Efficient lead immobilization by bio-beads containing Pseudomonas rhodesiae and bone char.

Mineralization of lead ions (Pb2+) to pyromorphite using phosphorus-containing materials is an effective way to remediate lead (Pb) contamination. Bone char is rich in phosphorus, but its immobilization of Pb2+ is limited by poor phosphate release. To utilize the phosphorus in bone char and provide a suitable growth environment for phosphate-solubilizing bacteria, bone char and Pseudomonas rhodesiae HP-7 were encapsulated into bio-beads, and the immobilization performance and mechanism of Pb in solution and soil by bio-beads were investigated. The results showed that 137 mg/g of phosphorus was released from bone char in the presence of the HP-7 strain. Pb2+ removal efficiency reached 100 % with an initial Pb2+ concentration of 1 mM, bone char content of 6 g/L, and bio-bead dosage of 1 %. Most Pb2+ was immobilized on the surface of the bio-beads as Pb5(PO4)3Cl. The soil remediation experiments showed a 34 % reduction in the acid-soluble fraction of Pb. The bio-beads showed good stability in long-term (30 d) soil remediation. The present study shows that bone char can be turned into an efficient Pb immobilization material in the presence of phosphate-solubilizing bacteria. Thus, bio-beads are expected to be used in the remediation of Pb-contaminated environments.

Identification and Evaluation of Microplastics from Tea Filter Bags Based on Raman Imaging.

Microplastic (MP) contamination is a public issue for the environment and for human health. Plastic-based food filter bags, including polyethylene terephthalate, polypropylene, nylon 6 (NY6), and polyethylene, are widely used for soft drink sub-packaging, increasing the risk of MPs in foods and the environment. Three types of commercially available filter bags, including non-woven and woven bags, were collected, and MPs released after soaking were mapped using Raman imaging combined with chemometrics. Compared with peak area imaging at a single characteristic peak, Raman imaging combined with direct classical least squares calculation was more efficient and reliable for identifying MP features. Up to 94% of the bags released MPs after soaking, and there was no significant correlation with soaking conditions. Most MPs were tiny fragments and particles, and a few were fibrous MPs 620-840 µm in size. Woven NY6 filter bags had the lowest risk of releasing MPs. Source exploration revealed that most MPs originated from fragments and particles adsorbed on the surface of bags and strings. The results of this study are applicable to filter bag risk assessment and provide scientific guidance for regulating MPs in food.

Estimation of contamination level in microplastic-exposed crayfish by laser confocal micro-Raman imaging.

Crayfish is one of the most important freshwater aquaculture species in China. The potential risks of crayfish consumption caused by environmental microplastic pollution have attracted much attention. In this study, a total of 72 crayfish samples were exposed to the microplastic concentrations of 1 mg/L, 3 mg/L, and 9 mg/L for 7, 14, and 28 days, and microplastic contamination levels in crayfish were then explored by laser confocal micro-Raman (LCM-Raman) imaging and scanning electron microscope (SEM). LCM-Raman imaging showed better performance in microplastics identification. Besides, the average percentage of the contaminated area in visualized LCM-Raman images was used to quantitatively assess contamination levels. Following 28 days of exposure to 9 mg/L microplastics, microplastic accumulation reached about 13,000 particles per crayfish. The results confirmed that LCM-Raman imaging combined with image processing technology could be used to construct a high-performance analytical strategy for the assessment of microplastic contamination in crayfish.

Transforming cerussite to pyromorphite by immobilising Pb(II) using hydroxyapatite and Pseudomonas rhodesiae.

Lead (Pb) pollution has become one of the most serious environmental problems in recent decades. However, there are few remediation technologies for insoluble cerussite (PbCO3), which are common in the environment and have high bioavailability. In this study, the immobilisation of Pb(II) released from PbCO3 by Pseudomonas rhodesiae HP-7 isolated from Pb-contaminated soil was studied. The results showed that hydroxyapatite and PbCO3 were dissolved by the organic acids secreted by the HP-7 strain, and then the dissolved Pb2+ and H2PO4- reacted to form low bioavailable Pb5(PO4)3Cl precipitate. XRD and mass conservation calculations showed that 85.7% of PbCO3 was transformed to Pb5(PO4)3Cl when P:Pb was 9:5. Our research showed that the HP-7 strain and hydroxyapatite could reduce the bioavailability of Pb(II) in PbCO3, which could be used for the remediation of Pb-polluted environments.

Degradation of low-concentration perfluorooctanoic acid via a microbial-based synergistic method: assessment of the feasibility and functional microorganisms.

