The chlorine-measuring method that uses a chlorine gas-permeable membrane is the polarographic method.

The chlorine-measuring method that uses a chlorine gas-permeable membrane is the polarographic method.

• A. Osmotic electrode method
• B. Polarographic method
• C. Membrane extraction method
• D. Functionalized polysulfonic extraction method

Answer: (B)

The main idea is that chlorine can be measured by allowing chlorine gas to diffuse through a membrane and then being detected electrochemically. In this gas-diffusion approach, a chlorine gas-permeable membrane separates the sample from the sensing solution. Chlorine species in the water equilibrate to chlorine gas, diffuse through the membrane, and arrive at the electrochemical cell where they are reduced (or oxidized) at the working electrode. The resulting current is proportional to the chlorine concentration in the sample. This gas-diffusion step is the defining feature of this method and ties directly to how polarographic sensing works with a membrane to transfer the analyte as a gas. Other methods do not rely on a gas-permeable membrane delivering chlorine gas to a polarographic cell. They use different mechanisms, such as osmotic effects across a membrane, extraction into a solvent across a membrane, or functionalized solid-phase extraction, none of which harness gas diffusion into the electrochemical sensor in the same way.

The main idea is that chlorine can be measured by allowing chlorine gas to diffuse through a membrane and then being detected electrochemically. In this gas-diffusion approach, a chlorine gas-permeable membrane separates the sample from the sensing solution. Chlorine species in the water equilibrate to chlorine gas, diffuse through the membrane, and arrive at the electrochemical cell where they are reduced (or oxidized) at the working electrode. The resulting current is proportional to the chlorine concentration in the sample. This gas-diffusion step is the defining feature of this method and ties directly to how polarographic sensing works with a membrane to transfer the analyte as a gas.

Other methods do not rely on a gas-permeable membrane delivering chlorine gas to a polarographic cell. They use different mechanisms, such as osmotic effects across a membrane, extraction into a solvent across a membrane, or functionalized solid-phase extraction, none of which harness gas diffusion into the electrochemical sensor in the same way.