Solvent Front Position Extraction with Semi-Automatic Device as a Powerful Sample Preparation Procedure Prior to Quantitative Instrumental Analysis

Sample preparation for planar chromatography

High-performance thin-layer chromatography has favorable properties for high-throughput separations with a high matrix tolerance. Sample preparation, however, is sometimes required to control specific matrix interferences and to enhance the detectability of target compounds. Trends in contemporary applications have shifted from absorbance and fluorescence detection to methods employing bioassays and mass spectrometry. Traditional methods (shake-flask, heat at reflux, Soxhlet, and hydrodistillation) are being challenged by automated instrumental approaches (ultrasound-assisted and microwave-assisted solvent extraction, pressurized liquid extraction, and supercritical fluid extraction) and the quick, easy cheap, efficient, rugged, and safe extraction method for faster and streamlined sample processing. Liquid-liquid extraction remains the most widely used approach for sample clean-up with increasing competition from solid-phase extraction. On-layer sample, clean-up by planar solid-phase extraction is increasingly used for complex samples and in combination with heart-cut multimodal systems. The automated spray-on sample applicator, the elution head interface, biological detection of target and non-target compounds, and straightforward mass spectrometric detection are highlighted as the main factors directing current interest toward faster and simpler sample workflows, analysis of more complex samples, and the determination of minor contaminants requiring high concentration factors.

A Review on Pretreatment and Analysis Methods of Polyether Antibiotics in Complex Samples

Polyether antibiotics (PAs) are the anti-coccidiosis drugs used for treating and preventing coccidiosis. Studies show the residues of these antibiotics in food cause adversities and threaten human health. PAs thus need robust, rugged, and accurate methods for their analysis. This review encompasses pretreatment and detection methods of PAs in diverse matrices since 2010. Both conventional and developed methods are part of the pretreatments, such as dispersive liquid-liquid microextraction, solid-phase extraction, solid-phase microextraction, solvent front position extraction, QuEChERS (Quick Easy Cheap Effective Rugged and Safe), supercritical fluid extraction, and others. The analysis methods involve liquid chromatography coupled with detectors, sensors, etc. The pros and cons of various techniques for PAs have been discussed and future tendencies are proposed.

Planar chromatography - Current practice and future prospects

Planar chromatography, in the form of thin-layer or high-performance thin-layer chromatography (TLC, HPTLC), continues to provide a robust and widely used separation technique. It is unrivaled as a simple and rapid qualitative method for mixture analysis, or for finding bioactive components in mixtures. The format of TLC/HPTLC also provides a unique method for preserving the separation, enabling further investigation of components of interest (including quantification/structure determination) separated in both time and space from the original analysis. The current practice of planar chromatography and areas of development of the technology are reviewed and promising future directions in the use of TLC/HPTLC are outlined.

Solvent Front Position Extraction and some conventional sample preparation techniques for the determination of coccidiostats in poultry feed by LC-MS/MS

Solvent Front Position Extraction is a novel technique developed for effective sample preparation of biological samples containing coccidiostats prior to LC–MS/MS. In this study the technique was used for isolation and determination of seven coccidiostats, from both main groups being: ionophores and chemical coccidiostats. Its effectiveness was evaluated by comparing with other sample preparation procedures, used in European routine laboratories. Results obtained by Solvent Front Position Extraction were very satisfactory (linearity R² ≥ 0.971, recovery 90.1–111.1%, RSDr: 8.7–16.6%, RSD_R: 9.0–17.7%) and fulfilled requirements described in Commission Regulation (EU) 2021/808 of 22 March 2021, which showed great potential of the technique in sample preparation of coccidiostats in poultry feed.

Advanced Solid-Phase Microextraction Techniques and Related Automation: A Review of Commercially Available Technologies

The solid-phase microextraction (SPME), invented by Pawliszyn in 1989, today has a renewed and growing use and interest in the scientific community with fourteen techniques currently available on the market. The miniaturization of traditional sample preparation devices fulfills the new request of an environmental friendly analytical chemistry. The recent upswing of these solid-phase microextraction technologies has brought new availability and range of robotic automation. The microextraction solutions propose today on the market can cover a wide variety of analytical fields and applications. This review reports on the state-of-the-art innovative solid-phase microextraction techniques, especially those used for chromatographic separation and mass-spectrometric detection, given the recent improvements in availability and range of automation techniques. The progressively implemented solid-phase microextraction techniques and related automated commercially available devices are classified and described to offer a valuable tool to summarize their potential combinations to face all the laboratories requirements in terms of analytical applications, robustness, sensitivity, and throughput.

Preparation of Antihypertensive Drugs in Biological Matrix with Solvent Front Position Extraction for LC–MS/MS Analysis

Solvent front position extraction procedure was used to prepare biological samples containing selected antihypertensive drugs (ramipril, lercanidipine, indapamide, valsartan, hydrochlorothiazide, perindopril, and nebivolol). Substances separated from the biological matrix components (bovine serum albumin) were quantified by means of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Sample preparation process was performed with the use of a prototype horizontal chamber with a moving pipette driven by a 3D printer mechanism enabling a controlled eluent flow velocity. Application of this device was advantageous for simultaneous preparation of several samples for further quantitative analysis, with a synchronized reduction of manual operations and solvent consumption. Quantitative results obtained for the majority of the investigated antihypertensive drugs in a complex biological matrix were satisfactory. The values of the %RSD were around 5% for six of the seven substances (with the exception of indapamide). The method exhibits a suitable accuracy (the relative error percentage was below 10% for most drugs). The values of LOD and LOQ were in the range of 1.19 µg/L–8.53 µg/L and 3.61 µg/L–25.8 µg/L, respectively.

