Study on the Determination of Heavy-Metal Ions in Tobacco and Tobacco Additives by Microwave Digestion and HPLC with PAD Detection

A new method for the simultaneous determination of heavy-metal ions in tobacco and tobacco additive by microwave digestion and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The tobacco and tobacco additive samples were digested by microwave digestion. The lead, cadmium, mercury, nickel, copper, and tin ions in the digested samples were precolumn derivated with tetra-(4-aminophenyl)-porphyrin (T₄-APP) to form color chelates; the Hg-T₄-APP, Cd-T₄-APP, Pb-T₄-APP, Ni-T₄-APP, Cu-T₄-APP, and Sn-T₄-APP chelates were then enriched by solid-phase extraction with C₁₈ disks and the retained chelates were eluted from the disks using tetrahydrofuran (THF). The chelates were separated on a Waters Xterra RP₁₈ column by gradient using methanol (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH 10.0) as a mobile phase at a flow rate of 0.5 mL/min and detected with a photodiode array detector in the range 350–600 nm. The detection limits of lead, cadmium, mercury, nickel, copper, and tin were 5, 4, 2.5, 5, 8, and 4 ng/L, respectively, in the original samples. The method was applied to the determination of lead, cadmium, mercury, nickel, copper, and tin in tobacco and tobacco additive with good results.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 542–548.Original English Text Copyright © 2005 by Yang, Li, Shi, Wang.This article was submitted by the authors in English.     

Determination of copper,nickel, cobalt,silver, lead,cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection

A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra( m-aminophenyl)porphyrin (T m-APP) to form colored chelates. The metal-T m-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase extraction with a C(18 )cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters Xterra()RP(18) column by gradient elution with methanol (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min(-1) and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L(-1), respectively, in the original sample. The method was also applied to the determination of these metals in water with good results.     

Study on Determination of Six Transition Metal Ions in Biological Samples by SPE and RP‐HPLC

This paper reports the utilization of solid phase extraction and the reversed‐phase high‐performance liquid chromatography (RP‐HPLC) for the determination of six transition metal ions (iron, cobalt, nickel, copper, zinc and manganese) in biological samples. The samples were digested by microwave digestion. The iron, cobalt, nickel, copper, zinc and manganese ions in the digested samples can react with 2‐(2‐quinolinylazo)‐5‐diethylaminophenol (QADEAP) to form colored chelates in pH 4.0 acetic acid‐sodium acetic buffer solutions and cetyl trimethylammonium bromide (CTMAB) medium. These chelates were enriched by solid phase extraction with C₁₈ cartridge. Then the chelates were separated on a Waters Nova‐Pak‐C₁₈ column (3.9 × 150 mm, 5 μm) by gradient elution with methanol (containing 0.5% of acetic acid and 0.1% of CTMAB) and 0.05 mol/L pH 4.0 acetic acid‐sodium acetic buffer solution (containing 0.1% of CTMAB) as mobile phase at a flow rate of 0.5 mL/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 3 ng/L, 4 ng/L, 2 ng/L, 4 ng/L, 8 ng/L, 10 ng/L, respectively. This method was applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in biological samples with good results.     

Determination of Lead, Cadmium, and Mercury by On-Line Enrichment Followed by RP-HPLC

A new method for the simultaneous determination of lead, cadmium, and mercury ions as metal tetra-(4-chlorophenyl)-porphyrin (T₄CPP) chelates was developed using reversed-phase-high performance liquid chromatography (RP-HPLC) and combined with on-line enrichment technique. When the Hg-T₄CPP, Pb-T₄CPP, and Cd-T₄CPP chelates were injected into the injector and sent to the enrichment column with 0.05 mol/L of pH = 10 pyrrolidine-acetic acid buffer solutions (containing 10% of THF) as mobile phase, they were absorbed onto the tip of the enrichment column. By switching the six ports switching valve, the retained chelates can be back-flushed by mobile phase and travel towards the analytical column. With 0.05 mol/L of pH = 10 pyrrolidine-acetic acid buffer solution (containing 10% of THF) and tetrahydrofuran (THF) (containing 0.05 mol/L pH = 10.0 pyrrolidine-acetic acid buffer salt) gradient elution as mobile phase, the separation of chelates on the analytical column was satisfactory. The linearity ranges are 0.01 ± 120 g/L for each metal chelate. The detection limits (S/N = 3) of lead, cadmium, and mercury are 2.0, 1.5, and 2.0 ng/L, respectively. This method was applied to the determination of the g/L level of lead, cadmium, and mercury ions in a water sample with good results.     

