Synthesis,characterization and antimicrobial studies on 13-membered-N6-macrocyclic transition metal complexes containing trimethoprim

Asymmetrical macrocyclic complexes of Mn^II, Co^II, Ni^II, Cu^II and Zn^II have been synthesized by the template process using bis(benzil)ethylenediamine as precursor. Bis(benzil)ethylenediamine reacts with transition metal chlorides and trimethoprim in a 1:1:1 molar ratio in methanol to give several solid metal complexes of the general composition [M(L)X₂] (M = Mn^II, Co^II, Ni^II, Cu^II and Zn^II, L = ligand and X = Cl^?). They were characterized by physicochemical and spectroscopic techniques. Based on analytical, spectral and magnetic moments, all the complexes are identified as distorted octahedral structures. All the complexes are of the [M(L)X₂] type. The shifts of the ν(CN) (azomethine) stretches have been monitored. To find out the donor sites of the ligands, the activity data show that the metal complexes are more potent than the parent ligand. The [M(L)X₂] complexes showed a broad spectrum of antimicrobial activity in vitro against both gram-positive and gram-negative human pathogenic bacterial isolates and the antimicrobial spectrum enhanced only with a combination of metal chlorides and trimethoprim complex. From the results it is imperative that the synthesized macrocyclic [M(L)X₂] complexes exhibit potent broad spectrum antibacterial activity.     

Design,stereoselective synthesis and computational calculations of novel hybrid compounds via Pauson-Khand reactions

A series of novel chiral hybrid compounds between benzofuran and bicyclic cyclopentenone and also benzothiophene and bicyclic cyclopentenone have been designed and synthesized. Chiral enynes derived from enantiomerically enriched homoallyl and homopropargyl alcohols were converted into bicyclic cyclopentenone structures by intramolecular Pauson-Khand reactions. This strategy provides a facile access to various bicyclic cyclopentenones substituted with benzofuran or benzothiophene ring systems in good yields. In addition to the experimental work, the ground state geometries of the hybrid compounds were optimized using Density Functional Theory applications at the B3LYP/6-31G(d,p) level in order to obtain information about the 3D geometries and electronic structure.     

Rational design of ternary NiS/CQDs/ZnIn2S4 nanocomposites as efficient noble-metal-free photocatalyst for hydrogen evolution under visible light

The NiS/CQDs nanocomposite (CQDs represents carbon quantum dots), with a mass ratio of NiS/CQDs to be 1.19:1 based on the ICP result, was obtained via a facile hydrothermal method from a mixture of CQDs, Ni(OAc)₂ and Na₂S. The self-assembly of ZnIn₂S₄ microspheres on the surface of NiS/CQDs was realized under microwave conditions to obtain a ternary NiS/CQDs/ZnIn₂S₄ nanocomposite. The as-obtained NiS/CQDs/ZnIn₂S₄ nanocomposite was fully characterized, and its photocatalytic hydrogen evolution under visible light irradiation was investigated. The ternary NiS/CQDs/ZnIn₂S₄ nanocomposite showed superior photocatalytic activity for hydrogen evolution than ternary CQDs/NiS/ZnIn₂S₄, which was obtained by deposition of NiS in the preformed CQDs/ZnIn₂S₄. The superior photocatalytic performance of ternary NiS/CQDs/ZnIn₂S₄ is ascribed to the introduction of CQDs, which act as a bridge to promote the vectorial transfer of photo-generated electrons from ZnIn₂S₄ to NiS. This result suggests that the rational design and fabrication of ternary CQDs-based systems are important for the efficient photocatalytic hydrogen evolution. This study provides a strategy for developing highly efficient noble-metal-free photocatalysts for hydrogen evolution using CQDs as a bridge to promote the charge transfer in the nanocomposite.     

