Phase Silica Gel Research Articles

Detection of Methamphetamine, Methylenedioxymethamphetamine, and 3,4-Methylenedioxy-N-ethylamphetamine in Spiked Plasma by HPLC and TLC

HPLC and TLC methods were developed for separation and detection of some amphetamine analogs: methamphetamine (MA); 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"); and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) in spiked plasma samples. The methods are based on purple chromogens formed by displacement reaction of these secondary aliphatic amine-bearing drugs with 7,7,8,8-tetracyanoquinodimethane at 80 degrees C for 25 min. For HPLC, both normal phase (silica gel) and RP (C18) columns were used. With the former, good detection limits in plasma were obtained with a 6 min run: 70, 100, and 500 ng/mL for MDMA, MA, and MDEA, respectively. For TLC, hexane-chloroform (1 + 9) and benzene-diethyl ether-petroleum ether (40-60 degrees)-acetonitrile-ethyl methyl ketone (2 + 3.5 + 3.5 + 0.5 + 0.5) were used as mobile phases for silica gel 60 TLC and cyano-bonded silica gel HPTLC plates, respectively. The former offered more sensitive results than the latter. Influence of evaporation steps on recovery and interferences for the HPLC and TLC methods were investigated. The developed methods are selective, simple, and easily applicable.

Diethyl sulfide modified silica and calix[4]pyrrole chelating resin: Synthesis and mercury(ii) cation retention properties

Diethyl sulfide was chemically immobilized on the surface of silica gel (0.2–0.5 and 0.06 mm) for the formation of two newly synthesized silica gel phases (S1 and S2). A new chelating resin containing meso-tetramethyl-tetrakis-(thiophene)calix[4]pyrrole, CP(I), was also synthesized via the condensation of CP(I) with formaldehyde. The selection of this receptor is based on fundamental studies. Among the cations and anions considered, CP(I) interacts only with mercury(II). The functionalized silicas and the calixpyrrole resin were characterized by elemental analysis and mass spectrometry. The batch removal of metal cations (Hg2+, Pb2+ and Cd2+) by these materials from aqueous solutions was investigated. The uptake capacities of the silica based materials (S1 and S2) and calixpyrrole polymers (R1) for the Hg2+ cation were determined. The Hg(II) cation uptake data have been found to fit both, the Langmuir and Freundlich isotherms, and the coefficients indicated favorable uptake of this cation by these materials. Parameters such as the kinetics of the uptake process, pH, temperature, silica particle size and metal-ion concentration effects were evaluated. The data obtained clearly indicate that S1 has the higher uptake capability and faster retention rate for Hg(II) ions relative to S2 and R1. In a column operation, it was observed that the Hg2+ cation was effectively removed from aqueous solution by the calixpyrrole resin, R1. The percentage of recovery of this resin for the Hg2+ cation was found to be higher than 95%. The results obtained are compared with previously reported materials for mercury removal from aqueous solutions.

Surface Modification of Porous Silica with Bi-thiophene Tripodal Ligand and Aplication to Adsorption of Toxic Metal Cations

The immobilization of a thiophene-based tripodal ligand, with a donor sulfur, on the surface of an epoxide group containing a silica gel phase for the synthesis of a newly functionalized material based on porous silica-bound bi-thiophene tripodal ligand (SGBT) is described. The modified silica surface was characterized by 13C NMR of a solid sample, elemental analysis, and infrared spectra. This new material was also studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and BJH pore sizes, respectively. The target material exhibits good thermal stability as determined by thermogravimetry curves. The synthesized material was utilized in column and batch methods for adsorption of Hg2+, Cd2+, Pb2+, Cu2+, Zn2+, K+, Na+, and Li+, and the material exhibits an affinity only towards toxic heavy metals.

Identification of dissolved organic species in non-drinking tap water by solid-phase extraction and gas chromatography–mass spectrometry

A method is presented for qualitative identification of dissolved volatile organic compounds (VOCs) in non-drinking tap water samples based on applications of both solid-phase extraction (SPE) and gas chromatography–mass spectrometric (GC–MS) techniques. Water samples were collected and passed over a micro-column packed with acid treated active silica gel phase (pH=2.6) for adsorption of dissolved organic species under this pH-condition. Silica-bound-organics were then divided into equal portions followed by suspension into organic solvents of different polarities such as methanol, ethanol, butan-1-ol, ethyl acetate, diethyl ether and chloroform. These suspensions were then automatically shaken for 1h at room temperature. The organic extracts were subjected to GC–MS analysis under temperature programming conditions. The mass spectrum of each eluted chromatographic peak was library searched or manually interpreted to identify the correct name and structure. Blank solvent and silica samples were also subjected to the same GC–MS analysis for comparison.

