Fast assay of angiotensin 1 from whole blood by cation-exchange restricted-access solid-phase microextraction

Development of a thin-film solid-phase microextraction (TF-SPME) method coupled to liquid chromatography and tandem mass spectrometry for high-throughput determination of steroid hormones in white sucker fish plasma

Steroid hormones (SH) play a number of important physiological roles in vertebrates including fish. Changes in SH concentration significantly affect reproduction, differentiation, development, or metabolism. The objective of this study was to develop an in vitro high-throughput thin-film solid-phase microextraction (TF-SPME)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for targeted analysis of endogenous SH (cortisol, testosterone, progesterone, estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2)) in wild white sucker fish plasma where the concentrations of the analytes are substantially low. A simple TF-SPME method enabled the simultaneous determination of free and total SH concentrations. The use of biocompatible coating allowed direct extraction of these hormones from complex biological samples without prior preparation. The carryover was less than 3%, thereby ensuring reusability of the devices and reproducibility. The results showed that TF-SPME was suitable for the analysis of compounds in the polarity range between 1.28 and 4.31 such as SH at different physicochemical properties. The proposed method was validated according to bioanalytical method validation guidelines. The limit of detection (LOD) and limit of quantification(LOQ) for cortisol, testosterone, progesterone, E1, E2, and EE2 were from 0.006 to 0.150 ng/mL and from 0.020 to 0.500 ng/mL, respectively. The recovery for the method was about 85%, and the accuracy and precision of the method for cortisol, testosterone, and progesterone were ≤ 6.0% and ≤ 11.2%, respectively, whereas those for E1, E2, and EE2 were ≤ 15.0% and ≤ 10.2%, respectively. On the basis of this study, TF-SPME demonstrated several important advantages such as simplicity, sensitivity, and robustness under laboratory conditions. Graphical abstract.

Fabric Phase Sorptive Extraction Explained

The theory and working principle of fabric phase sorptive extraction (FPSE) is presented. FPSE innovatively integrates the benefits of sol–gel coating technology and the rich surface chemistry of cellulose/polyester/fiberglass fabrics, resulting in a microextraction device with very high sorbent loading in the form of an ultra-thin coating. This porous sorbent coating and the permeable substrate synergistically facilitate fast extraction equilibrium. The flexibility of the FPSE device allows its direct insertion into original, unmodified samples of different origin. Strong chemical bonding between the sol–gel sorbent and the fabric substrate permits the exposure of FPSE devices to any organic solvent for analyte back-extraction/elution. As a representative sorbent, sol–gel poly(ethylene glycol) coating was generated on cellulose substrates. Five (cm2) segments of these coated fabrics were used as the FPSE devices for sample preparation using direct immersion mode. An important class of environmental pollutants—substituted phenols—was used as model compounds to evaluate the extraction performance of FPSE. The high primary contact surface area (PCSA) of the FPSE device and porous structure of the sol–gel coatings resulted in very high sample capacities and incredible extraction sensitivities in a relatively short period of time. Different extraction parameters were evaluated and optimized. The new extraction devices demonstrated part per trillion level detection limits for substitute phenols, a wide range of detection linearity, and good performance reproducibility.

In vivo and ex vivo SPME: a low invasive sampling and sample preparation tool in clinical bioanalysis

Solid phase microextraction (SPME) is well-established technology in bioanalysis. Current review discusses the features of SPME, which determine the non- or low-invasiveness of the method in biomedical analysis. In the first section we analyze the factors, which have significant influence on the SPME sampling device performance in the view of sampling safety and efficiency. In the later sections applicability of various SPME approaches for analysis of easily accessible samples routinely used for analysis (e.g., urine, blood) as well as limited availability samples (tissues) is discussed. Moreover, the examples of sampling alternative matrices such as hair, saliva, sweat or breath are presented. The advantages and limitation of the technology in the view of future development of SPME are also reviewed.

