Addition Of Tetramethylammonium Hydroxide Research Articles

Stable Metal-Organic Frameworks based mixed tetramethylammonium hydroxide for toluene adsorption

Volatile organic compounds (VOCs) are major air pollutants which could cause the haze and photo-chemical reaction, and the removal of VOCs in industrial processes is significance to environmental protection and human health. One of the high performance adsorbent in the removal of VOCs materials is Metal-Organic Frameworks (MOFs). TMAOH@MIL-101(Cr) was prepared by hydrothermal process, and the adsorption ability of the samples was investigated for toluene. X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TG), infrared spectroscopy analysis (IR) and nitrogen adsorption-desorption results indicated that TMAOH@MIL-101(Cr) with different filler loading ratios had been fabricated successfully. It was found that the adsorption capacity of TMAOH-2@MIL-101(Cr) was significantly higher than MIL-101(Cr) because of the higher BET surface area, and the adsorption ability could arrive at 339 ​mg/g for TMAOH-2@MIL-101(Cr). It could be concluded that alkaline medium promoted dissolution of the H2BDC during reaction progress so the pure sample was obtained easily, and the pure sample could provide more active sites for the adsorption of toluene. Meanwhile, the continuous cycle of the adsorption-desorption experiment was carried out, the results showed that the desorption efficiency of five cycles could also reach 85%. The addition of tetramethylammonium hydroxide can improve the preparation of high-purity, high-porosity nano MIL-101(Cr).

Di-μ-benzoato-di-μ-ethano-lato-tetra-kis-[μ3-5-(hy-droxy-meth-yl)-2-methyl-4-(oxidometh-yl)pyridin-1-ium-3-olato]tetra-kis-[μ3-5-(hy-droxy-meth-yl)-2-methyl-4-(oxidometh-yl)pyridin-3-olato]di-μ3-oxido-hepta-manganese(II,III) ethanol octa-solvate.

Our work in the area of synthesis of polynuclear manganese complexes and their magnetic properties led to the synthesis and crystallization of the title compound, [Mn7(C8H9NO3)4(C8H10NO3)4(C2H5O)2(C7H5O2)2O2]·8C2H5OH. Herein, we report the molecular and crystal structure of the title compound, which was synthesized by the reaction of Mn(C6H5COO)2 with pyridoxine (PNH2, C8H11NO3) followed by the addition of tetra-methyl-ammonium hydroxide (TMAOH). The core of this centrosymmetric complex is a cage-like structure consisting of six MnIII ions and one MnII ion bound together through Mn-O bonds. The compound crystallizes in hydrogen-bonded layers formed by O-H⋯N hydrogen bonds involving the aromatic amine group of the ligand PN2- with the neighboring O atoms from the PNH- ligand. The crystal structure has large voids present in which highly disordered solvent mol-ecules (ethanol) sit. A solvent mask was calculated and 181 electrons were found in a volume of 843 Å3 in one void per triclinic unit cell. This is consistent with the presence of seven ethanol mol-ecules per formula unit, which accounts for 182 electrons per unit cell. Additionally, one ethanol mol-ecule was found to be ordered in the crystal.

Corrosion Polarization Behavior of Al-SiO2 Composites in 1M and Related Microstructural Analysis

The composites combining aluminum and silica nanoparticles with the addition of tetramethylammonium hydroxide (Al-SiO2(T)) and butanol (Al-SiO2(B)) as mixing media have been successfully fabricated. Corrosion behavior of Al-SiO2 composites before and after exposure in 1M NaCl solution was examined using potentiodynamic polarization (Tafel curve analysis). The study was also equipped with scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) investigations. Before exposure, Al-SiO2(T) exhibited the best corrosion resistance. Performance improvement was indicated by Al-SiO2(B) up to 10 times better than Al-SiO2(T) after exposure. The increased SiO2 content did not significantly enhance the corrosion resistance of the composites. The Al-SiO2 composites with 5% SiO2 content showed very high corrosion resistance (as the optimum composition). Furthermore, pitting corrosion was observed in the Al-SiO2 composites, indicated by the formation of corrosion products at grain boundaries. The product was affected by the presence of SiO2 in the Al matrix and the NaCl environment at 90°C (approach to synthetic geothermal media: Na+, Cl, H+, OH-). Our study revealed the presence of g-Al2O3, g-Al(OH)3, and Al(OH)2Cl as the dominant corrosion products.

