Portable water quality instrument
A hand-held microfluidic testing device is provided that includes a housing having a cartridge receiving port, a cartridge for input to the cartridge receiving port having a sample input and a channel, where the channel includes a mixture of Raman-scattering nanoparticles and a calibration solution, where the calibration solution includes chemical compounds capable of interacting with a sample under test input to the cartridge and the Raman-scattering nanoparticles, and an optical detection system in the housing, where the optical detection system is capable of providing an illuminated electric field, where the illuminating electric field is capable of being used for Raman spectroscopy with the Raman-scattering nanoparticles and the calibration solution to analyze the sample under test input to the cartridge.
1. A method for determining the concentration of an analyte comprising the steps of,
collecting a water sample containing the analyte;
adding metallic Raman-scattering nanoparticles to the water sample;
adding an isotopic calibration standard to the water sample;
after collecting the water sample, adding a compound to the water sample wherein the compound is selected from the group consisting of thiols, silanes, polymeric particles, metallic particles, crown esters, cysteamine, cystamine, diethylaminethanethiol, mercaptopropionic acid, 1-propanethiol, octanethiol, octyldecanethiol, polystyrene, iron, and silica;
applying an illuminating electric field to the water sample thereby producing Raman spectra of the analyte and the isotopic reference standard simultaneously; and,
analysing the simultaneously produced analyte and isotopic calibration standard spectra to quantify the analyte in the water sample.
2. The method of claim 1 wherein the compound is a thiol.
3. The method of claim 1 wherein the compound is cysteamine or cystamine.
4. The method of claim 1 wherein the step of analysing comprises a ratiometric analysis of the simultaneously produced analyte and isotopic calibration standard spectra.
5. The method of claim 1 wherein the compound is selected from the group consisting of diethylaminethanethiol, mercaptopropionic acid, 1-propanethiol, octanethiol, and octyldecanethiol.
6. The method of claim 1 wherein the metallic Raman-scattering nanoparticles are gold, silver or copper beads.
7. The method of claim 1 wherein the isotopic calibration standard is an isotope of the analyte.