Comparison of the Partition Efficiencies of Multiple Phenolic Compounds Contained in Propolis in Different Modes of Acetonitrile–Water-Based Homogenous Liquid–Liquid Extraction

Abstract

Homogeneous liquid–liquid extraction (HLLE) has attracted considerable interest in the sample preparation of multi-analyte analysis. In this study, HLLEs of multiple phenolic compounds in propolis, a polyphenol-enriched resinous substance collected by honeybees, were performed for improving the understanding of the differences in partition efficiencies in four acetonitrile–water-based HLLE methods, including salting-out assisted liquid–liquid extraction (SALLE), sugaring-out assisted liquid–liquid extraction (SULLE), hydrophobic-solvent assisted liquid–liquid extraction (HSLLE), and subzero-temperature assisted liquid–liquid extraction (STLLE). Phenolic compounds were separated in reversed-phase HPLC, and the partition efficiencies in different experimental conditions were evaluated. Results showed that less-polar phenolic compounds (kaempferol and caffeic acid phenethyl ester) were highly efficiently partitioned into the upper acetonitrile (ACN) phase in all four HLLE methods. For more-polar phenolic compounds (caffeic acid, p-coumaric acid, isoferulic acid, dimethoxycinnamic acid, and cinnamic acid), increasing the concentration of ACN in the ACN–H2O mixture could dramatically improve the partition efficiency. Moreover, results indicated that NaCl-based SALLE, HSLLE, and STLLE with ACN concentrations of 50:50 (ACN:H2O, v/v) could be used for the selective extraction of low-polarity phenolic compounds. MgSO4-based SALLE in the 50:50 ACN–H2O mixture (ACN:H2O, v/v) and the NaCl-based SALLE, SULLE, and STLLE with ACN concentrations of 70:30 (ACN:H2O, v/v) could be used as general extraction methods for multiple phenolic compounds.

Matrix-Induced Sugaring-Out: A Simple and Rapid Sample Preparation Method for the Determination of Neonicotinoid Pesticides in Honey

“…Additionally, at the concentration of 70:30 ( v / v , ACN:H 2 O), recoveries were varied slightly when the sample amount of honey increased from 0.3 g to 2 g. These results suggested that extraction yields were increased as the sample amount of honey increased, then reached a plateau when the concentration of honey was above the critical concentration. The high recovery values under the high concentration of sugars were also observed in sugaring-out extraction of protein and organic compounds by glucose [22,24,26,27]. This indicates that we can use a larger amount of honey sample under the high concentration of ACN to improve the sensitivity of the proposed matrix-induced sugaring-out procedure.…”

“…In the honey matrix, ethanol was found to be hardly separated from the ethanol-water mixture. ACN was the most used extraction solvent in sugaring-out studies, which has advantages of rapid phase separation, excellent compatibility with liquid chromatography, and high recovery for polar compounds [26]. Thus, ACN was used in the present study.…”

“…We aim to demonstrate that this matrix-induced phase separation phenomenon can be applied for the pretreatment of the honey sample for the determination of three typical neonicotinoid residues (imidacloprid, acetamiprid, and thiacloprid). Our previous result on the partition of multiple phenolic compounds in ACN-water-based SULLE by glucose has demonstrated that the volume of the separated ACN phase was dependent on the concentration of sugar and the initial content of ACN in the ACN-water mixture [26]. Specifically, increasing the concentration of sugar and the initial content of ACN would both dramatically increase the volume of the upper ACN phase.…”

“…This novel two-phase system shows the advantages of fast phase separation and is environmentally friendly and has found applications in protein purification [22], natural products extraction [23,24], and bioanalysis [25]. Recently, we reported a sugaring-out assisted liquid-liquid extraction (SULLE) method for the partition of 10-hydroxy-2-decenoic acid (10-HDA) in royal jelly [24] and multiple phenolic compounds in propolis [26] and a SULLE-based sample preparation method for the determination of bisphenol residues in royal jelly [27]. Honey is a natural sweetener composed of ca.…”

Salting‐out assisted liquid–liquid extraction with dansyl chloride for the determination of biogenic amines in food

“…Salting-out assisted liquid-liquid extraction presents advantages in comparison with other extraction techniques, since it is faster and uses lower volume of organic solvent than liquid-liquid extraction (LLE), and it is more cost-efficient than solid-phase extraction (SPE) and other sample preparation techniques (Ramos et al, 2014;Mohammed et al, 2016). The salting-out has been largely applied in sample preparation processes (Chen et al, 2019), and one of its variations is SALLE (Matkovich & Christian, 1973;Valente et al, 2013), also commonly termed as 'saltinduced phase separation' (Kole et al, 2011). Although it is not a novel concept, it has gained momentum in the last decade (Kole et al, 2011;Valente et al, 2017;Tighrine et al, 2019).…”