Simultaneous determination of four heavy metal ions in tobacco and tobacco additive by online enrichment followed by RP-HPLC and microwave digestion

A new method for the simultaneous determination of tin, lead, cadmium, and mercury in tobacco and tobacco additive by reversed-phase high-performance liquid chromatography combined with microwave digestion and an online enrichment technique is developed. The tin, lead, cadmium, and mercury ions are precolumn derivatized with tetra-(4-dimethylaminophenyl)-porphyrin (T(4)-DMAPP) to form color chelates. The Sn-T(4)-DMAPP, Hg-T(4)-DMAPP, Cd-T(4)-DMAPP, and Pb-T(4)-DMAPP chelates are absorbed onto the front of the enrichment column using a buffer solution of 0.05 mol/L pyrrolidine-acetic acid (pH = 10.0) as the mobile phase. After the concentration is finished (by switching the six-port switching valve) the retained chelates are back-flushed by the mobile phase and move to the analytical column. The chelate separation on the analytical column is satisfactory using gradient elution with methanol (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0) and tetrahydrofuran (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0). The linearity range is 0.01-120 micro g/L for each metal ion. The detection limits (S/N = 3) of tin, lead, cadmium, and mercury are 0.6, 0.8, 0.5, and 0.6 ng/L, respectively. This method is applied to the determination of tin, lead, cadmium, and mercury in tobacco and it's additive with good results.     

Study on the Determination of Cobalt,Nickel, Copper,Zinc and Vanadium in Environmental Samples by a Rapid High‐Performance Liquid Chromatography

A new method for the simultaneous determination of five transition metal ions in water and food by rapid high‐performance liquid chromatography was developed. The cobalt, nickel, copper, zinc and vanadium ions were pre‐column derivatized with 2‐(2‐quinolinylazo)‐4‐methyl‐1,3‐dihydroxidebenzene (QAMDHB) to form colored chelates, then the Co‐QAMDHB, Ni‐QAMDHB, Cu‐QAMDHB, Zn‐QAMDHB and V‐QAMDHB chelates were enriched by solid phase extraction with a C18 cartridge. The enrichment factor of 50 was achieved by eluting the retained chelates from the cartridge with tetrahydrofuran (THF). These chelates were separated on a ZORBAX Stable Bound rapid analysis column (4.6 × 50 mm, 1.8 um) with 68% methanol (containing 0.1% of acetic acid and 0.1% of CTMAB) as mobile phase at a flow rate of 2.0 mL/min and detected with a photodiode array detector from 450?600 nm. The Co‐QAMDHB, Ni‐QAMDHB, Cu‐QAMDHB, Zn‐QAMDHB and V‐QAMDHB chelates were separated completely within 2.0 min. The detection limits of cobalt, nickel, copper, zinc and vanadium are 2 ng/L, 1.5 ng/L, 2 ng/L, 3 ng/L, and 3 ng/L, respectively, in the original samples. This method was applied to the determination of the five transition metal ions in water and food samples with good results.     

Simultaneous Determination of Palladium and Platinum by On‐Line Enrichment Followed by Rapid Column High Performance Liquid Chromatography

In this paper, a new method for the simultaneous determination of palladium and platinum ions was developed using a rapid column high performance liquid chromatograph equipped with an on‐line enrichment technique. The palladium and platinum ions were pre‐column derivatized with 5‐(p‐aminobenzylidene)‐thiorhodanine (ABTR) to form colored chelates. The Pd‐ABTR, Pt‐ABTR chelates can be absorbed onto the front of an enrichment column when they were injected into the injector and sent to the enrichment column [ZORBAX Stable Bound, 4.6 × 10 mm, 1.8 μm] with a buffer solution of 0.05 mol/L sodium acetate‐acetic acid buffer solution (pH 3.5) as mobile phase. After the enrichment had finished, by switching the six‐ports switching valve, the retained chelates were back‐flushed by mobile phase and traveled towards the analytical column. These chelates separation on the analytical column [ZORBAX Stable Bound, 4.6 × 50 mm, 1.8 μm] was satisfactory with 65% methanol (containing 0.05 mol/L of pH 3.5 sodium acetate‐acetic acid buffer salt and 0.01 mol/L of tritonX‐100) as mobile phase. The palladium and platinum were separated completely within 2 min. The detection limits (S/N = 3) of palladium and platinum are 1.4 ng/L and 1.6 ng/L, respectively. This method was applied to the determination of palladium and platinum in water and urine samples with good results.     

