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1.
This study was carried out to determine fluoride in drinking water and in urine of adolescents, ages 15-20 years, living in Northern Chihuahua Mexico. Participants are from a cross-sectional study on health effects of chronic fluoride exposure from drinking water. A total of 201 participants (106 female and 95 male) in the study were recruited from three counties. Samples of drinking water of each county were collected and analyzed using the U.S. EPA Fluoride Ion-Selective Method. Statistically significant difference of fluoride content in water was found among the three counties of recruitment (Cd. Juarez; 0.3 mg/L, Samalayuca, 1.0 mg/L, and Villa Ahumada, 5.3 mg/L). Fluoride content in wells and tap water samples of Villa Ahumada ranged from 5.0 to 5.7 mg/L. Fluoride content of these samples was above the level permitted by Mexican regulations. The fluoride content in bottled water obtained from local stores in Villa Ahumada ranged from 0.3 to 3.7 mg/l.Fluoride in urine samples of each participant was also analyzed using the U.S. EPA Ion-Selective Method. The mean fluoride urine concentration (reported in mg/g creatinine) in adolescents living in these counties was 0.792±0.39, 1.33±0.67 and 2.22±1.16 (Cd. Juarez, Samalayuca and Villa Ahumada), respectively. The high fluoride urinary levels found in participants from Villa Ahumada may be associated to the high fluoride level (5.3 mg/L) in dinking water.The accuracy of measurements was assessed with reference materials in water and in urine. Mean fluoride recovery was 99.0% and 99.6% in water and in urine, respectively. The levels obtained were within the assayed 5% confidence levels. 相似文献
2.
A novel 8-hydroxyquinoline derivative with a carbazole group substituting in the 5-position of quinoline was synthesized, where carbazole acted as a hole transporter. The single crystal of this 8-hydroxyquinoline derivative was obtained. Its coordination complex with Al(III) was also synthesized. This complex with the ability of hole transportation and electron transportation simultaneously was soluble in common organic solvents and showed yellow luminescence with high quantum yield. 相似文献
4.
A simple, selective, highly sensitive and accurate procedure for the determination of trace amounts of copper has been developed
based on solid-phase spectrophotometry. Copper reacts with 5-(2-benzothiazolylazo)-8-hydroxyquinoline (BTAHQ) to give a complex
with high molar absorptivity (3.17 × 10 7 L mol −1 cm −1, 3.07 × 10 8 L mol −1 cm −1, 1.22 × 10 9 L mol −1 cm −1, and 1.80 × 10 9 L mol −1 cm −1), fixed on a Dowex 1-X8 type anion-exchange resin for 10 mL, 100 mL, 500 mL, and 1000 mL, respectively. The absorbance at
667 nm and 800 nm packed in a 1.0 mm cell was measured directly. Calibration is linear over the range 0.2–3.7 μg L −1 with RSD of < 1.28 % ( n = 10). The detection and quantification limits of the 500 mL sample method are 79 ng L −1 and 260 ng L −1 when using 60 mg of Dowex 1-X8. For a 1000 mL sample, the detection and quantification limits are 67 ng L −1 and 220 ng L −1 using 60 mg of the exchanger. Increasing the sample volume can enhance the sensitivity. The proposed method was applied to
the determination of copper in different environmental water samples (tap, pit, spring, and river), food products (rice, corn
flour, and tea), and mushrooms, using the standard addition technique. 相似文献
5.
A robust and simple sequential injection (SI) method for the assay of aluminum ions in drinking water is described. The method is based on the complex formation between aluminum and 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid (HSNQ). The fluorescence of the complex is monitored at an emission wavelength of 492 nm with excitation at 357 nm. The HSNQ concentration, aspirated reagent and sample volumes were optimized simultaneously using 3(3) full factorial design. The optimum operating conditions are aspirated sample and reagent volumes of 90 and 70 microL, respectively, and HSNQ concentration of 20 microM. With these conditions linear calibration curves were obtained from 100 to 800 ppb. The detection limit was 4 ppb. The maximum relative standard deviation of the method was 1.43% (n=5). The method was successfully applied for the determination of aluminum in drinking water samples. 相似文献
6.
