Nomogram to predict severe retinopathy of prematurity in Southeast China.

AIM: To define the predictive factors of severe retinopathy of prematurity (ROP) and develop a nomogram for predicting severe ROP in southeast China. METHODS: Totally 554 infants diagnosed with ROP hospitalized in the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University and hospitalized in Taizhou Women and Children's Hospital were included. Clinical data and 43 candidate predictive factors of ROP infants were collected retrospectively. Logistic regression model was used to identify predictive factors of severe ROP and to propose a nomogram for individual risk prediction, which was compared with WINROP model and Digirop-Birth model. RESULTS: Infants from the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University (n=478) were randomly allocated into training (n=402) and internal validation group (n=76). Infants from Taizhou Women and Children's Hospital were set as external validation group (n=76). Severe ROP were found in 52 of 402 infants, 12 of 76 infants, and 7 of 76 infants in training group, internal validation group, and external validation group, respectively. Birth weight [odds ratio (OR), 0.997; 95% confidence interval (CI), 0.996-0.999; P<0.001], multiple births (OR, 1.885; 95%CI, 1.013-3.506; P=0.045), and non-invasive ventilation (OR, 0.288; 95%CI, 0.146-0.570; P<0.001) were identified as predictive factors for the prediction of severe ROP, by univariate analysis and multivariate analysis. For predicting severe ROP based on the internal validation group, the areas under receiver operating characteristic curve (AUC) was 78.1 (95%CI, 64.2-92.0) for the nomogram, 32.9 (95%CI, 15.3-50.5) for WINROP model, 70.2 (95%CI, 55.8-84.6) for Digirop-Birth model. In external validation group, AUC of the nomogram was also higher than that of WINROP model and Digirop-Birth model (80.2 versus 51.1 and 63.4). The decision curve analysis of the nomogram demonstrated better clinical efficacy than that of WINROP model and Digirop-Birth model. The calibration curves demonstrated a good consistency between the actual severe ROP incidence and the predicted probability. CONCLUSION: Birth weight, multiple births, and non-invasive ventilation are independent predictors of severe ROP. The nomogram has a good ability to predict severe ROP and performed well on internal validation and external validation in southeast China.

An ethanolic extract of Arctium lappa L. leaves ameliorates experimental atherosclerosis by modulating lipid metabolism and inflammatory responses through PI3K/Akt and NF-κB singnaling pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Atherosclerosis (AS), a lipid-induced inflammatory condition of the arteries, is a primary contributor to atherosclerotic cardiovascular diseases including stroke. Arctium lappa L. leaf (ALL), an edible and medicinal herb in China, has been documented and commonly used for treating stroke since the ancient times. However, the elucidations on its anti-AS effects and molecular mechanism remain insufficient. AIM OF THE STUDY: To investigate the AS-ameliorating effects and the underlying mechanism of action of an ethanolic extract of leaves of Arctium lappa L. (ALLE). MATERIALS AND METHODS: ALLE was reflux extracted using with 70% ethanol. An HPLC method was established to monitor the quality of ALLE. High fat diet (HFD) and vitamin D3-induced experimental AS in rats were used to determine the in vivo effects; and oxidized low-density lipoprotein-induced RAW264.7 macrophage foam cells were used for in vitro assays. Simvatatin was used as positive control. Biochemical assays were implemented to ascertain the secretions of lipids and pro-inflammatory mediators. Haematoxylin-eosin (H&E) and Oil red O stains were employed to assess histopathological alterations and lipid accumulation conditions, respectively. CCK-8 assays were used to measure cytotoxicity. Immunoblotting assay was conducted to measure protein levels. RESULTS: ALLE treatment significantly ameliorated lipid deposition and histological abnormalities of aortas and livers in AS rats; improved the imbalances of serum lipids including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C); notably attenuated serum concentrations of inflammation-associated cytokines/molecules including TNF-α, IL-6, IL-1ß, VCAM-1, ICAM-1and MMP-9. Mechanistic studies demonstrated that ALLE suppressed the phosphorylation/activation of PI3K, Akt and NF-κB in AS rat aortas and in cultured foam cells. Additionally, the PI3K agonist 740Y-P notably reversed the in vitro inhibitory effects of ALLE on lipid deposition, productions of TC, TNF-α and IL-6, and protein levels of molecules of PI3K/Akt and NF-κB singnaling pathways. CONCLUSIONS: ALLE ameliorates HFD- and vitamin D3-induced experimental AS by modulating lipid metabolism and inflammatory responses, and underlying mechanisms involves inhibition of the PI3K/Akt and NF-κB singnaling pathways. The findings of this study provide scientific justifications for the traditional application of ALL in managing atherosclerotic diseases.