Biocompatible Solid-Phase Microextraction Coatings Based on Polyacrylonitrile and Solid-Phase Extraction Phases

The applications of solid-phase microextraction (SPME) are continuously expanding, and one of the most interesting current aspects consists of applying SPME for fast analysis of biological fluids. The goal of this study is to develop biocompatible SPME coatings that can be utilized for in vivo and in vitro extractions, in direct contact with a biological matrix such as blood or tissue. The biocompatibility of the proposed new coatings is confirmed by X-ray photoelectron spectroscopy, and their performance is tested by developing an SPME/HPLC method for analysis of verapamil, loperamide, diazepam, nordiazepam, and warfarin in buffer solutions and in human plasma. The coatings prove to be biocompatible by not adsorbing proteins and are successfully applied for fast drug analysis and assay of drug plasma protein binding.

In vivo sampling with solid phase microextraction

This review discusses the most recent developments and future challenges in the application of solid phase microextraction (SPME) for sampling of live biological samples. The emphasis is placed on applications of fiber SPME for analysis of volatile emissions and drugs in biological fluids. The method development section highlights the main parameters that need to be considered in the case of in vivo experiments: extraction techniques, selection of extraction phases, calibration procedures, determination of free concentrations, and automation.

Determination of drug plasma protein binding by solid phase microextraction

The plasma protein binding of drugs has been shown to have significant effects on the quantitative relationship between clinical pharmacokinetics and pharmacodynamics. In many clinical situations, measurement of the total drug concentration does not provide the needed information concerning the unbound fraction of drug in plasma, which is available for pharmacodynamic action. Therefore, the accurate determination of unbound plasma drug concentrations is important in understanding drug action. Many methodologies exist for determining the extent of plasma protein binding, but different methods produce a rather wide range of results for the same compound at the same concentration level. The solid phase microextraction (SPME) method reported in the present study attempts to eliminate many experimental variables that could lead to the lack of reproducibility, such as the variable content of organic solvent or ionic strength in plasma, pH shifts, and volume shifts. Five well-known drugs were chosen to study plasma protein binding: ibuprofen, warfarin, verapamil, propranolol, and caffeine, with high, intermediate and low binding properties. Dilution of plasma with isotonic PBS or incubation with 10% CO(2) in the atmosphere was found to compensate for changes in pH during incubation. The data obtained using these pH-controlled methods correlate well with the average values of plasma protein binding found in the literature. SPME, which uses an extraction phase that dissolves or adsorbs the drug of interest and rejects proteins, overcomes several limitations of currently available techniques and is a thermodynamically sound method, since the measurements are always performed at equilibrium. Compared to other methods, SPME offers several advantages: small sample size, short analysis time, possibility to automate, and ability to directly study complex samples.

Silicone glue coated stainless steel wire for solid phase microextraction

A new solid phase microextraction (SPME) fiber based on high-temperature silicone glue coated on a stainless steel wire is presented. The fiber coating can be prepared easily in a few minutes, it is mechanically stable and exhibits relatively high thermal stability (up to 260 degrees C). The extraction properties of the fiber to benzene, toluene, ethylbenzene, and xylenes (BTEX) were examined using both direct and headspace SPME modes coupled to gas chromatography-flame ionization detection. The effects of the extraction and desorption parameters including extraction and desorption time, sampling and desorption temperature, and ionic strength on the extraction/desorption efficiency have been studied. For both headspace and direct SPME the calibration graphs were linear in the concentration range from 0.5 microg L(-1) to 10 mg L(-1) (R2>0.996) and detection limits ranged from 0.07 to 0.24 microg L(-1). Single fiber repeatability and fiber-to-fiber reproducibility were less than 6.8 and 21.5%, respectively. Finally, headspace SPME was applied to determine BTEX in petrol station waste waters with spiked recoveries in the range of 89.7-105.2%.

Recent developments in solid-phase microextraction coatings and related techniques

During the last decade, solid-phase microextraction (SPME) has gained widespread acceptance for analyte matrix separation and preconcentration. Relatively few data are currently available dealing with in-house production of fibres with tailor-made properties to be used for SPME, though recently the number of publications evaluating new coatings has been considerably growing. This review, centred on publications that appeared during the last five years, is resuming different approaches which can be used for fibre production and further summarises alternative techniques closely related to SPME, such as in-tube extraction or single-drop microextraction (SDME). The aim is to give the reader a concise overview of recent developments in new coating procedures and materials, including the respective applications.