Developing Preparation Methods for Biological Samples to Determine Trace Amounts of Heavy Metals: A Review Study

Introduction: Perpetration of samples is one of the most important stages needed for trace residue analysis of biological specimens when human exposure assessment is required. The samples preparation process makes the analyte get more purified and enriched as well as more compatible to the analysis instrument systems. The present study has concentrated on a systematic review of different articles published regarding the sample preparation methodologies of human biological samples. Material and Methods: In this systematic review, all articles related to the development of sample preparation for trace residue analysis of heavy metals in occupational biological samples published in English during 2009-2019, were considered. To meet the desired objective of the current study and facilitate the  related articles on physiochemical sample preparation methods accessibility combined keywords of Mesh and non-Mesh, without any limitation in the type of studies, the Pubmed, Web of Science, and Scopus were considered to be searched. Noteworthy, in this study, only the articles related to the workers’ biological samples were reviewed. Results: Based on the obtained results, after reviewing of the keywords trough websites, 2964 articles were identified. Then, the redundant papers were removed and59 articles were remained, based on their titles and abstracts,. After detailed review of selected articles, regarding the study criteria, 8 articles were selected for the final systematic review.  Five articles out of 8, (62.5%) were allocated to the development of sample preparation for mercury in biological samples. It is worth mentioning that the majority of biological samples were regarded to the urine samples (75%) in the current study. Based on the obtained results, Solid Phase Extraction (SPE), applied in 37.5% of studies, was a popular method used in sample preparation. Conclusion: The development of sample preparation approaches indicates a great promise for specified methods with low costs and less extraction time when separating different heavy metals from complex matrices. These sample preparation and preconcentration techniques ease the analyses processes and provide the quantitative recoveries, higher sensitivity, and lower detection limits.