“…However, matrix-matched standards are hardly ever available, especially for biological samples, hence a number of calibration strategies have emerged, 8 such as homogenization of tissue and standard addition of element(s) of interest, 9 spiking of the samples by soaking in solution (e.g. for hair samples), 10 preparation of external standards in gelatin that mimic the tissue matrix, 11,12 including microdroplet standards, 13 (in-cell or in-torch) aspiration of a standard solution during laser sampling, [14][15][16] and application of a "film" standard on/under a biological sample combined with total consumption (i.e. ablation of the entire depth) of the assembly.…”