Perfluorooctanoic acid (PFOA) is persistent in the environment. The activities of microorganisms alone are insufficient for the decomposition of PFOA, but microorganisms can contribute positively to the degradation of PFOA in synergistic systems. Herein, a synergistic system combining photocatalytic decay with microbial degradation of the transformation products was applied to degrade 500.0 µg L-1 PFOA. The microorganisms increased the total removed percentage by 30.7% to a final percentage of 79.7 ± 9.4% in comparison with the photocatalytic method alone. Moreover, an additional 44.2% of removed total organic carbon and additional defluorination percentage of 24.5% were obtained after the synergistic tests. The 16S RNA sequencing analysis indicated that Stenotrophomonas, Bacillus, Pseudomonas, and Brevundimonas were highly enriched in the functional microbial community, which was simultaneously shaped by photocatalysis and substances. This study found it would be feasible to use a synergistic method containing photocatalysis and a microbial community for the degradation of low-concentrations of PFOA, and the results provided a reference to modified the removal efficiency of the synergistic system by looking insight into the relationship between the functional microbial community and PFOA.

Effects of rice straw/wood sawdust addition on the transport/conversion behaviors of heavy metals during the liquefaction of sewage sludge.

Lignocellulosic biomass has been widely introduced into the liquefaction process of sewage sludge (SS) to improve the yield/quality of liquefaction products (bio-oil/biochar). This study explores the effect of adding rice straw (RS) and wood sawdust (WS) on the transport/conversion behaviors of heavy metals (HMs) during the liquefaction of SS. The introduction of lignocellulosic biomass, especially for RS, substantially lowers the total content of HMs in biochar. Most HMs (except Cd) still remain in biochar, although the introduction of RS/WS enhances the transport of HMs into bio-oils. The addition of RS/WS raises the percentage of HMs in active form, but the contents of bioavailable/leachable HMs are not considerably increased and even decreased in some cases, especially when RS is introduced. The overall pollution degree and environmental risk of HMs in biochars are lowered to a certain extent with the addition of RS/WS. Considering that the pollution degree and environmental risk of HMs present in biochars are still at a considerable level, appropriate pollution management measures should be undertaken when using such biochars for agricultural use.

Reduced graphene oxide/iron nanoparticles used for the removal of Pb (II) by one step green synthesis.

While nanomaterials are increasingly being proposed for contaminant remediation, a major challenge is how to develop high removal functionality while maintaining low cost and environmental friendliness. In this study, a hybrid reduced graphene oxide/iron nanoparticle (rGO/Fe NPs) was prepared via the in situ reduction of GO and FeCl3 by eucalyptus leaf extract in one-pot. The obtained rGO/Fe NPs could rapidly remove 72.7% of Pb(II) from aqueous solution in 10 mins and remove up to the maximum removal efficiency of 82.4%. Electron microscopy, XPS and BET showed that the irregular Fe3O4 nanoparticles, sized between 20 and 40 nm, were disorderly dispersed on rGO sheets, which constituted a mesoporous material. FTIR and XRD indicated that the surface of rGO/Fe NPs was capped by many active organic constituents from the eucalyptus leaf extract. rGO/Fe NPs also showed a high selectivity for Pb(II) with minimal interference from either calcium or magnesium ions in the solution. Finally, GC-MS separated 13 significant active organic constituents from the eucalyptus leaf extract that possibly contributed to the reduction of rGO/Fe NPs. Overall, eucalyptus leaf extracts, acted efficiently as green reducing agents and impacted reactivity of the final material by determining the components and surface properties of rGO/Fe NPs.

[Rapid analysis of the specific migration of seven terephthalates and benzoates from plastic food contact material and products by high performance liquid chromatography-ultraviolet detection].

A method based on high-performance liquid chromatography-ultraviolet (HPLC-UV) detection was developed for the rapid analysis of the specific migration of seven terephthalates and benzoates (TPBAs) in seven food simulants (10% (v/v) ethanol, 3% (m/v, i. e. 3 g/100 mL) acetic acid, 4% (v/v) acetic acid, 20% (v/v) ethanol, 50% (v/v) ethanol, 95% (v/v) ethanol, or olive oil)). Detailed comparisons were made on the extraction or purification of the seven TPBAs in olive oil food simulants by solvents, QuEChERS dSPE EMR-Lipid technology, and Captiva EMR-Lipid technology. The seven TPBAs were separated completely within 17 min by gradient elution on a phenyl column using water and methanol as the mobile phase. The detection wavelength was set at 237 nm. The injection volume was 10 µL. The linearities of the seven TPBAs were good, with r≥0.9998 at 1-80 mg/L or 8-160 mg/kg in the seven food simulants. The average recoveries of the seven TPBAs were between 91.7% and 106%, with relative standard deviations (RSDs) between 0.1% and 3.1% (n=6). The limits of quantification were 0.2-8.1 mg/kg. This method is simple, with convenient pretreatments, good chromatographic separation and linear relationships, as well as satisfactory recoveries and RSDs. The method has been applied to detect the specific migration of the seven TPBAs in real samples.

