C18 Sorbent Research Articles

Multi-Residue Analysis of Thyreostats in Animal Muscle Tissues by Hydrophilic Interaction Liquid Chromatography Tandem Mass Spectrometry: A Thorough Chromatographic Study

Τhyreostats (TSs) are veterinary drugs used in livestock farming for fattening. Their administration is banned in the European Union since 1981, and their monitoring for food quality and safety control requires sensitive and confirmatory methods. The present study describes the development and validation of a hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) method for the simultaneous determination of 2-thiouracil (TU), 6-methyl-2-thiouracil (MTU), 6-propyl-2-thiouracil (PTU), 6-phenyl-2-thiouracil (PhTU), tapazole (TAP), and 2-mercaptobenzimidazole (MBI) in bovine muscle tissues. Investigation of the retention mechanism of the six analytes on the selected amide-based stationary phase showed that hydrophilic partition was the dominant interaction. The sample preparation included extraction with ACN/H2O (80/20), followed by dispersive solid-phase extraction (d-SPE) with C18 sorbent and hexane partitioning. The method was validated according to European guidelines using internal standards, including isotopically labelled ones. The method’s LODs ranged between 2.8 ng g−1 (6-phenyl-2-thiouracil) and 4.1 ng g−1 (2-thiouracil). Application of the proposed method to 48 bovine tissue samples showed non-detectable results.

Determination of Free Glycidol and Total Free Monochloropropanediol in Fish and Krill Oil with Simple Aqueous Derivatization and High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

This study introduces a novel method for detecting free glycidol and total free monochloropropanediol (MCPD) in fish and krill oil. Before analysis on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), p-(dimethylamino)phenol was used for derivatization of these compounds, enabling the sensitive determination of these contaminants. The sample preparation procedure includes a simple, efficient pretreatment using NaCl aqueous solution extraction and C18 sorbent cleanup (for demulsification), distinguishing glycidol from MCPD under varied reaction conditions for derivatization (weak acidic and strong alkaline aqueous environments). This approach shows broad linearity from 1 to at least 256 ng·mL-1, improved sensitivity compared to standard GC-MS methods, with the limit of detection (LOD) and limit of quantification (LOQ) for MCPD and glycidol in both oil samples verified at 0.5 ng·mL-1 and 1 ng·mL-1, respectively. Different from previous HPLC-MS methods for direct detection of glycidol esters or MCPD esters, this is the first HPLC-MS method used for the detection of free glycidol and total free MCPD in edible oil. Furthermore, this method can be potentially developed for glycidol or monochloropropane diol esters, which is similar to the current official methods adopted for indirect detection of these contaminants in different food matrices. Application of this detection method to real dietary supplements (fish oil and krill oil) revealed MCPD residues in fish oil (maximum detected: 32.78 ng·mL-1) and both MCPD (maximum detected: 2767.3 ng·mL-1) and glycidol (maximum detected: 22.2 ng·mL-1) in krill oil, emphasizing its effectiveness and accuracy for assessing contamination in these supplements.

Ionic-liquid/Carbowax 20 M functionalized capsule phase microextraction platform for the extraction of phosphodiesterase-5 inhibitors from human serum and urine prior to their determination by LC–MS

Capsule phase microextraction (CPME) is an efficient bioanalytical technique that streamlines the sample preparation by integrating the filtration and stirring mechanism directly into the device. A novel composite sorbent designed to be selective towards the target analytes consisting of mixed-mode sorbent chemistry synthesized by sol–gel technology is found promising and superior to the conventional C18 sorbents. Herein we describe the encapsulation of an ionic liquid (IL)/Carbowax 20M-functionalized sol–gel sorbent (sol–gel IL/Carbowax 20 M) in the lumen of porous polypropylene tubes for the capsule phase microextraction of three phosphodiesterase-5 inhibitors namely avanafil, sildenafil, and tadalafil in human serum and urine samples. The CPME device was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR). The experimental parameters of CPME procedure (e.g. sample pH and ionic strength, extraction time, stirring rate, elution solvent and volume) were carefully optimized to achieve the highest possible extraction efficiency for the analytes. Method validation was conducted in terms of precision, linearity, accuracy, matrix effect, lower limits of quantification, and limits of detection (LOD). The method linearity was investigated in the range of 50–1000 ng mL−1 for all analytes while the precision was less than 11.8 % in all cases. For all analytes, the LOD values were 17 ng mL−1. The IL/CW 20M-functionalized microextraction capsules could be reused at least 25 times both for urine and serum samples. The green character and the applicability of the proposed method were evaluated using the ComplexGAPI and BAGI indexes. The optimized CPME protocol exhibited reduced consumption of organic solvent and generation of waste, cost-effectiveness, and simplicity. Finally, the proposed method was successfully applied to the analysis of sildenafil in human urine after administration of drug-containing formulation.

