Determination of Hydrogen Concentration in Hydrogen-rich Water by Headspace Gas Chromatography and Hydrogen Microelectrode

The hydrogen concentration is one of the key indicators of hydrogen-rich water, but there is no standard detection method at present. In this paper, the concentration of hydrogen in hydrogen-rich water was determined by headspace gas chromatography and hydrogen microelectrode followed by sample dilution. The detection method was optimized, the methodological evaluations were performed, and the hydrogen concentrations of hydrogen-rich water products were tested. Results showed that for headspace gas chromatography method, the optimized headspace sampling equilibrium temperature was 70 ℃ and the time was 20 min. The determination coefficient (R²) was 0.9976 in the range of 0~1.61 mg/L hydrogen content. The recoveries were 104.90%, 102.22%, 97.78%, and the relative standard deviations (RSD) were 3.87%, 2.29%, 1.69% at the spiked levels of 0.161, 0.805 and 1.449 mg/L. For hydrogen microelectrode method, the R² was 0.9978 in the range of 0~1.61 mg/L hydrogen content. The recoveries were 96.75%, 95.78%, 98.00%, and the RSD were 1.84%, 0.98%, 2.80% at the spiked levels of 0.161, 0.805 and 1.449 mg/L. For the detection of seven commercial hydrogen-rich water products, it showed that hydrogen content varies greatly, ranging from 0.8~6.2 mg/L, although they all met the requirements of the existing group standard. The hydrogen concentration decreased by 10% in 30 min and 50% in 6 h after the cover was opened. The present study would develop the methods for hydrogen concentration detection in hydrogen-rich water, and both of the headspace gas chromatography and hydrogen microelectrode methods were reliable and can be used in actual samples.