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BackgroundPrevious research on chlorinated paraffins (CPs) in fine particulate matter (PM2.5) has predominantly focused on short- and medium-chain chlorinated paraffins (SCCPs and MCCPs), and few studies could simultaneously determine short-, medium-, and long-chain chlorinated paraffins (LCCPs). Simultaneous extraction and determination of SCCPs, MCCPs, and LCCPs in PM2.5 could provide technical support for their environmental monitoring and human health risk assessment.ObjectiveTo establish a method based on QUEChERS pretreatment method in conjunction with ultra-performance liquid chromatography-quadrupole/orbitrap high resolution mass spectrometry for simultaneously determining the levels of SCCPs, MCCPs, and LCCPs in PM2.5. MethodsThe extraction solvents, extraction salts, and extraction steps of a QuEChERS method were optimized. The extraction efficiencies of the target substances were compared under 4 extraction solvents [acetonitrile, dichloromethane, and n-hexane solvents in sequence; acetonitrile: dichloromethane: n-hexane = 1: 1: 2 (v/v/v) mixed solvent; 1% acetic acid-acetonitrile: dichloromethane: n-hexane = 1: 1: 1 (v/v/v) mixed solvent; acetonitrile: dichloromethane: n-hexane = 1: 1: 1 (v/v/v) mixed solvent], 2 dehydrated salts (anhydrous MgSO4+NaCl and anhydrous Na2SO4+NaCl), 2 purification salts (C18 and PSA), and 4 vortex time (5, 7.5, 10, and 12.5 min) conditions. Then internal standard was utilized to estimate linear range and detection limit of the refined QuEChERS approach. ResultsThe linearities of SCCPs, MCCPs, and LCCPs were good in the range of 10~1000 ng·mL−1 with the correlation coefficients all greater than 0.96. The method detection limits (MDLs) ranged from 0.01 to 0.29 ng·m−3. The spiked recoveries of SCCPs, MCCPs, and LCCPs at the low, medium, and high concentrations were 77.38%-81.64%, 93.11%-99.78%, and 87.41%-101.39%, respectively, and the relative standard deviations (RSDs) were 2.90%-12.84%. This method was used to determine the CPs levels in 11 PM2.5 samples from Shijiazhuang. The positive rates of ∑SCCPs, ∑MCCPs, and ∑LCCPs were all 100%, the concentration ranges were 0.24-2.18 ng·m−3 (mean 0.84 ng·m−3), 0.17-1.67 ng·m−3 (mean 0.70 ng·m−3), and 0.01-0.16 ng·m−3 (mean 0.04 ng·m−3), respectively, and the percentages to ΣCPs were 52.95%, 44.39%, and 2.66%, respectively. ConclusionThe method established in this study is simple, time-saving, solvent saving, and can simultaneously detect SCCPs, MCCPs, and LCCPs in PM2.5, which is suitable for the determination of PM2.5 samples in large quantities, and can also provide a reference for the detection methods of other halogenated organic compounds in PM2.5.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Non-targeted small molecule screening methods are used to analyze samples for potential compounds of interest without focusing on specific molecular species. There is great interest in these methods for metabolomic, environmental, forensic, and food safety applications, among others, to determine compounds that are responsible for a particular disease state or the presence of a harmful compound. In order for non-targeted analyses to become standardized and routine, best practices for sample preparation, data collection, and data analysis must be determined. This work focuses on optimizing specific aspects of a non-targeted workflow that utilizes high-resolution mass spectrometry using an Orbitrap instrument coupled to liquid chromatography. Sample preparation, liquid chromatography gradient length, and mass spectrometry resolving power and ionization modes were investigated to determine optimal conditions for detecting and extracting compounds from the data that cover broad molecular and polarity ranges. Infant rice cereal, orange juice, and yogurt with spiked standards were analyzed; food is inherently challenging to analyze due in part to sample complexity and diversity. Of the conditions tested, optimal conditions included a generic sample extraction using acetonitrile, water, and formic acid, a 25 min chromatographic gradient, collecting data in both positive and negative ion modes, and using 70 k resolving power. There are of course tradeoffs associated with each of these options that will be described in detail so that the appropriate conditions can be chosen for the desired application. Image 1 • An extraction using water, acetonitrile, and formic acid yielded the most features. • A 25 min gradient was the best compromise for feature detection and data quality. • The 70 k resolving power setting increased feature detection and data quality. • Polarity switching with 70 k resolution resulted in the best molecular coverage. [ABSTRACT FROM AUTHOR]