Mechanical Strength and Corrosion Rate of Aluminium Composites (Al/SiO2): Nanoparticle Silica (NPS) as Reinforcement

The fabrication and characteristics of amorphous silica reinforced Al matrix composites are studied in this paper. The major starting materials were commercial Al powder and extracted nanoparticle SiO2 (NPS) powder from Indonesian silica sands. Two different active solutions,namely N-butanol and tetramethylammonium hydroxide (TMAH), were introduced during synthesis. Characterisations in terms of physical, mechanical, microstructural and corrosion rate examinations were also employed. Introducing the SiO2 nanoparticles into the Al matrix has decreased the density and increased the porosity of the composites. The addition of N-butanol into Al/SiO2(Al/SiO2(B)) led to broader and lower X-ray diffraction profiles than the addition of TMAH (Al/SiO2(T)). From the microstructural analysis, we found that the SiO2 particles enter and agglomerate into the opening gap of the Al sheets. Furthermore, yield strength, ultimate compression strength and modulus of elasticity tended to reduce the addition of SiO2. The corrosion rate of Al/SiO2(T) was lower than that of Al/SiO2(B) composites.

Effect of TMAH on the rheological behavior of alumina slurries for gelcasting

Tetramethyl ammonium hydroxide (TMAH) has been demonstrated to increase solids loading effectively and to accelerate gelling rate of alumina slurries gelled by Isobam (a copolymer of isobutylene and maleic anhydride) system. With 0.5 vol% addition of TMAH, solids loading of alumina slurry was increased from 56 vol% to 58 vol%. Meanwhile, storage modulus (G’) of the slurry with 56 vol% solids loading was increased from 964 Pa to 2850 Pa at a testing time of 30 min. The enhanced dispersing and gelling behavior was ascribed to the hydrolysis and hydrophobic modification of Isobam by TMAH. Flexural strength of the final alumina ceramics from 58 vol% solids loading was 543 ± 10 MPa, higher than that of the ceramics from 56 vol% solids loading (531 ± 13 MPa).

Dispersion of nano-sized yttria powder using triammonium citrate dispersant for the fabrication of transparent ceramics

In the present work, transparent Y2O3 ceramics were prepared via colloidal processing method from nano-sized Y2O3 powders. The effects of triammonium citrate (TAC) on the colloid stability of aqueous suspensions of nano-sized Y2O3 powders were studied. The surface properties of yttria powders were notably affected by the addition of TAC dispersant. The adsorption of TAC on the particle surface shifts the IEP to lower pH values and increases the absolute zeta potential in alkaline region. Rheological characterization of the investigated system revealed an optimal dispersant concentration of 1wt%, which correlated well with the saturation adsorption of TAC on Y2O3 powder surfaces. The suspensions with solid loadings up to 35vol% were achieved with further addition of Tetramethylammonium hydroxide (TMAH) into the dispersing system. The consolidated green bodies were treated by cold isostatic pressing to further increase the green density. Transparent Y2O3 ceramics were prepared after vacuum-sintering at 1700°C for 5h. The transmittances of the sample were 74.5% at 800nm and 79.8% at 2000nm, respectively.

The use of inductively coupled plasma mass spectrometry for the evaluation of the mobility of iodine in bentonite

Inductively coupled plasma mass spectrometry (ICP-MS) was used for investigating iodine in deep geological repository barriers. Major problems that can arise in the method application include different behaviours of individual iodine species, memory effects and strong non-spectral interferences owing to high salt content in samples. When proper conditions were applied (i.e. the addition of tetramethylammonium hydroxide, use of Ge as an internal standard, and spiking of iodate calibration solutions with sample matrix), ICP-MS provided accurate results, irrespective of the iodine speciation. The quantification limit of iodine determination in highly saline samples was 1.1 μg/L I. The calibration was linear at least within the range of 1–100 μg/L I. The analysis accuracy was verified by an analysis of a model sample of synthetic bentonite water and a 0.1 mol/L NaCl matrix that contained various iodine species (iodide, elemental iodine and iodate) and their mixtures, and recovery ranged from 97 to 101%. The analysis by ICP-MS coupled with liquid chromatography (LC) could also distinguish between the main iodine species of iodide and iodate. The detection limits were less than 2.0 μg/L I for both species. Both ICP-MS determination of the total iodine and the LC-ICP-MS speciation analysis were applied to a preliminary investigation of iodine diffusion through Czech bentonite from the Rokle deposit. No iodide speciation changes were observed during the diffusion experiment which was performed under atmospheric conditions.