High-performance liquid chromatography - Ultraviolet method for the determination of total specific migration of nine ultraviolet absorbers in food simulants based on 1,1,3,3-Tetramethylguanidine and organic phase anion exchange solid phase extraction to remove glyceride.

The glyceride in oil food simulant usually causes serious interferences to target analytes and leads to failure of the normal function of the RP-HPLC column. In this work, a convenient HPLC-UV method for the determination of the total specific migration of nine ultraviolet (UV) absorbers in food simulants was developed based on 1,1,3,3-tetramethylguanidine (TMG) and organic phase anion exchange (OPAE) SPE to efficiently remove glyceride in olive oil simulant. In contrast to the normal ion exchange carried out in an aqueous solution or aqueous phase environment, the OPAE SPE was performed in the organic phase environments, and the time-consuming and challenging extraction of the nine UV absorbers from vegetable oil with aqueous solution could be readily omitted. The method was proved to have good linearity (r≥0.99992), precision (intra-day RSD≤3.3%), and accuracy(91.0%≤recoveries≤107%); furthermore, the lower limit of quantifications (0.05-0.2mg/kg) in five types of food simulants(10% ethanol, 3% acetic acid, 20% ethanol, 50% ethanol and olive oil) was observed. The method was found to be well suited for quantitative determination of the total specific migration of the nine UV absorbers both in aqueous and vegetable oil simulant according to Commission Regulation (EU) No. 10/2011. Migration levels of the nine UV absorbers were determined in 31 plastic samples, and UV-24, UV-531, HHBP and UV-326 were frequently detected, especially in olive oil simulant for UV-326 in PE samples. In addition, the OPAE SPE procedure was also been applied to efficiently enrich or purify seven antioxidants in olive oil simulant. Results indicate that this procedure will have more extensive applications in the enriching or purification of the extremely weak acidic compounds with phenol hydroxyl group that are relatively stable in TMG n-hexane solution and that can be barely extracted from vegetable oil.

[Simultaneous determination of total specific migration limit of seven benzene polycarbonic acids and their derivatives in food simulants by high performance liquid chromatography-ultraviolet detection].

A novel method for simultaneous determination of total specific migration limits (SML (T)) of trimellitic, isophthalic, terephthalic, phthalic acid and their derivatives (1, 2, 4-benzenetricarboxylic anhydride, isophthaloyl chloride and terephthaloyl chloride) in food simulants (10% (v/v) ethanol, 20% (v/v) ethanol, 50% (v/v) ethanol, 3% (w/v) acetic acid and olive oil) was developed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). After the migration test, the soaking solution was cooled down and vortexed. After the extraction of olive oil food simulants with 0. 1% (w/v) ammonium acetate aqueous solution, the clear aqueous solution or other aqueous food simulants was filtered through a hydrophilic polytetrafluoroethylene filter with a disposable syringe before injection. The Synergi Polar-RP column (250 mm x 4.6 mm, 4 µm) and gradient elution mode were selected. The variable wavelength detector was set at 232 nm. The limits of quantification were 0.1-0.2 mg/kg; the linearity of the method was good with r2 > 0.999 91 over the range from 0.5 to 12 mg/L for aqueous food simulants or 0.5 to 12 mg/kg for olive oil food simulants. The recoveries of them were between 94. 3% and 105% with the relative standard deviations between 0.1% and 2.3% at the levels of 1.25, 2.50, 6.25 mg/kg. The method shows the low limits of detection, good recoveries and accuracies, and meets the requirement of ( EU) No 10/2011 regulation for the total specific migration limits of trimellitic, isophthalic, terephthalic, phthalic acids and their derivatives. The method has been applied to the analysis of food contact material samples.

Automated cell analysis of cerebrospinal fluid with XE-5000.

BACKGROUND: Hematology analyzers have been able to make automated counts of cells present in CSF samples in recent years. Most of them cannot provide reliable counts of the low cell levels usually present in CSF. METHODS: Functional sensitivity, precision, analytical measurement range, and method comparisons were deter- mined according to Clinical Laboratory Standards Institute (CLSI) guidelines. RESULTS: The functional sensitivity for white blood cells (WBC) and red blood cells (RBC) was 18/µL and 725/µL (minimum reported concentration), respectively. The total precision ranged from 6.1% to 16.3% for WBC counts within the concentration of 33-183/µL and from 4.1% to 19.4% for RBC counts within the concentration of 745-11,350/µL. The within-run precision for WBC was 3.1% at 7,592/µL. The analytical measurement range was 18-10,078/µL for WBC and 725-5,222,550/µL for RBC. There was good correlation between WBC and RBC counts determined by the XE5000 and microscopic examination, according to slopes and R2 method comparisons. The correlation of the two methods for mononuclear cell (MN) counts was 0.907 with the WBC count of 50-5,000/µL. The reliability of WBC counts produced by the XE-5000 was 0.7. CONCLUSIONS: The XE-5000 performed satisfactorily in the CSF assay, but it is still necessary to manually confirm the WBC count when it is less than 18/µL.

