procedure. Analyses included Kaplan-Meier, Mantel-Cox log-rank test, and Cox proportional hazards regression. RESULTS: In group A, 37 (125)I brachytherapy procedures were performed in 33 patients with 126 lung metastatic lesions and the success rate was 87.9% (29 of 33 patients). The local control rate of 3, 6, 12, 24, and 36 months was 75.8%, 51.5%, 33.3%, 24.2%, and 9.1%, respectively. A small amount of pulmonary hematoma occurred in five patients, and six patients presented with pneumothorax with pulmonary compression of 30%-40%. No massive bleeding or radiation pneumonitis occurred. The mean overall survival (OS) of group A was significantly longer than that of group B, and (125)I brachytherapy was an independent factor that affected the OS (group A, 18.8 months; group B, 8.6 months; hazard ratio, 0.391 [95% confidence interval: 0.196, 0.779]; P = .008). CONCLUSION: CT-guided (125)I brachytherapy is feasible and safe for the treatment of bilateral lung recurrences from colorectal carcinoma.

Determination of boron in water samples by dispersive liquid-liquid microextraction based on the solidification of a floating organic drop coupled with a fluorimetric method.

In this work, a new, rapid and reliable method for the determination of boron in water samples by dispersive liquid-liquid microextraction based on the solidification of a floating organic drop (DLLME-SFO) prior to fluorescence spectra analysis was developed. As a result of its complexation with boric acid, the method relies on the enhancement of the fluorescence (λex = 350 nm, λem = 373 nm) of chromotropic acid. The influences of DLLME-SFO parameters, including the extraction solvent type and its volume, pH, the disperser solvent type and its volume, and salt effects were investigated. Under the optimized conditions, the limit of detection was 0.11 ng L(-1), with a preconcentration factor of 86 times. The calibration curve was linear in the range of 0-40 nM. The proposed method has also been successfully applied to analyze real water samples and the relative recoveries of water samples ranged from 86.9 to 93.2%.

Dispersive solid-phase extraction followed by vortex-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet for the determination of benzoylurea insecticides in soil and sewage sludge.

A novel dispersive solid-phase extraction combined with vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the determination of eight benzoylurea insecticides in soil and sewage sludge samples before high-performance liquid chromatography with ultraviolet detection. The analytes were first extracted from the soil and sludge samples into acetone under optimized pretreatment conditions. Clean-up of the extract was conducted by dispersive solid-phase extraction using activated carbon as the sorbent. The vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet procedure was performed by using 1-undecanol with lower density than water as the extraction solvent, and the acetone contained in the solution also acted as dispersive solvent. Under the optimum conditions, the linearity of the method was in the range 2-500 ng/g with correlation coefficients (r) of 0.9993-0.9999. The limits of detection were in the range of 0.08-0.56 ng/g. The relative standard deviations varied from 2.16 to 6.26% (n = 5). The enrichment factors ranged from 104 to 118. The extraction recoveries ranged from 81.05 to 97.82% for all of the analytes. The good performance has demonstrated that the proposed methodology has a strong potential for application in the multiresidue analysis of complex matrices.

Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet combined with flame atomic absorption spectrometry for the fast determination of cadmium in water samples.

A novel vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet (VSLLME-SFO) was developed for the fast, simple and efficient determination of cadmium (Cd) in water samples followed by flame atomic absorption spectrometry (FAAS). In the VSLLME-SFO process, the addition of surfactant (as an emulsifier), could enhance the mass transfer from the aqueous solution into the extraction solvent. The extraction solvent could be dispersed into the aqueous phase under vigorous shaking with the vortex. In this paper, we investigated the influences of analytical parameters, including pH, extraction solvent type and its volume, surfactant type and its volume, concentration of chelating agent, salt effect and vortex time, on the extraction efficiency of Cd. Under the optimized conditions, the limit of detection was 0.16 µg/L. The analyte enrichment factor was 37.68. The relative standard deviation was 3.2% (10 µg/L, n = 10) and the calibration graph was linear, ranging from 0.5 to 30 µg/L. The proposed method was successfully applied for the analysis of ultra-trace Cd in river water and wastewater samples.