Expansion-clotting chitosan fabrics based on unidirectional fast-absorption fibers for rapid hemorrhage control.

The rapid absorption of water from the blood to concentrate erythrocytes and platelets, thus triggering quick closure, is important for hemostasis. Herein, expansion-clotting chitosan fabrics are designed and fabricated by ring spinning of polylactic acid (PLA) filaments as the core layer and highly hydrophilic carboxyethyl chitosan (CECS) fibers as the sheath layer, and subsequent knitting of obtained PLA@CECS core spun yarns. Due to the unidirectional fast-absorption capacity of CECS fibers, the chitosan fabrics can achieve erythrocytes and platelets aggregate quickly by concentrating blood, thus promoting the formation of blood clots. Furthermore, the loop structure of coils formed in the knitted fabric can help them to expand by absorbing water to close their pores, providing effective sealing for bleeding. Besides, They have enough mechanical properties, anti-penetrating ability, and good tissue-adhesion ability in wet conditions, which can form a physical barrier to resist blood pressure during hemostasis and prevent them from falling off the wound, thus enhancing hemostasis synergistically. Therefore, the fabrics exhibit superior hemostatic performance in the rabbit liver, spleen, and femoral artery puncture injury model compared to the gauze group. This chitosan fabric is a promising hemostatic material for hemorrhage control.

Influence of pH on property and lipolysis behavior of cinnamaldehyde conjugated chitosan-stabilized emulsions.

In the present study, we prepared cinnamaldehyde (CA) conjugated chitosan-stabilized emulsions (CSCAEs), and the influence of pH on their properties and lipolysis behavior was investigated. Compared to the emulsions stabilized by chitosan itself (CSEs), CSCAEs had better stability against pH during storage. As pH increased from 2.5 to 6.25, the viscosity and modulus of CSCAEs increased. However, when pH shifted from 6.25 to 6.5, emulsion showed lower viscosity and modulus. Confocal laser scanning microscopy results demonstrated that oil droplets still kept intact and individually distributed, and chitosan homogenously covered on the oil droplets at low pH conditions (pH 2.5, 4.0). At higher pH conditions (pH 5.0, 5.5), a few chitosan aggregates on the oil droplets were observed. At pH 6.0 and 6.25, the compact gel network structure was formed. At pH 6.5, some void was found among the chitosan gel network. In vitro simulated digestion experiments presented that pH had no significant effect on the lipolysis process of emulsions. When the oil content varied from 10% to 50%, emulsions still kept good stability against pHs, but the lipolysis extent after digestion decreased. This knowledge provides a strategy for improving stability of chitosan-stabilized emulsion against harsh pH conditions.

Selectively reduction of tobacco specific nitrosamines in cigarette smoke by use of nanostructural titanates.

In this study, titanate nanosheets, nanotubes, and nanowires, were synthesized by hydrothermal treatment anatase TiO2 in different temperatures. The obtained products are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron micrograph (TEM) and Brunauer-Emmett-Teller (BET) nitrogen sorption-desorption measurement. Then, the nanostructural titanates were used as additives for selectively reducing tobacco-specific nitrosamines (TNSAs) in mainstream cigarette smoke (CS) for the first time. These nanomaterials exhibited high reduction ability of TSNAs which was related to their intrinsic properties. The N-NO functional group of TSNAs with a negative charge would react with H(+) on the surface of nanomaterials via chemical absorption and can be retained on the surface of the titanates. Among these materials, titanate nanowires (TNW) captured more TNSAs owing to their network structure, which resulted in the selective reduction ratio of TSNAs being improved significantly. Thus, TNW is a useful additive for selectively reducing the TSNAs in CS without changing the cigarette flavor.

Significant reduction of harmful compounds in tobacco smoke by the use of titanate nanosheets and nanotubes.

Titanate nanosheets and nanotubes have first been introduced into cigarette filter, a great range of harmful compounds including tar, nicotine, ammonia, hydrogen cyanide, selected carbonyls and phenolic compounds can be reduced efficiently.

