The Innovation Showcase will take place on the 3rd floor of Anadarko Petroleum’s headquarters building in The Woodlands.

The event will run from 8:00 am to 4:30 pm.

To attend, please register now (www.oilandgasinnovation.com/events).
United Science is scheduled to give a 15 minute presentation.  The presentations will be given in alphabetical order as indicated on the.

I look forward to meeting you on April 30th in The Woodlands.

Jon Thompson

Visit  http://ssaoac2013.eventbrite.com/  to register.

Stop in and say hi!

Doug Fryer

United Science will be launching new sensor and sorbent products at Pittcon.  Come visit us at  booth 3506 for free sample coupons and to discuss new applications.

Email Doug Fryer (dfryer@unitedsciencecorp.com)  to organise a meeting at the event

Click 2013 pittcon press release to view the  United Science press release.

Pittcon

Oral and Poster Presentations

 Introduction: A novel highly selective sensor for silver is described below. This sensor is based on Teflon^®like matrixes and a new fluorophilic silver receptors.

Background: Silver is utilized for a wide range of applications. Due to their antibacterial properties, silver salts and silver nanoparticles are used for the disinfection of drinking water and the preparation of topical gels, specialty bandages, implantable prostheses, and catheters. Every year, about 2500 tons of silver are released into the environment and approximately 80 tons end up in surface waters. Although silver is not as toxic to humans as many other heavy metals, the U.S. Environmental Protection Agency has set the maximum contaminant level for total silver in drinking water to 0.9 ?M. While other methods for the determination of silver are available, such as atomic absorption spectrometry,  and the use of an inductively coupled plasma in combination with atomic emission or mass spectrometry, these techniques often require quite extensive and time-consuming sample pretreatment, including preconcentration and matrix separation. In comparison, ion-selective electrodes require little sample preparation and manipulation while still permitting very wide ranges of linear response, low limits of detection, high selectivities, and the possibility to distinguish between the free metal ion and its complexes.

Method: Our sensors take advantage of the highly selective and fouling-resistant fluorous membranes licensed from the University of Minnesota. Fluorous phase has extremely low polarity and is immiscible with either aqueous phase or organic phase, therefore, lowering the solvation of interferences in the membrane phase. To develop fluorous silver electrodes, a series fluorophilic silver ionophores with one or two thioether groups were tested and their selectivities for silver over interfering ions were found to depend on host preorganization and the length of the ?(CH₂)_n? spacers separating the coordinating thioether group from the strongly electron withdrawing perfluoroalkyl groups. The best ionophore provided much higher selectivities for Ag⁺ over many alkaline and heavy metal ions than most silver ISEs reported in the literature (e.g., 10 orders of magnitude more selective than Pb²⁺,  13 orders of magnitude more selective than Cu²⁺ and Cd²⁺). Combing the benefit of the high selectivity from fluorous membrane and the elimination of transmembrane ion fluxes from solid-contact electrode setup, a detection limit for silver of 4.1 ppt (3.8 × 10^?11 M) has been achieved, and this is the lowest detection limit has ever been reported for silver sensor.

Application: Our fluorous silver sensors could be used in a wide variety of matrixes, such as waste water and drinking water, wetlands. Ongoing research will expand the application of the electrode to measure in blood and food.

Li Chen, Ph. D.

Introduction: We developed potentiometric cyanide (CN^-) sensors based on receptor-doped polymeric membranes, as described below. This sensor can be applied to erform on-line CN^– monitoring in mining industry for controlling of cyanide leaching and detoxification processes.

Background: The high toxicity of cyanide and environmental concerns from its widely and continuously industrial use arouse interests in selective and sensitive methods for cyanide detection in various matrices, such as drinking water, surface water and biological fluids. To date, cyanide leaching is used as a key extraction process in the mining industry for the efficient recovery of gold from complex ores. Thus, on-line cyanide analyzers that could be used to monitor cyanides are very important for controlling of cyanide leaching and detoxification processes.

Methods: Potentiometric cyanide sensors, composed by cationic site, tridodecylmethylammonium chloride (TDDMACl), receptor, Zn(II) metallotetraphenylporphyrin, and o-NPOE plasticized polyvinylchloride (PVC), were prepared.  The sensors exhibit a linear response range of 10^-1 to 10^-5 M and a lower detection limit of 10^–5.5 M (i.e., 3 ?M), which is below the maximum contaminant level for cyanide in drinking water (200 ?g/L) permissible in the USA. The Zn(II) tetraphenylporphyrin-based ISEs have a high selectivity over interfering ions relevant to applications in the mining industry, i.e., chloride, sulfate, thiosulfate. The logarithmic selectivity coefficients for CN^- over chloride, sulfate and thiosulfate are -3.71, -5.08 and -6.57, respectively. Importantly, this electrode exhibits a higher selectivity for CN^– over OH^– (logarithmic selectivity coefficient for CN^- over OH^–is -3.42), which enables accurate monitoring of CN^– in cyanide-leaching processes in the mining industry, where sample matrices are maintained above pH 10.5 and include anions such as Cl^–, S₂O₃^2– and SO₄^2–. While the suitability of this electrode will depend on the local ore composition at specific mining sites, preliminary results show that cyanide can be detected in the relevant concentration range in samples that also contain SCN^–, Cu(CN)₄^3-, Zn(CN)₄^3-, Ni(CN)₄^3-, and Fe(CN)₆^4-, as representative of gold mine tailings.

Reference: Chen, L. D., Zou, X. U., Buhlmann, P. “A Cyanide-Selective Electrode Based on Zn (II) Tetraphenylporphyrin as Ionophore” Analytical Chemistry, 2012, published on-line.2012, 84, 9192–9198.

Introduction: A novel highly selective sensor for carbonate (CO₃^2-) is described below. This sensor is based on Teflon^®like matrixes and a new fluorophilic carbonate receptors. In conjugation with Teflon^®like pH sensors, this sensor system can provide in situ monitoring of Carbonate (CO₃^2-) /Bicarbonate (HCO₃^-) /Carbon Dioxide (CO₂).

Background: A need for accurate and rapid determination of total carbon dioxide (i.e., carbon dioxide, bicarbonate and carbonate) arises from clinical chemistry, environmental analysis and industry. Polymeric membrane electrodes with trifluoroacetophenone derivatives as ionophores for carbonate were reported and have been applied for measurements in blood serum/plasma despite the low concentration of carbonate at physiological pH. Unfortu­nately, poor selectivities for CO₃^2- over chloride and interference from salicylate limit their real-life applications. There has been no major improvement of selectivity since the 1990s.

Methods: Fluorophilic receptors and perfluorinated matrixes, with extremely low polarity and polarizability, were employed for this sensor. Benefiting from their noncoordinating and poorly solvating properties, the sensing membranes of these sensors are not only chemically very inert but also exhibit very high selectivities. The receptors exhibited enhanced selectivity for carbonate enhanced by several orders of magnitude as compared to existing sensors. In particular, the interference from chloride and salicylate was reduced by two and six orders of magnitude. The detection limit is below 10^-5 M and covered the physiological range of CO₃^2- concentration in the blood serum. Combined with pH value obtained by pH meters, concentration of CO₃^2-, HCO₃^- and CO₂can be determined simultaneously. This sensor system could be applied to analyze biological and environmental samples.

Reference: Chen, L. D., Mandal, D., Pozzi, G., Gladysz, J. A., Bühlmann, P. “Potentiometric Sensors Based on Fluorous Membranes Doped with Highly Selective Ionophores for Carbonate.” Journal of the American Chemistry Society, 2011, 133, 20869-20877.