A novel LIBS method for quantitative and high-throughput analysis of macro- and micronutrients in plants

Abstract

Laser induced breakdown spectroscopy (LIBS) is an emerging technique for the analysis of elements in plant tissue. This study reports the validation of a newly developed LIBS instrument and a method for analysis of plant material. The LIBS setup consists of a press, a searing unit, and an analyser with an Nd:YAG laser with a pulse energy of 0.15 mJ operating at a central wavelength of 1064 nm in a nitrogen atmosphere. The LIBS measurements were conducted on 257 plant samples from eight different plant species. The plant samples were also analysed with inductively coupled plasma optical emission spectroscopy (ICP-OES) to obtain reference values for phosphorus (P), potassium (K), magnesium (Mg), sulphur (S), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn), boron (B), and copper (Cu). Based on the reference values and the LIBS spectra, partial least squares regression was used to build prediction models for each nutrient. Mixed models and specific models for wheat and faba bean were made. Specific models for wheat and faba bean performed better than mixed species models. Prediction models for P, K, Mg, S, Ca, Zn, Fe, B and Cu from wheat were superior and were sufficiently precise and accurate to enable detection of plant nutrient deficiencies. However, for Mn the accuracy needs to be improved. The results document the usefulness of the novel LIBS setup for plant tissue analysis and for detection of plant nutrient deficiencies.