Determination of polycyclic aromatic hydrocarbons in water by solid-phase microextraction and liquid chromatography.

This study describes the determination of polycyclic aromatic hydrocarbons (PAHs) in water using high-performance liquid chromatography (HPLC) coupled with fluorescence detection (FLD). Because individual PAHs are generally present in water only at trace levels, a sensitive and accurate determination technique is essential. The separation and detection of five PAHs were run completely within 25 min by the HPLC/FLD system with an analytical C18 column, a fluorescence detection, and acetonitrile-water gradient elution. Calibration graphs were linear with very good correlation coefficients (r > 0.9998), and the detection limits were in the range of 2-6 ng/l for five PAHs. Solid phase microextraction (SPME) was performed for sample pretreatment prior to HPLC-FLD determination, and the governing parameters were investigated. Compared to conventional methods, SPME has high recovery, saves considerable time, and reduces solvents waste. The extraction efficiencies of five PAHs were above 88% and the extraction times were 35 min in one pretreatment procedure. One particular discovery is that 1.5 M sodium monochloroactate (ClCH2COONa) can improve the extraction yield of PAH compounds more than other inorganic salts. The SPME-HPLC-FLD technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine five PAHs in water from authentic water samples.     

扫描探针显微学中的云纹方法

在扫描探针显微镜（SPM）的扫描过程中，由SPM的扫描线与物质表面周期性晶格结构进行干 涉可以形成纳米云纹图像.采用高取向热解石墨（HOPG）和云母作为试件，分别对扫描隧道 显微镜（STM）和原子力显微镜（AFM）云纹进行了研究，实验结果与理论分析完全一致.SPM 纳米云纹法在纳米测量和表征方面具有较大的应用前景. 关键词： 云纹 SPM 晶格栅线 纳米测量     

由咪唑-4,5-二羧酸和1,4-对苯二甲酸构筑的一个三维镉(Ⅱ)配位聚合物的合成、结构及荧光性质

以CdCl₂、咪唑-4,5-二羧酸(H₃IDC)和1,4-对苯二甲酸(H₂BDC)为原料,在水热条件下合成得到了一个新的三维镉(Ⅱ)配位聚合物[Cd₂(HIDC)(BDC)(H₂O)]_n(1),通过元素分析、红外光谱、粉末X-射线衍射、热重分析和单晶X-射线衍射法等对其组成和结构进行了表征。单晶X-射线结构分析表明,在配合物1的晶体结构中含有沿a轴方向的一维无限的{[Cd₂(CO₂)]₂(CO₂)₂}_n配位聚合链。此聚合链再通过桥连HIDC²与BDC^2-配体的连接,最终形成一复杂的三维金属-有机框架结构。配合物1的固体室温荧光测试结果表明,在波长为350nm的光激发下于456nm处出现强烈的荧光发射。     

Cu(II)-3-(5-chlor-2-hydroxy-3-sulfophenylazo)-6-(2,4,6-tribromophenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic Acid-Co(II) binuclear complexation and its application to the selective determination of cobalt at ng/ml level.

The chromophore, 3-(5-chlor-2-hydroxy-3-sulfophenylazo)-6-(2,4,6-tribromophenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (CSTDD) was used to complex Cu(II) and Co(II) in aqueous solution at pH 9.43. A binuclear complex of Cu-CSTDD-Co was formed and showed a high selectivity for the determination of Co(II). The spectral correction technique was applied to characterize the complexes. The results showed the formation of complexes of Cu(CSTDD), Co(CSTDD)3 and Cu2(CSTDD)2Co. The quantitative analysis of Co(II) at ng/ml level was carried out by the light-absorption ratio variation approach (LARVA). The results showed that the technique is satisfactory to determine Co(II) at trace level in water samples with a detection limit of 2.3 ng/ml.     

双波长光度法测定水中硝酸盐

本文依据在氨性溶液中，硝酸盐（ＮＯ３＾－）与酚二磺酸发生显色反应，以及悬浊液吸收公式，利用双波长法研究水中ＮＯ３＾－测定的新方法，结果表明，该法分析灵敏度，精密度和准确度均优于普通光度法。     

Continuous flow analysis combined with a light-absorption ratio variation approach for determination of copper at ng/ml level in natural water.