[Two new phenylpropanoids from wine-processed Corni Fructus].

Six compounds were isolated from aqueous extract of wine-processed Corni Fructus through silica gel, ODS column chromatography, Sephadex LH-20 gel column chromatography, reverse phase preparative HPLC and other chromatographic separation technologies. Their structures were identified with multiple spectroscopical methods including HR-ESI-MS, UV, IR, NMR and ECD and so on. Their structures were established as pinoresinoside B(1), cornusgallicacid A(2),(+)-isolariciresinol-9'-O-ß-glucopyranoside(3),(-)-isolariciresinol 3α-O-ß-D-glucopyranoside(4),(7R,8S)-dihydrodehydrodiconiferyl alcohol 9-O-ß-D-glucopyranoside(5), and(-)-seco isolariciresinol-9'-O-ß-D-glucopyranoside(6). Among them, compounds 1 and 2 were two new compounds. The biological activity evaluation results showed that compounds 2 and 6 had strong DPPH free radical scavenging ability, with EC_(50) values of(4.18±1.96) and(21.45±1.19) µmol·L~(-1), respectively. Compounds 1 and 2 had protective effects on H_2O_2-induced oxidative damage in NRK-52E cells in a dose-dependent manner, and the cell survival rate of compound 2 at 100 µmol·L~(-1) was 96.09%±1.77%.

[A new norsesquiterpenoid from Arctium lappa leaves].

Chemical constituents were isolated and purified from ethyl acetate fraction of Arctium lappa leaves by silica gel, ODS, MCI, and Sephadex LH-20 column chromatography. Their structures were identified with multiple spectroscopical methods including NMR, MS, IR, UV, and X-ray diffraction combined with literature data. Twenty compounds(1-20) were identified and their structures were determined as arctanol(1), citroside A(2), melitensin 15-O-ß-D-glucoside(3), 11ß,13-dihydroonopordopicrin(4), 11ß,13-dihydrosalonitenolide(5), 8α-hydroxy-ß-eudesmol(6), syringin(7), dihydrosyringin(8), 3,4,3',4'-tetrahydroxy-δ-truxinate(9),(+)-pinoresinol(10), phillygenin(11), syringaresinol(12), kaeperferol(13), quercetin(14), luteolin(15), hyperin(16), 4,5-O-dicaffeoylquinic acid(17), 1H-indole-3-carboxaldehyde(18), benzyl-ß-D-glucopyranoside(19), and N-(2'-phenylethyl) isobutyramide(20). Among them, compound 1 is a new norsesquiterpenoid, and compounds 2-5, 7-8, and 18-20 are isolated from this plant for the first time.

An Emerging Family of Piezocatalysts: 2D Piezoelectric Materials.

Piezocatalysis is an emerging technique that holds great promise for the conversion of ubiquitous mechanical energy into electrochemical energy through piezoelectric effect. However, mechanical energies in natural environment (such as wind energy, water flow energy, and noise) are typically tiny, scattered, and featured with low frequency and low power. Therefore, a high response to these tiny mechanical energies is critical to achieving high piezocatalytic performance. In comparison to nanoparticles or 1D piezoelectric materials, 2D piezoelectric materials possess characteristics such as high flexibility, easy deformation, large surface area, and rich active sites, showing more promise in future for practical applications. In this review, state-of-the-art research progresses on 2D piezoelectric materials and their applications in piezocatalysis are provided. First, a detailed description of 2D piezoelectric materials are offered. Then a comprehensive summary of the piezocatalysis technique is presented and examines the piezocatalysis applications of 2D piezoelectric materials in various fields, including environmental remediation, small-molecule catalysis, and biomedicine. Finally, the main challenges and prospects of 2D piezoelectric materials and their applications in piezocatalysis are discussed. It is expected that this review can fuel the practical application of 2D piezoelectric materials in piezocatalysis.

[Iridoids of wine-processed Corni Fructus].