Effect of the addition of hydroxyl-terminated polydimethylsiloxane to TEOS-based stone consolidants

Hybrid stone consolidants prepared from tetraethoxysilane (TEOS) and α,ω-hydroxyl-terminated polydimethylsiloxane (PDMS-OH) have been considered as one of the most promising approaches to improve the effectiveness of traditional alkoxysilane-based formulations. They have emerged as response to the negative reports commonly found in the literature: the resulting silica gel phase (SiO2) tends to develop fractures and fissures inside the stone as the gel shrinks during the drying stage. In this work, we employed SEM, solid-state 29Si NMR spectroscopy and compressive tests to characterize SiO2-PDMS hybrid gels. We report the morphological characteristics exhibited by gels prepared in vitro and in situ. It was found an appreciable reduction of gel fracture for hybrids prepared from 5% w/w of PDMS. As TEOS polycondenses, PDMS-OH is chemically incorporated into the gel matrix via Si-O-Si bonds. The inclusion of these elastic chains provides the necessary flexibility to resist the stress imposed by capillary pressure. Additionally, an important hydrophobic character is imparted to the stone.

제초제 Bentazon과 그 대사산물들의 토양 중 흡착양상

제초제 bentazon과 그 대사산물들의 토양흡착 양상을 Freundlich, Langmuir 그리고 linear isotherm을 이용하여 파악하고 기능이 다른 흡착제들과의 흡착특성을 조사하였다. 토양에 대한 bentazon의 <TEX>$K_f$</TEX> = 0.55 L/kg, <TEX>$Q^0$</TEX> = 3.97mg/kg, Kd = 0.18 L/kg 그리고 <TEX>$K_{oc}$</TEX> = 18 L/kg로 나타났다. Deisopropylbentazon을 제외한 다른 대사산물들의 토양 흡착량은 bentazon보다 많았으며 특히 8-hydroxybentazon의 경우 <TEX>$K_f$</TEX> = 316.5 L/kg, <TEX>$Q^0$</TEX> = 3,448 mg/kg, <TEX>$K_d$</TEX> = 29.7 L/kg 그리고 <TEX>$K_{oc}$</TEX> = 2,970 L/kg으로 토양 중에서 대부분이 흡착되는 것으로 나타났다. 여러 기능을 가진 SPE 충진제를 이용하여 bentazon과 그 대사산물들의 흡착양상을 확인한 결과 bentazon, deisopropylbentazon 및 8-hydroxybentazon은 <TEX>$NH_2$</TEX>와 anion exchange phase에 친화성이 큰 것으로 나타났다. N-methylbentazon의 경우 <TEX>$C_{18}$</TEX>에 큰 친화력을 보였으나 normal phase인 silica gel에는 상대적으로 다른 화합물보다 친화력이 낮았다. IBA는 silica gel, COOH 그리고 cation exchange phase에 강한 흡착을 보였으며 상대적으로 <TEX>$NH_2$</TEX> 그리고 anion exchange phase에는 친화력이 낮았다. 2-Aminobenzoic acid의 경우 pH 3.0에서는 COOH, cation exchange phase에 많은 retention을 보였으며 pH 7.0에서는 <TEX>$NH_2$</TEX>, anion exchange phase에 큰 흡착량을 보였다. In order to elucidate the adsorption mechanism of the herbicide, bentazon and its metabolites on soil, their adsorption patterns on soil and six adsorbents were investigated with Freundlich, Langmuir and linear isotherm. Freundlich constants (<TEX>$K_f$</TEX>) and maximum adsorption amount(<TEX>$Q^0$</TEX>) of bentazon on soil was 0.55 and 3.97. Kd and Koc values of it were 0.18 and 18. The all of metabolites used except deisopropylbentazon amounts sorbed on the soil were much higher than bentazon. The most of 8-hydroxybentazon was adsorbed on soil showing <TEX>$K_f$</TEX> = 316.6, <TEX>$Q^0$</TEX> = 3,488, Kd = 29.7 and Koc = 2,970. Bentazon, deisopropylbentazon and 8-hydroxybentazon were shown high affinity to anion exchange regardless of pH and <TEX>$NH_2$</TEX> in low pH range. Reversed phase <TEX>$C_{18}$</TEX> resulted in 100% retention of N-methylbentazon regardless of pH and other metabolites were retained below 40%. The AIBA was strongly adsorbed in silica gel, COOH and cation exchange phase but poor retention was on anion exchange sorbent. 2-Aminobenzoic acid showed an amphipathic nature which had high affinity for COOH and cation exchange phase at pH 7.0 as well as <TEX>$NH_2$</TEX> and anion exchange sorbent at pH 3.0.