Determination of lead, cadmium and mercury in microwave-digested foodstuffs by RP-HPLC with an on-line enrichment technique.

A new method for the simultaneous determination of lead, cadmium and mercury ions in microwave-digested foodstuffs by reversed-phase high-performance liquid chromatography combined with on-line enrichment technique has been developed. The foodstuff samples were digested by microwave digestion. The lead, cadmium and mercury ions can be precolumn derivatized with 5,10,15,20-tetrakis(3-aminophenyl)porphine (T3APP) to form color chelates; then, the Hg-T3APP, Cd-T3APP and Pb-T3APP chelates can be enriched and separated on a valve switching HPLC system combined with on-line enrichment technique. The linearity ranges are 0.01-120 microg/l for each metal ion. The detection limits (S/N = 3) of lead, cadmium and mercury are 1.2 ng/l, 0.5 ng/l and 0.8 ng/l, respectively. This method was applied to the determination of lead, cadmium and mercury in foodstuffs with good results.     

Determination of trace lead, cadmium and mercury by on-line column enrichment followed by RP-HPLC as metal-tetra-(4-bromophenyl)-porphyrin chelates

This paper reports the utilization of tetra-(4-bromophenyl)-porphyrin (T(4)BPP) as a chelating reagent using Waters Xterratrade mark RP(18) column for the on-line column enrichment and the separation of trace lead, cadmium and mercury ions by reversed-phase high-performance liquid chromatography (RP-HPLC) with photodiode array detector. When the Hg-T(4)BPP, Pb-T(4)BPP and Cd-T(4)BPP chelates were injected into the injector and sent to the enrichment column with 0.05 mol l(-1) of pH 10.0 pyrrolidine-phosphoric acid buffer solution (containing 10% of tetrahydrofuran (THF)) as mobile phase. The chelates were retained on the top of the enrichment column. After the enrichment is finished, by switching the valve of six-ports switching valve, the retained metal-T(4)BPP chelates will be eluted by mobile phase in reverse direction and will travel towards analytical column. With THF (containing 0.05 mol l(-1), pH 10.0 pyrrolidine-phosphoric acid buffer salt) and 0.05 mol l(-1), pH 10.0 pyrrolidine-phosphoric acid buffer solution (containinging 10% THF) gradient elution as mobile phase, the chelates separation on the analytical column was satisfactory. The linearity ranges are 0.01-120 mug l(-1) for each metal ion. The detection limits (S/N=3) of lead, cadmium and mercury are 1.0, 0.5 and 1.0 ng l(-1), respectively. This method can be applied to the determination (mug l(-1)) level of lead, cadmium and mercury in drinking water with satisfactory results.     

Simultaneous Determination of Palladium,Platinum and Rhodium by On‐Line Column Enrichment and a Rapid Column High Performance Liquid Chromatography with 2‐Carboxyl‐1‐Naphthalthiorhodamine as Precolumn Derivatization Reagent

Abstract

In this paper, 2‐carboxyl‐1‐naphthalthiorhodamine (CNTR) was synthesized, and a new method for the simultaneous determination of palladium, platinum, and rhodium ions as metal‐CNTR chelates was developed using rapid column high performance liquid chromatography combined with on‐line enrichment. The palladium, platinum, and rhodium ions were precolumn derivatized with CNTR to form colored chelates. The Pb‐CNTR, Pt‐CNTR, and Rh‐CNTR chelates could be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column (ZORBAX Stable Bound, 4.6×10 mm, 1.8 µm) with a buffer solution of 0.05 mol/L sodium acetate–acetic acid buffer solution (pH 3.5) as mobile phase. After enrichment, and by switching the six ports switching valve, the retained chelates were back‐flushed by mobile phase and traveling towards the analytical column. The separation of these chelates on the analytical column (ZORBAX Stable Bound, 4.6×50 mm, 1.8 µm) was satisfactory with 54% methanol (v/v) in 0.05 mol/L sodium acetate buffer (pH 3.5) containing 1 g/L Triton X‐100 as mobile phase. Palladium, platinum, and rhodium were separated completely within 2 min. The detection limits (S/N=3) of palladium, platinum, and rhodium are 1.4 ng/L, 1.2 ng/L, and 1.8 ng/L, respectively. This method was applied to the determination of palladium, platinum, and rhodium in water, urine, and soil samples with good results.     