A new iridoid glycoside, cornushmf A(1) and nine known iridoids(2-10) were isolated from the water extract of the wine-processed Corni Fructus by various column chromatographies. Their chemical structures were identified by comprehensive spectroscopic methods as 7ß-O-(2″-formylfuran-5″-methylene)-morroniside(1), 7-dehydrologanin(2), sweroside(3), 7ß-O-methylmorroniside(4), 7α-O-methylmorroniside(5), 7ß-O-ethylmorroniside(6), 7α-O-ethylmorroniside(7), cornuside(8), sarracenin(9), and loganin(10).

Four New Gallate Derivatives from Wine-Processed Corni Fructus and Their Anti-Inflammatory Activities.

Four new gallate derivatives-ornusgallate A, ent-cornusgallate A, cornusgallate B and C (1a, 1b, 2, 3)-were isolated from the wine-processed fruit of Cornus officinalis. Among them, 1a and 1b are new natural compounds with novel skeletons. Their chemical structures were elucidated by comprehensive spectroscopy methods including NMR, IR, HRESIMS, UV, ECD spectra and single-crystal X-ray diffraction analysis. The in vitro anti-inflammatory activities of all compounds were assayed in RAW 264.7 cells by assessing LPS-induced NO production. As the result, all compounds exhibited anti-inflammatory activities at attested concentrations. Among the tested compounds, compound 2 exhibited the strongest anti- inflammatory activity.

A new ent-kaurane diterpene from Isodon henryi.

One new ent-Kaurane diterpenoid (1) was isolated from the ethyl acetate fraction of Isodon henryi. Along with ten diterpenoids (2-11) were isolated from this plant for the first time, including six 7,20-epoxy diterpenoids, three enmenol-type diterpenoids and one 6,7-seco-ent-kaurene diterpenoid. Their structures were elucidated by 1 D and 2 D NMR, confirmed by HRESIMS and electronic circular dichroism analyses. Furthermore, the cytotoxicities of twelve compounds were investigated in five human cancer cell lines, including A2780, BGC-823, HCT-116, HepG2 and HeLa. And the IC50 values of these diterpenoids ranged from 2.1 to 88.8 µM in the tested cell lines. Based on the molecular structures of 12 compounds and the bioassay results, it suggests that α,ß-unsaturated pentanone is the cytotoxic active site of 7,20 epoxy ent-kaurane diterpenoid, but it does not contribute much to enmenol-type diterpenoid.Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1675067.

Author Correction: Isolation and identification of two pairs of cytotoxic diterpene tautomers and their tautomerization mechanisms.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Isolation and identification of two pairs of cytotoxic diterpene tautomers and their tautomerization mechanisms.

Discovering anticancer drugs that do not have adverse side effects has been a developing research field worldwide in recent decades. In this work, four previously undescribed cytotoxic diterpenoids were isolated from the aerial parts of Isodon excisoides. Interestingly, these four diterpenoids were two pairs of tautomers that were first reported in plants. Their structures were further elucidated using various spectroscopic methods. The tautomerization phenomenon and mechanism for these two pairs of tautomers were emphatically described. The theoretical simulation results indicated that the diterpene tautomerization is greatly related to certain factors, including the existence of a transition state, the change of bond length and the level of conversion energy; the tautomerization for the two pairs of tautomers is mainly caused by proton transfer. For bioassays, the cytotoxicities of the tautomers against five human cancer cell lines were also investigated. The results indicated that each of the four diterpenoids showed significant cytotoxicity in at least three cell lines and could serve as potential anticancer agents for further investigation.

Four New ent-Kaurane Diterpene Glycosides from Isodon henryi.

To obtain diterpene glycosides from an aqueous extract of the aerial parts of Isodon henryi and further investigate their cytotoxicities, in this study, a total of seven compounds were isolated, including six ent-kaurane diterpene glycosides (1-6) and one diterpene aglycon (7). Among the seven ent-kaurane diterpenes obtained, four were novel compounds, including ent-7,20-epoxy- kaur-16-en-1α,6ß,7ß,15ß-tetrahydroxyl-11-O-ß-d-glucopyranoside (1), ent-7,20-epoxy-kaur-16-en- 6ß,7ß,14ß,15ß-tetrahydroxyl-1-O-ß-d-glucopyranoside (2), ent-7,20-epoxy-kaur-16-en-6ß,7ß,15ß- trihydroxyl-1-O-ß-d-glucopyranoside (3), and ent-7,20-epoxy-kaur-16-en-7ß,11ß,14α,15ß-tetrahydr- oxyl-6-O-ß-d-glucopyranoside (4), and three were isolated from this plant for the first time (5-7). Their structures were elucidated by utilizing spectroscopic methods and electronic circular dichroism analyses. Furthermore, the cytotoxicities of all seven compounds were investigated in four human cancer cell lines, including A2780, BGC-823, HCT-116, and HepG2. The IC50 values of these diterpenes ranged from 0.18 to 2.44 mM in the tested cell lines. In addition, the structure-cytotoxicity relationship of diterpene glycosides was also evaluated to study the effect of glycosylation on the cytotoxicity of diterpene compounds.

