Ultrasonic-Assisted Aqueous Two-Phase Extraction Combined with Macroporous Resin Enrichment of Lignans from Flaxseed Meal and Their Antioxidant Activities

Background Secoisolariciresinol di glucoside (SDG) is a natural antioxidant generally extracted from flaxseed, which is one of the most important oil crops in China, the by-product of the flaxseed oil, i.e., flaxseed meal, still contains a lot of lignans. However, flaxseed meal is generally treated as waste, resulting in a huge waste of resources. Objective To establish an efficient and convenient method for extraction and purification of lignans from flaxseed meal. Methods First, we used response surface methodology (RSM) to optimize the extraction conditions of the ultrasonic-assisted aqueous two-phase system (UAATPS), and we obtained the purified extracts by macroporous resin purification (MRP). Second, the antioxidant ability of the extracts was studied in vitro. Results The best extraction conditions obtained were as follows: 9.0 wt% sodium hydroxide, 30.0 wt% isopropanol, extraction time 39 min, liquid-to-solid ratio of 52.0 mL/g, ultrasonic wave 560 W, and extraction temperature 40 °C. Under the optimal conditions, the purity of crude extracts (SDG-APTS-C) reached 21.5%. The desorption conditions of MRP were as follows: eluting 3 BV with ultrapure water, and then eluting with 25% ethanol at 2 BV/h to collect eluents. The purified extracts (SDG-ATPS-P) had a purity quotient of 73.9%, 52.4% higher than that of SDG-ATPS-C. Additionally, experiments conducted in this paper revealed that SDG-ATPS-C and SDG-ATPS-P could effectively remove DPPH, ABTS, and hydroxyl free radicals in vitro. Conclusions The method was validated for extracting SDG from flaxseed meal, thus achieving the reuse of flaxseed meal. Highlights This research provides some references for the application of UAATPS combined with MRP in natural products.

A Complementary, Quantitative and Confirmatory Method to UHPLC/ESI Q-Orbitrap Screening based on UPHLC/ESI-MS/MS for Analysis of 416 Pesticides in Fruits and Vegetables

Background Triple quadrupole (MS/MS) and high-resolution mass spectrometer (HRMS), coupled with ultra-high performance liquid chromatography (UHPLC) or gas chromatography (GC), are technologies used to analyse pesticide residues in fruits and vegetables. LC-MS/MS has been the gold standard for analysis of pesticides, offering reliable performance and sensitivity, while LC-HRMS is expanding in applications to serve as another benchmark. Method development and testing scope expansion are constantly required with new generation mass spectrometers. Objective This paper discusses the development and validation of a quantitative and confirmatory method that can analyse over 400 pesticide residues using state-of-the-art UHPLC/ESI-MS/MS system. Method Homogenized fruit and vegetable samples were fortified with pesticides and were extracted using a modified QuEChERS method. Samples were injected onto a UHPLC/ESI-MS/MS system, and data were acquired in multiple reaction monitoring mode. The method was validated using a nested experimental design, and was able to quantify and confirm 416 pesticide in fruits and vegetables. It was also complimentary to the UHPLC/ESI Q-Orbitrap quantitative and screening methods previously developed in the authors’ laboratory. Results The method demonstrated good performance. In all matrices, 92% of pesticides yielded recoveries between 81–110%, more than 95% of pesticides yielded intermediate precision ≤ 20%, and about 65% of pesticides yielded measurement uncertainties ≤ 20%, and 96% of pesticides yielded measurement uncertainties ≤ 50%. Highlights This method was developed using the same mobile phases, analytical columns, and extraction procedure, as UHPLC/ESI Q-Orbitrap methods. Extracts can be run on either system, streamlining monitoring programs and offering high sample throughput.