Phytochemical Constituents fromCassia alatawith Inhibition against Methicillin-ResistantStaphylococcus aureus(MRSA)

The methanolic extract of the leaves of CASSIA ALATA was sequentially partitioned in increasing polarity to afford the hexane, chloroform, butanol and residual extract. Crude extracts were evaluated against MRSA using the agar well diffusion assay. The butanol and chloroform extracts both exhibited inhibition against MRSA with inhibition indexes of 1.03 +/- 0.16 and 0.78 +/- 0.07 at the concentration of 50 mg/mL. The butanol extracts were further purified using silica gel and reverse phase chromatography to afford kaempferol ( 1), kaempferol 3- O-beta-glucopyranoside ( 2), kaempferol 3- O-gentiobioside ( 3) and aloe emodin ( 4). The four constituents showed varying degrees of inhibition against MRSA. Both 1 and 4 exhibited MIC (50) values of 13.0 +/- 1.5 microg/mL and 12.0 +/- 1.5 microg/mL, respectively. The kaempferol glycosides 2 and 3 were less active with MIC (50) values of 83.0 +/- 0.9 microg/mL and 560.0 +/- 1.2 microg/mL, respectively. A free hydroxyl group at C-3 of the flavonol structure is a structural requirement for the inhibition of MRSA.

Synthesis and characterization of a new material based on porous silica—Chemically immobilized C, N-pyridylpyrazole for heavy metals adsorption

The immobilization of C, N-pyridylpyrazole on the surface of epoxy group containing silica gel phase for the formation of a newly synthesized material based on porous silica-bound C, N-pyridylpyrazole (SGPP) is described. The surface modification was characterized by 13C NMR of solid sample, elemental analysis and infrared spectra and was studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and BJH pore sizes, respectively. The new material exhibits good thermal stability determined by thermogravimetry curves. The synthesized material was utilised in column and batch methods for separation and trace extraction of (Hg 2+, Cd 2+, Pb 2+, Cu 2+, Zn 2+, K +, Na + and Li +) and compared to results of classical liquid–liquid extraction with the unbound C, N-pyridylpyrazole compound. The grafting at the surface of silica does not affect complexing properties of the ligand and the material exhibits a high selectivity toward Hg(II).

Selective Preconcentration of Uranyl Ion by Silica Gel Phases Modified with Chelating Compounds as Inorganic Polymeric Ion Exchangers

Four chemically modified chelating silica gel phases (I - IV) with ion exchange groups were tested for their potential capability to selectively bind, extract and preconcentrate uranyl ions (UO(2)(2+)) from different aqueous solutions as well as ore samples. Factors affecting such determination processes were studied and optimized. These included the pH of the contact solution, the mass of the silica gel phase extractant, the stirring time during the application of a static technique and the eluent concentration for desorption of the surface-bound uranyl ion and interfering anions and cations. All these factors were evaluated on the basis of determinations of the distribution coefficient value (K(d)) and the percent recovery (R%). Percent recovery values of 91% for silica phase (II) and 93% for silica phase (IV) were identified in the optimum conditions. The proposed preconcentration method was further applied to uranium ore samples as well as granite samples. The determined percentage and ppm values are in good agreement with the standard assigned ones. The structure of the synthesized silica gel phases (I - IV) and their uranyl bound complexes were identified and characterized by means of infrared analysis, thermal analysis (TGA) and potentiometric titration.

Purification of a Precursor to a Potential Phospholipid Analog of Phosphatidylserine

The purpose of this project is to develop a method to purify the protected cyclic phosphatidylserine (PcycPS), an intermediate in the multi‐step synthesis of a proposed phospholipid analog (PLA). The PLA is important because it will allow us to study the structure and function of the naturally occurring phospholipid, phosphatidylserine (PS). The PLA will also allow us to study the structural interactions characteristic of the lipid bilayer and proteins in the presence of calcium by mimicking the structure and function of PS.Chromatographic purification methods investigated have used silica gel, reverse‐phase, and cation exchange solid phases. Following the purification, the product was characterized by using 1H and 31P nuclear magnetic resonance (NMR) and thin layer chromatography (TLC) utilizing molybdenum and ninhydrin reagents for visualization. PcycPS was purified to greater than 85% purity. The final step of the synthesis uses hydrogenolysis to yield the final deprotected compound. This research is supported by The College of Wooster.