Synthesis and characterization of titania hollow fiber and its application to the microextraction of trace metals.

A titania hollow fiber membrane was successfully synthesized in a macro range via a template method coupled with a sol-gel process. Thermal gravimetric and differential thermal analysis (TG-DTA) was employed to study the effect of heat treatment on the synthesized hollow fiber, and the crystal forms of the titania hollow fiber membranes at different temperatures were studied by X-ray diffraction (XRD). The pore structure of the prepared titania hollow fiber was characterized by scanning electron micrograph (SEM) and nitrogen adsorption/desorption measurements. The prepared titania hollow fiber membrane was explored as a new adsorption material for trace metals for the first time and a new method of titania hollow fiber membrane solid phase microextraction (MSPME) online coupled to inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace amount of Cd, Co, V and Ni in human serum samples. In order to validate the developed method, two certified reference materials of NIES.No.10-b rice flour and BCR No.184 bovine muscle were analyzed and the determined values were in good agreement with the certified values.

Titania immobilized polypropylene hollow fiber as a disposable coating for stir bar sorptive extraction-high performance liquid chromatography-inductively coupled plasma mass spectrometry speciation of arsenic in chicken tissues.

The bottleneck of applying stir bar sorptive extraction (SBSE) to elemental speciation analysis is lack of suitable extraction phases with good affinities to different elemental species. In this paper, a newly high polar extraction phase of titania immobilized polypropylene hollow fiber (TiO2-PPHF) was prepared by sol-gel immersion and low temperature hydrothermal process and the obtained TiO2-PPHF inherits the adsorption properties of TiO2 and the toughness of PPHF. With a suitable size of stainless steel magnetic bar inserted into the prepared TiO2-PPHF, a disposable TiO2-PPHF coating stir bar was obtained. The prepared TiO2-PPHF was characterized by X-ray diffraction spectrometry and scanning electron microscopy and the significant parameters affecting the extraction efficiency of different arsenic species were studied. Based on the above facts, a new method of SBSE combined with high performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for the speciation of phenyl arsenic compounds and their possible transformation products in chicken tissues. Under the optimal conditions, limits of detection (LODs) of the developed method for eight target arsenic species were in the range of 11.4-64.6 ng L⁻¹ with enrichment factors of 8.5-22.3 (theory enrichment factor was 50), and the relative standard deviations (RSDs) were varying from 6.3 to 12.6% (c(AsIII/V)=5 µg L⁻¹, c(MMA,DMA,p-ASA,4-OH,3-NHPAA,PA,4-NPAA)=10 µg L⁻¹, n=7). The proposed method was successfully applied to the speciation of arsenic in chicken meat/liver samples and the recoveries for the spiked samples were in the range of 78.5-120.4%. In order to validate the accuracy of the proposed method, a certified reference material of BCR-627 tuna fish tissue was analyzed and the determined values were in good agreement with the certified values. The TiO2-PPHF was demonstrated to be a highly selective coating for the target arsenic species, and could be easily prepared in batches with low cost. In addition, with the disposable coating, the carry-over effect commonly encountered in conventional SBSE was avoided.

Chitosan modified ordered mesoporous silica as micro-column packing materials for on-line flow injection-inductively coupled plasma optical emission spectrometry determination of trace heavy metals in environmental water samples.

