Portable water quality instrument

A portable testing device comprising:

• a portable testing device housing, wherein said portable testing device housing comprises a cartridge receiving port;
• a cartridge for input to said cartridge receiving port, wherein said cartridge comprises a mixture of a water sample comprising an analyte under investigation, metallic nanoparticles and a calibration solution, wherein said calibration solution comprises an isotopic calibration standard of the analyte under investigation;
• and
• an optical detection system in said portable testing device housing, wherein said optical detection system is configured to provide an illuminating electric field, wherein said illuminating electric field is configured for Raman spectroscopy with said mixture,
• wherein said cartridge and said optical detection system are configured to produce analyte and isotopic calibration standard simultaneously and the cartridge comprises the isotopic calibration standard in an amount sufficient to allow for a ratiometric analysis of the simultaneously produced spectra to quantify the analyte,
• wherein the isotopic calibration standard is an isotope of selenate or sulfate.

A portable testing device comprising:

• a. a portable testing device housing, wherein said portable testing device housing comprises a cartridge receiving port;
• b. a cartridge for input to said cartridge receiving port, wherein said cartridge comprises a channel, wherein said channel comprises a mixture of a water sample comprising an analyte under investigation, metallic Raman-scattering nanoparticles and a calibration solution, wherein said calibration solution comprises an isotope of the analyte under investigation, wherein said isotope comprises a first number of neutrons and said analyte comprises a second number of neutrons, wherein said isotope differs from said analyte only by the number of said neutrons;
• and
• c. an optical detection system in said portable testing device housing, wherein said optical detection system is configured to provide an illuminating electric field, wherein said illuminating electric field is configured for Raman spectroscopy with said metallic Raman-scattering nanoparticles and mixture, and wherein said cartridge and said optical detection system are configured to produce Raman spectra of the analyte and isotope simultaneously,
• wherein the analyte is selenate and the isotope is an isotope of selanate or sulfate.

A method of testing a water sample to determine a concentration of an analyte in the water sample comprising the steps of,

• collecting a water sample containing an analyte at a site;
• adding metallic Raman-scattering nanoparticles, an isotopic reference standard and an amine or thiol to the sample to produce a mixture;
• providing a portable testing device comprising, (i) a portable testing device housing, wherein said portable testing device housing comprises a cartridge receiving port;
• (ii) a cartridge for input to said cartridge receiving port, wherein said cartridge contains the mixture;
• and (iii) an optical detection system in said portable testing device housing, providing an illuminating electric field from said optical detection system thereby producing Raman spectra of the analyte and isotope simultaneously while the cartridge is input to said cartridge receiving port;
• and
• performing a ratiometric analysis of the simultaneously produced analyte and isotope spectra to quantify the analyte originally present in the water sample,
• wherein the analyte under investigation is selenate and the isotopic calibration standard comprises a selenate isotope or a sulfate isotope.

A portable testing device comprising,

• a portable testing device housing, wherein said portable testing device housing comprises a cartridge receiving port;
• a cartridge for input to said cartridge receiving port, wherein said cartridge contains a mixture including a water sample comprising selenate, metallic Raman-scattering nanoparticles, and a selenate isotope or a sulfate isotope;
• and
• an optical detection system in said portable testing device housing, wherein said optical detection system is configured to provide an illuminating electric field, wherein said illuminating electric field is configured to produce Raman spectra of the selenate and isotope simultaneously while the cartridge is input to said cartridge receiving port to allow for a ratiometric analysis of the simultaneously produced selenate and isotope spectra to quantify the selenate in the water sample.

A method for determining the concentration of selenate in a water sample comprising the steps of,

• adding metallic Raman-scattering nanoparticles to the water sample;
• adding a selenate isotope or a sulfate isotope to the water sample;
• applying an illuminating electric field to the water sample thereby producing Raman spectra of the selenate and isotope simultaneously;
• and,
• analysing the simultaneously produced selenate and isotope spectra to quantify the selenate in the water sample.