Calibration strategies for determination of the In content in discarded liquid crystal displays (LCD) from mobile phones using laser-induced breakdown spectroscopy (LIBS)

Author(s)

Andrade, Daniel Fernandes ^[1] ; Fortunato, Felipe Manfroi ^[1] ; Pereira-Filho, Edenir Rodrigues ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Chem, Grp Appl Instrumental Anal, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Analytica Chimica Acta; v. 1061, p. 42-49, JUL 11 2019.
• Web of Science Citations: 6

Abstract

Mobile phones are one of the fastest growing types of electronic waste disposed of world-wide. One of the main components in these devices is the LCD (liquid crystal display) panel that contains conductive electrodes made of indium tin oxide. A large amount of In, which is categorized as a critical raw element, has been used to manufacture indium tin oxide films. This study applies laser-induced breakdown spectroscopy (LIBS) for the analysis of LCD samples from mobile phones in order to determine the In content. Both conventional univariate calibration and non-traditional calibration using different transition energies (emission lines), named multi-energy calibration (MEC), were assessed. To evaluate the accuracy of the results, Method EPA 3052 was performed for acid digestion of the samples using microwave-assistance, and the In content was determined by ICP OES. Indium concentrations ranged from 35 to 47 mg kg(-1) for all samples evaluated. The results showed the best accuracy for LIBS methods after the spectra were normalized by the carbon line at 193.09 nm. The univariate-LIBS model showed a standard error of calibration (SEC) about 10-fold lower than the samples' concentration, LOD and LOQ of 0.3 and 1.0 mg kg(-1), respectively. MEC proved to be a fast and efficient alternative for direct solid analysis, and In concentrations were determined by LIBS using only two calibration pellets. The LOD and LOQ for MEC-LIBS method were 2.1 and 7 mg kg(-1), respectively. (C) 2019 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 16/01513-0 - Laser-Induced Breakdown Spectroscopy (LIBS) application in the analyses of electronic waste (printed circuit boards and polymers), food and difficult preparation liquid samples
• Grantee: Edenir Rodrigues Pereira Filho
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/17304-0 - Proposition of methods for direct analysis of electronic waste samples: determination of precious, strategic and toxic elements in printed circuits boards and LCD screens
• Grantee: Daniel Fernandes de Andrade
• Support Opportunities: Scholarships in Brazil - Doctorate