[Studies on chemical constituents of Isodon henryi].

The chemical constituents of the water extraction of the aerial parts of Isodon henryi were investigated by various chromatographic methods including D-101 macroporous adsorptive resins,silica gel,sephadex LH-20,and semi-preparative HPLC. As a result,ten compounds were separated and purified. By analyses of the UV,IR,MS,NMR spectra,their structures were determined as rabdosinate( 1),lasiokaurin( 2),epinodosinol( 3),rabdosichuanin C( 4),epinodosin( 5),hebeirubescensin k( 6),rubescensin C( 7),enmenol( 8),oridonin( 9),and enmenol-1-ß-glucoside( 10). Compounds 1-8 and 10 were isolated from I. henryi for the first time. Compounds 2 and 9 showed inhibitory effects against four tumor cells,with IC50 values of 2. 25-9. 32 µmol·L-1.

Isolation and purification of diterpenoids from the aerial parts of Isodon excisoides target-guided by UPLC-LTQ-Orbitrap-MS.

Cytotoxic diterpenoids were enriched and orientation prepared from the aerial parts of Isodon excisoides target-guided by UPLC-LTQ-Orbitrap-MS. Four diterpenoids were obtained, including a novel compound: 1α-acetoxy-7α, 14ß, 20α-trihydroxy-ent-kaur-16-en-15-one (1); together with three known compounds kamebakaurin (2), lasiokaurin (3), enmenol-1-ß-glucoside (4). Their structures were elucidated on the basis of spectroscopic methods in conjunction with published data for their analogues. All compounds were tested for their cytotoxic effects against five human cancer cell lines HCT-116, HepG2, A2780, NCI-H1650 and BGC-823, respectively. Compounds 1 and 2 showed obviously cytotoxic activity against the five cancer cell lines with IC50 ranging from 1.06 to 3.60 µM. Compounds 3 and 4 showed selective cytotoxic activity.

[Studies on chemical constituents of Isodon excisoides].

The chemical constituents of the water extraction of the aerial parts of Isodon excisoides were investigated by various chromatographic methods including D-101 macroporous adsorptive resins, silica gel, Sephadex LH-20, MCI and semi-preparative HPLC. As a result, six compounds were separated and purified.By analyses of the HR-ESI-MS, 1D and 2D NMR spectra, their structures were determined as 3-O-ß-D-allopyranosyl-1-octen-3-ol(1), blumenolA (2), lumichrome (3), loliolide(4), cirsiliol(5) and pedalitin(6). Compound 1 was a new compound, and compounds 2-4 were isolated from this plant for the first time.

[Ilaprazole based bismuth-containing quadruple regimen for the first-line treatment of Helicobacter pylori infection: a multicenter, randomized, controlled clinical study].