Syntheses,characterization, in vitro antiglycation and DPPH radical scavenging activities of isatin salicylhydrazidehydrazone and its Mn (II), Co (II), Ni (II), Cu (II), and Zn (II) metal complexes

2-Hydroxy salicylhydrazide isatin hydrazone (L) and its Mn (II), Co (II), Ni (II), Cu (II), and Zn (II), metal complexes were synthesized. ¹H NMR, UV–Vis, IR spectroscopy and elemental (CHN/S) analysis techniques were applied for characterization. TG/DTA techniques revealed that all the synthetic compounds are thermally stable up to 300 °C. They were found non-electrolytes in nature. Furthermore, all these complexes were evaluated for antiglycation and DPPH radical scavenging activities. They showed varying degree of activity with IC₅₀ values between 168.23 and 269.0 μM in antiglycation and 29.63–57.71 μM in DPPH radical scavenging activity. Mn (II), Co (II), Ni (II), Cu (II), and Zn (II), metal complexes showed good antiglycation as well as DPPH radical scavenging activity. The IC₅₀ values for antiglycation activity are 168.23 ± 2.37, 234.27 ± 4.33, 257.1 ± 6.43, 267.7 ± 8.43, 269.0 ± 8.56 Ni for Co, Zn, Mn, Cu, and Ni complexes, respectively, while IC₅₀ value were found to be 29.63 ± 2.76, 31.13 ± 1.41, 35.16 ± 2.45, 43.53 ± 3.12, 57.71 ± 2.61 μM for Cu, Zn, Mn, Co and Ni complexes, respectively, for DPPH radical scavenging activity. These synthesized metal complexes were found to be better active than standards Rutin (IC₅₀ = 294.46 μM) for anti-glycation, and tert-butyl-4-hydroxyanisole (IC₅₀ = 44.7 μM) for DPPH radical scavenging activity.     

Ho改性的Mn-Ce/TiO2催化剂低温脱硝性能的评价和表征

作为引起酸雨、光化学烟雾、雾霾等大气污染问题的主要根源,氮氧化物(NOx)的防治已成为亟待解决的问题.选择性催化还原技术作为最成熟有效的脱硝技术,目前已经被广泛应用于各燃煤电厂.低温脱硝催化剂具有优秀的低温活性,使得脱硝装置可以安放在脱硫装置和除尘装置下游,受到了学者广泛的研究.目前低温脱硝催化剂的研究主要是对催化剂进行改性以提高催化剂的性能,已有许多研究报道了Sn、Ni、Co、Zr、Cr、Ni等对催化剂的改性影响.Ho作为一种改性元素被应用于光催化领域,能提高TiO2的光催化能力.但Ho应用于脱硝领域的研究鲜有报道,其氧化物具有酸性位点有助于脱硝反应,因此研究Ho对低温SCR催化剂的改性作用具有重要意义.本文采用浸渍法制备Ho掺杂的Mn-Ce/TiO2催化剂,研究了Ho的掺杂对于Mn-Ce/TiO2催化剂低温脱硝性能的影响,同时还研究了烟气中的SO2和H2O对催化剂活性的影响,并利用XPS、XRD、H2-TPR、NH3-TPD等表征方法从物理性质和化学性质两方面对Ho改性的影响机理进行了研究.研究发现,Ho的掺杂能提高Mn-Ce/TiO2催化剂的脱硝能力,有助于催化剂N2选择性的提高.分析表明,Ho的掺杂有助于催化剂比表面积的提升,且能提高催化剂的酸性,有利于催化剂对NH3的吸附,从而提高催化剂的性能.XPS表征结果表明Ho掺杂后的催化剂具有更高的化学吸附氧浓度和较高的Mn4+/Mn3+比例, 使得脱硝反应更容易进行.改性后催化剂的抗水抗硫实验结果表明,Ho的掺杂能够提高催化剂的抗水抗硫性能.XRD结果表明,抗水抗硫实验后催化剂表面形成了硫酸铵盐,硫酸铵盐的形成会堵塞催化剂表面的活性位,限制脱硝反应的进行,从而影响催化剂的脱硝活性.同时,400°C下进行再生实验后的催化剂活性有所恢复,但是未能达到抗水抗硫实验前的活性,表明在抗水抗硫实验中催化剂表面形成了除硫酸铵盐以外的其他硫酸盐类.结合XPS和XRD表征结果,推断生成的盐类物质为硫酸锰和硫酸铈,从而导致再生后的催化剂的脱硝活性无法恢复到最初的活性水平.由此可以看出,硫酸盐的形成是催化剂在含硫气氛中失活的主要原因.     

