Comparative measurements of mineral elements in milk powders with laser-induced breakdown spectroscopy and inductively coupled plasma atomic emission spectroscopy

Abstract

Mineral elements contained in commercially available milk powders, including seven infant formulae and one adult milk, were analyzed with inductively coupled plasma atomic emission spectrometry (ICP-AES) and laser-induced breakdown spectroscopy (LIBS). The purpose of this work was, through a direct comparison of the analytical results, to provide an assessment of the performance of LIBS, and especially of the procedure of calibration-free LIBS (CF-LIBS), to deal with organic compounds such as milk powders. In our experiments, the matrix effect was clearly observed affecting the analytical results each time laser ablation was employed for sampling. Such effect was in addition directly observed by determining the physical parameters of the plasmas induced on the different samples. The CF-LIBS procedure was implemented to deduce the concentrations of Mg and K with Ca as the internal reference element. Quantitative analytical results with CF-LIBS were validated with ICP-AES measurements and nominal concentrations specified for commercial milks. The obtained good results with the CF-LIBS procedure demonstrate its capacity to take into account the difference in physical parameters of the plasma in the calculation of the concentrations of mineral elements, which allows a significant reduction of the matrix effect related to laser ablation. We finally discuss the way to optimize the implementation of the CF-LIBS procedure for the analysis of mineral elements in organic materials.

A critical review of recent progress in analytical laser-induced breakdown spectroscopy

“…Quantitative and qualitative (identification and classification) analyses both occur in the literature, and the sample types have great variety. For example, toxic heavy metals and nutrients were determined in, e.g., orange, potato, wheat, milk powder, gelatin, breakfast cereals, and bakery products [171][172][173]. In addition, toys, hair dyes, talcum, coffee, and tobacco were analyzed for toxic elements.…”

Plastic identification based on molecular and elemental information from laser induced breakdown spectra: a comparison of plasma conditions in view of efficient sorting

“…Plastic sample with different polymers and additives could imply varying efficiency of the laser ablation, and therefore varying properties of the generated plasma and eventually its stoichiometry, from previous works it could be estimated from the rotational temperature and electron density from different spectra that the plasma is different from one matrix to the other [24,25]. In this work it was important to evaluate the risk of mis-identification or wrong estimation of the concentration of an element due to the matrix effect.…”

Application of laser-induced breakdown spectroscopy to the analysis of secondary materials in industrial production

“…Food and food supplements (Agrawal • et al , 2011;Barnett et al , 2011;Lei et al , 2011). Gases and exhaust gases (Haisch • et al , 1996;Ferioli et al , 2003;D'Ulivo et al , 2006;Sturm et al , 2007;Esseler et al ., 2012).…”