Determination of Five Anthraquinone Derivatives in Sticky Traditional Chinese Patent Medicines by Subzero-Temperature Liquid–Liquid Extraction Combined with High-Performance Liquid Chromatography

Subzero-temperature homogeneous liquid-liquid extraction for the stereoselective determination of chiral triadimefon and its metabolite in water, fruit juice, vinegar, and fermented liquor by HPLC

A novel method based on homogeneous liquid-liquid extraction with deep eutectic solvents (DES) under subzero-temperature conditions in combination with high performance liquid chromatography (HPLC) for the determination of chiral fungicide triadimefon (TF) and its metabolite triadimenol (TN) in water, fruit juice, vinegar, and fermented liquor was developed in this study. The method involved using deep eutectic solvents (DES) under subzero-temperature conditions in combination with high performance liquid chromatography (HPLC). This novel technique, known as subzero-temperature homogeneous liquid-liquid extraction (STHLLE), offers several advantages, including high efficiency, time-saving, low-cost, and eco-friendliness. The enantiomers of chiral TF and TN were simultaneously separated and quantified using HPLC coupled with a Daicel Chiralpak OD-RH column. Various experimental parameters such as DES composition and volume, freezing condition, salt concentration, and pH were optimized to enhance the recoveries of the target analytes. Under the optimized conditions, spiked recoveries of six enantiomers (i.e., S-TF, R-TF, SR-TN, RS-TN, SS-TN, and RR-TN) in the water, fruit juice, vinegar, and fermented liquor samples were 82.2-100.1% with relative standard deviations of 0.4-10.1%. The current method demonstrated a detection range of 0.03-0.06 mg L-1 in the target analytes. This established technique exhibits potential for efficient and precise extraction and quantification of the enantiomers of TF and TN in water phase samples.

Cold-induced phase separation for the simple and reliable extraction of sex hormones for subsequent LC-MS/MS analysis

Sex hormones, including androgens, estrogens, and progestogens, are important biomarkers for various diseases. Quantification of sex hormones is typically conducted by LC-MS/MS. At present, most methods require liquid-liquid extraction or solid phase extraction for sample preparation. However, these pretreatments are prone to compromise LC-MS/MS throughput. To improve on the current standard practices, we investigated cold-induced phase separation for sex hormone extraction. After protein precipitation with acetonitrile and adjusting the solution constitution with water, samples were stored at -30°C for 10 min to generate two distinct phases: an acetonitrile-rich layer on top of a water-rich layer. During this process, the hydrophobic sex hormones spontaneously separate into the upper layer. This simple and reliable cold-induced phase separation-based LC-MS/MS methodology was used here to simultaneously detect estrone, estradiol, estriol, testosterone, androstenedione, dehydroepiandrosterone, progesterone, and 17-hydroxyprogesterone in serum. Validation of this method indicated satisfactory performance, including acceptable linearity, accuracy, precision, and tractability. Compared with the mainstream liquid-liquid extraction-based method, this new method exhibits significant progress in throughput, which shortens the time cost of sample preparation from 90 to 40 min. We propose that this method can be an excellent alternative for sex hormone analysis in routine clinical laboratories.

Hydrophobicity-switchable deep eutectic solvent-based effervescence-assisted dispersive liquid-liquid microextraction with solidification of floating droplets for HPLC determination of anthraquinones in fried Cassiae semen tea infusions

In this paper, a hydrophobicity-switchable deep eutectic solvent was evaluated for the first time as an efficient extractant in the effervescence-assisted dispersive liquid-liquid microextraction method combined with the solidification of floating droplets for HPLC determination of anthraquinones in fried Cassiae semen tea infusions. Prepared from choline chloride and octanoic acid, the deep eutectic solvent could be switched between hydrophobic and hydrophilic forms by pH adjustment. The dispersion of the extractant was assisted by in situ CO₂ produced from the effervescence reaction between H₂SO₄ and Na₂CO₃ without using any organic solvent or auxiliary equipment. Owing to the low melting/freezing point and low density compared with water, the extractant was solidified in an ice bath for the convenience of complete separation with the sample matrix. Some important parameters, such as species, molar ratio and volume of deep eutectic solvent, species and volume of effervescent agents were optimized to achieve the best extraction efficiency. Under the optimal conditions, extraction recoveries were obtained for four anthraquinones in the range of 91.1% to 111.9%. Relative standard deviations for intraday and interday precision were less than 3.3% and 4.0%, respectively. Greenness assessment demonstrated that the proposed method was greener than other reported methods for the determination of anthraquinones.

Homogeneous liquid–liquid microextraction based on liquid nitrogen-induced phase separation followed by GFAAS for sensitive extraction and determination of lead in lead-adulterated opium and refined opium

Herein, we developed a novel homogeneous liquid–liquid microextraction based on liquid nitrogen-induced phase separation (HLLME-LNPS) for the extraction and determination of lead (Pb) in Pb-adulterated opium and refined opium by GFAAS analysis. In this procedure, first, 400 μl of acetonitrile (extractant) containing 7.0 μl of diethyl dithiophosphoric acid (DDTP) is injected into a sample solution and a homogeneous solution is formed. Subsequently, the homogeneous mixture is cooled using liquid nitrogen for 16 seconds. By this process, due to the difference in the freezing points of the organic and aqueous phases, the homogeneous state is broken and the Pb-DDTP species are extracted into the liquid organic phase collected on top of the frozen aqueous phase. The introduced method exhibited a good linearity with a coefficient of determination (r²) of 0.9988 and an acceptable linear range of 0.6–100 μg l⁻¹. Accordingly, the detection limit was 0.2 μg l⁻¹ (S/N = 3) for Pb ions, and a high enrichment factor was obtained. The proposed method was successfully utilized to determine trace levels of Pb in opium samples. The results of the sample analysis showed that 65% of the opium samples and 85% of the refined opium samples had much higher than expected levels of contaminating Pb, and this contamination poses a serious threat to drug users.

Herein, we developed a novel homogeneous liquid–liquid microextraction based on liquid nitrogen-induced phase separation (HLLME-LNPS) for the extraction and determination of lead (Pb) in Pb-adulterated opium and refined opium by GFAAS analysis.

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

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.

Solubility and solution thermodynamics of rhein in eight pure solvents from (288.15 to 313.15) K

Solubility of rhein in water, dichloroethane, glycol, ethanol, methanol, ethyl acetate, propanol, and butanol was measured. Two equations including the modified Apelblat equation, and λh equation can correlate the solubilities of rhein.