Synthesis,characterization and electrochemical properties of cation selective ion exchange composite membranes

In this work polystyrene based strontium phosphate membranes (SPMs) were prepared by applying different pressures. The membrane potential is measured with uni-univalent electrolytes (KCl, NaCl, and LiCl) solutions using saturated calomel electrodes (SCEs). The effective fixed charge density of these membranes is determined by the Torell, Meyer and Sievers method and it showed the dependence of membrane potential on the porosity, the charge on the membrane matrix, charge and size of permeating ions. The membranes are characterized by X-ray diffraction, scanning electron microscopy and IR spectroscopy. The order of surface charge density for electrolytes is KCl > NaCl > LiCl. Other parameters such as transport number, distribution coefficient, charge effectiveness and related parameters are calculated. The membrane was found to be mechanically stable, and can be operated over a wide pH range.     

Synthesis,characterization and electrochemical properties of copper(II) complexes derived from succinoyldihydrazine Schiff base ligands

Four new copper(II) complexes of the composition [Cu(H₂L)(H₂O)] have been synthesized by template method from reaction of copper(II) acetate, succinoyldihydrazine and some o-hydroxy aromatic aldehydes and ketones in aqueous methanol media. The composition of the complexes has been established on the basis of data obtained from analytical and mass spectral studies. The structure of the complexes has been discussed in the light of molar conductance, magnetic moment, Uv-vis, EPR and IR spectral studies. All of the complexes are non-electrolyte in DMSO. The μ_eff values for the complexes fall in the region 1.76–1.85 BM which rules out the possibility of any M–M interaction in the structural unit of the complexes. The ligands coordinate to the metal centre in enol form through phenolate/naphtholate oxygen atoms and azomethine nitrogen atoms. The NMR spectra show that ligands are present in anti-cis configuration in uncoordinated state. In all of the complexes the copper centre adopts square pyramidal stereochemistry. The unpaired electron is present in $d_{x^2-y^2}$ orbital in the ground state for copper centre in the complexes. The electron transfer reactions for the complexes have been studied by cyclic voltammetry.     

Synthesis of gold nanoparticles using herbal Acorus calamus rhizome extract and coating on cotton fabric for antibacterial and UV blocking applications

Gold nanoparticles (AuNPs) have been synthesized by greener method using chloroauric acid as precursor and extract of Acorus calamus rhizome as reducing agent. Formation of AuNP was confirmed by the presence of Surface Plasmon Resonance (SPR) peak in UV–Visible spectral analysis. XRD and FT-IR spectral analyses were performed for characterization. SEM images show spherical morphology and HR-TEM images reveal nanosize of AuNPs. The AuNPs were then coated on cotton fabric by pad-dry-cure method and characterized by SEM with EDAX technique. The results reveal the deposition of AuNPs on the surface of cotton fabric. Uncoated cotton, neat extract coated cotton and extract containing AuNPs coated cotton fabrics were then tested for antibacterial activity against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacterial strains by AATCC 100 test method. It showed that the extract containing AuNPs coated cotton fabric had higher antibacterial activity than other test samples against E. coli. UV-DRS analysis performed on extract containing AuNPs coated cotton fabric showed improved UV-blocking property than uncoated cotton fabric and neat extract coated cotton fabric.     

Phenomenological modeling and intensification of texturing/grinding-assisted solvent oil extraction: case of date seeds (Phoenix dactylifera L.)

Accelerated Solvent Extraction (ASE) and Dynamic Maceration (DM) were used with n-hexane to study the extraction of oil from date seed powders with different particle sizes. The intensification was studied with instant controlled pressure drop (DIC) as texturing pretreatment. DM yields increased from 4.57% to 10.49 ± 0.05% dry–dry basis (ddb) when particle size decreased from 1.4 to 0.2 mm. For coarsely grounded seed powder, ASE oil yields were 11.35 ± 0.05% ddb and 14.15% ddb for untreated and DIC date-seeds, respectively. Optimized DIC pretreatment allowed the smallest particle size powder to get 15.2 ± 0.05% ddb as ASE yields, while the 2-h DM yields increased from 4.67 to 11.62 ± 0.05% ddb for particle size decreased from 1.4 to 0.2 mm, respectively. Fundamental analysis of various powders was achieved through washing–diffusion phenomenological model. DIC texturing implied higher washing stage, with relative starting accessibility %δY_s of 70% against 55% for untreated particles. Consequently, the diffusion stage time was dramatically reduced, without great modification of effective diffusivity D_eff value. Therefore, DIC ground seeds greatly enhanced the mass transfer mechanism. The evaluation of starting accessibility δY_s enables to establish an empirical relationship between δY_s and particle diameter δY_s = f(D). Finally, DIC texturing did not imply any modification of the lipid profile.     

