This article reports the findings and methodology of an evaluation of laser ablation inductively coupled plasma optical emission spectroscopy (LAICP OES) for the direct analysis of pelleted plant material.
Ground leaves of orange citrus, soy, and sugarcane were comminuted using a high-speed ball mill, pressed into pellets, and sampled directly with laser ablation and analyzed by ICP OES. The limits of detection (LODs) for the method ranged from as low as 0.1 mg kg− 1 for Zn to as high as 94 mg kg− 1 for K but were generally below 6 mg kg− 1 for most of the elements of interest. A certified reference material consisting of a similar matrix (NIST SRM 1547 peach leaves) was used to check the accuracy of the calibration, and the reported method resulted in an average bias of ~ 5 percent for all the elements of interest. The precision for the reported method ranged from as low as 4 percent relative standard deviation (RSD) for Mn to as high as 17 percent RSD for Zn, but averaged ~ 6.5 percent RSD for all the elements (n = 10). The proposed method was tested for the determination of Ca, Mg, P, K, Fe, Mn, Zn and B, and the results were in good agreement with those obtained for the corresponding acid digests by ICP-OES. No differences were observed by applying a paired t-test at the 95 percent confidence level. The reported direct solid sampling method provides a fast alternative to acid digestion that results in similar and appropriate analytical figures of merit regarding sensitivity, accuracy, and precision for plant material analysis. (publisher abstract modified)