CHAPTER 4 Solid-phase microextraction Neeraj Verma 1 , Nikhilesh Arya 2 and Varoon Singh 3 1 Future Industries Institute, University of South Australia, Mawson Lakes, SA, Australia 2 Department of Chemistry, Banasthali University, Jaipur, Rajasthan, India 3 National Dope Testing Laboratory, Ministry of Youth and Sports Affairs, New Delhi, Delhi, India 4.1 Introduction Sampling and sample preparation are primary and critical phases for the analytical analysis of forensic samples. At first glance, analyzing a forensic sample and reporting the result, such as the concentration of target ana- lytes, appears to be as simple as reporting a simple number; however, getting to analyze the obtained results from the analysis and being able to trust them is far from trivial (Kabir et al., 2013). In a forensic science context, analytical science must use analytical methods that adhere to stringent standard operating procedures (SOPs) to ensure that the analy- sis process can be further verified, resulting in not only consistent, repro- ducible results but also quantifiable confidence in these results. Preparing the samples to analyze at the trace and ultra-trace level is a challenging task when the target compounds are in extremely complex matrices such as blood, serum, urine, soil, environment, and debris from the crime scene, as in most cases the volume of samples available to the scientists is very limited (Budowle et al., 2009; Parker et al., 2021). An expert must handle the samples with utmost care. A schematic represen- tation of the forensic sampling handling has been presented in Fig. 4.1. While developing a method to analyze the collected samples from the crime scenes, assessing sample preparation must be part of the method validation. The process may include calculating the reproducibility of subsampling and the reproducibility of any further sample extraction procedure to check how this affects the precision and accuracy of the whole method (Jickells, 2021). Any changes in the sample preparation method for both standard samples and non-standard samples must be validated and documented accordingly to develop a robust process. Advances in the microextraction technique are a paradigm shift in foren- sics studies in comparison to the conventional method of sampling. 79 Green Analytical Methods and Miniaturized Sample Preparation Techniques for Forensic Drug Analysis DOI: https://doi.org/10.1016/B978-0-443-13907-9.00005-X © 2025 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.