Determination of α-tocopherol and ergocalciferol by thin-layer chromatography

A procedure was developed for determining α-tocopherol (vitamin E) and ergocalciferol (vitamin D2) in oils. The procedure involved the alkaline hydrolysis of an oil according to GOST (State Standard) 30417 followed by the independent recovery of vitamins by extraction with organic solvents. The extracts were separated on Sorbfil plates with the stationary phase of silica gel with a particle size of 5–12 μm by eluting vitamin E with an octane-diethyl ether mixture (7: 1) and vitamin D2 with a tetrachloromethane-diethyl ether mixture (4: 1). The zones of α-tocopherol and ergocalciferol were developed with conc. HNO3 and conc. H2SO4, respectively. The plate scanning and image processing were performed with a Sorbfil Videodensitometer software. The calibration plots were linear in the range of 2.5–15 and 15–50 mg/mL for α-tocopherol and 0.08–0.13 mg/mL for ergocalciferol. The procedure was used to determine vitamins in bur marigold oily extract and grape seed oil.

Solid phase extraction of lead (II), copper (II), cadmium (II) and nickel (II) using gallic acid-modified silica gel prior to determination by flame atomic absorption spectrometry

The immobilization of gallic acid on the surface of amino group-containing silica gel phases for the formation of a newly chelating matrix (GASG) is described. The newly synthesized extractant, characterized by the diffuse reflectance infrared Fourier transformation spectroscopy and elemental analysis, was used to preconcentrate Pb(II), Cu(II), Cd(II) and Ni(II). The pH ranges for quantitative sorption and the concentrations of HCl for eluting Pb(II), Cd(II), Cu(II) and Ni(II) were opimized, respectively. The sorption capacity of the matrix has been found to be 12.63, 6.09, 15.38, 4.62 mg/g for Pb(II), Cd(II), Cu(II) and Ni(II), respectively, with the preconcentration factor of ∼200 (∼100 for Cd(II)). The effects of flow rates, the eluants, the electrolytes and cations on the metal ions extraction, as well as the chelating matrix stability and reusability, were also studied. The extraction behavior of the matrix was conformed with Langmuir's equation. The present preconcentration and determination method was successfully applied to the analysis of synthetic metal mixture solution and river water samples. The 3 σ detection limit and 10 σ quantification limit for Pb(II), Cu(II), Cd(II) and Ni(II) were found to be 0.58, 0.86, 0.65, 0.92 μg/L and 1.08, 1.23, 0.87, 1.26 μg/L, respectively.

Extraction of Metal Ions Using Chemically Modified Silica Gel Covalently Bonded with 4,4’-Diaminodiphenylether and 4,4’-Diaminodiphenylsulfone-salicylaldehyde Schiff Bases

Two new chelating materials (Si-DDE-o-HB, and Si-DDS-o-HB) were synthesized by modifying the activated silica gel phase with Schiff bases of 4,4'-diaminodiphenylether (DDE)/4,4'-diaminodiphenylsulfone (DDS) and o-hydroxybenzaldehyde (o-HB). The synthesized materials were characterized by FTIR and BET surface area measurement techniques. The extraction of metal ions such as Zn2+, Mn2+ and Cr3+ by the chelating material Si-DDE-o-HB was found to be higher than that by Si-DDS-o-HB. The order of metal sorption was found to be Zn2+ > Mn2+ > Cr3+. The correlation coefficients for Freundlich and Langmuir adsorption isotherms were compared for the sorption of Zn2+ onto the chelating material. The loading and elution of the metal ion solution was examined at optimum pH 7.5 and 0.5 cm3 min-1 flow rate of the solution using a column technique. The preconcentration factor for the elution of Zn2+ using dilute HNO3 was found to be 66.2 with a breakthrough volume of 15 cm3. The data obtained for the preconcentration of Zn2+ by the column technique suggested that the material Si-DDE-o-HB can find industrial applications.

