Directly suspended droplet microextraction in a rotating vial

Analytical Methods for the Determination of Quercetin and Quercetin Glycosides in Pharmaceuticals and Biological Samples

Flavonoids are plant-derived compounds that have several health benefits, including antioxidative, anti-inflammatory, anti-mutagenic, and anti-carcinogenic effects. Quercetin is a flavonoid that is widely present in various fruits, vegetables, and drinks. Accurate determination of quercetin in different samples is of great importance for its potential health benefits. This review, is an overview of sample preparation and determination methods for quercetin in diverse matrices. Previous research on sample preparation and determination methods for quercetin are summarized, highlighting the advantages and disadvantages of each method and providing insights into recent developments in quercetin sample treatment. Various analytical techniques are discussed including spectroscopic, chromatographic, electrophoretic, and electrochemical methods for the determination of quercetin and its derivatives in different samples. UV-Vis (Ultraviolet-visible) spectrophotometry is simple and inexpensive but lacks selectivity. Chromatographic techniques (HPLC, GC) offer selectivity and sensitivity, while electrophoretic and electrochemical methods provide high resolution and low detection limits, respectively. The aim of this review is to comprehensively explore the determination methods for quercetin and quercetin glycosides in diverse matrices, with emphasis on pharmaceutical and biological samples. The review also provides a theoretical basis for method development and application for the analysis of quercetin and quercetin glycosides in real samples.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Liquid phase microextraction techniques combined with chromatography analysis: a review

Sample pretreatment is the first and the most important step of an analytical procedure. In routine analysis, liquid–liquid microextraction (LLE) is the most widely used sample pre-treatment technique, whose goal is to isolate the target analytes, provide enrichment, with cleanup to lower the chemical noise, and enhance the signal. The use of extensive volumes of hazardous organic solvents and production of large amounts of waste make LLE procedures unsuitable for modern, highly automated laboratories, expensive, and environmentally unfriendly. In the past two decades, liquid-phase microextraction (LPME) was introduced to overcome these drawbacks. Thanks to the need of only a few microliters of extraction solvent, LPME techniques have been widely adopted by the scientific community. The aim of this review is to report on the state-of-the-art LPME techniques used in gas and liquid chromatography. Attention was paid to the classification of the LPME operating modes, to the historical contextualization of LPME applications, and to the advantages of microextraction in methods respecting the value of green analytical chemistry. Technical aspects such as description of methodology selected in method development for routine use, specific variants of LPME developed for complex matrices, derivatization, and enrichment techniques are also discussed.

Hollow fiber liquid-phase microextraction based on the use of a rotating extraction cell: A green approach for trace determination of rhodamine 6G and methylene blue dyes

In this work, a novel mode of hollow fiber liquid-phase microextraction (HF-LPME) technique namely rotating extraction cell solvent bar microextraction (REC-SBME) was introduced. The proposed method was applied for the preconcentration of methylene blue (MB) and rhodamine 6G (RG) in some real samples, including soft drink, lipstick, environmental water, and wastewater samples. In the extraction setup, two pieces of hollow fibers were fixed on a mechanical support and immersed in a rotating extraction cell containing the sample solution during the extraction process. The rotation of the extraction cell by using an electric motor led to an enhancement in the mass transfer of the dyes from the sample solution into the organic acceptor phase. In the developed procedure, the UV-Vis spectrophotometry and HPLC-UV/Vis were employed as detection methods for the analysis of the acceptor phase and the obtained results were compared. Optimization of the extraction factors affecting the method, including organic solvent type, sample solution pH, extraction time, rotational rate, the volume of sample and acceptor solutions, salt addition, and temperature was performed in order to obtain the best preconcentration factor. Linear dynamic range obtained by HPLC-UV/Vis and spectrophotometry was observed in the ranges of 2.5-1200 ng mL^-1 for RG and 1.6-600 ng mL^-1 for MB with R² more than 0.9971. Also, relative standard deviation (RSD) values (n = 3) less than 3.8% were obtained. The good conformity of the obtained results makes UV-Vis spectrophotometric method an ideal tool for routine analysis of trace dyes in the complex matrices after REC-SBME.