The effect of iridium(III) ions on the formation of iron oxides in a highly alkaline medium

The effect of the presence of Ir 3+ ions on the formation of iron oxides in a highly alkaline precipitation system was investigated using X-ray powder diffraction (XRD), 57Fe Mössbauer and FT-IR spectroscopies, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Monodispersed lath-like α-FeOOH (goethite) particles precipitated by hydrothermal treatment in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH) were used as reference material. The presence of Ir 3+ ions in the precipitation system strongly influenced the phase composition, magnetic, structural and morphological properties of obtained samples. The formation of α-Fe 2O 3 (hematite) along with α-FeOOH in the first stage of hydrothermal treatment and the transformation of α-FeOOH and α-Fe 2O 3 to Fe 3O 4 (magnetite) by a longer hydrothermal treatment was caused by the presence of Ir 3+ ions. Ir 3+ for Fe 3+ substitution in the structure of α-FeOOH brought about changes in unit-cell dimensions, crystallinity, particle size and shape, hyperfine magnetic field and infrared bands positions. Ir 3+ for Fe 3+ substitution in the structure of α-Fe 2O 3 led to an increase in the temperature of the Morin transition; Mössbauer spectroscopy showed the presence of α-Fe 2O 3 in the antiferromagnetically ordered state at 293 K.

The influence of platinum(IV) ions on the formation of iron oxides in a highly alkaline medium

The effect of the presence of platinum(IV) ions, in the form of Pt ( OH ) 6 2 - at a high pH, on the formation of iron oxides in a highly alkaline precipitation system was investigated using X-ray powder diffraction (XRD), 57Fe Mössbauer and FT-IR spectroscopies, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Monodispersed lath-like α-FeOOH (goethite) particles precipitated by hydrothermal treatment in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH) were used as reference material. In the presence of 1 or 5 mol% of platinum ions in the precipitation system the lath-like α-FeOOH particles were formed as a single phase after a short hydrothermal treatment (2 h). No significant change in the size and shape of these particles in comparison to the reference sample was observed. After 6 h of autoclaving the formation of platinum nanoparticles at the surface of α-FeOOH particles via reduction by TMAH and/or its decomposition products became visible. These nanoparticles acted as a catalyst for the reduction of Fe(III) ions into Fe(II) and gradual transformation of α-FeOOH into a mixed Fe(II)–Fe(III) oxide (Fe 3O 4, magnetite) by the dissolution–recrystallization mechanism. The presence of a higher concentration of platinum ions accelerates the process of α-FeOOH → Fe 3O 4 transformation with the appearance of α-Fe 2O 3 (hematite) particles as an intermediate product.

Growth of uniform lath-like α-(Fe,Al)OOH and disc-like α-(Fe,Al) 2O 3 nanoparticles in a highly alkaline medium

The effects of aluminium (Al 3+)-dopant on the precipitation of uniform lath-like α-FeOOH particles, the obtention and growth of α-(Fe,Al)OOH and α-(Fe,Al) 2O 3 solid solutions, particle size and shape were investigated using X-ray powder diffraction, Mössbauer and Fourier transform infrared spectroscopies, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Acicular α-FeOOH particles, precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH), were used as reference material. The influence of Al-dopant was investigated by adding varying amounts of Al 3+ ions to the initial FeCl 3 solution. In the presence of lower concentrations of aluminium ions (up to 11.11 mol%) α-(Fe,Al)OOH as a single phase was formed, whereas higher concentrations led to an additional obtention and growth of α-(Fe,Al) 2O 3. Al-for-Fe substitution in the α-FeOOH and α-Fe 2O 3 structures was confirmed by a decrease in the unit-cell dimensions, a decrease in the hyperfine magnetic field and an increase in the wave number of the infrared absorption bands. The presence of lower concentrations of aluminium ions (up to 11.11 mol%) in the precipitation system did not affect the size and shape of the α-(Fe,Al)OOH particles, whereas higher concentrations influenced a decrease in the length and aspect ratio. In the presence of 42.86 mol% Al 3+ ions fairly uniform disc-shaped α-(Fe,Al) 2O 3 were formed.

