Quantitative inkjet application on self-printed, binder-free HPTLC layers for submicromole-scaled analytical 1H NMR spectroscopy

Application of three-dimensional printing technology in environmental analysis: A review

The development of environmental analysis devices with high performance is essential to assess the potential risks of environmental pollutants. However, it is still challenging to develop environmental analysis equipment with miniaturization, portability, and high sensitivity based on traditional processing techniques. In recent years, the popularity of 3D printing technology (3DP) with high precision, low cost, and unlimited design freedom has provided opportunities to solve the existing challenges of environmental analysis. 3D printing has brought solutions to promote the high performance and versatility of environmental analysis equipment by optimizing printing materials, enhancing equipment structure, and integrating multidisciplinary technology. In this paper, we comprehensively review the latest progress in 3D printing in various aspects of environmental analysis procedures, including but not limited to sample collection, pretreatment, separation, and detection. We highlight their advantages and challenges in determining various environmental contaminants through passive sampling, solid-phase extraction, chromatographic separation, and mass spectrometry detection. The manufacturing of 3D-printed environmental analysis devices is also discussed. Finally, we look forward to their development prospects and challenges.

Development of a 3D-Printable, Porous, and Chemically Active Material Filled with Silica Particles and its Application to the Fabrication of a Microextraction Device

We report on the first successful attempt to produce a silica/polymer composite with retained C18 silica sorptive properties that can be reliably printed using three-dimensional (3D) FDM printing. A 3D printer provides an exceptional tool for producing complex objects in an easy and inexpensive manner and satisfying the current custom demand of research. Fused deposition modeling (FDM) is the most popular 3D-printing technique based on the extrusion of a thermoplastic material. The lack of appropriate materials limits the development of advanced applications involving directly 3D-printed devices with intrinsic chemical activity. Progress in sample preparation, especially for complex sample matrices and when mass spectrometry is favorable, remains a vital research field. Silica particles, for example, which are commonly used for extraction, cannot be directly extruded and are not readily workable in a powder form. The availability of composite materials containing a thermoplastic polymer matrix and dispersed silica particles would accelerate research in this area. This paper describes how to prepare a polypropylene (PP)/acrylonitrile-butadiene-styrene (ABS)/C18-functionalized silica composite that can be processed by FDM 3D printing. We present a method for producing the filament as well as a procedure to remove ABS by acetone rinsing (to activate the material). The result is an activated 3D-printed object with a porous structure that allows access to silica particles while maintaining macroscopic size and shape. The 3D-printed device is intended for use in a solid-phase microextraction (SPME) procedure. The proposed composite's effectiveness is demonstrated for the microextraction of glimepiride, imipramine, and carbamazepine. The complex honeycomb geometry of the sorbent has shown to be superior to the simple tubular sorbent, which proves the benefits of 3D printing. The 3D-printed sorbent's shape and microextraction parameters were fine-tuned to provide satisfactory recoveries (33-47%) and high precision (2-6%), especially for carbamazepine microextraction.

Inkjet Printing and 3D Printing Strategies for Biosensing, Analytical, and Diagnostic Applications

Inkjet printing and 3D inkjet printing have found many applications in the fabrication of a great variety of devices, which have been developed with the aim to improve and simplify the design, fabrication, and performance of sensors and analytical platforms. Here, developments of these printing technologies reported during the last 10 years are reviewed and their versatile applicability for the fabrication of improved sensing platforms and analytical and diagnostic sensor systems is demonstrated. Illustrative examples are reviewed in the context of particular advantages provided by inkjet printing technologies. Next to aspects of device printing and fabrication strategies, the utilization of inkjet dispensing, which can be implemented into common analytical tools utilizing customized inkjet printing equipment as well as state-of-the-art consumer inkjet printing devices, is highlighted. This review aims to providing a comprehensive overview of examples integrating inkjet and 3D inkjet printing technologies into device layout fabrication, dosing, and analytical applications to demonstrate the versatile applicability of these technologies, and furthermore, to inspire the utilization of inkjet printing for future developments.

Open-source all-in-one LabToGo Office Chromatography

Print and media technologies were used uncommonly in the field of chromatography and explored in application to create a miniaturized all-in-one LabToGo system. This novel research field termed Office Chromatography (OC) uses additive manufacturing in terms of 3D printing of operational parts as well as open-source hard- and software. The OCLab2 presented here has been considerably extended in its functionalities. For inkjet printing of solutions, a newly designed printhead was manufactured controlled by a self-constructed ink-jet board, allowing to check the nozzles' resistance heating circuit. Plate heating was newly integrated, especially favorable for the demonstrated application of higher volumes of aqueous samples. The UV/Vis/FLD plate images were captured by a Raspberry Pi V2 camera module under illumination by novel light emitting diodes (LEDs) for highly selective RGBW color (Vis), UVC 278-nm (UV) and UVA 366-nm (FLD) detection, installed in a newly created miniature cabinet to protect from extraneous light. The spectral separation of differently colored food dyes was achieved by the fully addressable driver controlled RGBW LEDs. The software was newly written in R to speed-up the processes, supported by the new Raspberry Pi 4B computer with 4 GB RAM. The analysis of Stevia leaves for steviol glycosides yielded results comparable to the status quo. Different water samples were analyzed for bioactive compounds. Thereby, compounds of general cytotoxicity were effect-directed detected by bioluminescent A. fischeri bacteria. It allowed the bioanalytical screening for potential risks in tap water, surface waters, rain water, landfill leachates and biogas slurries.