Reversed-phase pH gradient thin-layer chromatography of biologically active substances with controlled developing solvent velocity

For the first time, stepwise pH gradient thin-layer chromatograms of biologically active substances with controlled developing solvent velocity are presented and described in the paper. Change in buffer pH of the mobile phase solution influences retardation, selectivity, and shape of the separated substances' spots. The conducted research has confirmed that the mobile phase's pH gradient could be an essential factor to optimize the conditions of the separation of substances in reversed-phase high-performance thin-layer chromatography. The reproducibility of the gradient retardation factor values of separated substance zones is satisfactory.

Optimization of Adsorbent Layer Type and Developing Solvent in Coccidiostats Sample Preparation with Procedure of Solvent Front Position Extraction

Coccidiostats are drugs used against coccidiosis, a common disease among breeding animals. Their widespread application leads to the appearance of their residues in food, which is potentially harmful for human health and life. The European Union has established limits of concentrations of these drugs in premixtures and food. Nowadays, there are many methods for monitoring coccidiostats’ presence in market products, but their frequent weakness is sample preparation. Solvent Front Position Extraction is a planar chromatography-based sample preparation method that allows for effective assay of samples with coccidiostats when coupled with LC-MS/MS. The purpose of this research was to find common conditions for the effective isolation of eight coccidiostats from biological sample components with both lower and higher retention than the substances of interest. The acquired results were used for effective isolation of monensin and salinomycin from the premixture samples and allowed for their quantitative determination. The application of a semi-automatic device for the development of chromatograms positively impacted the results, confirming the effectiveness of the method for determining coccidiostats in biological samples.

Comparison of the Retention and Separation Selectivity of Aromatic Hydrocarbons with Polar Groups in RP-HPLC Systems with Different Stationary Phases and Eluents

In this manuscript, the retention of aromatic hydrocarbons with polar groups has been compared for systems with various nonpolar columns of the types from C3 to C18 and different mobile phases composed of methanol, acetonitrile, or tetrahydrofuran as modifiers. The selectivity separation of the solutes in systems with different adsorbents, when one eluent modifier is swapped by another, has been explained, taking into account molecular interactions of the solutes with components of the stationary phase region (i.e., extracted modifier depending on the chain length of the stationary phase).

Solvent front position extraction with semi-automatic device as a powerful sample preparation procedure to quantitatitation of tryptophan in human plasma

In the paper the results of the tryptophan determination in human plasma samples prepared with the novel Solvent Front Position Extraction (SFPE) technique are presented. The SFPE procedure is used for preparation of real biological sample for the first time. The results obtained using SFPE are compared with those using the classical sample preparation procedure. Under the optimal conditions, tryptophan and its internal standard were separated from other plasma compounds (matrix) as a small common zone/spot on a chromatographic plate using semiautomatic device equipped with moving pipet, which distributed developing solvent on the adsorbent layer. Tryptophan and the internal standard were evenly distributed within the small common zone from that the both substances were extracted and the solution obtained was transferred to quantitation with LC–MS and MS techniques. The determination results are satisfactory, the percentage values of relative error and RSD relative standard deviation do not exceed 5%. The procedure is characterized by simplicity, high analysis throughput, very good sample purification and seems to be easy applicable to other biological samples with these advantages mentioned.

Retardation of some drugs in thin-layer chromatographic systems with impregnated silica gel plates with hen's egg white and bovine serum albumin

The influence of impregnation the chromatographic plate adsorbent layer, silica, with hen's egg white albumin (OVA) or bovine serum albumin (BSA) on the retention of some popular medicines (paracetamol, aminophenazone, theophylline, caffeine, acetanilide, ciprofloxacin, tramadol, acetylsalicylic acid, acebutolol) is investigated. The effect of composition and buffer pH of the mobile phase on solute separation selectivity is also studied. The chromatographic systems with and without above mentioned albumins and their influence on investigated drug retention are compared. In general, it has been turned out that retention of tested medicines in systems with the sorbent impregnated with albumin significantly increase relative to those with non-impregnated.

Optimization of the procedure of solvent front position extraction for preparation of multi-component sample for instrumental analysis

Solvent Front Position Extraction (SFPE) procedure has been recently introduced as a novel concept for multi-component sample preparation. According to the procedure, thin-layer chromatography (TLC) is used to separate the compounds of interest from matrix components, and to focus them into a common zone from which the compounds are extracted and transferred to apparatus for instrumental analysis. In the paper, we investigate different adsorbent types of the chromatographic plates and various mobile phases, including pH of their buffers, in respect of optimization conditions of the SFPE procedure. The research was carried out using a test sample containing 9 compounds characterised by different chemical properties, hence the conclusions from the obtained results can be applied to other multi-component samples. Under the optimal conditions, all target compounds are separated from other compounds (matrix), and evenly distributed along a narrow strip, which is advantageous for their quantitation. The determination results are good, the percentage values of relative error and relative standard deviation do not exceed 6%.