A novel adsorbent of chitosan chemically modified ordered mesoporous silica was synthesized and employed as a solid phase extraction (SPE) material for flow injection (FI) micro-column preconcentration on-line coupled with inductively coupled plasma optical emission spectrometry (ICP-OES) determination of trace heavy metals V, Cu, Pb, Cd and Hg in environmental water samples. The factors affecting separation and preconcentration of target heavy metals such as pH, sample flow rate and volume, eluent concentration and volume, interfering ions were investigated. Under the optimized experimental conditions, an enrichment factor of 20 and sampling frequency of 10h(-1) were obtained. The detection limits of the method for V, Cu, Pb, Cd and Hg were 0.33, 0.30, 0.96, 0.05 and 0.93 ng mL(-1), and the relative standard deviations (RSDs) were 2.8%, 6.7%, 1.8%, 4.0% and 5.3% (n=7, C=10 ng mL(-1)), respectively. The adsorption capacities of chitosan modified ordered mesoporous silica for V, Cu, Pb, Cd, and Hg were found to be 16.3, 21.7, 22.9, 12.2 and 13.5 mg g(-1), respectively. In order to validate the developed method, a certified reference material of GSBZ50009-88 environmental water sample was analyzed and the determined values were in good agreement with the certified values. The proposed method has also been applied to the determination of trace heavy metals in natural water samples with satisfactory results.

Separation/preconcentration of trace amounts of Cr, Cu and Pb in environmental samples by magnetic solid-phase extraction with Bismuthiol-II-immobilized magnetic nanoparticles and their determination by ICP-OES.

A new method for separation/preconcentration of trace amounts of Cr, Cu and Pb in environmental samples by magnetic solid-phase extraction (SPE) with Bismuthiol-II-immobilized magnetic nanoparticles and their determination by ICP-OES has been developed. The separation of the target analytes from the aqueous solution containing the target analytes and Bismuthiol-II-immobilized magnetic nanoparticles was simply achieved by applying external magnetic field. Optimal experimental conditions including pH, sample volume, eluent concentration and volume and co-existing ions have been studied and established. Under the optimal experimental conditions, the detection limits for Cr, Cu and Pb with enrichment factors of 96, 95 and 87 were found to be 0.043, 0.058 and 0.085 ngmL(-1) and their relative standard deviations (R.S.D.s) were 3.5%, 4.6% and 3.7% (n=5, C=2 ngmL(-1)), respectively. The method was validated with certified reference material (GBW50009-88) of environmental water sample and the analytical results coincided well with the certified values. Furthermore, the method was successfully applied to the determination of target analytes in river and lake water samples. Compared with established methods, the proposed method is characterized with high enrichment factor, fast separation and low detection limits.

Separation and preconcentration of inorganic arsenic species in natural water samples with 3-(2-aminoethylamino) propyltrimethoxysilane modified ordered mesoporous silica micro-column and their determination by inductively coupled plasma optical emission spectrometry.

A simple and sensitive method using micro-column packed with 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS) modified ordered mesoporous silica combined with inductively coupled plasma optical emission spectrometry (ICP-OES) for the speciation of inorganic arsenic (As(III) and As(V)) has been developed. The adsorption behaviors of As(III) and As(V) on AAPTS modified ordered mesoporous silica were investigated. It was found that As(V) can be selectively adsorbed on the micro-column within pH of 3-9, while As(III) could not be retained in the studied pH range and passed through the micro-column directly. Total inorganic arsenic was extracted after the oxidation of As(III) to As(V) with 50.0 micromol L(-1) KMnO(4). The assay of As(III) was based on subtracting As(V) from total As. The effect of various parameters on the separation/preconcentration of As(III) and As(V) have been investigated and the optimal experimental conditions were established. The adsorption capacity of AAPTS modified ordered mesoporous silica for As(V) was found to be 10.3 mg g(-1). The detection limit of the method for As(V) was 0.05 microg L(-1) with an enrichment factor of 100, and the relative standard deviation (R.S.D.) was 5.7% (n=7, C=1.0 microg L(-1)). In order to validate the developed method, a certified reference material GSBZ50004-88 environmental water sample was analyzed and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the speciation analysis of inorganic arsenic in natural water samples.

Determination of Cd, Co, Ni and Pb in biological samples by microcolumn packed with black stone (Pierre noire) online coupled with ICP-OES.

