High-throughput platforms for microextraction techniques

Lab-made open-source controlled robotic workstation for sorbent-based dispersive microextraction of low-volume samples

BACKGROUND

Despite microextraction techniques have gained prominence over traditional extraction ones, they usually involve repetitive and tedious manual procedures. Full or partial automation could help alleviate this drawback. Even though commercial systems are available to automate sample preparation, they are very expensive and not affordable for a high number of laboratories.

RESULTS

With the aim of contributing to automation on sample preparation, and more specifically, on microextraction techniques, a lab-made open-source robotic workstation is presented. It allows to carry out sorbent-based dispersive microextraction in low-volume samples in a semiautomated way. The robotic system is made from low-cost hardware electronic gadgets conveniently assembled in a 3D-printed casing, and it is controlled by the open-source Arduino software. To demonstrate the potential of the developed robotic workstation, it was employed for the determination of three long-chain acylcarnitines in serum of newborns by flow injection analysis-tandem mass spectrometry (FIA-MS/MS). The method was validated in terms of sensitivity, precision and accuracy and it was successfully applied to the analysis of samples from 5 newborns.

SIGNIFICANCE

The presented robotic workstation is the first non-commercial one dedicated to sorbent-based dispersive microextraction. It is in line with the trends on sample preparation field focused on the development of automated procedures due to their huge advantages over manual procedures. Moreover, the use of open-source and low-cost elements alleviates the high cost of commercially-available systems, which are not affordable for all laboratories.

Automated Droplet Ejection from a Digital Microfluidics Sample Pretreatment Device Enables Batch-Mode Chemiluminescence Immunoassay

Digital microfluidics (DMF) features programmed manipulation of fluids in multiple steps, making it a valuable tool for sample pretreatment. However, the integration of sample pretreatment with its downstream reaction and detection requires transferring droplets from the DMF device to the outside world. To address this issue, the present study developed a modified DMF device that allows automated droplet ejection out of the chip, facilitated by a tailor-designed interface. A double-layered DMF microchip with an oil-filled medium was flipped over, with a liquid infusion port and a liquid expulsion port accommodated on the top working PCB plate and the bottom grounded ITO plate, respectively, to facilitate chip-to-world delivery of droplets. Using chemiluminescent immunoassay (CLIA) as an illustrative application, the sample pretreatment was programmed on the DMF device, and CLIA droplets were ejected from the chip for signal reading. In our workflow, CLIA droplets can be ejected from the DMF device through the chip-to-world interface, freeing up otherwise occupied electrodes for more sample pretreatment and enabling streamlined droplet microreactions and batch-mode operation for bioanalysis. Integrated with these interfacing portals, the DMF system achieved a single-channel throughput of 17 samples per hour, which can be further upscaled for more productive applications by parallelizing the DMF modules. The results of this study demonstrate that the droplet ejection function that is innovated in a DMF sample pretreatment microsystem can significantly improve analytical throughput, providing an approach to establishing an automated but decentralized biochemical sample preparation workstation for large-scale and continuous bioanalysis.

A novel honeycomb-like 3D-printed device for rotating-disk sorptive extraction of organochlorine and organophosphorus pesticides from environmental water samples

In this study, 3D-printing based on fused-deposition modeling (FDM) was employed as simple and cost-effective strategy to fabricate a novel format of rotating-disk sorptive devices. As proof-of-concept, twenty organochlorine and organophosphorus pesticides were determined in water samples through rotating-disk sorptive extraction (RDSE) using honeycomb-like 3D-printed disks followed by gas chromatography coupled to mass spectrometry (GC-MS). The devices that exhibited the best performance were comprised of polyamide + 15 % carbon fiber (PA + 15 % C) with the morphology being evaluated through X-ray microtomography. The optimized extraction conditions consisted of 120 min of extraction using 20 mL of sample at stirring speed of 1100 rpm. Additionally, liquid desorption using 800 µL of acetonitrile for 25 min at stirring speed of 1100 rpm provided the best response. Importantly, the methodology also exhibited high throughput since an extraction/desorption platform that permitted up to fifteen simultaneous extractions was employed. The method was validated, providing coefficients of determination higher than 0.9706 for all analytes; limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.15 to 3.03 μg L-1 and from 0.5 to 10.0 μg L-1, respectively. Intraday precision ranged from 4.01 to 18.73 %, and interday precision varied from 4.83 to 20.00 %. Accuracy was examined through relative recoveries and ranged from 73.29 to 121.51 %. This method was successfully applied to analyze nine groundwater samples from monitoring wells of gas stations in São Paulo. Moreover, the greenness was assessed through AGREEprep metrics, and an overall score of 0.69 was obtained indicating that the method proposed can be considered sustainable.

Batch Scale Production of 3D Printed Extraction Sorbents Using a Low-Cost Modification to a Desktop Printer

This study reports a simple modification to a commercial resin 3D printer that significantly reduces the amount of prepolymer material needed for the production of extraction sorbents. The modified printing platform is demonstrated in the printing of two imidazolium-based ionic liquid (IL) monomers. Two geometries resembling a blade-type polymeric ionic liquid (PIL) sorbent used in thin-film microextraction and a fiber-type sorbent used in solid-phase microextraction (SPME) were printed. The SPME PIL sorbents were used to extract 10 organic contaminants, including plasticizers, antimicrobial agents, UV filters, and pesticides, from water followed by high-performance liquid chromatographic (HPLC) analysis. To compare the extraction performance of the SPME sorbents, seven fibers printed with the same prepolymer composition from the same printing batch as well as different batches were evaluated. The results revealed highly reproducible extraction efficiencies for all tested sorbents with no statistical difference in their extraction performance. Method validation showed acceptable linearity (R2 > 0.92) for all analytes with limits of detection and limits of quantification ranging from 0.13 to 45 μg L-1 and 0.43 to 150 μg L-1, respectively.