We present an automated analysis system for the detection of the chemical warfare blister agents, sulfur mustard (HD) and lewisite (L), in aqueous samples without any chemical derivatization. The system is compact in size and designed to operate in the field in a safe, autonomous manner for near real-time monitoring applications. It uses anionic surfactant-based capillary micellar electrokinetic chromatography (MEKC) to separate the sample followed by UV detection. The analysis time is sufficiently fast to allow direct detection of HD which enabled the estimation of effective hydrolysis rates in the aqueous sample matrix. The estimated hydrolysis half-life of HD in our system was 4.85 ± 0.05 min. The detection limit of HD was determined to be 10 ppm with a signal to noise ratio of 5. By contrast, L hydrolyzed too rapidly in aqueous samples to enable direct detection. Instead the first hydrolysis product 2-chlorovinyl arsonous acid (CVAA), also considered a blister agent, was detected with a detection limit of 0.7 ppm with a signal to noise ratio of 5.

For domestic and military security, an autonomous system capable of continuously monitoring for airborne biothreat agents is necessary. At present, no system meets the requirements for size, speed, sensitivity, and selectivity to warn against and lead to the prevention of infection in field settings. We present a fully automated system for the detection of aerosolized bacterial biothreat agents such as Bacillus subtilis (surrogate for Bacillus anthracis) based on protein profiling by chip gel electrophoresis coupled with a microfluidic sample preparation system. Protein profiling has previously been demonstrated to differentiate between bacterial organisms. With the goal of reducing response time, multiple microfluidic component modules, including aerosol collection via a commercially available collector, concentration, thermochemical lysis, size exclusion chromatography, fluorescent labeling, and chip gel electrophoresis were integrated together to create an autonomous collection/sample preparation/analysis system. The cycle time for sample preparation was approximately 5 min, while total cycle time, including chip gel electrophoresis, was approximately 10 min. Sensitivity of the coupled system for the detection of B. subtilis spores was 16 agent-containing particles per liter of air, based on samples that were prepared to simulate those collected by wetted cyclone aerosol collector of approximately 80% efficiency operating for 7 min.

This study demonstrates the scalability of insulator based dielectrophoresis (iDEP) technology, and its application to both on-chip and bench-scale biological sample concentration systems. iDEP employs fluidic channels that contain insulating structures between opposing electrodes to create non-uniformities in an applied electric field. We present two different high-throughput iDEP particle concentrator design strategies. The first design contains 250 Pm deep microchannels molded into a polymer substrate and the second adapts a commercially available microporous membrane. The results demonstrate the ability of iDEP to accommodate a broad range of flow rates, amenable to the specific needs of an application.

We report the development of a hand-held instrument capable of performing two simultaneous microchip separations (gel and zone electrophoresis), and demonstrate this instrument for the detection of protein biotoxins. Two orthogonal analysis methods are chosen over a single method in order to improve the probability of positive identification of the biotoxin in an unknown mixture. Separations are performed on a single fused-silica wafer containing two separation channels. The chip is housed in a microfluidic manifold that utilizes o-ring sealed fittings to enable facile and reproducible fluidic connection to the chip. Sample is introduced by syringe injection into a septumsealed port on the device exterior that connects to a sample loop etched onto the chip. Detection of low nanomolar concentrations of fluorescamine-labeled proteins is achieved using a miniaturized laser-induced fluorescence detection module employing two diode lasers, one per separation channel. Independently controlled miniature highvoltage power supplies enable fully programmable electrokinetic sample injection and analysis. As a demonstration of the portability of this instrument, we evaluated its performance in a laboratory field test at the Defence Science and Technology Laboratory with a series of biotoxin variants. The two separation methods cleanly distinguish between members of a biotoxin test set. Analysis of naturally occurring variants of ricin and two closely related staphylococcal enterotoxins indicates the two methods can be used to readily identify ricin in its different forms and can discriminate between two enterotoxin isoforms.

The design, fabrication, and demonstration of a hand-held microchip-based analytical instrument for detection and identification of proteins and other biomolecules are reported. The overall system, referred to as muChemLab, has a modular design that provides for reliability and flexibility and that facilitates rapid assembly, fluid and microchip replacement, troubleshooting, and sample analysis. Components include two independent separation modules that incorporate interchangeable fluid cartridges, a 2-cm-square fused-silica microfluidic chip, and a miniature laser-induced fluorescence detection module. A custom O-ring sealed manifold plate connects chip access ports to a fluids cartridge and a syringe injection port and provides sample introduction and world-to-chip interface. Other novel microfluidic connectors include capillary needle fittings for fluidic connection between septum-sealed fluid reservoirs and the manifold housing the chip, enabling rapid chip priming and fluids replacement. Programmable high-voltage power supplies provide bidirectional currents up to 100 microAlpha at 5000 V, enabling real-time current and voltage monitoring and facilitating troubleshooting and methods development. Laser-induced fluorescence detection allows picomolar (10(-11) M) detection sensitivity of fluorescent dyes and nanomolar sensitivity (10(-9) M) for fluorescamine-labeled proteins. Migration time reproducibility was significantly improved when separations were performed under constant current control (0.5-1%) as compared to constant voltage control (2-8%).

The μChemLab™ program is developing hand-portable systems for detecting a broad range of chemical, biological, and viral agents in both gas and liquid samples. The μChem Lab liquid sample analyzer employs electrokinetic sample injection, chip-based electrophoretic microseparations and laser-induced florescence detection to analyze liquid samples. A second-generation liquid phase prototype is described. The device incorporates improvements from technological advances and applied research experience. New features include a modular design that readily accommodates on-chip preconcentration and additional separation techniques. The redesign reduces hardware failures, minimizes downtime during component replacement, improves usability, and provides increased sensitivity. Improvements have been made without compromising previous system performance.

The authors have developed a research prototype device for low level detection of SEB, ricin, botulinum toxin and ovalbumin in liquid samples. This hand-held, low power device analyzes samples by capillary zone electrophoresis (CZE) and capillary gel electrophoresis (CGE) in a parallel microchannel format, and provides sensitive detection of fluorescently-tagged analytes using miniature 392 nm diode laser-induced fluorescence. They have successfully demonstrated simultaneous parallel channel separations, fully automated high voltage control of fluidics and automated data analysis with toxin identification and semi-quantitation in the presence of aerosol backgrounds in a stand-alone self-contained unit. Tests of the fully integrated device indicate high sensitivity detection (as low as 5 nM) and cycle times of 5-10 minutes.

The ~ChemLabTM program is developing hand-portable systems for detecting a broad range of chemical, biological, and viral agents in both gas and liquid samples. The ~Chem Lab liquid sample analyzer employs electrokinetic sample injection, chip-based electrophoretic microseparations and laser-induced florescence detection to analyze liquid samples. A second-generation liquid phase prototype is described. The device incorporates improvements from technological advances and applied research experience. New features include a modular design that readily accommodates on-chip preconcentration and additional separation techniques. The redesign reduces hardware failures, minimizes downtime during component replacement, improves usability, and provides increased sensitivity. Improvements have been made without compromising previous system performance.