Efficacy of planar chromatography coupled to (tandem) mass spectrometry for employment in trace analysis

HPTLC/MS by a plunger-based extraction device was shown to be an appropriate technique for quantitative planar chromatography, even in trace analysis. Reproducible extraction from silica gel phases in the lower-pg range distinguishes this technique from other approaches. Repeatability of the MS signal showed a mean RSD of 12.5% for the example of Harman, a heterocyclic aromatic amine. Analytical response within a plate and over various plates/days showed determination coefficients of 0.9915 and 0.9488, respectively. Limit of detection (LOD) by a single quadrupole was better than 40 pg and limit of quantitation (LOQ) by a tandem mass spectrometer better than 20 pg. LOQ/LOD obtained were of similar magnitude as reported for HPLC/MS methods, however, this order of sensitivity was shown for the first time in the field of HPTLC/electrospray ionization MS.

Geochemical modelling of hardpan formation in an iron slag dump

The geochemical processes underlying hardpan formation in an alkaline iron slag dump containing up to 30 cm thick hardpans were investigated. A modelling approach has been developed to simulate mineral precipitation sequences upon pore water evaporation with PHRQPITZ and PHREEQC. This modelling approach follows the thermodynamic reaction path in which reaction products, except for calcite, may react again with the aqueous phase and form new products as evaporation proceeds. Phases that were allowed to precipitate include am-SiO 2, am-Al(OH) 3, ferrrihydrite, calcite, and salts that are known to occur in natural evaporites. The predicted results were compared with the observed mineralogy of evaporites and hardpans as analysed by XRD, FTIR-spectroscopy, and/or SEM–EDS. The evaporites precipitating from relatively unweathered iron slag were found to consist mainly of sodium salts (mirabilite, trona, glaserite) and to a smaller extent of calcite and gel-like phases of in particularly Si, but also Al and Fe. After 10 years of weathering, amorphous Si-gels and calcite were found to be most abundant. These results are based on model predictions as well as on observations. This silica gel phase, which actually consists of heterogeneous Ca- and Fe-rich silica gels, covers particles and fills micropores and -cracks in the hardpan. Hardpans formed by gel-like phases may hold rain water by their swelling properties.

Optimization of TLC detection by phosphomolybdic acid staining for robust quantification of cholesterol and bile acids

In this paper we describe a robust and sensitive detection procedure for cholesterol and selected bile acids (cholic acid, lithocholic acid, and taurodeoxycholic acid sodium salt) using the common derivatization reagent phosphomolybdic acid (PMA). Visualization conditions were studied and optimized for steroids separated on glass TLC and HPTLC plates coated with silica gel (K60WF 254 S) and octadecylsilane (RP-18W) stationary phases. Spot intensities on the plates were quantified after spraying with PMA in methanol (10% w/v ) and heating at temperatures from 40 to 120°C for times ranging from 2 to 40 min. The best conditions for high signal intensity were determined by using 3D temperature ( X )-time ( Y )-analytical signal ( Z ) maps generated from the raw experimental data. In contrast with the number of “universal procedures” described in the literature our study indicated that for robust and sensitive quantification of our components of interest heating should be performed at relatively low temperatur...

Heptemerones A—G, Seven Novel Diterpenoids from Coprinus heptemerus: Producing Organism, Fermentation, Isolation and Biological Activities.

Seven novel diterpenoids, named heptemerones A-G, were isolated from the broth of submerged cultures of Coprinus heptemerus, a basidiomycete which previously had not been known to produce secondary metabolites. The compounds were purified by solid phase extraction and silica gel chromatography followed by preparative HPLC. Among the biological activities the inhibition of fungal germination was the most potent, and depended highly on the composition of the assay medium. In water, inhibition occurred at 5 - 10 fold lower concentrations as compared to complex media. Heptemerone G was the most active compound with MICs starting at 1 microg/ml. Four of the antifungal compounds exhibited plant protective activity in a leaf segment assay using Magnaporthe grisea as the pathogen. Growth of yeasts and bacteria was hardly affected. Cytotoxic activities were moderate and only heptemerone D was phytotoxic.