OBJECTIVE: To explore the effects of 7-day quadruple regimen as the first-line therapy strategy for Helicobacter pylori(H. pylori)infection and compare the eradication rate of ilaprazole versus esoprazole-based regimen. METHODS: A total of 440 patients with H. pylori infection, who had never received H. pylori eradication treatment, were enrolled from 10 domestic hospitals from October 2010 to July 2011. Diagnosed as chronic gastritis or duodenal ulcer according to their endoscopic examination results, they were randomized into ilaprazole and(or) esoprazole-based bismuth-containing quadruple regimen group with amoxicillin and clarithromycin (n = 110 each). After a 7-day eradication treatment, all patients with duodenal ulcer received PPI (ilaprazole and(or) esoprazole) treatment for 14 days and (13)C urea breath test was performed at least 28 days after the end of therapy. The patients with failed eradication treatment underwent endoscopy examination and biopsy. H. pylori culture and detection of antibiotic-resistant genes were also performed. RESULTS: In gastritis patients, the eradication rate (per-protocol, PP value) were 78.2% (79/101) and 82.0% (82/100) in ilaprazole and esoprazole groups (P = 0.50) while the (intention-to-treat) ITT value of eradication rate were 71.8% (79/110) and 74.5% (82/110) in ilaprazole and esoprazole groups respectively (P = 0.65). And there was no statistical difference (P > 0.05). In duodenal patients, the eradication rate (PP) were 92.1% (93/101) and 91.4% (96/105) in ilaprazole and esoprazole group (P = 0.86) while the ITT value of eradication rate were 84.5% (93/110) and 87.3% (96/110) in ilaprazole and esoprazole groups respectively (P = 0.56). And no significant difference existed between two groups in gastritis and duodenal ulcer patients (P > 0.05). In total, the eradication rate was 80.1% (161/201) (PP) and 73.2% (161/220) (ITT), 91.7% (189/206) (PP) and 85.9% (189/220) (ITT) in chronic gastritis and duodenal ulcer patients respectively. The symptomatic improvements of stomachache, burning, belching and nausea remained almost unchanged. No severe side effect was observed. The point mutations for clarithromycin resistance were detected in all 53 H. pylori strains (100%) isolated from the patients with failed eradication treatment. CONCLUSIONS: The eradication rate of PPI based bismuth-containing quadruple regimen as the first-line treatment is satisfactory in chronic gastritis and duodenal ulcer patients. No significant difference exists between the effects of ilaprazole and esoprazole-based groups. And the treatment failure may be attributed mainly to the clarithromycin resistance of H. pylori.

The relationship between polymorphisms at 17 gene sites and hypertension among the Aboriginal Tibetan people.

OBJECTIVE: The incidence of hypertension in Tibet ranks highest among all Chinese provinces. This may be due to genetic changes caused by Tibet's unique natural environment and agrarian lifestyle, prompting us to investigated the relationship between gene polymorphisms and hypertension. METHODS: Blood samples were collected from 229 hypertensive participants and 372 healthy (control) participants from five Tibetan counties. Seventeen single nucleotide polymorphisms were investigated for their connection to hypertension. RESULTS: The C allele at rs2070744 of the NOS3 gene was shown to be significantly associated with hypertension (P=0.0443; OR=1.636). Additionally, the T allele of rs4961 of the ADD gene was correlated with hypertension in women (P=0.03124; OR=1.584). CONCLUSION: In this study we found that the NOS3 and ADD genes were related to a high incidence of hypertension among Tibetans. NOS3 gene plays a role in regulating vascular tone and blood vessel diameter, which may be altered by the low-oxygen environment of Tibet. ADD is involved in water and salt metabolism, which is consistent with the high-salt diet of Tibetans. The correlations elucidated by our study were different from those of other ethnic groups, indicating that these findings may be specific to the Tibetan people.

[Jinghuaweikang capsules combined with triple therapy in the treatment of Helicobacter pylori associated gastritis and duodenal ulcer and analysis of antibiotic resistance: a multicenter, randomized, controlled, clinical study].