Study on the Solid Phase Extraction of Hg(II)‐ABR Chelate with C18 Disks and its Application to the Determination of Mercury in Tobacco and Tobacco Additives

A highly sensitive, selective and rapid method for the determination of mercury based on the rapid reaction of mercury(II) with 5‐(p‐aminobenzylidene)‐rhodanine (ABR) and the solid phase extraction of the colored chelate with C₁₈ disks has been developed. In the presence of pH = 3.5 sodium acetate‐acetic acid buffer solution and Emulsifier‐OP medium, ABR reacts with mercury(II) to form a red chelate of a molar ratio 1:2 (mercury to ABR). This chelate was enriched by the solid phase extraction with C₁₈ disks and eluted the retained chelate from the disks with dimethyl formamide (DMF). The enrichment factor of 50 was achieved. In the DMF medium, the molar absorptivity of the chelate is 1.16 × 10⁵ L.mol^?1.cm^?1 at 540 nm. Beer's law is obeyed in the range of 0.01?3 μg/mL in the measured solution. The relative standard deviation for eleven replicated samples of 0.01 μg/mL level is 1.83%. This method was applied to the determination of mercury in tobacco and tobacco additives with good results.     

Determination of Heavy Metal Ions in Chinese Herbal Medicine by Microwave Digestion and RP-HPLC with UV-Vis Detection

A new method for the simultaneous determination of heavy metal ions in Chinese herbal medicine by microwave digestion and reversed-phase high-performance liquid chromatography (RP-HPLC) has been developed. The Chinese herbal medicine samples were digested by microwave digestion. Lead, cadmium, mercury, nickel, copper, zinc, and tin ions in the digested samples were pre-column derivatized with tetra-(4-chlorophenyl)-porphyrin (T₄-CPP) to form the colored chelates which were then enriched by solid phase extraction with C₁₈ cartridge and eluted from the cartridge with tetrahydrofuran (THF). The chelates were separated on a Waters Xterra RP₁₈ column by gradient elution with methanol (containing 0.05molL^–1 pyrrolidine-acetic acid buffer salt, pH=10.0) and THF (containing 0.05molL^–1 pyrrolidine-acetic acid buffer salt, pH=10.0) as mobile phase at a flow rate of 0.5mLmin^–1 and detected with a photodiode array detector in the range of 350–600nm. In the original samples the detection limits of lead, cadmium, mercury, nickel, copper, zinc and tin are 4ngL^–1, 3ngL^–1, 6ngL^–1, 5ngL^–1, 2ngL^–1, 6ngL^–1, and 4ngL^–1, respectively. This method was applied to the determination of lead, cadmium, mercury, nickel, copper, zinc and tin in Chinese herbal medicine samples with good results.     

Supramolecular Hydrogen‐Bonded Frameworks from a New Bisphosphonic Acid and Transition Metal Ions

The reaction of 2‐morpholinoethylimino‐bis(methylenephosphonic acid) (H₄L) with cobalt(II), nickel(II) acetate, and cadmium(II) chloride in ethanol/water mixed solvents afforded three new crystal‐engineered supramolecular metal phosphonates, Co(H₃L)₂ · 2H₂O ( 1 ), Ni(H₃L)₂ · 2H₂O ( 2 ), and [Cd₂Cl₄(H₂O)₆]_0.5[H₄L] ( 3 ) by using a layering technique. The cobalt(II) ions in complex 1 are hexacoordinated by four phosphonate oxygen atoms and two imino nitrogen atoms. The mononuclear units of complex 1 are connected through hydrogen bonds to form a three dimensional supramolecular network. The structure of compound 2 is analogous to that of 1 except that the cobalt(II) ion in compound 1 is replaced by nickel(II) in compound 2 . In the molecular structure of compound 3 , cadmium is coordinated to three chloride ions and three aqua oxygen atoms to form a novel neutral dinuclear complex. Several hydrogen bonds connect the dinuclear complex and the neutral form of the ligand to build a supramolecular three dimensional structure.     