Hydrothermal synthesis,thermal decomposition and optical properties of Fe2F5(H2O)(Htaz)(taz)(Hdma)

Crystal structure of Fe₂F₅(H₂O)(Htaz)(taz)(Hdma) which crystallizes in the triclinic system space group $\text{P}\overline{1}$ with unit cell parameters a = 8.8392(5) Å, b = 9.1948(5) Å, c = 9.5877(5) Å, α = 82.070(3)°, β = 63.699(3)°, γ = 89.202(3)°, Z = 2, and V = 690.91(7) ų, was synthesized under hydrothermal conditions at 393 K for 72 h, by a mixture of FeF₂/FeF₃, 1,2,4-triazole molecule (Htaz), and hydrofluoric acid solution (HF 4%) in dimethylformamide solvent (DMF). The main feature of this material is the coexistence of two oxidation states for iron atoms (Fe²⁺, Fe³⁺) in the unit cell, which associate by opposite fluorine corners of FeF₅N and FeF₂N₄ octahedra, and/or triazole molecule which originates the 2D produces material. The structure determination, performed from single crystal X-ray diffraction data, lead to the R₁/_WR₂ reliability factors 0.031/0.087. Thermal stability studies (TG/DTG/DTA) show that the decomposition provides in the temperature range 473–773 K and no mass loss was detected before 473 K. Mass spectrometry (MS) has been used. The optical absorption of the solid was measured at the corresponding λ_max using UV–vis diffuse-reflectance spectrum.     

Effect of size and shape controlled biogenic synthesis of gold nanoparticles and their mode of interactions against food borne bacterial pathogens

In this study, size and shape controlled biogenic synthesis of gold nanoparticles and their antibacterial activity against food borne bacterial pathogens were investigated. Synthesis of gold nanoparticles was carried out using two medicinally important plants Cucurbita pepo and Malva crispa and the size and shape of the nanoparticles were controlled by altering various parameters in the reaction medium. Results obtained from UV–Vis, FE-SEM, EDS and HR-TEM analyses supported the nanoparticles formation. FT-IR analysis confirmed the presence of biomolecules in the plant leaves extracts responsible for reducing and capping agents. Interestingly, the plant extract synthesized gold nanoparticles showed effective inhibition zone against Gram-positive and Gram-negative pathogens. The minimum inhibitory concentration (MIC) of synthesized gold nanoparticles at 400 μg/ml concentration showed effective inhibitory activity against Escherichia coli and Listeria monocytogenes. Conductivity of the medium continuously increased during the nanoparticles treatment with food borne bacterial pathogens resulting in indirect indication of the disruption of bacterial cell membranes. In addition, mode of interactions of gold nanoparticles against food borne bacterial pathogens was demonstrated using Bio-TEM analysis which is clear evident for the disruption of bacterial cell membranes.     

Advancements in tetronic acid chemistry. Part 1: Synthesis and reactions

The preparation and the properties of the elusive tetronic acid are reviewed, including its synthesis, chemical reactivity and reactions.     

Spectroscopic studies on the formation of charge transfer complexes of l-phenylalanine with 2,3,5-trichloro-6-alkoxy-1,4-benzoquinones in aqueous medium

UV–Vis, FT-IR, LC–MS and fluorescence spectral techniques were employed to investigate the mechanism of interaction of l-phenylalanine with new π-acceptors, 6-alkoxy-2,3,5-trichloro-1,4-benzoquinones. The interaction of these quinones with l-phenylalanine (LPA) yielding radical ion pair was found to proceed through the formation of donor–acceptor complex. The stoichiometry of the complexes was determined by Job’s continuous variation method and was found to be 1:1 in all the cases. Kinetic and thermodynamic properties of the complexes were determined in aqueous medium at physiological conditions (pH = 7). Fluorescence quenching studies indicated that the interaction between the donors and the acceptor is spontaneous. Correlation of association constants of the CT complexes with Taft’s polar and steric constants indicated that the electronic effects of the substitutions play a significant role in governing the reactivity of the quinones when compared to steric factors.     