A simple and sensitive method using microcolumn (20-mm length x 2.0-mm i.d.) packed with black stone (Pierre noire) for the separation/preconcentration of Cd, Co, Ni and Pb in biological samples prior to their online determination by inductively coupled plasma optical emission spectrometry (ICP-OES) has been developed. Optimal experimental conditions including pH, eluent concentration and volume, sample volume and sample flow rate were investigated and established. The adsorption capacity of black stone for Cd, Co, Ni and Pb were found to be 23.4, 21.2, 18.1 and 22.2 mg g(-1), respectively. With a preconcentration time of 72 s and an elution time of 4s, an enrichment factor of 20 and a sampling frequency of 25 h(-1) were obtained. The detection limits corresponding to three times the standard deviations of the blank for Cd, Co, Ni and Pb were found to be 0.3, 0.4, 0.4 and 1.1 ng mL(-1). The precision for seven replicate determinations of Cd, Co, Ni and Pb gave relative standard deviations (RSDs) of 5.9, 4.8, 2.7 and 1.1%, respectively (n=7, C=10 ng mL(-1)). The method was validated with certified reference material GBW09103 human urine and the results obtained were in good agreement with the certified values. The method was also applied to the determination of the target analytes in biological samples with satisfactory results.

Speciation of inorganic tellurium from seawater by ICP-MS following magnetic SPE separation and preconcentration.

A new method was developed for the speciation of inorganic tellurium species in seawater by inductively coupled plasma-MS (ICP-MS) following selective magnetic SPE (MSPE) separation. Within the pH range of 2-9, tellurite (Te(IV)) could be quantitatively adsorbed on gamma-mercaptopropyltrimethoxysilane (gamma-MPTMS) modified silica-coated magnetic nanoparticles (MNPs), while the tellurate (Te(VI)) was not retained and remained in solution. Without filtration or centrifugation, these tellurite-loaded MNPs could be separated easily from the aqueous solution by simply applying external magnetic field. The Te(IV) adsorbed on the MNPs could be recovered quantitatively using a solution containing 2 mol/L HCl and 0.03 mol/L K2Cr2O7. Te(VI) was reduced to Te(IV) by L-cysteine prior to the determination of total tellurium, and its assay was based on subtracting Te(IV) from total tellurium. The parameters affecting the separation were investigated systematically and the optimal separation conditions were established. Under the optimal conditions, the LOD obtained for Te(IV) was 0.079 ng/L, while the precision was 7.0% (C = 10 ng/L, n = 7). The proposed method was successfully applied to the speciation of inorganic tellurium in seawater.

Organic and inorganic selenium speciation in environmental and biological samples by nanometer-sized materials packed dual-column separation/preconcentration on-line coupled with ICP-MS.

A novel, fast, and cheap nonchromatographic method for direct speciation of dissolved inorganic and organic selenium species in environmental and biological samples was developed by flow injection (FI) dual-column preconcentration/separation on-line coupled with ICP-MS determination. In the developed technique, the first column packed with nanometer-sized Al(2)O(3) could selectively adsorb the inorganic selenium [Se(IV), Se(VI)], and the retained inorganic selenium could be eluted by 0.2 mol l(-1) NaOH, while the organic Se [selenocystine (SeCys(2)) and selenomethionine (Se-Met)] was not retained. On the other hand, the second column packed with mesoporous TiO(2) chemically modified by dimercaptosuccinic acid (DMSA) could selectively adsorb Se(IV) and SeCys(2) and barely adsorb Se(VI) and Se-Met. When the sample solution was passed through the column 1, separation of inorganic selenium and organic selenium could be achieved first. Then, the effluent from column 1 was successively introduced into the column 2 and the speciation of organic selenium could be attained due to the different adsorption behaviors of Se-Met and SeCys(2) on DMSA modified TiO(2). After that, the eluent from column 1 contained Se(IV), and Se(VI) was adjusted to desired pH and injected into column 2, and the speciation of Se(IV) and Se(VI) could also be realized thanks to their different retention on column 2. The parameters affecting the separation were investigated systematically and the optimal separation conditions were established. The detection limits obtained for Se(IV), Se(VI), Se-Met and SeCys(2) were 45-210 ng l(-1) with precisions of 3.6-9.7%. The proposed method has been successfully applied for the speciation of dissolved inorganic and organic selenium in environmental and biological samples. In order to validate the methodology, the developed method was also applied to the speciation of selenium in certified reference material of SELM-1 yeast, and the determined values were in good agreement with the certified values.

