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1.
Materials (Basel) ; 6(4): 1403-1419, 2013 Apr 02.
Article in English | MEDLINE | ID: mdl-28809217

ABSTRACT

Sorbent materials were developed utilizing two morphological structures, comprising either hexagonally packed pores (HX) or a disordered pore arrangement (CF). The sorbents were functionalized with combinations of two types of alkylammonium groups. When capture of perchlorate by the sorbents was compared, widely varying performance was noted as a result of differing morphology and/or functional group loading. A material providing improved selectivity for perchlorate over perrhenate was synthesized with a CF material using N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. Materials were applied in batch and column formats. Binding isotherms followed the behavior expected for a system in which univalent ligands of varying affinity compete for immobilized sites. Performance of the sorbents was also compared to that of commercial Purolite materials.

2.
Sensors (Basel) ; 12(11): 14953-67, 2012 Nov 06.
Article in English | MEDLINE | ID: mdl-23202195

ABSTRACT

We have previously described the application of novel porous organosilicate materials to the preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbents and the advantages of these types of materials over commercially available solid phase extraction sorbents have been demonstrated. Here, the development of systems for application of those sorbents to in situ monitoring is described. Considerations such as column pressure, particulate filtration, and component durability are discussed. The diameter of selected column housings, the sorbent bed depth, and the frits utilized significantly impact the utility of the sorbent columns in the prototype system. The impact of and necessity for improvements in the morphological characteristics of the sorbents as they relate to reduction in column pressure are detailed. The results of experiments utilizing a prototype system are presented. Data demonstrating feasibility for use of the sorbents in preconcentration prior to ion mobility spectrometry is also presented.


Subject(s)
Environmental Monitoring , Nitrogen Compounds/analysis , Water Pollutants, Chemical/analysis , Chromatography, High Pressure Liquid , Microscopy, Electron, Scanning , Solid Phase Extraction , Spectrophotometry, Ultraviolet
3.
J Environ Monit ; 13(5): 1404-9, 2011 May.
Article in English | MEDLINE | ID: mdl-21409222

ABSTRACT

A novel porous organosilicate material was evaluated for application as a solid phase extraction sorbent for preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbent in spiked deionized water, groundwater, and surface water was evaluated. Targets considered included 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, RDX, HMX, and nitroglycerin. The sorbent was shown to provide improved performance over Sep-Pak RDX. The impact of complex matrices on target preconcentration by the sorbent was also found to be less dramatic than that observed for LiChrolut EN. The impact of changes in pH on target preconcentration was considered. Aqueous soil extracts generated from samples collected at sites of ordnance testing were also used to evaluate the materials. The results presented here demonstrate the potential of this novel sorbent for application as a solid phase extraction material for the preconcentration of nitroenergetic targets from aqueous solutions.


Subject(s)
Explosive Agents/analysis , Nitrogen Compounds/analysis , Organosilicon Compounds/chemistry , Solid Phase Extraction/methods , Water Pollutants, Chemical/analysis , Azocines/analysis , Azocines/chemistry , Chromatography, High Pressure Liquid , Dinitrobenzenes/analysis , Dinitrobenzenes/chemistry , Explosive Agents/chemistry , Fresh Water/chemistry , Nitrogen Compounds/chemistry , Nitroglycerin/analysis , Nitroglycerin/chemistry , Triazines/analysis , Triazines/chemistry , Trinitrotoluene/analysis , Trinitrotoluene/chemistry , Water Pollutants, Chemical/chemistry
4.
Talanta ; 81(4-5): 1454-60, 2010 Jun 15.
Article in English | MEDLINE | ID: mdl-20441922

ABSTRACT

Hierarchical organosilicate sorbents were synthesized which possess structure on two length scales: macropores of approximately 1microm lined by mesopores (35-45A). The incorporation of macropores provides enhanced flow-through characteristics over purely mesoporous materials, thereby reducing back pressure when used in column formats. Materials of this type with varied surface groups were applied to the adsorption of 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) in both batch and column formats. The results presented here demonstrate the potential of these materials for application as solid phase extraction materials for the pre-concentration of nitroenergetic targets from aqueous solutions. The structural and binding characteristics of the materials have been evaluated and preliminary data on the impact of complex matrices is provided.


Subject(s)
Chemistry Techniques, Analytical , Environmental Monitoring/methods , Silicon Dioxide/chemistry , Trinitrotoluene/analysis , Trinitrotoluene/isolation & purification , Adsorption , Environmental Monitoring/instrumentation , Explosive Agents/chemistry , Microscopy, Electron, Scanning/methods , Microscopy, Electron, Transmission/methods , Solutions , Triazines/analysis , Volatilization
5.
Sensors (Basel) ; 10(3): 2315-31, 2010.
Article in English | MEDLINE | ID: mdl-22294928

ABSTRACT

Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the semi-selective adsorption of small molecule contaminants. These structures offer high surface areas and large pore volumes within an organized framework. The organic bridging groups in the materials can be altered to provide varied binding characteristics. This effort seeks to utilize the tunable binding selectivity, high surface area, and low materials density of these highly ordered pore networks and to combine them with the unique spectrophotometric properties of porphyrins. In the porphyrin-embedded materials (PEMs), the organosilicate scaffold stabilizes the porphyrin and facilitates optimal orientation of porphyrin and target. The materials can be stored under ambient conditions and offer exceptional shelf-life. Here, we report on the design of PEMs with specificity for organophosphates and compounds of similar structure.


Subject(s)
Fluorescent Dyes/chemistry , Paraoxon/analysis , Silicates/chemistry , Organosilicon Compounds/chemistry , Paraoxon/chemistry , Porphyrins/chemistry , Spectrometry, Fluorescence , Surface-Active Agents
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