A method of distinguishing a control solution from a sample in an electrochemical test sensor is performed. The method includes adding a control marker to the control solution. The control solution includes the control marker and analyte. The test sensor includes working and counter electrodes, and a reagent. A potential is applied to the test sensor to oxidize the control marker and the analyte. The resulting electrical current is measured. A potential is applied to the test sensor lower than the other potential in which the potential is sufficient to oxidize the analyte and not the control marker. The resulting electrical current is measured. Determining whether a control solution or a sample is present based on the measured electrical currents. To increase the measured current, a salt may be added to the control solution in an amount sufficient to increase the electrical current by at least 5% as compared to a control solution in the absence of a salt.

We disclose a method of tagging pharmaceutical and nutritional products with nanoparticles which include noble metals. The disclosure describes a plurality of nanoparticles each with either a different size and/or shape. The nanoparticles of different sizes and shapes are distinguishable using spectroscopic techniques because each is associated with different optical properties and have a different spectral signature. The different optical properties are at least due to the unique size or shape of the nanoparticles. Each of the plurality of nanoparticles may be associated with a different characteristic of the tagged pharmaceutical or nutritional product. The method includes mixing the nanoparticles with or adhering the nanoparticles to the tagged pharmaceutical or nutritional product. Two or more of the plurality of nanoparticles may be mixed with or adhered to the tagged pharmaceutical or nutritional product in a ratio and the ratio may be associated with a characteristic of the product.

Provided is a method for supplementing a sample with specific information. This method includes the following steps: intrinsically marking a sample by adding a chemical marker having a defined composition to the sample; storing data reflecting the composition of the chemical marker and information assigned to the chemical marker, wherein this marker-assigned information is not related to the composition of the chemical marker itself; analyzing the sample with an analysis method, wherein the analysis method is suited to detect the composition of the chemical marker, to obtain a marker-related result; comparing the marker-related result with the stored data; and assigning the marker-assigned stored information to the sample based on the preceding comparison.

Compositions and methods for determining the origin location of subterranean rock samples. In some implementations, the compositions include a nanoparticle tag that includes a natural polysaccharide, a fluorescent dye, and superparamagnetic nanoparticles. In some implementations, a method of determining the origin location of a subterranean rock sample includes mixing the nanoparticle tag into a fluid, flowing the fluid into a subterranean formation, recovering subterranean rock samples from the formation, separating tagged rock samples from untagged rock samples using a magnet, and determining the origin location by analyzing a fluorescent signal of the nanoparticle tag.

A method of distinguishing a control solution from a sample in an electrochemical test sensor is performed. The method includes adding a control marker to the control solution. The control solution includes the control marker and analyte. The test sensor includes working and counter electrodes, and a reagent. A potential is applied to the test sensor to oxidize the control marker and the analyte. The resulting electrical current is measured. A potential is applied to the test sensor lower than the other potential in which the potential is sufficient to oxidize the analyte and not the control marker. The resulting electrical current is measured. Determining whether a control solution or a sample is present based on the measured electrical currents. To increase the measured current, a salt may be added to the control solution in an amount sufficient to increase the electrical current by at least 5% as compared to a control solution in the absence of a salt.

We disclose a drug tracking system and method of use which may be used to screen a subject's bodily waste and to identify the drug the subject has consumed. The system includes a drug that is tagged with a food dye that may be detected in the subject's bodily waste using absorption spectroscopic analysis. The subject consumes the tagged drug and a user obtains a sample of the subject's bodily waste. The user may analyze the subject's urine using an absorption spectroscopic technique. The user may enter the emission spectrum obtained from the absorption spectroscopic analysis into a database that includes the signature emission spectra from multiple food dyes that are used as drug tags. The emission spectra may be compared and the identity of the food dye and its associated drug may be determined.

A system and method for tagging, tracking, locating and identifying people and vehicles transporting people using Perfluorocarbon tracers. An on-going problem faced by military as well as law enforcement personnel is that of friendly fire incidents. To prevent possible friendly-fire incidents, troops would separate the two layers of the uniform patch, thereby releasing a controlled release of the Perfluorocarbon vapors. Other friendly troops, equipped with sensors tuned to the specific perfluorocarbon characteristics would thus be able to literally view a plume around the tagged person or object. The system may conversely be used to tag enemies. Formulations of mixed perfluorocarbons may be used to provide coding of emissions.

Methods and compositions are provided that include a multichromophore and/or multichromophore complex for identifying a target biomolecule. A sensor biomolecule, for example, an antibody can be covalently linked to the multichromophore. Additionally, a signaling chromophore can be covalently linked to the multichromophore. The arrangement is such that the signaling chromophore is capable of receiving energy from the multichromophore upon excitation of the multichromophore. Since the sensor biomolecule is capable of interacting with the target biomolecule, the multichromophore and/or multichromophore complex can provide enhanced detection signals for a target biomolecule.

The present disclosure provides compositions, methods, and systems for identifying marked hydrocarbon fluids. These compositions, methods, and systems utilize a gas chromatography marker including a pyrrolidinone. The methods and systems can identify the presence or absence of the gas chromatography marker and/or the pyrrolidinone. The compositions, methods, and systems can optionally utilize a spectroscopic marker.

Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.