ICP-AES determination of trace rare earth elements in environmental and food samples by on-line separation and preconcentration with acetylacetone-modified silica gel using microcolumn.

A novel method of online microcolumn separation and preconcentration coupled to inductively coupled plasma atomic emission spectrometry (ICP-AES) with the use of acetylacetone-modified silica gel as packing material was developed for the determination of trace rare earth elements (REEs) in environmental and food samples. The main parameters affecting online separation/preconcentration, including pH, sample flow rate, sample volume, elution and interfering ions, have been investigated in detail. Under the optimized operating conditions, the adsorption capacity values for Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were 25.65, 23.23, 24.01, 19.40, 22.89, 23.77, 24.40, 23.96, 25.58, 25.15, 24.86, 22.75, 16.05, 24.13, 26.51 and 27.93 mg g(-1), respectively. Detection limits (3sigma) based on three times standard deviations of the blanks by 8 replicates were in the range from 48 pg mL(-1) for Lu to 1003 pg mL(-1) for Sm. With 90 s preconcentration time and 10 s elution time, the enrichment factor was 10 and the sample frequency was 28 h(-1). The precisions (RSDs) obtained by determination of a 250 ng mL(-1) (n = 8) REEs standard solution were in the range from 1.7% for Y to 4.4% for Sm. The proposed method was successfully applied to the determination of trace REEs in pig liver, agaric and mushroom. To validate the proposed method, we analyzed three certified reference materials (GBW07401 soil, GBW07301a sediment, and GBW07605 tea leaves). The determined values were in a good agreement with the certified values. The method is rapid, selective, sensitive and applicable to the determination of trace REEs in biological and environmental samples with complicated matrix effects.

A new ion-imprinted silica gel sorbent for on-line selective solid-phase extraction of dysprosium(III) with detection by inductively coupled plasma-atomic emission spectrometry.

Dysprosium(III)-imprinted thenoyltrifluoroacetone (TTA) modified silica gel sorbent was synthesized by surface imprinting technique and was employed as a selective solid-phase extraction material for flow injection solid-phase extraction on-line coupled with inductively coupled plasma-atomic emission spectrometry (ICP-AES) determination of Dy(III). The largest selectivity coefficient for Dy(III) in the presence of competitive ions such as La(III), Nd(III) and Gd(III) was above 350. The static adsorption capacity and selectivity coefficient of the imprinted sorbent are higher than those of the non-imprinted sorbent and the imprinted TTA modified silica gel sorbent offered a fast kinetics for the adsorption and desorption of Dy(III). With a sample loading flow rate of 2.5 mL min(-1) for 48 s preconcentration and elution flow rate of 1.5 mL min(-1) for 8 s elution, an enrichment factor of 10 and the sample frequency of 40 sample h(-1) were obtained. Detection limits (3sigma) based on three times standard deviations of the blanks by eight replicates was 0.2 ng mL(-1) and the precisions (R.S.D.s) was 1.5% (n=8, c=40 ng mL(-1)). To validate the proposed method, two certified reference materials of GBW07401 soil and GBW07301a sediment were analyzed and the determined values were in a good agreement with the certified values. The method is rapid, selective, sensitive and applicable to the determination of trace Dy(III) in environmental samples with complicated matrix.

Mesoporous titanium dioxide as a novel solid-phase extraction material for flow injection micro-column preconcentration on-line coupled with ICP-OES determination of trace metals in environmental samples.