Design,synthesis of novel N prenylated indole-3-carbazones and evaluation of in vitro cytotoxicity and 5-LOX inhibition activities

A series of novel N-1 and C-3 substituted indole derivatives (5a–f) were designed, synthesized and evaluated for their cytotoxic properties, viz Brine Shrimp Lethality Bioassay (BSLB) besides 5-Lipoxygenase (5-LOX) inhibitory activities through in vitro assays. Structure Activity Relation (SAR) studies showed that compound 5d with an LC₅₀ of 6.49 μM and 5c with an IC₅₀ of 33.69 μM were found to be interesting for cytotoxicity and 5-LOX inhibitory activity respectively.     

Synthesis of functionalized Cu:ZnS nanosystems and its antibacterial potential

Copper doped Zinc Sulfide (Cu:ZnS) nanoparticles were synthesized as potential antibacterial agents, through a solvothermal approach using Mercaptosuccinic acid (MSA) and Sodium citrate (SC) as differential capping agents. Multiple variants of the Cu:ZnS nanoparticles were generated based on the refluxing intervals of the reactions and a choice of the capping agents. The microstructural properties and the elemental composition of the synthesized nanosystems were examined using Scanning Electron Microscopy (SEM) and powder X-ray Diffraction (XRD), along with Energy-Dispersive X-ray spectroscopy (EDX) and Microwave Plasma-Atomic Emission Spectroscopy (MP-AES). The as-synthesized nanosystems were also characterized for their surface attributes using Fourier Transform Infrared spectroscopy (FT-IR), while the optical properties were studied using UV–Vis spectroscopy. The electrostatic stability of the aqueous dispersions of Cu:ZnS was studied as a function of their solvent pH, using Photon Correlation Spectroscopy. For the assessment of the antibacterial properties of the different variants of Cu:ZnS nanosystems, the disk diffusion assay was performed against both Gram-positive and Gram-negative bacteria. The results show a promising antibacterial activity for the Cu:ZnS variants synthesized, with a prominent activity in the [email protected]:ZnS nanoparticle making them a novel class of potential antibacterial agents.     

Potentiometric and antimicrobial studies on the asymmetric Schiff bases and their binuclear Ni(II) and Fe(III) complexes; synthesis and characterization of the complexes

The protonation constants of two nitro-Schiff bases SB¹, SB² and three asymmetric tetradentate diimines H₂L¹, H₂L² and H₂L³ and the stability constants of their ML type binuclear Ni(II) and Fe(III) complexes have been determined potentiometrically. The asymmetric diimines are (2OH) RCHNC₆H₄CHNR′ (2OH) type compounds [where R = R′ = phenyl for H₂L¹; R = naphthyl, R′ = phenyl for H₂L² and R = R′ = naphthyl for H₂L³]. The effect of tautomeric forms on the acid-base properties of the diimines has been investigated and discussed. In addition, dimeric and binuclear Ni(II) and Fe(III) complexes of the diimines have been synthesized and characterized by physical and spectroscopic techniques. Also, in vitro antimicrobial activities of the diimines and the complexes have been evaluated against three bacteria: Micrococcus luteus (NRLL B-4375), Bacillus cereus (RSKK 863), Escherichia coli (ATCC 11230) and the fungus: Candida albicans (ATCC 10239).     

Withering timings affect the total free amino acids and mineral contents of tea leaves during black tea manufacturing

The aim of the present study was to investigate the effect of withering timings (i.e. 0, 21, 22, 23 and 24 h) on the moisture, total free amino acids, ash, essential and toxic mineral element contents of tea (Camellia sinensis L.) leaves during black tea manufacturing. Moisture, ash, Na, P, Mg, Cu, Zn, Mn, Al, Ni and Pb contents were significantly (P < 0.05) affected by withering, whereas non-significant (P > 0.05) results were noted for total free amino acids, K, Fe and Cd contents. The highest moisture content (76.4%) was examined in fresh leaves that progressively decreased to 63.8% in 24 h withering. Total free amino acid contents gradually increased up to 23 h and then decreased. Ash, P, Cu, Zn and Mn contents showed an increasing trend with withering time. Conversely, significantly lowered amounts of Na (162.5 mg/kg) and Mg (803 mg/kg) were recorded in tea leaves after 24 h withering. Among the toxic elements, Al, Ni and Pb contents were progressively increased over withering time. It was concluded that tea is a potential source of essential chemical constituents and during processing proper care should be taken to produce high quality black tea.     

