Selective Adsorption and Determination of Hexavalent Chromium in Water Samples by Chemically Modified Activated Carbon with Tris(hydroxymethyl)aminomethane

This study introduces a sensitive and simple method for selective adsorption of hexavalent chromium, Cr(VI), from water samples prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The method utilized activated carbon modified with tris(hydroxymethyl)aminomethane (AC-TRIS) as an adsorbent. Surface properties of the new chemically modified AC-TRIS phase were confirmed by Fourier transform infrared (FTIR) spectroscopy. Seven metal ions, including Co(II), Cu(II), Ni(II), Pb(II), Cr(III), Cr(VI), and Fe(III) were evaluated and determined at different pH values (1.0–8.0), except for Fe(III) at pH values (1.0–4.0). Based on the results of the effect of pH on adsorption of these metal ions on AC-TRIS, Cr(VI) was selected for the study of other parameters controlling its maximum uptake on AC-TRIS under batch conditions and at the optimum pH value 1.0. The maximum static adsorption capacity of Cr(VI) onto the AC-TRIS was found to be 43.30 mg g^?1 at this pH and after 1 hour contact time. The adsorption data of Cr(VI) were modeled using both Langmuir and Freundlich classical adsorption isotherms. Results demonstrated that the adsorption of Cr(VI) onto AC-TRIS followed a pseudo second-order kinetic model. In addition, the efficiency of this methodology was confirmed by applying it to real environmental water samples.     

Diiodobis(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)cadmium(II)

The Cd atom in Cd(Hmmi)₂I₂ is five‐coordinate with a trigonal bipyramidal geometry in which the apical sites are occupied by I and O atoms. Copyright © 2005 John Wiley & Sons, Ltd.     

Glycolurils in α-ureido-and α-aminoalkylation reactions 1. α-Ureidoalkylation of sulfamides with <Emphasis Type="Italic">N</Emphasis>-(hydroxymethyl)glycolurils

α-Ureidoalkylation of sulfamides with 2-hydroxymethyl-, 2,6-and 2,8-bis(hydroxymethyl)-, and 2,4,6,8-tetrakis(hydroxymethyl)glycolurils gave novel bi-, tri-, and tetracyclic fused systems combining the glycoluril and sulfamide fragments. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2195–2199, November, 2007.     

Synthesis of macroporous polymer rods based on an acrylamide derivative monomer

New macroporous polymer rods were prepared by free‐radical crosslinking copolymerization from N‐acryloyl‐tris(hydroxymethyl)aminomethane and N,N′‐methylenebisacrylamide as a crosslinking agent with different porogenic mixtures and with azobisisobutyronitrile as an initiator. The porous properties of these materials were controlled through changes in the proportions of the porogenic mixture, the polymerization temperature, or the concentration of the crosslinking agent. Pore size distribution profiles that shifted toward a larger pore size were obtained in the following cases: when the percentage of the coporogen was increased, when the copolymerization reactions were carried out at a low temperature (55 °C), and when the crosslinking concentration was reduced. Alternatively, a porogenic mixture formed from dimethyl sulfoxide and a 1:1 combination of tetradecanol and poly(ethylene glycol) 6000 as coporogens yielded a polymer rod with a high porosity and pore size. These hydrophilic materials are promising as base supports for different chromatographic processes and as throughput bioreactors. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6616–6623, 2006     

Grafting of silica with a hydrophilic triol acrylamide polymer via surface-initiated "grafting from" method for hydrophilic-interaction chromatography

A novel hydrophilic polymer-coated silica sorbent has been prepared using the radical "grafting from" polymerization method through surface-bound azo initiators for hydrophilic-interaction chromatography (HILIC). The azo groups were introduced to the surface of silica gel through the reaction with amino groups on the surface of silica gel with 4,4'-azobis(4-cyanopentanoic acid chloride) (ACVC). The resultant azo-immobilized silica gel served as surface initiator to polymerize hydrophilic triol acrylamide monomer N-acryloyltris(hydroxymethyl) aminomethane (NA) in methanol to get hydrophilic polymer-coated silica sorbent. The obtained poly(NA)-coated silica (pNA-sil) was characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), and nitrogen sorption porosimetry (NSP). Then the pNA-sil was packed into the stainless-steel column and evaluated in high-performance liquid chromatography (HPLC). Good chromatographic performance for the separation of peptides and nucleosides was obtained under HILIC mode. The results indicated that the pNA-sil stationary phase behaved as mixed-mode retention mechanisms of hydrophilic and ionic interactions. Furthermore, the pNA-sil phase was used to separate tryptic digest of β-casein and our results showed that more than 12 peptides peaks were resolved and well distributed within the elution window. Finally, the pNA-sil stationary phase was demonstrated to possess remarkable reproducibility and stability. Taken together, the pNA-sil stationary phase prepared in the current study offers a potential application in proteomics study.     