Preconcentration Ultra Trace of Cd(II) in Water Samples Using Dispersive Liquid‐Liquid Microextraction with Salen(N,N′‐Bis(Salicylidene)‐Ethylenediamine) and Determination Graphite Furnace Atomic Absorption Spectrometry

Dispersive liquid–liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 μL methanol (disperser solvent) containing 34 μL carbon tetrachloride (extraction solvent) and 0.00010 g Salen(N,N′‐bis(salicylidene)ethylenediamine) (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with Salen(N,N′‐bis(salicylidene)‐ethylenediamine), and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25 ± 1 μL). Then a 20 μL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 122 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the range of 2‐21 ng L^?1 with a detection limit of 0.5 ng L^?1. The relative standard deviation (R.S.D._s) for ten replicate measurements of 20 ng L^?1 of cadmium was 2.9%. The relative recoveries of cadmium in tap, sea and rain water samples at a spiking level of 5 and 10 ng L^?1 are 99, 94, 97 and 96%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on‐line liquid‐liquid extraction, single drop microextraction (SDME), on‐line solid phase extraction (SPE) and co‐precipitation based on bibliographic data. Therefore, DLLME combined with GF AAS is a very simple, rapid and sensitive method, which requires low volume of sample (5.00 mL).     

Voltammetric Determination of Mercury(II) at Poly(3‐hexylthiophene) Film Electrode. Effect of Halide Ions

The well‐known method for the determination of mercury(II), which is based on the anodic stripping voltammetry of mercury(II), has been adapted for applications at the thin film poly(3‐hexylthiophene) polymer electrode. Halide ions have been found to increase the sensitivity of the mercury response and shift it more positive potentials. This behavior is explained by formation of mercuric halide which can be easily deposited and stripped from the polymer electrode surface. The procedure was optimized for mercury determination. For 120 s accumulation time, detection limit of 5 ng mL^?1 mercury(II) has been observed. The relative standard deviation is 1.3% at 40 ng mL^?1 mercury(II). The performance of the polymer film studied in this work was evaluated in the presence of surfactants and some potential interfering metal ions such as cadmium, lead, copper and nickel.     

Development and validation of a UPLC‐MS/MS method for the determination of 7‐hydroxymitragynine,a μ‐opioid agonist,in rat plasma and its application to a pharmacokinetic study

A simple, sensitive and specific ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method was developed and validated to determine the concentrations of 7‐hydroxymitragynine in rat plasma. Following a single‐step liquid–liquid extraction of plasma samples using chloroform, 7‐hydroxymitragynine and the internal standard (tryptoline) were separated on an Acquity UPLC^TM BEH C₁₈ (1.7 µm, 2.1 × 50 mm) column using an isocratic elution at a flow rate of 0.2 mL/min. The mobile phase consisted of 0.1% acetic acid in water and 0.1% acetic acid in acetonitrile (10:90, v/v). The run time was 2.5 min. The analysis was carried out under the multiple reaction‐monitoring mode using positive electrospray ionization. Protonated ions [M + H]⁺ and their respective product ions were monitored at the following transitions: 415 → 190 for 7‐hydroxymitragynine and 173 → 144 for the internal standard. The calibration curve was linear over the range of 10–4000 ng/mL (r² = 0.999) with a lower limit of quantification of 10 ng/mL. The extraction recoveries ranged from 62.0 to 67.3% at concentrations of 20, 600 and 3200 ng/mL). Intra‐ and inter‐day assay precisions (relative standard deviation) were <15% and the accuracy was within 96.5–104.0%. This validated method was successfully applied to quantify 7‐hydroxymitragynine in rat plasma following intravenous administration. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of a hydrophilic paclitaxel derivative, 7‐xylosyl‐10‐deacetylpaclitaxel in rat plasma by LC–MS/MS

A LC‐MS/MS method for the determination of a hydrophilic paclitaxel derivative 7‐xylosyl‐10‐deacetylpaclitaxel in rat plasma was developed to evaluate the pharmacokinetics of 7‐xylosyl‐10‐deacetylpaclitaxel in the rats. 7‐Xylosyl‐10‐deacetylpaclitaxel and docetaxel (IS for 7‐xylosyl‐10‐deacetylpaclitaxel) were extracted from rat plasma with acetic ether and analyzed on a Hypersil C₁₈ column (4.6 × 150 mm i.d., particle size 5 µm) with the mobile phase of ACN/0.05% formic acid (50:50, v/v). The analytes were detected using an ESI MS/MS in the multiple reaction monitoring mode. The standard curves for 7‐xylosyl‐10‐deacetylpaclitaxel in plasma were linear (r >0.999) over the concentration range of 2.0–1000 ng/mL with a weighting of 1/concentration². The method showed a satisfactory sensitivity (2.0 ng/mL using 50 µL plasma), precision (CV ≤ 10.1%), accuracy (relative error ?12.4 to 12.0%), and selectivity. This method was successfully applied to the pharmacokinetic study of 7‐xylosyl‐10‐deacetylpaclitaxel in rat plasma after intravenous administration of 7‐xylosyl‐10‐deacetylpaclitaxel to female Wistar rats. Copyright © 2008 John Wiley & Sons, Ltd.     