Influence of relevant parameters on the extraction efficiency and the stability of the microdrop in the single drop microextraction

Single drop microextraction technique uses microamounts of organic solvents. Simplicity, low cost, low environmental impact, compatibility with chromatographic systems as well as its applicability to different matrices are main advantages of single drop microextraction. This technique has become frequently used for the extraction of a broad scope of compounds for numerous analytical applications. This review provides an overview of the existing single drop microextraction modes of realisation and the main scope is devoted to the optimization of parameters influencing the efficiency. The state of the art is discussed on the basis of examples selected from representative application areas. Extraction parameters for toxic organic compounds extraction and microdrop stability were evaluated.

Low-cost and convenient ballpoint tip-protected liquid-phase microextraction for sensitive analysis of organic molecules in water samples

Simplification and miniaturization in analytical procedures are highly preferred by analysts and other researchers. In this study, a low-cost, convenient and efficient liquid-phase microextraction method, termed ballpoint tip-protected liquid-phase microextraction (BT-LPME), was established. The bullet-shaped BT possessed a hollow cavity of several microliters for solvent storage and an opening tail for solute extraction. Magnetic field-induced BT spinning significantly accelerated the extraction process. By virtue of the adhesion between a stainless steel sheath and an organic solvent, along with cave protection, finely stable storage of extractant was achieved even under high spinning speeds (>1000 rpm). The BT-LPME performance was evaluated by extracting five polycyclic aromatic hydrocarbons (PAHs) from aqueous solution, followed by gas chromatography-mass spectrometry (GCMS) analysis. Compared to static single drop microextraction (SDME), the BT-LPME method provided higher enrichments (128-173-fold) for the five PAHs. Good linearities (from 0.01∼0.05 μg L^-1 to 50 μg L^-1) with a regression coefficient (r²) ≥0.9993, as well as low limits of detection (LODs, 0.002-0.011 μg L^-1) and limits of quantification (LOQs, 0.007-0.023 μg L^-1), were obtained. Relative recoveries varied from 92.3% to 103.4% at three spiked levels of 0.1, 1 and 10 μg L^-1. The BT-LPME technique was also successfully applied to the enrichment of other organic compounds, such as organophosphorus compounds, organochlorines and triazines.

Determination of aroma components in Chinese southwest tobacco by directly suspended droplet microextraction combined with GC-MS

In this paper, a simple and efficient approach, directly suspended droplet microextraction (DSDME), has been applied to extract aroma components in Chinese southwest tobacco prior to analysis by gas chromatography-mass spectrometry (GC-MS). The extraction parameters such as organic solvent type, extraction time, temperature, stirring speed and volume were systemically optimized. A single drop of cyclohexane was placed on the top of the aqueous sample which was used as solvent. Under the optimal conditions of DSDME, 62 aroma components of tobacco were analyzed and identified by GC-MS. The approach was used to determine some important aromas in tobacco with the relative recoveries ranged from 75.92 to 102.88%, relative standard deviations in the range of 3.40-7.14% (n = 5) and the limits of detection of 0.0002-0.002 μg/mL. Moreover, the DSDME was applied to identify the aromatic components in Chinese southwest tobacco in this research for the first time and the results suggested that the method can be used as rapid determination of the tobacco. This method can enhance the extracting rate of tobacco aromatic components and meet the need of qualitative analysis of large amount samples.

An overview of liquid phase microextraction approaches combined with UV-Vis spectrophotometry

Ultraviolet and visible spectrophotometer has become a popular analytical instrument in the modern day laboratories. However, the low concentrations of many analytes in samples make it difficult to directly measure them by UV-Vis spectrophotometry. This overview focuses on the combinations of microvolume UV-Vis spectrophotometry with miniaturized approaches to sample preparation, namely, single drop microextraction (SDME), dispersive liquid-liquid microextraction (DLLME), cold induced aggregation microextraction (CIAME), in situ solvent formation microextraction (ISSFME), ultrasound assisted emulsification microextraction (USAEME), solidified floating organic drop microextraction (SFODME), and hollow fiber based liquid phase microextraction (HF-LPME) to improve both the selectivity and sensitivity. Integration of these techniques provides unique advantages which include availability, simplicity of operation, low cost, speed, precision and accuracy; hence making them a powerful tool in chemical analysis.