Precise analysis of potassium isotopic composition in plant materials by multi-collector inductively coupled plasma mass spectrometry

Potassium (K) is a crucial macronutrient for plants and is the predominant inorganic cation in plants, constituting up to 10% of plant biomass on a dry weight basis and originating from the soil. The utilization of potassium isotopes enables the examination of potassium cycling in the soil-plant. In this investigation, the potassium isotopic composition (δ41K) of five certified plant reference materials with varying potassium concentrations (BCR 679, GSV-2, GSB-2a, GSB-3 and GSB-6a) was assessed using multi-collector inductively coupled plasma mass spectrometry technique, employing a reduced Radio Frequency (RF) forward power and low-resolution mode without collision cell. The δ41K values of the plant reference materials BCR 679, GSV-2, GSB-2a, GSB-3 and GSB-6a are reported as −2.44 ± 0.03‰, −0.37 ± 0.04‰, −0.37 ± 0.05‰, −1.27 ± 0.04‰ and − 0.62 ± 0.01‰, respectively. This study not only presents the δ41K values of plants but also establishes a methodology for the pre-treatment and determination of δ41K in plant. Additionally, the observed variations in δ41K values among the plant reference materials suggest that δ41K has the potential to serve as a significant tracer in “soil-plant systems” within ecosystems.