A method comprising: maintaining a scrubber medium at a temperature in a range of -20°C to 85°C, the scrubber medium comprising nanoparticles of a reactive metal oxide material having first aerodynamic diameters of less than 250 nm that are adhered to carrier particles having second aerodynamic diameters in a range of 10 to 250 microns and that are inert relative to one or more background compounds, wherein a mass ratio of the reactive metal oxide to the carrier particles is in a range of 20% to 30%, and wherein the nanoparticles of the reactive metal oxide are adhered to the carrier particles by one or more of van der Waals and electrostatic forces, the scrubber medium having resulted from a process that comprises combining of the nanoparticles with the carrier particles by agitating for a period sufficient to cause the nanoparticles to become so adhered to the carrier particles, the nanoparticles having been formed prior to being combined with the carrier particles; and contacting a gas mixture with the scrubber medium while the scrubber medium is maintained at the temperature, the gas mixture comprising a reactive compound and the one or more background compounds, the reactive compound comprising a gas-phase acid, wherein the gas-phase acid comprises hydrogen sulfide, the contacting causing the reactive compound to react with the reactive metal oxide material to convert the reactive compound and at least one metal oxide site on the nanoparticles to one or more metal-anion surface compounds, characterized in that the contacting of the gas mixture with the scrubber medium is employed in a system configured to detect the presence or concentration of hydrogen sulfide. maintaining a scrubber medium at a temperature in a range of -20°C to 85°C, the scrubber medium comprising nanoparticles of a reactive metal oxide material having first aerodynamic diameters of less than 250 nm that are adhered to carrier particles having second aerodynamic diameters in a range of 10 to 250 microns and that are inert relative to one or more background compounds, wherein a mass ratio of the reactive metal oxide to the carrier particles is in a range of 20% to 30%, and wherein the nanoparticles of the reactive metal oxide are adhered to the carrier particles by one or more of van der Waals and electrostatic forces, the scrubber medium having resulted from a process that comprises combining of the nanoparticles with the carrier particles by agitating for a period sufficient to cause the nanoparticles to become so adhered to the carrier particles, the nanoparticles having been formed prior to being combined with the carrier particles; and contacting a gas mixture with the scrubber medium while the scrubber medium is maintained at the temperature, the gas mixture comprising a reactive compound and the one or more background compounds, the reactive compound comprising a gas-phase acid, wherein the gas-phase acid comprises hydrogen sulfide, the contacting causing the reactive compound to react with the reactive metal oxide material to convert the reactive compound and at least one metal oxide site on the nanoparticles to one or more metal-anion surface compounds, characterized in that the contacting of the gas mixture with the scrubber medium is employed in a system configured to detect the presence or concentration of hydrogen sulfide.