The complexation between Cu(II) and naphthochrome green (NG) is very sensitive at pH 4.09 with the formation of complex ion [Cu(NG)2(H2O)2](2-). It can thus used for the determination of Cu(II) by the light-absorption ratio variation approach (LARVA) with a good selectivity. Both the ordinary detection procedure and continuous flow analysis (CFA) were carried out, where the latter is fit for continuous and rapid analysis of samples. The limit of detection (LOD) of Cu(II) is only 1 ng/ml, which is favorable for direct monitoring of natural water. About 30 samples could be analyzed per hour by CFA. Cu(II) contents in Yangtze River, West Lake, Taihu Lake of China and seawater near Shanghai were determined with satisfactory results. The CFA-LARVA spectrophotometry was the first to be coupled and it will play an important role in the in-situ analysis of natural water quality.     

类数公式的机器证明——Chowla一个猜想的注记

设素数 p=4N² + 1 (N为一个正整数 )使得实二次数域Q(√p)的类数为1 ,作为追随吴文俊数学定理机器证明方向的一次尝试 ,用微机证明了一些虚二次数域Q√( -qp)的类数公式 ,这里 q =3,7,1 1 ,1 9,2 3,31 ,43和 47.     

A New 2D Zinc(Ⅱ) Coordination Polymer Constructed by Imidazole-4,5-dicarboxylic Acid(H_3IDC) and 1,4-Bis(imidazol-1-ylmethyl)-benzene(bix)

A new 2D Zn(Ⅱ) coordination polymer [Zn(HIDC)(bix)0.5]n(1) was obtained by the hydrothermal reaction of ZnCl2,imidazole-4,5-dicarboxylic acid(H3IDC) and 1,4-bis(imidazol-1-ylmethyl)-benzene(bix) with a 2:2:1 mole ratio.X-ray diffraction crystal structural analysis reveals it crystallizes in monoclinic,space group P21/n with a = 12.125(3),b = 10.541(3),c = 12.484(3) ,β = 115.834(4)°,V = 1436.0(6) 3,Mr = 338.60,Z = 4,Dc = 1.566 Mg·m-3,F(000) = 684,μ(MoKα) = 1.730 mm-1,the final R = 0.0439 and wR = 0.0888 for 2101 observed reflections with I ≥ 2σ(I).In 1,each zinc(Ⅱ) ion is five-coordinated with a slightly distorted trigonal bipy-ramidal coordination geometry,and each μ2-HIDC2-acts as a bridge to bond two neighboring Zn(Ⅱ) ions,leading to a 1D zigzag chain architecture.The adjacent zigzag chains are further linked by μ2-bix to form an infinite 2D network structure.The fluorescence spectrum of 1 exhibits intense emission at 466 nm when excited at 397 nm in solid state at room temperature.     

二维网状锌(Ⅱ)配位聚合物[Zn(HIDC)(bib)0.5]n的合成、晶体结构和荧光性质

A new 2D Zn(Ⅱ) coordination polymer [Zn(HIDC)(bib)_0.5]_n(1) was obtained by the hydrothermal reaction of ZnCl₂, imidazole-4,5-dicarboxylic acid (H₃IDC), and 1,4-bis(imidazol-1-yl)-butane (bib) with 2∶2∶1 mole ratio. X-ray diffraction crystal structural analysis reveals its crystallizes in monoclinic, space group P2₁/n with a=0.943 38(16), b=1.022 48(18), c=1.393 8(2) nm, β=109.434(3)°, V=1.267 9(4) nm³,Z=4, D_c=1.648 Mg·m^-3, F(000)=636, the final R₁=0.044 1, and wR₂=0.100 3 for 1 742 observed reflections with I≥2σ(I). In 1, each Zn(Ⅱ) ion is five-coordinated with a distorted trigonal bipyramidal coordination geometry, and each μ₂-HIDC² acts as a bridge to bond two neighboring Zn(Ⅱ) ions, leading to an 1D zigzag chain architecture. The adjacent chains are further linked by bib to form an infinite 2D network structure. The fluorescence spectrum of 1 exhibits intense emission at 436 nm when excited at 380 nm in solid state at room temperature. CCDC: 748259.     

Recent advances in organic-dye-based photoacoustic probes for biosensing and bioimaging

Photoacoustic imaging(PAI) is a non-destructive biomedical imaging technology with broad application prospects. PAI combines the advantages of optical imaging and ultrasound imaging with high selectivity and deep penetration to overcome the high scattering limitation of light in tissues. This emerging technology also achieves high-resolution and high-contrast imaging of deep tissue in vivo. Recently, photoacoustic(PA) probes based on organic dyes have emerged prominently in biosensing and bioimaging due to their excellent optical properties and structural adaptability. This paper gives an outline of the basic PAI principles and focuses on the application of organic-dye-based PA probes for molecular detection and in vivo imaging. The advantages of PAI technology and the drawbacks of current PA probes are then summarized. Finally, the prospects for application are evaluated considering the potential challenges in the biomedical fields.