Quantitative analysis of mineral elements in hair and nails using calibration-free laser-induced breakdown spectroscopy

Abstract Human biomarkers, such as hair and nails, often provide a continuous record of element concentration to indicate the nutritional status and metabolic changes. Laser-induced breakdown spectroscopy (LIBS), as a rapid detection method without sample preparation, provides a good alternative for measuring mineral elements in hair and nails. For biomedical applications of LIBS, high-precision and high-sensitivity instruments are commonly used in LIBS systems, such as Mechelle 5000 coupled with iStar ICCD. Their high cost limits the wide application of LIBS instruments. In this work, we used a low-cost autofocus LIBS system to obtain the spectral lines directly from hair and nails. The calibration-free LIBS (CF-LIBS) assisted with the standard reference line method was used to quantify the content ratio of Ca/Na and Mg/Na in hair and nails. The results showed that the relative errors between quantitative results of CF-LIBS and ICP-OES were less than 10% in hair and nails, which verified the accuracy of this method. These results illustrated that CF-LIBS assisted with the standard reference line method is a promising tool for biomedicine.