[Rapid analysis of 28 primary aromatic amines in aqueous food simulants by high performance liquid chromatography-tandem mass spectrometry].

A novel method for rapid analysis of the migration amounts of 28 primary aromatic amines (PAAs) in aqueous food simulants (10% ethanol, 30 g/L acetic acid and 20% ethanol aqueous solution) was developed using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After the migration test, the soaking solution was cooled down from 100 degrees C, vortexed, filtered through a hydrophilic polytetrafluoroethylene filter with a disposable syringe, and then the filtrate was analyzed by HPLC-MS/MS. A Zorbax SB-Phenyl column (250 mm x 4.6 mm, 5 microm) was selected for chromatography. The mobile phase consisted of water and 0.1% formic acid-25% acetonitrile-methanol solution with gradient elution. The 28 PAAs in aqueous food simulants were detected by tandem mass spectrometer operated in positive electrospray ionization (ESI+) and multiple reaction monitoring (MRM) mode. The limits of quantification for the 28 PAAs were between 0.002 microg/L and 10 microg/L. The linearity of the method was good with correlation coefficients (r2) greater than 0.995 over the concentration range from 5 microg/L or 10 microg/L to 100 microg/L. The average recoveries of the 28 PAAs were between 76.6% and 114% with the relative standard deviations between 1.53% and 8.97% at the levels of 10, 20, and 40 microg/L. The method shows rapid pretreatment, the lower limits of quantification, good recoveries and accuracies, and meets the requirement of European Union (EU) No 10/2011 regulation for the specific migration of PAAs. The method has been applied to analyze the 28 PAAs in different aqueous food simulants from the migration test of 30 batches of food contact material samples exported to EU.

Biotin tagging coupled with amino acid-coded mass tagging for efficient and precise screening of interaction proteome in mammalian cells.

In mammalian cells, when tandem affinity purification approach is employed, the existence of untagged endogenous target protein and repetitive washing steps together result in overall low yield of purified/stable complexes and the loss of weakly and transiently interacting partners of biological significance. To avoid the trade-offs involving in methodological sensitivity, precision, and throughput, here we introduce an integrated method, biotin tagging coupled with amino acid-coded mass tagging, for highly sensitive and accurate screening of mammalian protein-protein interactions. Without the need of establishing a stable cell line, using a short peptide tag which could be specifically biotinylated in vivo, the biotin-tagged target/bait protein was then isolated along with its associates efficiently by streptavidin magnetic microbeads in a single step. In a pulled-down complex amino acid-coded mass tagging serves as "in-spectra" quantitative markers to distinguish those bait-specific interactors from non-specific background proteins under stringent criteria. Applying this biotin tagging coupled with amino acid-coded mass tagging approach, we first biotin-tagged in vivo a multi-functional protein family member, 14-3-3epsilon, which was expressed at close to endogenous level. Starting with approximately 20 millions of 293T cells which were significantly less than what needed for a tandem affinity purification run, 266 specific interactors of 14-3-3epsilon were identified in high confidence.

Determination of angiotensin converting enzyme inhibitory activity by high-performance liquid chromatography/electrospray-mass spectrometry.

A sensitive and rapid method for determination of angiotensin converting enzyme (ACE) inhibitory activity was developed based on a combination of enzymatic reaction followed by high performance liquid chromatography/electrospray-mass spectrometry (HPLC-ESI-MS) determination of its product. The most commonly used substrate hippuryl-histidyl-leucine (HHL) or hippuryl-glycyl-glycine (HGG) hydrolysis catalyzed by purified rabbit lung ACE or human plasma ACE was investigated in the presence of benazeprilat. The incubation time was 8 min for purified lung ACE, and 16 min for human plasma ACE. The produced hippuric acid (HA) was separated from substrate HHL or HGG by HPLC on a C(18) column with isocratic elution within 6.5 min, and quantified by electrospray ionization mass spectrometry (ESI-MS) with p-phthalic acid as an internal standard (IS). The limit of detection of HA was 6.0 ng/ml. HHL or HGG hydrolysis catalyzed by purified lung ACE displayed excellent accuracy and reproducibility. The small total reaction volume, the low concentration of substrate, and the simple treating procedures present the advantages of the new method. Furthermore, the total time of the whole procedure for one sample with the novel method is less than 1/2 of that of the conventional HPLC or spectrophotometry method, while the accuracy and the precision of the new method are almost the same as the conventional HPLC method with UV detection.