OBJECTIVE: To explore the efficacy of Jinghuaweikang capsules plus triple therapy (LACJ) in treatment of Helicobacter pylori (H. pylori) associated gastritis or duodenal ulcer, compare it with bismuth-containing quadruple therapy (LACB) and standard triple therapy (LAC) and analyze the antibiotic sensitivity of gastric mucosal H. pylori strains from the failed patients. METHODS: A total of 565 patients with H. pylori infection were recruited from 11 hospitals from January 2010 to June 2011. There were 336 males and 229 females. They underwent gastroendoscopy examination due to upper gastrointestinal symptoms and had never received H. pylori eradication therapies. Duodenal ulcer patients were divided randomly into LACJ therapy group, LACB therapy group and LAC therapy group while gastritis patients LACJ therapy group and LACB therapy group. Group LAC received lansoprazole 30 mg + amoxicillin 1000 mg + clarithromycin 500 mg, twice a day, for 7 d (d1-7). Group LACJ: LAC therapy plus Jinghuaweikang, 3 capsules, twice a day, for 7 d (d1-7) then Jinghuaweikang, 3 capsules, twice a day, for 14 d (d8-21). Group LACB: LAC plus bismuth potassium citrate 220 mg, twice a day, for 7 d (d1-7) and then bismuth potassium citrate 220 mg, twice a day, for 14 d (d8-21). All duodenal ulcer patients received lansoprazole (30 mg, once a day) for 14 days after the first 7-day of treatment (d 8-21). At least 28 days after the end of treatment, all patients underwent (13)C urea breath test. Gastric mucosa was collected under endoscopy from the failed patients. The detection technique of gene chip was employed to detect antibiotics resistant gene from mucosa. RESULTS: The eradication rates of duodenal ulcer patients in groups LACJ, LACB and LAC were as follows: per-protocol (PP), 80.2% (77/96), 89.9% (89/99) and 72.2% (70/97) (P = 0.007), intention-to-treat (ITT), 78.6% (77/98), 88.1% (89/101) and 70.0% (70/100) (P = 0.007). No statistical differences existed between groups LACJ and LACB or LAC (all P > 0.05). But there were statistical differences between groups LACB and LAC (both P = 0.002). The eradication rates of PP and ITT of chronic gastritis patients in groups LACJ and LACB were as follows: 75.8% (97/128), 74.6% (97/130) vs 83.8% (109/130), 80.1% (109/136) (both P > 0.05). The symptomatic improvements of abdominal pain, burning and acid reflux of duodenal ulcer patients in group LACJ were higher than those in groups LACB and LAC. There were statistical differences between groups LACJ and LAC (all P < 0.05). The symptomatic improvements of bloating and belching for chronic gastritis patients in group LACJ were higher than those of group LACB. But no significant difference existed between two groups (all P > 0.05). Sixty samples of gastric mucosa were collected from the failed patients. The detection rates of antibiotic-resistant gene to clarithromycin and amoxicillin were 60.0% (36/36) and 18.3% (11/60) respectively. CONCLUSIONS: The efficacy of LACJ for the treatment of H. pylori infection patients is similar to LACB and superior to LAC. And the symptomatic improvement of patients is better than the other two regimens. The main cause of treatment failure is antibiotic resistance of H. pylori strains.

Relationship between dyslipidemia and gene polymorphism in Tibetan population.

OBJECTIVE: To investigate the relationship between SNPs reported in previous studies and the blood lipid level in the Tibetan population. METHODS: Random cluster sampling was employed in 5 areas (Lhasa, Shigatse, Shannan, Nagqu, and Nyingchi). The levels of cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) from blood samples were determined and DNA was extracted for genotyping and statistical analyses. RESULTS: Among 1 318 subjects aged >18 years enrolled in this study, 367 had dyslipidemia with a prevalence of 27.8%, of whom dyslipidemia males accounted for 33.1% and dyslipidemia females -24.5%. Results of the correlation analysis between all SNPs and TG showed that the SNPs of rs714052 and rs964184 were related to the serum TG level. Subjects with rs714052 CC genotype had the lowest TG level, and the highest TG level was found in those with rs714052 TT genotype. The serum TG level in individuals with TC genotype lied in between the above two population groups. Subjects with rs964184 CC genotype had the lowest TG level, and the highest serum TG level was noted in those with rs964184 GG genotype. CONCLUSION: Several SNPs were found to be related to the serum TG level in the Tibetan population. The APOA5 gene and MLXIPL gene may be closely associated with the serum TG level in this ethnic population group.

Modified mesoporous silica materials for on-line separation and preconcentration of hexavalent chromium using a microcolumn coupled with flame atomic absorption spectrometry.

A modified SBA-15 mesoporous silica material NH(2)-SBA-15 was synthesized successfully by grafting γ-aminopropyl-triethoxysilane. The material was characterized using transmission electron microscopy (TEM) and Fourier transform infrared/Raman (FT-IR/Raman) spectroscopy, and used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Effective sorption of Cr (VI) was achieved at pH 2.0 with no interference from Cr (III) and other ions and 0.5 mol L(-1) NH(3)·H(2)O solution was found optimal for the complete elution of Cr (VI). An enrichment factor of 44 and was achieved under optimized experimental conditions at a sample loading of 2.0 mL min(-1) sample loading (300 s) and an elution flow rate of 2.0 mL min(-1) (24s). The precision of the 11 replicate Cr (VI) measurements was 2.1% at the 100 µg L(-1) level with a detection limit of 0.2 µg L(-1) (3s, n=10) using the FAAS. The developed method was successfully applied to trace chromium determination in waste water. The accuracy was validated using a certified reference material of riverine water (GBW08607).