Fast determination of electrolyte elements in human blood plasma using surface-enhanced laser-induced breakdown spectroscopy combined with a gel film method

Abstract

Electrolyte elements in human blood plasma play an important role in maintaining the osmotic pressure and acid-base balance of body fluids. Rapid and accurate detection of electrolyte concentrations in blood plasma is critical in clinical practice. Laser-induced breakdown spectroscopy (LIBS) is a simple and rapid method with great application potential for the detection of electrolyte elements in human blood plasma. However, when LIBS directly detects blood, splashing, surface ripples, and plasma quenching reduce the LIBS detection capability. In this work, surface-enhanced laser-induced breakdown spectroscopy (SE-LIBS) combined with a gel film method was used to improve the LIBS detection sensitivity and accuracy of electrolyte elements in blood plasma. In this method, blood plasma samples were deposited on metal substrates and naturally coagulated for LIBS detection. The physical state change process of the blood plasma with standing time was analyzed. The effects of the sample volume, coagulation time, and metal substrate on the LIBS spectral intensity were analyzed. The results showed that the physical state of the blood plasma goes through a liquid state, gel state and solid state, and the Na I 588.99 nm and K I 766.49 nm spectral lines collected from the gel state blood plasma have the highest intensities and signal stabilities. The spectral intensities of Na I 588.99 nm and K I 766.49 nm were increased by 8.19 and 5.38 times under the optimized parameters. The calibration curves of Na and K were constructed under the optimized parameters. According to the calibration curves, SE-LIBS combined with the gel film method improved the detection sensitivity, detection accuracy, and LIBS signal stability of Na and K in human blood plasma. For the Na element, the limit of detection (LoD) was improved by 3.67 times, the root mean square error of cross validation (RMSECV) was improved by 4.24 times, and the average relative standard deviation (ARSD) was decreased by 11.41%. For the K element, the LoD was improved by 3.10 times, RMSECV was improved by 2.60 times, and ARSD was decreased by 23.96%.