HPTLC-Based Chemical Profiling: An Approach to Monitor Plant Metabolic Expansion Caused by Fungal Endophytes

Fungal endophytes isolated from two latex bearing species were chosen as models to show their potential to expand their host plant chemical diversity. Thirty-three strains were isolated from Alstonia scholaris (Apocynaceae) and Euphorbia myrsinites (Euphorbiaceae). High performance thin layer chromatography (HPTLC) was used to metabolically profile samples. The selected strains were well clustered in three major groups by hierarchical clustering analysis (HCA) of the HPTLC data, and the chemical profiles were strongly correlated with the strains' colony size. This correlation was confirmed by orthogonal partial least squares (OPLS) modeling using colony size as "Y" variable. Based on the multivariate data analysis of the HPTLC data, the fastest growing strains of each cluster were selected and used for subsequent experiments: co-culturing to investigate interactions between endophytes-phytopathogens, and biotransformation of plant metabolites by endophytes. The strains exhibited a high capacity to fight against fungal pathogens. Moreover, there was an increase in the antifungal activity after being fed with host-plant metabolites. These results suggest that endophytes play a role in plant defense mechanisms either directly or by biotransformation/induction of metabolites. Regarding HPTLC-based metabolomics, it has proved to be a robust approach to monitor the interactions among fungal endophytes, the host plant and potential phytopathogens.

Low-cost and open-source strategies for chemical separations

In recent years, a trend toward utilizing open access resources for laboratory research has begun. Open-source design strategies for scientific hardware rely upon the use of widely available parts, especially those that can be directly printed using additive manufacturing techniques and electronic components that can be connected to low-cost microcontrollers. Open-source software eliminates the need for expensive commercial licenses and provides the opportunity to design programs for specific needs. In this review, the impact of the "open-source movement" within the field of chemical separations is described, primarily through a comprehensive look at research in this area over the past five years. Topics that are covered include general laboratory equipment, sample preparation techniques, separations-based analysis, detection strategies, electronic system control, and software for data processing. Remaining hurdles and possible opportunities for further adoption of open-source approaches in the context of these separations-related topics are also discussed.

Same analytical method for both (bio)assay and zone isolation to identify/quantify bioactive compounds by quantitative nuclear magnetic resonance spectroscopy

Differing sensitivity is the main obstacle for a direct combination of HPTLC with NMR spectroscopy. A sufficient amount of the isolated compound zone must be provided by HPTLC for subsequent offline NMR detection (HPTLC//NMR). To fill the gap, a straightforward procedure was developed using the same analytical HPTLC system for both bioprofiling and isolation of bioactive zones from multicomponent mixtures. The HPTLC-effect-directed analysis (EDA) revealed several bioactive compounds in five botanical extracts, i.e. Salvia officinalis, Thymus vulgaris and Origanum vulgare, all Lamiaceae, and peels of red and green apples (Jonagored and Granny Smith, respectively), both Rosaceae. A tricky case study was designed to show how to deal with potentially coeluting bioactive structural isomers, e.g., ursolic (UA), oleanolic (OA) and betulinic acids (all C30H48O3), which are most difficult to identify and assign. A multipotent bioactive HPTLC zone showed the same hRF value and mass signal in HPTLCHRMS, though containing the coeluting structural isomers UA and OA. After zone isolation from the HPTLC plate, first the 1H NMR spectrum allowed to distinguish distinct allylic H-18 protons, i.e. 2.20 ppm for UA and 2.85 ppm for OA, and at the same time, to quantify the two isomers by using the PUlse Length-based CONcentration methodology (HPTLC//1H qNMR-PULCON). In case of a partial overlap of the diagnostic signal with that of the matrix, results were corroborated with those obtained by using the 1H deconvoluted or 2D 1H-13C Heteronuclear Single Quantum Coherence spectra. The comparison of the quantitative results showed a good correlation (R2 = 0.9718) between the two orthogonal methods HPTLC-Vis and HPTLC//1H qNMR-PULCON. A sufficient zone isolation from the HPTLC plate (mean isolation rate of 82%) for both UA and OA (0.27 - 4.67 mM) was achieved for HPTLC//qNMR, comparing the isolated bioactive compound zone with the respective zone in the botanical extract via HPTLC-Vis densitometry. The HPTLC-EDA-Vis//1H qNMR-PULCON procedure for bioprofiling and quantification/identification/confirmation of bioactive compounds in botanical extracts is considered as straightforward, eco-friendly (only 16 mL solvent required), simple (NMR calibration used over weeks) and reliable new alternative to the status quo of bioactivity-guided fractionation.

3D printing in analytical chemistry: current state and future

The rapid development of additive technologies in recent years is accompanied by their intensive introduction into various fields of science and related technologies, including analytical chemistry. The use of 3D printing in analytical instrumentation, in particular, for making prototypes of new equipment and manufacturing parts having complex internal spatial configuration, has been proved as exceptionally effective. Additional opportunities for the widespread introduction of 3D printing technologies are associated with the development of new optically transparent, current- and thermo-conductive materials, various composite materials with desired properties, as well as possibilities for printing with the simultaneous combination of several materials in one product. This review will focus on the application of 3D printing for production of new advanced analytical devices, such as compact chromatographic columns for high performance liquid chromatography, flow reactors and flow cells for detectors, devices for passive concentration of toxic compounds and various integrated devices that allow significant improvements in chemical analysis. A special attention is paid to the complexity and functionality of 3D-printed devices.