Blood is one of the most assessable matrices for the determination of pesticide residue exposure in humans. Effective sample preparation/cleanup of biological samples is very important in the development of a sensitive, reproducible, and robust method. In the present study, a simple, cost-effective, and rapid gas chromatography-tandem mass spectrometry method has been developed and validated for simultaneous analysis of 31 multiclass (organophosphates, organochlorines, and synthetic pyrethroids) pesticide residues in human plasma by means of a mini QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. We have adopted a modified version of the QuEChERS method, which is primarily used for pesticide residue analysis in food commodities. The QuEChERS method was optimized by use of different extraction solvents and different amounts and combinations of salts and sorbents (primary-secondary amines and C) for the dispersive solid-phase extraction step. The results show that a combination of ethyl acetate with 2% acetic acid, magnesium sulfate (0.4 g), and solid-phase extraction for sample cleanup with primary-secondary amines (50 mg) per 1-mL volume of plasma is the most suitable for generating acceptable results with high recoveries for all multiclass pesticides from human plasma. The mean recovery ranged from 74% to 109% for all the analytes. The limit of quantification and limit of detection of the method ranged from 0.12 to 13.53 ng mL and from 0.04 to 4.10 ng mL respectively. The intraday precision and the interday precision of the method were 6% or less and 11% or less respectively. This method would be useful for the analysis of a wide range of pesticides of interest in a small volume of clinical and/or forensic samples to support biomonitoring and toxicological applications. [ABSTRACT FROM AUTHOR]

Over the past decade, QuEChERS (quick, easy, cheap, effective, rugged, and safe) has evolved into one of the most widely used extraction techniques for residue analysis. Since its inception, this method is considered particularly adept in the extraction of polar and basic compounds, and hence the majority of methods developed using QuEChERS involve extracting pesticides and contaminants from various matrices, particularly fruits, vegetables, and other food products. Combining a liquid–liquid extraction and dispersive solid-phase extraction cleanup, QuEChERS provides a clean sample for analysis by gas chromatography or liquid chromatography, and is therefore ideal for samples with complex matrices. This study describes recent QuEChERS research with gas chromatography (QuEChERS–GC), focusing on areas beyond pesticide extraction from food, and provides insight into possible new applications of the technique in forensic science and drug extraction. [ABSTRACT FROM AUTHOR]

A simple extraction technique has been developed for seven macrolide antibiotics in milk. The procedure involves a modified quick, easy, cheap, effective, rugged, and safe method based on acetonitrile extraction, followed by the addition of a mixture of salts (sodium sulfate, sodium chloride, and potassium carbonate) not yet reported in literature. The method was validated for tylosin and was selective, free of matrix effect, and linear in the range of 0.78-18.75 ng/mL in the final extract, corresponding to 0.125-3 times the maximum residue limit. The limit of detection, limit of quantification, decision limit, and detection capability were, respectively, 0.84, 2.79, 58.4, and 71.7 μg/kg. The overall average recovery at 25, 50, and 75 μg/kg ranged from 89-97%. Repeatability and intermediate precision expressed by relative standard deviations were below 10.5 and 12%, respectively. The extension of the validation for spiramycin, throleandomycin, oleandomycin, roxithromycin, erythromycin, and clarithromycin is under consideration since the procedure proved to be able to efficiently extract all studied macrolides, with recoveries from 74-104% at 50 μg/kg for tylosin, erythromycin, spiramycin, and oleandomycin and 20 μg/kg for throleandomycin, roxithromycin, and clarithromycin. [ABSTRACT FROM AUTHOR]

Abstract: A new method for the analysis of phenoxy acid herbicide residues in rice, based on the use of liquid extraction/partition and dispersive solid phase extraction (dispersive-SPE) followed by ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC–ESI–MS/MS), is reported. 5% (v/v) formic acid in acetonitrile as the extraction solvent and inclusion of citrate buffer helped partitioning of all the analytes into the acetonitrile phase. The extract was then cleaned up by dispersive-SPE using C18 and alumina neutral as selective sorbents. Further optimization of sample preparation and determination allowed recoveries of between 45 and 104% for all 13 phenoxy acid herbicides with RSD values lower than 13.3% at 5.0μgkg−1 concentration level. Limit of detections (LODs) of 0.5μgkg−1 or below were attained for all 13 phenoxy acids. Quantitative analysis was done in the multiple-reaction monitoring (MRM) mode using two combinations of selected precursor ion and product ion transition for each compound. This developed method produced relatively higher recoveries of the acid herbicides with a smaller range of variation and less susceptibility to matrix effects, than the original QuEChERS ( Quick, Easy, Cheap, Effective, Rugged, and Safe) method. [Copyright &y& Elsevier]