Multi-drug extraction using octanol supported rotating cellulose paper disc (RPD) device from complex biological matrices: Fabrication and application in forensic case work

Abstract

For the first time, a novel rotating paper disk (RPD) device to simplify the sample preparation process for the analysis of a broad spectrum of analytes with varying log Kow (i.e., 0.65–5.4) values is introduced.These analytes encompass diverse classes, including benzodiazepines (such as diazepam, chlordiazepoxide, flurazepam), barbiturates (such as barbital, allobarbital, phenobarbital), antihistamines (i.e., pheniramine, chlorpheniramine), antidepressants (such as fluoxetine, amitriptyline, venlafaxine), antipsychotics (like clozapine, chlorpromazine), opioids (i.e., tramadol) and z-drugs (such as zolpidem). RPD synergistically utilizes the adsorption capabilities of cellulose paper (solid substrate) in conjunction with 1-octanol supported onto the paper. In order to fabricate the RPD device, a magnetic bar was sandwiched between octanol supported cellulose paper layers. RPD was then directly immersed into the diluted biological samples (postmortem biological matrices i.e blood and urine) and allowed to rotate at 400 rpm for 30 min for optimum adsorption of target analytes. Subsequently, adsorbed analytes were back-extracted into 1 mL of methanol without any external diffusion process and finally determined by gas chromatography-mass spectrometry (GC-MS). Design of experiment-based optimization was performed using Box-Behnken design (BBD) for the optimization of significant factors of sample preparation such as pH of the sample, stirring speed, extraction time and ionic strength. Under the optimized conditions, the method was found to be linear in the range of 0.1–10 μg mL−1 for blood and urine samples. Limit of quantification (LOQ) for blood and urine samples were determined within the range of 0.084–0.099 and 0.060–0.078 μg mL−1, respectively. Intra-day and inter-day precisions were less than 6 and 10%, respectively. Good relative recoveries in the range of 50.4–98.2%, were obtained for the proposed procedure. Furthermore, the proposed method has been effectively applied in forensic toxicology case work. Additionally, the proposed method underwent evaluation for its whiteness and blueness using the RGB12 algorithm and BAGI software, respectively.