Advances in Measurement Techniques for Volatile Light Elements in Solid Samples

Accurate quantification of volatile elements such as hydrogen (H), carbon (C), nitrogen (N), oxygen (O), fluorine (F), sulfur (S), chlorine (Cl), and bromine (Br) in solid samples is of great significance for understanding geological processes, material properties, and biological effects. However, direct analysis of these elements remains challenging due to their high ionization energies, weak spectral signals, and susceptibility to spectral and background interferences. Traditional indirect methods, including vacuum heating–gas chromatography and inert gas fusion–infrared absorption, have been widely applied, but they involve complex procedures and inevitably destroy the original in situ distribution of elements in solid samples. In recent years, various direct solid analysis techniques have been developed, such as X-ray fluorescence spectroscopy (XRF), laser-induced breakdown spectroscopy (LIBS), and mass spectrometric methods including secondary ion mass spectrometry (SIMS), glow discharge mass spectrometry (GDMS), and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). Although these techniques enable in situ or micro-area analysis, they are generally limited in the detection of light volatile elements by low ionization efficiency, severe spectral interferences, and high background noise. This paper systematically reviews the principles, recent advances, and limitations of the above techniques, and further discusses the innovative mechanisms of helium-assisted laser ionization time-of-flight mass spectrometry (LAI-TOFMS), an emerging analytical approach. By introducing a buffer gas, this technique effectively suppresses multiply charged ion interferences and ion kinetic energy dispersion, thereby improving detection sensitivity and spectral quality, and providing a new solution for high-throughput, high-sensitivity in situ analysis of light volatile elements. Finally, the remaining challenges in solid analysis of light volatile elements, including the lack of suitable reference materials and the limited comparability and accuracy of quantitative results, are summarized. Future developments are expected to focus on improving detection sensitivity, enhancing micro-scale spatial resolution, and strengthening the standardization of data processing and quantitative methodologies.