Adsorption and Enthalpic Partition in Liquid Chromatography of Non‐Charged Synthetic Polymers, 3

AbstractSummary: Two kinds of retention mechanisms of polystyrene (PS) macromolecules are considered in liquid chromatography (LC) applying alkane‐bonded silica gel phases as column packings. They are based on non‐polar interactions between polymer segments and alkane groups, which lead to adsorption of polymer species on the surface situated between bonded alkane groups and eluent on the one hand (interphase adsorption) and to partition of macromolecules between bonded phase volume and eluent (enthalpic partition) on the other hand. The roles of both retention mechanisms were assessed for PS species with different molar masses and several series of binary eluents. Bare silica and C‐1, C‐4, C‐8, as well as C‐18‐bonded phases were compared. The results demonstrated that the eluent had to be a thermodynamically poor solvent for macromolecules to push them onto/into the bonded phase. However, no quantitative dependence between the eluent's thermodynamic quality for macromolecules and the extent of retention of polymer species was found. Similarly, no correlation was identified between eluent quality and prevailing retention mechanism – either interphase adsorption on the trimethylsilylated silica gel or interphase adsorption plus enthalpic partition in the case of C‐4, C‐8 and C‐18‐bonded phases. The explanation is to be sought in the actual “composition” of the preferentially solvated macromolecules and bonded alkane groups. The bonded phase probably has to be a slightly better “solvent” than the eluent for a polymer species to cause their retention. Enthalpic partition of PS plays an especially important role in DMF/THF mixed eluents. The results indicate, however, that only three to five terminal CH2 groups plus the methyl end‐group take part in the enthalpic partition process. This means that silica gel bonded with shorter alkane groups may be advantageous compared to the C‐18 packings in some coupled high performance liquid chromatography methods for synthetic polymers, combining entropic and enthalpic retention mechanisms.log Vh vs. VR for bare Kromasil (▪), as well as for C‐18 (♦), C‐8 (▾), C‐4 (▴) and C‐1 (•) phases.magnified imagelog Vh vs. VR for bare Kromasil (▪), as well as for C‐18 (♦), C‐8 (▾), C‐4 (▴) and C‐1 (•) phases.

Fluorescent organogels as templates for sol–gel transcription toward creation of optical nanofibers

1,10-Phenanthroline-appended cholesterol-based gelators (1 and 2) and their non-gelling reference compounds (1′ and 2′) were synthesized. It was shown that the gelation abilities of 1 and 2 are quite different, in spite of their structural similarity. Compound 1 can form gels with various kinds of organic solvents, whereas 2 is capable of gelation only in acidic solvents. This difference in gelation abilities seems to be due to the difference in the stacking mode of the phenanthroline moieties, as confirmed by CD spectra. TEM and AFM observations showed that fibrillar aggregates are entangled in a three-dimensional network structure. The gels also showed beautiful fluorescence, characteristic of their molecular structures and gelation conditions (in the presence and the absence of acid). Organic assemblies thus characterized were subjected as templates for sol–gel polycondensation of metal alkoxide such as tetraethyl orthosilicate (TEOS) and tetra-n-butyl titanate. The resultant organic–inorganic composite materials showed the same fluorescence properties as the organic gels. After calcination, it was revealed by TEM observation that the silica and titania materials have a hollow structure, indicating that the sol–gel polycondensation reaction proceeds selectively at the surface of the organic assemblies. The CD spectrum of the organic–inorganic composite was similar to that of the organogel, indicating that the aggregation stacking mode of the original phenanthroline moieties is still retained even in the silica-gel phase. The organic–inorganic hybrids obtained are expected to lead to various nanostructured optoelectronic devices.

Aspects of surface modification, structure characterization, thermal stability and metal selectivity properties of silica gel phases-immobilized-amine derivatives

Four silica gel phases-bound-amine derivatives (I–IV) were prepared based on chemical immobilization technique. The surface modification was identified by determination of the coverage values in mmol g −1 via thermal desorption method (1.463–1.807) and elemental analysis of nitrogen and carbon contents (1.089–2.456). Structure characterization related to immobilization of the amine derivatives was accomplished and evaluated by means of infrared (IR) and secondary ion mass spectrometric (SIMS) technique. The modified silica gel phases (I–IV) along with their interaction products with copper(II) were also examined by electron impact mass spectrometric analysis (EI-MS) as a method for evaluation of their thermal stability and structure elucidation. Potentiometric titration as a method of characterization was applied for the modified silica gel phases (II–IV) and their copper(II)-adduct. A series of bi- and trivalent metal ions were selected to focus more aspects of the selectivity properties incorporated into the modified silica gel phases for binding and interaction with these metals based on determination of the distribution coefficient and separation factor. The results of these evaluation processes were found to prove higher selectivity and preference of these four phases for binding with lead(II) and cadmium(II) compared to other metal ions.