The analyzing method for quantifying urea in a sample solution includes: a pretreatment step of pretreating the sample solution with at least one of a membrane device including a reverse osmosis membrane and an ion exchange device including an ion exchanger; and an analyzing step of analyzing a target substance in the pretreated sample solution. The analyzing step is based on, for example, flow injection analysis (FIA), and includes a step of quantifying the target substance by measuring the absorbance of a liquid containing a substance generated by reacting the target substance with a reagent.

A method and system for testing a liquid sample for an organic compound is disclosed, the method including the steps of collecting the liquid sample from a liquid source; transmitting light having a wavelength of between about 190 nanometers and about 310 nanometers into the liquid sample; measuring absorption/transmission of the light by the organic compound in the liquid sample; and determining a concentration of the organic compound within the liquid sample based on the absorption/transmission of the light by the organic compound. The system can include a spectrophotometer for measuring the absorption of UV light by the organic compound, an ion exchange column for removing ion contaminants from the liquid sample, and a vacuum degasser unit for removing gases and other impurities from the liquid sample.

The invention relates to the field of microfluidic detection and analyses. Described herein are methods and devices for the separation, detection and measurement of molecules in liquid samples. Certain aspects of the invention concerns the separation of analyte(s) of interest based on the combined use of: (i) membrane separation, (ii) an electric field and/or a magnetic field; and (iii) capillary action and/or gravity. Envisioned applications include separation, detection and/or measurement of analytes in blood samples, food samples and environmental samples. One particular example is a portable biosensor for the detection and measurement of histamine and diamine oxidase (DOA) in a drop of blood.

An apparatus is disclosed for separating and preserving biomolecules of a biological fluid sample. The apparatus includes an assembly having sides forming a hollow shape having a first opening at one end and second opening at the opposite end, a sample mixing chamber positioned adjacent the first opening within the assembly, the sample mixing chamber from which a flow of the biological fluid sample is actuated in a direction from the sample mixing chamber to the first matrix layer, the sample mixing chamber being in a direction downstream of the first opening, a first valve positioned between the sample mixing chamber and the first matrix layer, the first valve configured to control the flow to the first matrix layer, a first input in fluid communication with the sample mixing chamber and positioned upstream of the first valve, a second input positioned between the first matrix layer and the second matrix layer, and a second valve positioned between the second matrix layer and the second opening, the second valve configured to control the flow to the second matrix layer.

Described are methods for detecting and quantifying biomolecules such as polynucleotides or polypeptides in an electrophoresis matrix using ion concentration polarization and nanoparticle aggregation.

Disclosed are methods, compositions, and devices for an integrated, heterogeneous ion-exchange membrane-based plastic microfluidic biochip platform that can be used to detect multiple diagnostic markers present in real samples. Its various components can be easily integrated in a modular fashion for different applications. Automated control allows sequential and dynamic activation of different components on the chip. The integrated platform consists of three units and is designed to execute the following functions: (i) separation of the target biomolecules from the real sample, (ii) localizing and concentrating the targeted molecules at a specific location in the microfluidic chip, and (iii) detection of the targeted molecules using hybridization/docking events against a complementary ssDNA oligoprobe sequence or a specific antibody.

The present exemplary embodiments provide a sample separation device which applies an electric field to a selective ion permeable layer based on origami to concentrate a target material in a specific area and concentrates a target material and separates a non-target material through a filter layer in which a paper is compressed to adjust a size of micro pore.

A kit for extracting mycotoxin residues in agricultural products according to the present disclosure includes a pipe, a first powder mixture layer and a second powder mixture layer. The pipe has an output port at the bottom thereof and an input port at the top thereof for inputting a sample solution. The first powder mixture layer is in the form of powder and filled in the pipe. The first powder mixture layer contains cation exchange resin powder, C18 and diatomaceous earth powder. The second powder mixture layer is in the form of powder and filled in the pipe. The second powder mixture layer is located below the first powder mixture layer and above the output port. The second powder mixture layer contains PSA powder, anhydrous magnesium sulfate powder, activated carbon, PLS powder, diatomaceous earth powder and C18 powder. The present disclosure further provides a method of obtaining a primary test liquid from agricultural products using the above kit.

An amphoteric dissociation ion exchange separation medium, the surface of which is an amphoteric dissociation covalently-modified layer. When an environmental pH value is lower than the isoelectric point, pIm, of the covalently-modified layer, the type of net charges on the surface of the covalently-modified layer is positive and the separation medium has the properties of an anion exchanger; when the environmental pH value is higher than the pIm, the type of net charges on the covalently-modified layer surface is negative and the separation medium has the properties of a cation exchanger. The separation medium has the properties of an anion exchanger and a cation exchanger at both sides of the pIm, respectively. The pH of an eluent can be adjusted to allow the separation medium surface and the target substance to have the same type of net charges, so that the target substance can be released by electrostatic repulsion.

Exosomes carry microRNA biomarkers, occur in higher abundance in cancerous patients than in healthy ones, and because they are present in most biofluids, including blood and urine, can be obtained non-invasively. Standard laboratory techniques to isolate exosomes are expensive, time-consuming, provide poor purity, and recover on the order of 25% of the available exosomes. We present a new microfluidic technique to simultaneously isolate exosomes and preconcentrate them by electrophoresis using a high transverse local electric field generated by ion-depleting ion-selective membrane. We use pressure-driven flow to deliver an exosome sample to a microfluidic chip such that the transverse electric field forces them out of the cross flow and into an agarose gel which filters out unwanted cellular debris while the ion-selective membrane concentrates the exosomes through an enrichment effect. We efficiently isolated exosomes from 1PBS buffer, cell culture media and blood serum. Using flow rates from 150 L/hr to 200 L/hr and field strengths of 100 V/cm, we consistently captured between 60% to 80% of exosomes from buffer, cell culture media, and blood serum as confirmed by both fluorescence spectroscopy and nanoparticle tracking analysis. Our microfluidic chip maintained this recovery rate for more than twenty minutes with a concentration factor of 15 for ten minutes of isolation.