The quantification of 3-chloro-4-(dichloromethyl)-5-hydroxy-2( 5H)-furanone (Mutagen X or MX) in drinking water is difficult due to the low concentration of MX in drinking water, its high sensitivity to pH change, and matrix effects that interfere with the derivatization and analysis. Typically, the quantification of MX involves derivatization by methylation. We present a one-step derivatization procedure for MX using N-methyl-bis-trifluoroacetamide (MBTFA) and analysis by ion trap GC/MS/MS. The new method resulted in a significant reduction in analysis time, and improved detection limits. The abundant and selective ions in the mass spectrum of the trifluoroacylated MX (trifluoroacetic acid-4-chloro-3-dichloromethyl-5-oxo-2-hydro-furan-2-yl ester) allowed for a clear identification and quantification of the compound, with a method detection limit of 7.7 ng L −1, and a limit of quantitation of 24.4 ng L −1. The trifluoroacylated MX was shown to be stable for 30 days in an excess of the derivatization reagent. The new method was applied for the determination of MX in several drinking water samples, with a concentration range from not-detected to 517 ng L −1; these values are comparable to those obtained in previous studies. The development of this new simplified analytical method for MX is an important step forward in the field of disinfection by-product (DBP) research, particularly in light of the recent scientific recognition of halogenated furanones as emerging drinking water contaminants. Increased analytical ability may well be a decisive factor in the monitoring of these disinfection by-products. 相似文献
8.
A 2-substituted-8-hydroxyquinoline ( E) -2 -[2 -(3 -thienyl)ethenyl] -8 -quinolinol (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a tetranuclear complex [Cd 4L 6Br 2]·6DMF ( 1) was fabricated by assembly of Cd(II) with HL. X-ray structural analysis shows that 1 exhibits a double open cubane-like core structure, which is bridged by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of 1 features a 3-D porous solid constructed by aromatic stacking interactions, C–H··· π interactions and C–H···O hydrogen bonds. The assembly of cadmium salts and HL in solution was investigated by UV–vis and photoluminescence. We also studied the thermal stability and photophysical properties (fluorescent emission, lifetime, and quantum yield) of 1. The results show that 1 emits yellow luminescence in the solid state. 相似文献
9.
4-(2-Benzothiazolylazo)pyrocatechol (BTAPC), a new organic reagent, reacts with Fe(II) to form a stable, water-soluble, violet, positively charged, binary complex over a pH range of 6.3 to 6.8. Some water-miscible organic solvents and surfactants have solubilization and sensibilization effects. In 40% acetone-water medium at 25 °C, a (ionic strength) value of 0.1 and a pH value of 6.5, the ratio of Fe(II) to BTAPC in the complex is 1 2 with an apparent stability constant of 1.97 × 10 9 and two absorption peaks at 535 and 615 nm. If the absorbance is measured at 615 nm, not only the sensitivity is high ( 615 = 1.10 × 10 5 1 · mol –1 · cm –1) and the contrast () is large (90 nm), but also the selectivity is fairly good. Beer's law is obeyed for iron along the range of 0 to 16 g per 25 ml. The satisfactory results have been achieved after applying the method to the determination of traces of iron in water. 相似文献
10.
The interactions of the CpVC 10H 8Yb(THF)Cp complex with H 2O, CO, CO 2, Cr(CO) 6, CpTl, azobenzene, and other reagents are followed by the breaking of the bond between ytterbium and the naphthalene ligand. The reaction of CpVC 10H 8Yb(THF)Cp with H 2O leads to CpYbOH(THF) 2 and CpVC 10H 8 formation. Ytterbocene, CpVC 10H 8 and insoluble carboxylates are isolated as a result of the interaction of CpVC 10H 8Yb(THF)Cp with CO and CO 2. The reaction of CpVC 10H 8Yb(THF)Cp with an equimolar amount of Cr(CO) 6 proceeds not only via the breaking of the C 10H 8–Yb bond, but is followed by the destruction of the CpVC 10H 8 fragment to form Cp 2Yb, Cp 2V, CpVC 10H 8, CpVC 10H 8VCp, and C 10H 8. Under mild conditions, the reaction of CpVC 10H 8Yb(THF)Cp with CpTl occurs leading to the formation of Cp 2Yb and CpVC 10H 8 in high yield. The diphenylhydrazine complex of ytterbium [CpYb(THF)] 2[Ph 2N 2] 2 is isolated in the reaction of CpVC 10H 8Yb(THF)Cp with azobenzene.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1470–1472, August, 1993. 相似文献
11.
合成了新型偶氮显色剂:5-[2(5-甲基-1,3,4-噻二唑)偶氮]-8-羟基喹啉(简称MTADQ),并研究了它与铜的显色反应。实验结果表明:在pH 5.8~7.8的水溶液中该试剂与铜离子形成一种稳定的黄色络合物,其最大吸收波长位于530 nm处,表观摩尔吸光系数ε=9.5×104L.mol-1.cm-1,配合物的组成比为1∶1。铜离子质量浓度在0~1.2 mg/L范围内服从朗伯-比尔定律。已用于测定矿石样品中的微量铜。 相似文献
12.
