Molecular hydrogen water is water that contains dissolved H2 gas. This dissolved gas is distinct from the hydrogen atoms already bonded within the water molecule (H2O). Claims about the benefits of molecular hydrogen are directly tied to the concentration of this dissolved H2 gas. Because the gas is highly volatile and begins to escape immediately upon exposure to air, testing is necessary to verify the amount of H2 delivered by manufacturers or generated by home devices.
Testing Hydrogen Water Using Reagent Drop Kits
The most accessible method for testing dissolved hydrogen concentration involves using a titration kit, often called a reagent drop kit. This technique relies on a redox titration, utilizing a reagent—typically methylene blue dye combined with colloidal platinum—that acts as a catalyst. The test principle is based on molecular hydrogen (H2) acting as a reducing agent that reacts with the blue methylene blue (MB) molecule, converting it into its colorless form.
To perform the titration, a small, measured sample of the hydrogen water is poured into a testing vial. The blue reagent is added drop by drop, with gentle swirling. Each drop reacts with and consumes a specific, known amount of the dissolved hydrogen in the sample.
The test reaches its endpoint when the added drop of reagent no longer turns clear and the water remains a faint blue color. The total number of drops added is proportional to the total amount of hydrogen originally dissolved. For most common kits, each drop consumed represents approximately \(0.1 \text{ PPM}\) of dissolved hydrogen concentration.
Measuring Hydrogen Concentration with Digital Meters
For faster, real-time measurement, digital meters are available to measure dissolved hydrogen concentration. These instruments use specialized amperometric sensors that provide a direct reading. The sensor’s tip contains a gas-permeable membrane, allowing dissolved H2 gas to pass through to an internal electrode.
Inside the sensor, the H2 gas undergoes an electrochemical oxidation reaction, generating a tiny electrical current proportional to the hydrogen gas partial pressure. The meter converts this current into a digital display reading, typically shown in PPM or PPB.
While highly accurate professional models exist, they are expensive and used primarily in laboratory settings. More affordable handheld testers often rely on Oxidation-Reduction Potential (ORP) technology. ORP meters measure the water’s overall tendency to gain or lose electrons. Since this measurement is influenced by multiple factors like pH and temperature, ORP meters do not provide a reliable, direct measurement of H2 concentration.
Dedicated digital hydrogen meters require proper maintenance, including keeping the sensor’s metallic diaphragm clean and storing the tip in a soaking solution. The sensor itself has a limited lifespan, often requiring replacement after about one year.
Understanding Units and Ensuring Test Accuracy
The concentration of dissolved hydrogen is measured using parts per million (PPM) or parts per billion (PPB). One PPM is equivalent to \(1 \text{ milligram}\) of hydrogen gas dissolved in \(1 \text{ liter}\) of water, and \(1 \text{ PPM}\) equals \(1,000 \text{ PPB}\).
Understanding these units is important for assessing potential biological activity, as studies cite minimum concentrations for observable effects. Most research suggests the concentration should be at least \(0.5 \text{ PPM}\), with \(1.0 \text{ PPM}\) or higher being a common target for general wellness. Higher concentrations, such as \(5.0 \text{ PPM}\) or \(6.0 \text{ PPM}\), are possible with certain generation methods, especially those using pressure.
Obtaining an accurate measurement depends heavily on proper sample handling, regardless of the testing method used. Molecular hydrogen is highly volatile and dissipates rapidly once the water is exposed to air. Therefore, the water sample must be tested immediately after generation or pouring from a sealed container to capture the peak concentration.
Agitating the sample, such as by excessive swirling or pouring from a height, must be avoided because it accelerates the loss of the dissolved gas. Water temperature also influences the results, as colder water holds more dissolved gas than warmer water. Minimizing the time between generation and measurement is the most important factor for accuracy.