Synthesis,spectral, crystal structural,antimicrobial, DNA interaction and thermal behavior of some new zinc halide complexes: 3D supramolecular structure of zinc bromide complex

Three new four coordinated zinc(II) complexes have been synthesized and characterized by IR, UV, elemental analysis, ¹H and ¹³C NMR and X-ray single crystal analysis. The elemental analyses of the complexes are in agreement with the general formula of ZnLX₂ wherein L = Schiff base ligand and X = Cl^?, Br^? and I^?. Low molar conductivities in DMF indicated non-electrolyte character of all complexes. Spectroscopic studies well confirmed the coordination via azomethine nitrogens of the ligand to zinc ion. The single crystal X-ray analysis shows that ZnLBr₂ crystallizes in the triclinic crystal system with space group $\mathit{P}\overline{1}$. It contains two crystallographically independent molecules noted as A and B, with both Zn1A and Zn1B being almost in perfect tetrahedral environments (τ₄ = 0.94 for Zn1A and τ₄ = 0.93 for Zn1B). A detailed structural analysis shows that there are three non-classical hydrogen bondings of C–H…Br in the structure. Various C–H…π and C–H…Br interactions play an important role in stabilizing the molecular structure and then give rise to a 3D supramolecular structure of the ZnLBr₂ complex. After characterization, the Schiff base and its complexes were screened in vitro for their antibacterial and antifungal activities by disk diffusion technique. Also the ability of the complexes for DNA cleavage was studied by agarose gel electrophoresis method. Finally, thermal behavior of the complexes has been studied by thermo-gravimetry and then some activation kinetics parameters of decomposition steps were evaluated based on TG/DTG plots.     

Pistacia integerrima gall extract mediated green synthesis of gold nanoparticles and their biological activities

This paper reports a rapid, facile and one-pot synthesis of environmentally safe gold nanoparticles capped and stabilized with galls extract of Pistacia integerrima. The aqueous gold ions when exposed to P. integerrima galls extract were rapidly reduced as evident from abrupt color change to ruby red, suggesting the biosynthesis of gold nanoparticles (Au-NPs) which were further characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Their stability was evaluated against varying pH and different volumes of sodium chloride (NaCl) as well as at a range of temperature (20–80 °C). Au-NPs were tested for enzyme inhibition, antibacterial, antifungal, antinociceptive, muscle relaxant and sedative activities. The UV–Vis spectra of the gold nanoparticles gave surface plasmon resonance at 540 nm while the SEM analysis revealed the particle size in the range of 20–200 nm. FTIR spectra confirmed the involvement of amines, amide groups and alcohols in capping and reduction of gold nanoparticles. Au-NPs showed remarkable stability in different NaCl and pH solutions as well as at elevated temperature. Au-NPs have good antifungal activity and possessed antinociceptive and muscle relaxant properties as observed from their zone of inhibition and significant attenuation of acetic acid induced writhing and reduction of time spent on the rota rod respectively. These results concluded that the gall extract of P. integerrima is a very good bioreductant for the synthesis of gold nanoparticles that have potential for various biomedical and pharmaceutical applications.     

Single drop microextraction or solid phase microextraction-gas chromatography-mass spectrometry for the determination of iodine in pharmaceuticals, iodized salt, milk powder and vegetables involving conversion into 4-iodo-N,N-dimethylaniline

A rapid sequence of oxidation and iodination using 2-iodosobenzoate as an oxidizing agent and N,N-dimethylaniline as an iodine scavenger at pH 6.4, when 4-iodo-N,N-dimethylaniline is formed, has been used for the determination of iodide by GC-MS. Solid phase microextraction (SPME) and single drop microextraction (SDME) have been used for the extraction of the iodo-derivative and their relative efficiencies compared. Pharmaceutical samples were subjected to solid phase extraction (SPE) for cleanup and the eluate analyzed for iodide. Iodate in salt samples was reduced to iodide with ascorbic acid. Milk powder and dried vegetables were wet combusted with peroxydisulfate to liberate covalently bound iodine as iodate which was reduced before derivatization. A rectilinear calibration graph was obtained for 0.1 microg-10 mg l(-1) iodide by both extraction methods, the correlation coefficient and limit of detection (LOD) were 0.9995 and 25 ng l(-1) iodide by SPME method, and 0.9998 and 10 ng l(-1) iodide by SDME method, respectively. SDME appeared to be more efficient technique than SPME for the present system. From the pooled data, the average recovery of spiked iodide to real samples was 100.7% (range 96.5-107.0%) with an average R.S.D. of 3.1% (range 2.6-4.5%).