Summary An indirect GC method is described for the determination of Ethephon in drinking water on the basis of the headspace analysis of the ethylene formed from Ethephon. In order to reach the necessary detection limit, the entire volume of the static headspace distribution is transferred into a cold injection system (CIS). There, the ethylene is adsorbed on Carbosieve SIII at 10°C and, subsequently, desorbed at 300 °C. The water vapour included in the headspace is completely eliminated through the splitting system. By means of this technique, a detection limit of 0.05 g/l water was reached. 相似文献
13.
An extraction-spectrophotometric method is described for the determination of traces of iron(II) with 2-[2-(3,5-dibromopyridyl)azo]-5-diethyl-aminobenzoic acid. The reagent forms a stable and blue 12 iron/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the iron(II) complex is 1.09 × 10 5 1 mol –1 cm –1 at 624 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper, nickel and vanadium can be removed by using dimethylglyoxime and EDTA. The method is applied to the determination of iron (II) in sea water and aluminium alloys with good precision and accuracy. 相似文献
14.
In the present study, the ?5-(4-dimethylaminobenzylidene)rhodanin-modified SBA-15? was applied as stable solid sorbent for the separation and preconcentration of trace amounts of cobalt ions in aqueous solution. SBA-15 was modified by ?5-(4-dimethylaminobenzylidene)rhodanin reagent. The sorption of Co 2+ ions was done onto modified sorbent in the pH range of 6.8–7.9 and desorption occurred in 5.0 mL of 3.0 mol L ?1 HNO 3. The results exhibit a linear dynamic range from 0.01 to 6.0 mg L ?1 for cobalt. Intra-day (repeatability) and inter-day (reproducibility) for 10 replicated determination of 0.06 mg L ?1 of cobalt was ±1.82% and ?±1.97%?. Detection limit was 4.2 µg L ?1 (3S b, n = 5) and preconcentration factor was 80. The effects of the experimental parameters, including the sample pH, flow rates of sample and eluent solution, eluent type and interference ions were studied for the preconcentration of Co 2+. The proposed method was applied for the determination of cobalt in standard samples, water samples and agricultural products. 相似文献
15.
研究了 5- ( 5-氯 - 2 -吡啶偶氮 ) - 2 .4-二氨基甲苯 ( 5- Cl- PADAT)与钌 ( )的显色反应。在 p H4.0~ 6.5HAc- Na Ac缓冲溶液中 ,在加热的条件下 ,5- Cl-PADAT与 Ru( )形成稳定的配合物 ,加入无机酸 ( HCl,HCl O4 ,H2 SO4 ,H3 PO4 )酸化后 ,其最大吸收波长位于 50 5nm处 ,表观摩尔吸光系数为 8.5×1 0 4 L· mol-1· cm-1,钌浓度在 0~ 6μg/ 1 0 m L范围内服从比耳定律 ,Ru( )与 5- Cl- PADAT配合物的摩尔比为 1∶ 2。以 EDTA为掩蔽剂 ,方法具有良好的选择性 ,已应用于合成样中钌的测定。 相似文献
16.
Abstract Sixteen new diazadi(or tri)thiacrown ethers containing two 5-substituent(or 2-methyl)-8-hydroxyquino-lin-2-ylmethyl side arms have been prepared by a three-step process. First, the appropriate bis(α-chloroamide)s were treated with five dimercaptans in base to form macrocyclic di(or tri)thiadiamides. The macrocyclic diamides were reduced by BH 3-THF to form 1,7-diaza-4-oxa-10,13-dithia-cyclopentadecane (11); 1,7-diaza-4,13-dioxa-10,16-dithiacyclooctadecane (12); 1,7-diaza-4-oxa-10,13,16-trithiacyclooctadecane (13); 1,7-diaza-4,13,16-trioxa-10,19-dithiacycloheneicosane (14); and 1,10-diaza-4,7-dioxa-13,16-dithiacyclooctadecane (15). The diazadi(or tri)thiacrown ethers were then treated with 8-hydroxyquinoline, 8-hydroxy-5-methylquinoline, 5-chloro-8-hydroxyquinoline, and 8-hydroxyquinaldine in the presence of paraformal-delyde in refluxing benzene to form the bis(8-hydroxy-5-substituent(or 2-methyl)quinolin-7-ymethy)-substituted diazadi(or tri)thiacrown ethers 16-31. The crown ethers containing two 8-hydroxyquinoline or 8-hydroxyquinaldine side arms proved to be mixtures of about 90% bis(8-hydroxyquinolin-7-ylmethyl)-substituted crown ethers; 9% mixed (8-hydroxyquinolin-7-ymethyl)-substituted and (8-hydroxyquinolin-5-ylmethyl)-substituted crown ethers; and 1% bis(8-hydroxyquinolin-5-ylmethyl)-substituted crown ethers. 相似文献
17.