Mesoporous titanium dioxide as a novel solid-phase extraction material for flow injection micro-column preconcentration on-line coupled with ICP-OES determination of trace metals (Co, Cd, Cr, Cu, Mn, Ni, V, Ce, Dy, Eu, La and Yb) in environmental samples was described. Possessing a high adsorption capacity towards the metal ions, mesoporous titanium dioxide has found to be of great potential as an adsorbent for the preconcentration of trace metal ions in samples with complicated matrix. The experimental parameters including pH, sample flow rate, volume, elution and interfering ions on the recovery of the target analytes were investigated, and the optimal experimental conditions were established. Under the optimized operating conditions, a preconcentration time of 90s and elution time of 18s with enrichment factor of 10 and sampling frequency of 20h(-1) were obtained. The detection limits of this method for the target elements were between 0.03 and 0.36mugL(-1), and the relative standard deviations (R.S.D.s) were found to be less than 6.0% (n=7, c=5ngmL(-1)). The proposed method was validated using a certified reference material, and has been successfully applied for the determination of the afore mentioned trace metals in natural water samples and coal fly ash with satisfactory results.

Speciation of dissolved iron(II) and iron(III) in environmental water samples by gallic acid-modified nanometer-sized alumina micro-column separation and ICP-MS determination.

A method has been developed for the speciation of trace dissolved Fe(II) and Fe(III) in water by coupling gallic acid (GA) modified nanometer-sized alumina micro-column separation with inductively coupled plasma mass spectrometry (ICP-MS). The separation of Fe(II) and Fe(III) was achieved based on the obvious difference in reaction kinetics between Fe(II) and Fe(III) with GA. Fe(III) was selectively retained on the micro-column at pH 5.5-6.5, while Fe(II) could not be retained by the micro-column at the whole tested pH range of 1.0-6.5, and passed through the micro-column. The Fe(II) can be determined by ICP-MS directly without preconcentration/separation procedure, while Fe(III) retained on the micro-column was then eluted with 1.0 mL of 1 mol L(-1) HCl and determined by ICP-MS. The parameters affecting the separation of Fe(II) and Fe(III) were investigated systematically and the optimum separation conditions were established. Under the optimized conditions, the detection limits of 0.48 microg L(-1) and 0.24 microg L(-1) with relative standard deviation of 5.6% and 4.3%(C= 5 microg L(-1), n= 7) for Fe(II) and Fe(III) were found, respectively. No obvious effect on the speciation of Fe(II) and Fe(III) was found with the change of the ratio of Fe(II) and Fe(III) from 0 ratio 10 to 10 ratio 0. The proposed method was applied for the determination of trace Fe(II) and Fe(III) in environmental water and the recoveries for spiked samples were found to be in the range of 97-105%.

Speciation of aluminum in drink samples by 8-hydroxyquinoline loaded silylanization silica gel microcolumn separation with off-line ICP-MS detection.

A technique using a flow injection microcolumn separation coupled with ICP-MS detection has been developed for the speciation of Al in drink samples. The retention behaviors of different Al species were studied with 8-hydroxyquinoline (8-HQ) loaded silylanization silica gel as the packing material and inorganic acid (HNO3) as the elution. The results indicated that in a pH range of 5.0 to 8.0, all labile monomeric Al species were retained on the microcolumn while nonlabile monomeric Al species were directly passed through the column. Various Al species after separation were detected by ICP-MS. The detection limit of 0.2 ng mL(-1) and a relative standard deviation (RSD) of 4.2% at 10 ng mL(-1) (n = 11) were achieved, and the recoveries for the spiked samples were 95-108%. The proposed method has been applied to the analysis of Al species in tea infusions, coffee, and tap waters with satisfactory results. The results obtained by this method were compared with that obtained by the cation exchange microcolumn separation and ICP-MS detection system, and some valuable conclusions were drawn.