Spectroscopic and electron microscopic investigation of iron oxides formed in a highly alkaline medium in the presence of rhodium ions

The effect of the presence of rhodium ions on the formation of iron oxides in a highly alkaline precipitation system was investigated using X-ray powder diffraction (XRD), 57Fe Mössbauer and FT-IR spectroscopies, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Acicular α-FeOOH particles precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH) were used as reference material. Characterization of α-FeOOH samples formed in the presence of rhodium ions showed a somewhat smaller mean crystallite size, increased unit-cell dimensions, a reduced average hyperfine magnetic field and a slight shift in the position of IR absorption bands in comparison with the reference α-FeOOH sample. By additional heating of the precipitation system, α-FeOOH precipitated in the presence of rhodium ions transformed to α-Fe 2O 3 crystals in the form of hexagonal bipyramids via a dissolution–recrystallization process. Metallic rhodium nanoparticles were formed simultaneously by the reduction of Rh 3+ ions in the presence of the products of TMAH thermal decomposition (trimethylamine and methanol). These rhodium nanoparticles acted as a catalyst for the reductive dissolution of α-Fe 2O 3 particles and the formation of Fe 3O 4 crystals in the form of octahedrons.

Formation of iron oxides in a highly alkaline medium in the presence of palladium ions

The effect of the presence of palladium ions in a highly alkaline precipitation system on the formation of iron oxides was investigated using X-ray powder diffraction (XRPD), Mössbauer and FT-IR spectroscopies, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Acicular α-FeOOH particles precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH) were used as reference material. The initial addition of palladium ions to that precipitation system had a significant effect on the formation of iron oxide phases and their properties. In the presence of palladium ions, the initially formed α-FeOOH has been transformed to α-Fe 2O 3 crystals in the form of hexagonal bipyramids via a dissolution–reprecipitation mechanism with a simultaneous formation of metallic palladium nanoparticles. These palladium nanoparticles acted as a catalyst for the reductive dissolution of α-Fe 2O 3 particles and the formation of Fe 3O 4 crystals in the form of octahedrons. Increase in the initial concentration of palladium ions in the precipitation system accelerated the transformation process α-FeOOH → α-Fe 2O 3 → Fe 3O 4 and influenced changes in the shape of α-Fe 2O 3 and Fe 3O 4 particles.

A novel route for the synthesis of nanosize particles of metallic palladium

A novel route for the synthesis of metallic palladium consisting of nanosize particles has been reported. The synthesis is based on (a) the addition of tetramethylammonium hydroxide (TMAH) to the aqueous solution of PdCl 2, and (b) autoclaving of this precipitation system at 160 °C. The distribution of the nanosize particles of metallic palladium has its mean value at about 18 nm. The mechanism of the metallic palladium formation is briefly discussed.

Effect of tetramethyl ammonium hydroxide on rheological properties of aqueous zirconia suspensions with polyacrylate

The role of tetramethyl ammonium hydroxide (TMAH) in determining the rheological properties of aqueous zirconia suspensions containing polyacrylate (PANH 4) was investigated. At acidic pH, the addition of TMAH after PANH 4 could result in a much higher stability in zirconia slurries than that with only polymer as dispersant. While in alkaline media, it was more easily realized to lower yield stress of suspensions by adding TMAH before PANH 4. Moreover, the both TMAH and PANH 4 contained systems were found to need the less polyacrylate for obtaining complete dispersion than those stabilized with PANH 4 alone.