Three Transition Metal(II) Coordination Polymers Constructed by a Semi‐rigid Bis‐pyridyl‐bis‐amide and Dicarboxylates Mixed Ligands: Assembly,Structures and Properties

Three coordination polymers, namely [Co(BDC)( L )] · H₂O ( 1 ), [Co(NPH)( L )] · H₂O ( 2 ), and [Ni(NPH)( L )(H₂O)₃] · H₂O ( 3 ) [H₂BDC = 1, 3‐benzenedicarboxylic acid, H₂NPH = 3‐nitrophthalic acid, L = N,N′‐bis(3‐pyridyl)‐terephthalamide] were hydrothermally synthesized by self‐assembly of cobalt/nickel chloride with a semi‐rigid bis‐pyridyl‐bis‐amide ligand and two aromatic dicarboxylic acids. Single crystal X‐ray diffraction analyses revealed that complexes 1 and 2 are two‐dimensional (2D) coordination polymers containing a one‐dimensional (1D) ribbon‐like Co‐dicarboxylate chain and a 1D zigzag Co‐ L chain. Although the coordination numbers of Co^II ions and the coordination modes of two dicarboxylates are different in complexes 1 and 2 , they have a similar 3, 5‐connected {4².6⁷.8}{4².6} topology. In complex 3 , the adjacent Ni^II ions are linked by L ligands to form a 1D polymeric chain, whereas the 1D chains does not extend into a higher‐dimensional structure due to the ligand NPH with monodentate coordination mode. The adjacent layers of complexes 1 and 2 and the adjacent chains of 3 are further linked by hydrogen bonding interactions to form 3D supramolecular networks. Moreover, the thermal stabilities, fluorescent properties, and photocatalytic activities of complexes 1 – 3 were studied.     

Speciation analysis of mercury by dispersive solid‐phase extraction coupled with capillary electrophoresis

A pretreatment method of dispersive solid‐phase extraction (DSPE) along with back‐extraction followed by CE‐UV detector was developed for the determination of mercury species in water samples. Sulfhydryl‐functionalized SiO₂ microspheres (SiO₂−SH) were synthesized and used as DSPE adsorbents for selective extraction and enrichment of three organic mercury species namely ethylmercury (EtHg), methylmercury (MeHg), and phenylmercury (PhHg), along with L‐cysteine (L‐cys) containing hydrochloric acid as back‐extraction solvent. Several main extraction parameters were systematically investigated including sample pH, amount of adsorbent, extraction and back‐extraction time, volume of eluent, and concentration of hydrochloric acid. Under optimal conditions, good linearity was achieved with correlation coefficients over 0.9990, in the range of 4−200 μg/L for EtHg, and 2−200 μg/L for MeHg and PhHg. The LODs were obtained of 1.07, 0.34, and 0.24 μg/L for EtHg, MeHg, and PhHg, respectively, as well as the LOQs were 3.57, 1.13, and 0.79 μg/L, respectively, with enrichment factors ranging from 109 to 184. Recoveries were attained with tap and lake water samples in a range of 62.3−107.2%, with relative standard deviations of 3.5–10.1%. The results proved that the method of SiO₂−SH based DSPE coupled with CE‐UV was a simple, rapid, cost‐effective, and eco‐friendly alternative for the determination of mercury species in water samples.     

Synthesis of β‐Cyclodextrin‐2,4‐dihydroxyacetophenone‐phenylhydrazine and Its Application

A novel host reagent of β‐cyclodextrin‐2,4‐dihydroxyacetophenone‐phenylhydrazine(β‐CDP‐DHPH) was synthesized and characterized by IR and ¹H NMR spectra. A highly selective and sensitive spectrofluorimetric determination of trace amounts of cadmium was proposed based on the reaction between Cd²⁺ and β‐CDP‐DHPH at pH 10.0. The molar ratio of β‐CDP‐DHPH to Cd²⁺ was 1:1. The linear range of this method was 0.56‐120 μg·L^?;1 with a detection limit of 0.20 μg·L^?;1. The interferences of 39 common ions in the determination of cadmium were investigated, and the results showed that the host reagent had a quite high selectivity. This method was rapid and simple in determination of trace amounts of cadmium in mineral, tap and river water.