Removal of sample background buffering ions and myoglobin enrichment via a pH junction created by discontinuous buffers in capillary electrophoresis

Traditional CE sample stacking is ineffective for samples containing a high concentration of salt and/or buffer. We recently reported the use of a discontinuous buffer system for protein enrichment that was applicable to samples containing millimolar concentrations of salt. In this paper, the technique was investigated for samples containing unwanted buffering ions, including TRIS, MES, and phosphate, which are commonly used in biological sample preparation. Using myoglobin as a model protein, the results demonstrated that background buffering ions can be effectively removed or separated from the enriched protein. The key is to use either the acid or the base of the discontinuous buffers to adjust the pH of the sample, such that the net charge of the unwanted buffering ions is near-zero. The successful isolation and enrichment of myoglobin from up to 100 mM TRIS and 50 mM MES was demonstrated. The enrichment factors remained at approximately 200. Removal of phosphate was more challenging because its net charge was anionic in both the acid and the base of the discontinuous buffers. The enrichment was only achievable up to 30 mM of sodium phosphate, the enrichment factors observed were significantly lower, below 50, and the process was delayed due to the higher ionic strength resulted from phosphate. The migration of phosphate during enrichment was studied using a UV-absorbing analogue, phenyl phosphate. In addition, Simul 5.0 was used to simulate the discontinuous buffers in the absence and presence of TRIS and phosphate. The stimulated TRIS and phosphate concentration profiles were generally in agreement with the experimental results. The simulation also provided a better understanding on the effect of phosphate on the formation of the pH junction.     

Solvatochromism of Ternary Iron (II) Diimine Cyanide Complexes in 2-Ethyl-2-(hydroxymethyl) 1,3-Propanediol (Trimethylol Propane)

The solvatochromic behaviour of bis-(2,2′-bipyridyl)-biscyanoiron (II) and 2,2′- bipyridyltetracyanoiron (II) in 2-ethyl-2-(hydroxymethyl)-1,3-propanediol has been established. The significance and sensitivities of the solvatochromic shifts of these charge-transfer bands are outlined for the two iron complexes above.     

Tris(hydroxymethyl)aminomethane as an efficient organobase catalyst for the synthesis of β-phosphonomalonates

Tris(hydroxymethyl)aminomethane (THAM) is a highly efficient and recyclable organobase catalyst for the nucleophilic phosphonylation of benzylidene malononitrile under solvent-free conditions. This new catalytic methodology is applicable without a solvent, eco-friendly, economically viable, avoids conventional isolation procedures, and has a facile work-up procedure and wide scope. THAM is an inexpensive, commercially available, non-toxic, and biodegradable novel organocatalyst. Furthermore, it can be reused in up to five cycles without loss in catalytic activity, and no chromatographic separation is needed to obtain the desired products.     

Effect of tris(hydroxymethyl) aminomethane on the phase behavior of poly(ethylene imine)/cinnamic acid conjugate and the release property of cubic phase containing the conjugate

The upper critical solution temperature (UCST) of poly(ethylene imine)/cinnamic acid (PEI/CA) conjugate decreased as the tris(hydroxymethyl) aminomethane (THMAM) concentration increased. On the optical micrographs of PEI/CA mixture solutions at 25°C, the microspheres were found when the THMAM concentration was 0?mM and 100?mM, but hardly found at 200?mM. Monoolein (MO) cubic phase containing PEI, CA, and THMAM exhibited a bilayer structure on the TEM micrograph. The release degree of methylene blue loaded in the cubic phase was not strongly dependent on THMAM concentration at 25°C and 37°C, but strongly dependent on the concentration at 50°C.