Influence of Ni-dopant on the properties of synthetic goethite

The influence of Ni-dopant on the properties of α-FeOOH was investigated by XRD, FT-IR, 57Fe Mössbauer spectroscopy and transmission electron microscopy. α-FeOOH was synthesized at a highly alkaline pH by precipitation from the FeCl 3 solution with the addition of tetramethylammonium hydroxide and autoclaving at 160 °C. The samples doped with Ni 2+ ions were precipitated in the same way, but in the presence of varying concentrations of NiCl 2. Solid solutions, having the structure of α-FeOOH, were observed in samples with the Ni/Fe ratio up to 0.05. Upon increasing the amount of Ni-dopant the XRD lines were gradually broadened. The sample with the ratio Ni/Fe = 0.10 showed NiFe 2O 4, besides the dominant phase having the structure type of α-FeOOH. Shifts of IR bands at 892 and 796 cm −1 were not observed in all samples doped with Ni. For the ratio Ni/Fe = 0.10, the IR bands centered at 631 and 404 cm −1 were significantly broadened. RT Mössbauer spectrum of undoped α-FeOOH and Ni-doped α-FeOOH showed distributions of hyperfine magnetic fields. B hf decreased from 35.1 T for an undoped α-FeOOH to 32.1 T for α-FeOOH containing Ni 2+ ions (Ni/Fe = 0.05). The saturation of the α-FeOOH structure with Ni 2+ ions in amounts higher than ∼5 mol% was also observed by Mössbauer spectroscopy. The particle size (length) of acicular α-FeOOH particles with a maximum in the interval 180–220 nm was slightly decreased with Ni-doping, but the distribution of the length/width ratio showed no change, having a maximum at 4–5. TEM photographs additionally showed small populations of cubic-shaped or pseudocubic particles of ∼10 nm in size for the ratio Ni/Fe = 0.05 and about 10–20 nm in size for the ratio Ni/Fe = 0.10. These particles were assigned to NiFe 2O 4.

Effect of off-line methylation using carbanion and methyl iodide on pyrolysis-gas chromatographic analysis of humic and fulvic acids

The effect of off-line alkylation using a powerful methylating reagent of carbanion and methyl iodide on the kind and yield of degradation products of humic and fulvic acids in their pyrolysis-gas chromatography (Py-GC) was examined. The humic and fulvic acids used were prepared from three soils including a Dystric Cambisol, an Umbric Andosol, and a Podzol. The yields of aliphatic and lignin-derived phenolic compounds did not increase or decreased generally after the off-line methylation in comparison with conventional thermally assisted hydrolysis and methylation (THM) using tetramethylammonium hydroxide (TMAH) for unmethylated samples. However, benzenetetracarboxylic acid tetramethyl esters and benzenepentacarboxylic acid pentamethyl ester became detectable or increased in yield for all the three fulvic acids examined and one humic acid sample characterized by its high concentration of carboxyl groups. Benzenehexacarboxylic acid hexamethyl ester was also detected in off-line methylated fulvic acids soluble in dichloromethane and purified with Sephadex LH-20. The addition of TMAH in pyrolysis of the off-line methylated samples did not improve the yields. Hence, the conventional THM comparatively lead to lower yields of the benzenepolycarboxylic acids (BPCAs) with 4–6 carboxyl groups, and the Py-GC after the off-line methylation could give additional information on structural unit of humic substances, although its single use did not increase total yields of degradation products.

Multivariate Statistics of the Pyrolysis Products of High Molecular Components in Pulping Wastewaters to Explain Their Toxicity (6 pp)