In this work, a characterization of reagent chromophere 5-(4-sulphophenylazo)-8-aminoquinoline [SPA] by IR and 1H RMN was carried out and a p Ka value of 3.55 ± 0.03 was found as well. An 1:2 stoichiometry for the Cu(II)-SPA complex was determined at pH 9 by Job and molar ratio methods. A value of 1.4 × 10 14 for the stability constant was also found. Based on the formation of this complex a new method for the copper determination in presence of gold and silver was developed by derivative spectrophotometry using a previous preconcentration on solid phase. In this method, the analytical measures were executed directly in the solid phase containing the complex. The Cu(II) reacts with the reagent chromophere SPA previously retained in the anionic exchange DEAE Sephadex A25. In this determination, the first derivative at 605 nm was used. The quantification range was between (3.2 ± 0.3 × 10 −1) × 10 −8 and (94.4 ± 0.9) × 10 −8 mol L −1 (3.2 ± 0.3 × 10 −1) × 10 −8 , and (94.4 ± 0.9) × 10 −8 mol L −1. The repeatability expressed as RSD was between 1.1 and 2.0%. The method was applied successfully for the copper determination in mineral residuals and natural water samples. The results were consistent with those provided by ICP-mass spectrometry. 相似文献
18.
A solvent impregnated hollow fibre (SIHF) module has been developed for the preconcentration of lead by using bis(2-ethylhexyl) phosphoric acid (DEHPA) dissolved in kerosene as extractant. The module has been designed for an on-line determination of trace amounts of lead(II) at mg l −1 (ppm) level by flame atomic absorption spectrometry (FAAS). The SIHF system is based on the metal liquid–liquid distribution between aqueous solutions of different acidity and the mentioned organic solution. The highest enrichment factor of Pb(II) was determined at pH=4.0 using a formic acid/formiate buffer solution. Preconcentration experiments were carried out at low lead(II) concentration (mg l−1 level) by using the SIHF module. This study includes the influence of hydrodynamic and chemical conditions on the loading and elution of Pb(II) on the SIHF, i.e., flow rate through the fibres, acidity of the eluent (as nitric acid concentration) and the chemical nature of the acid used in the elution. Breakthrough curves were determined for different sampling flow rates, 0.54 ml min−1 was selected to minimise the loading volume of Pb(II) sample. 0.1 M nitric acid was chosen as eluent solution, and perchloric acid also shows appropriate elution characteristics. The degree of concentration obtained for Pb(II) are of 10 fold the original concentration. The quantification limit for Pb(II) achieved with this preconcentration system is 0.17 mg l−1. The results obtained indicate that the SIHF system can be applied for on-line determination of trace amounts of lead(II) by FAAS. 相似文献
19.
2-甲基异莰醇(2-methylisoborneol, 2-MIB)和土臭素(geosmin, GSM)在水源水中大量分泌排放是造成饮用水土霉异味突发事件、引发居民用水恐慌的重用因素之一。使用顶空固相微萃取(HS-SPME)与气相色谱-质谱联用技术(GC-MS)建立了水库水、水库附近土壤、居民自来水中2-MIB和GSM的测定方法。结合正交分析优化了加盐量、萃取温度、萃取时间条件,在电子轰击(EI)-选择离子扫描(SIM)模式下进行了目标物的定性定量分析。结果表明:在5~1000 ng/L范围内,2-MIB和GSM的色谱峰面积与其质量浓度的线性关系良好( r2≥0.998), 2-MIB与GSM的检出限分别为0.72 ng/L和0.34 ng/L,定量限分别为2.40 ng/L和1.13 ng/L;目标物加标水平为10~600 ng/L时,平均回收率为93.6%~107.7%,相对标准偏差(RSD)≤6.1%( n=6)。基于上述方法,对辽宁省某地区水库水、水库附近土壤、居民自来水中的目标物进行检测,结果表明:水库水目标物质量浓度范围为3.0~3.6 ng/L,水库附近土壤中提取的2-MIB为8.1 ng/L、提取的GSM为17.8 ng/L,居民自来水中的目标物未检出。该方法操作简便、准确可靠,灵敏度高,无需有机溶剂,适合于饮用水中2-MIB和GSM的分析检测。 相似文献
20.
以4-[(8-羟基-5-喹啉)偶氮]-苯磺酸与氯化钴为原料,采用溶剂热法通过原位反应合成{[Co(5-氨基-8-羟基喹啉)_2]·H_2O}_n,并通过X-射线单晶衍射方法确定了该配合物的晶体结构.结构分析表明:标题配合物属于斜方晶系,Pbcn空间群,晶胞参数a=1.321(2)nm,b=0.811(2)nm,c=1.511(2)nm,α=β=γ=90.00°,V=1.619(3)nm~3,Z=4,R_1=0.0516,w R_2=0.1025.配合物中存在ππ堆积相互作用和氢键作用,将配合物连接形成三维超分子网络结构. 相似文献
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