Quantifying ethanol in ethanol-based hand sanitizers by headspace gas chromatography with flame ionization detector (HS-GC/FID)

Background The COVID-19 pandemic sharply increased the demand for ethanol-based gel hand sanitizers, leading to a shortage of these products. Consequently, regulatory health agencies worldwide have altered their regulatory guidelines, on ethanol quality, to meet this high demand, raising concern about the products quality. Objective The aim of this study was to quantify ethanol content and to qualitatively assess common impurities in ethanol-based gel hand sanitizers by headspace gas chromatography with flame ionization detector (HS-GC/FID). Methods To quantify the ethanol content, 0.10 g of the sample was weighed in a 20 mL headspace vial and 5 mL of deionized water was added. Regarding the qualitative approach, 0.25 g of the sample was weighed and 4 mL of deionized water and was added. The samples were incubated, and then 400 µL of the headspace was injected into the GC/FID. Forty-eight products purchased in Brazil were analyzed. Results Thirteen products presented at least one nonconformity regarding the ethanol quantity. Two samples presented an average ethanol concentration below the lower limit considered effective. Twelve samples presented acetaldehyde or ethyl acetate. Conclusion The huge demand for ethanol-based gel hand sanitizers may have impacted their quality. Because concern with proper hand hygiene tends to remain an issue for a long period, more studies about quality control of hand sanitizers will be needed. Highlights A simple and fast HS-GC/FID method to quantify ethanol in ethanol-based gel hand sanitizers was developed, validated and applied to commercial samples in Brazil. The regulatory authorities must be more vigilant to ensure that the commercially available products meet the recommended specifications.

Mercury Determination in Certifiable Color Additives Using Thermal Decomposition Amalgamation and Atomic Absorption Spectrometric Analysis

Background Color additives requiring batch certification by the U.S. Food and Drug Administration (FDA) have Code of Federal Regulations (CFR) specification limits for certain elements and are usually analyzed by x-ray fluorescence spectrometry (XRF). However, sensitivity for Hg is too low in some color additives. Objective The thermal decomposition amalgamation-atomic absorption spectrometric (TDA-AAS) technique was investigated for providing quick and accurate determinations of Hg in certifiable color additives. Methods Tests were performed to optimize conditions and test reliability of Hg determinations at and below the CFR specification limit of 1 mg/kg. Results Sensitivity is much improved over XRF with limits of quantitation of 0.03 mg/kg for highly homogeneous color additives. Conclusions The TDA-AAS method can be used for determining Hg concentrations at and below the CFR specification limit. The technique is effective for all color additives, including those that are difficult to analyze by XRF, but less efficient for color additives that quickly deteriorate the catalyst. Regular quality checks using certified reference materials and in-house matrix-matched check standards are essential. Highlights The TDA-AAS method is applicable for use in routine color additive batch certification. Certain matrices (notably those that release nitrogen or sulfur oxides or halogens upon combustion) necessitate more frequent replacement of the catalyst and recalibration, impacting productivity. Color additives containing BaSO4, in color additive lakes, that are difficult to analyze by other techniques are well suited for TDA-AAS analysis.

A Sensitive Ultra-High Performance Liquid Chromatography–Tandem Mass Spectrometry Method Based on Derivatization with 1-Nitro-2-Naphthaldehyde for Determination of Alkylhydrazines in Surface water

Background Alkylhydrazines are widely used in the industrial fields. An analysis of alkylhydrazines in surface water is need because these chemicals are likely to be discharged into wastewater and enter aquatic environments. Objective An ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method was developed to determine the levels of five alkylhydrazines (N,N-dimethylhydrazine, ethylhydrazine, 1-isopropylhydrazine, phenylhydrazine and 1-methyl-1-phenylhydrazine) in surface water. Methods This method is based on the derivatization of alkylhydrazines with 1-nitro-2-naphthaldehyde (NNA) in water. A derivatization reagent dosage of 0.5 mg of NNA, a pH of 2, and a reaction time of 30 min at 40 °C were determined to be the optimal conditions for UHPLC–MS/MS detection. The derivatives were injected into the LC system without additional extraction or purification steps. Results The proposed method was used under optimized conditions to detect alkylhydrazines in surface water, with the limit of quantification found to be 0.01–0.03 μg/L. The accuracy ranged from 91.0 to 106.0%, and the precision, expressed as the relative standard deviation, was less than 10%. Of the five alkylhydrazines, only N,N-dimethyl hydrazine was detected in the real samples at a concentration range of 0.010 to 0.041 μg/L. Conclusion The developed method can be used to confirm the presence of alkylhydrazine residues in surface water and represents an important tool for evaluating the fate of alkylhydrazines in surface water. Highlights This method to determine alkylhydrazine in surface water was developed simply and rapidly after derivatization reaction without an extraction or clean-up step in UHPLC-MS/MS.