At present, large-scale paper manufacture involves delignification and bleaching by elemental chlorine free (ECF), or totally chlorine free (TCF) processes. The wastewater is purified by secondary treatment (mechanical, chemical and biological) which removes most of the toxic substances from the discharge. However, we found residual toxicity in the high molecular (> 1000 D) matter (HMWM) of the discharge by test of the RET (reverse electronic transfer) inhibition. This fraction consists mainly of polydispersed lignin (LIG) and carbohydrate (CH) macromolecules. Structural units in these molecules are studied by pyrolysis gas chromatography/mass spectrometry (Pyr-GC/MS). In the present work, our aim was to find out those structural units which could explain the RET toxicity of LIG or CH molecules. We compared statistically RET toxicity values of the HMWM samples from treated wastewaters of pilot pulping experiments and intensity variation of the pyrolysis product gas chromatograms of these samples. This application is a novel study procedure. Pyrolysis products (Py-GC/MS results) and inhibition of RET (reverse electronic transport toxicity) as TU50 and TU20 of HMWM (High Molecular Weight Material; Mw > 1000 D) were compared by multivariate statistics. The samples were from laboratory pilot stages of TCF (Totally Chlorine Free) and ECF (Elemental Chlorine Free) manufacture of softwood pulp. Py-GC/MS was done without and with the addition of TMAH (Tetra Methyl Ammonium Hydroxide). The name and structure of each abundant fragment compound was identified from its retention time and mass spectrum compared to authentic reference compounds or literature. Four sets of Toxicity Units (TUs) and GC peak areas of the pyrolysis fragments were obtained. The data were normalized by division with LIG (lignin content of each sample). TU values were dependent and the fragment values independent (explanatory) variables in statistical treatments by SPSS system. Separate analyses of correlations, principal components (PCA) and stepwise multiple linear regression (SMLR) were performed from the four sample sets TCF and ECF with and without TMAH. From the CH fragments, 2-furfural in TCF, and from the LIG fragments, styrene in ECF showed the highest probabilities of originating from source structures of toxicity. Other possible compounds in concern were indicated to be CH fragment 2-methyl-2-cyclopenten-1-one in ECF and LIG fragments 2-methoxy-4-methylphenol, 4,5-dimethoxy-2-methylphenol and 2-methylphenol in TCF.

Identification of Indigo Dyes in Painting Layers by Pyrolysis Methylation and Silylation. A Case Study: ?The Dinner of Emmaus? by G. Preti

Reactive pyrolysis, under methylating or silylating conditions, in combination with gas chromatography-mass spectrometry (GC-MS) was evaluated as an analytical method for the detection of indigo dyes in painting layers. Samples with the addition of tetramethylammonium hydroxide (TMAH) or hexamethyldisilazane (HMDS), for pyrolysis/methylation and pyrolysis/silylation experiments, respectively, were pyrolysed at 600 °C by means of a heated filament pyrolyser and the evolved products were analysed on-line by GC-MS. Methyl and silylated pyrolytic markers, related to 2-aminobenzoic acid and the indoxyl moiety, were established from the analysis of synthetic indigo, neat or as a pigment of artificial painting layers containing a siccative oil. The occurrence of these markers was investigated in a real sample, taken from the painting “The dinner of Emmaus” by G.Preti (XVII century), in order to identify the blu pigment. Positive identification of indigo was achieved by pyrolysis/silylation and confirmed by RAMAN spectroscopy.

The effect of surface properties on visible luminescence of nanosized colloidal ZnO membranes

Luminescence properties of nanosized zinc oxide (ZnO) colloids depend greatly on their surface properties, which are in turn largely determined by the method of preparation. ZnO nanoparticles in the size range from 3 to 9 nm were prepared by addition of tetramethylammonium hydroxide ((CH 3) 4NOH) to an ethanolic zinc acetate solution. X-ray diffraction (XRD) indicates nanocrystalline ZnO membranes with polycrystalline hexagonal wurtzite structure. The ZnO membranes have a strong visible-emission intensity and the intensity depends upon hydrolysis time. The infrared spectra imply a variety of forms of zinc acetate complexes present on the surface of ZnO particles. The effect of the ZnO membrane surface properties on photoluminescence is discussed.

Enhanced selectivity and sensitivity for inorganic anions using an ion-pairing reagent and sample stacking in capillary zone electrophoresis with direct UV detection.

In this paper, the use of an ion-pairing reagent to improve the separation selectivity of inorganic anions in CZE was demonstrated by the addition of tetramethylammonium hydroxide (TMAOH) to the electrolyte. The separation of inorganic anions (Cl(-), I(-), Br(-), NO(2)(-), NO(3)(-) and SCN(-)) was performed using co-electroosmotic flow (EOF) with direct UV detection at 185 nm. The parameters affecting the mobility of the tested anions and the EOF such as the electrolyte pH and concentration of TMAOH in the electrolyte were examined to optimise the separation conditions. In addition, sample-stacking techniques were investigated to improve detection sensitivity. Detection sensitivities were improved 5-13-fold using electrokinetic sample stacking. The detection limits ranged from 1-3 micro mol L(-1). Finally, the proposed method was used for the separation of anions in groundwaters.