Paradigm Shift: Major Role of Ion-Pairing-Dependent Size Exclusion Effects in Bottom-Up Proteomics Reversed-Phase Peptide Separations.

Can reversed-phase peptide retention be the same for C8 and C18 columns? or increase for otherwise identical columns with a smaller surface area? Can replacing trifluoroacetic acid (TFA) with formic acid (FA) improve the peak shape? According to our common understanding of peptide chromatography, absolutely not. Surprisingly, a thorough comparison of the peptide separation selectivity of 100 and 120 Å fully porous C18 sorbents to maximize the performance of our in-house proteomics LC-MS/MS setup revealed an unexpectedly higher peptide retentivity for a wider pore packing material, despite it having a smaller surface area. Concurrently, the observed increase in peptide retention─which drives variation in separation selectivity between 100 and 120 Å pore size materials─was more pronounced for smaller peptides. These findings contradict the central dogmas that underlie the development of all peptide RP-HPLC applications: (i) a larger surface area leads to higher retention and (ii) increasing the pore size should benefit the retention of larger analytes. Based on our intriguing findings, we compared reversed-phase high-performance liquid chromatography peptide retention for a total of 20 columns with pore sizes between 60 and 300 Å using FA- and TFA-based eluents. Our results unequivocally attest that the larger size of ion pairs in FA- vs TFA-based eluents leads to the observed impact on selectivity and peptide retention. For FA, peptide retention peaks at 200 Å pore size, compared to between 120 and 200 Å for TFA. However, the decrease in retention for narrow-pore particles is more profound in FA. Our findings suggest that common assumptions about analyte size and accessible surface area should be revisited for ion-pair RP separation of small peptides, typical for proteomic applications that are predominantly applying FA eluents. Hybrid silica-based materials with pore sizes of 130-200 Å should be specifically targeted for bottom-up proteomic applications to obtain both superior peak shape and peptide retentivity. This challenging task of attaining the best RPLC column for proteomics calls for closer collaboration between LC column manufacturers and proteomic LC specialists.

Estrogenic activity in wastewater treatment plants through in vitro effect-based assays: Insights into extraction phase

Effluents of wastewater treatment plants can abundantly spread endocrine disrupting chemicals in the environment. To improve water quality monitoring, the use of effect-based tools that measure estrogenic activity has been suggested, however their results could be influenced by different factors.This study compared the estrogenic activity of wastewater samples extracted with two stationary phases and tested with two in vitro effect-based assays to investigate whether and how stationary phases and assays could influence biomonitoring data.During four seasonal periods, the effluents of six WWTPs located in northern Italy were sampled. After the extraction using two different stationary phases (HLB, C18), the samples (n = 72) were tested using two effect-based assays: a gene reporter luciferase assay on mammalian cells (MELN) and yeast estrogen screen assay (YES).The results showed that estrogenic activity of HLB extracts was significantly different from the activity of C18 extracts, suggesting that extraction phase can influence biomonitoring data. Moreover, the estrogenic activity was overall higher using gene reporter MELN assay than using YES assay, suggesting that, due to difference in cell membrane permeability and metabolic activation, the applied cell model can affect the biomonitoring results. Finally, from the comparison between the activity of the final effluent and the environmentally safe estrogenic levels in surface waters, MELN data suggested that the activity of this effluent may pose an environmental risk, while YES data showed that it should not be considered a threat to the receiving surface waters.This study pointed out that a standardized approach is needed to assess the estrogenic activity of waters; it reported important data to select the most suitable stationary phase for samples extraction (samples extracted with C18 sorbent showed higher estradiol equivalent concentration values) and the most appropriate bioassay (gene reporter luciferase MELN assay was more sensitive than YES assay) to assess the environmental risk, thus protecting human health.

Advanced nanofibrous sorbents for the extraction of pollutants from river water and protein-containing matrices

The extraction efficiencies of thirty types of fibers produced by meltblown, alternating current electrospinning, and meltblown-co-electrospinning technologies were tested as advanced sorbents for on-line solid-phase extraction in a high-performance liquid chromatography system have been tested and compared with a commercial C18 sorbent. The properties of each fiber, which were often depended on the production process, and their applicability were demonstrated with the extraction of the model analytes nitrophenols and chlorophenols from various matrices including river water and to purify complex matrix human serum and bovine serum albumin from macromolecular ballast. Polycaprolactone fibers outperformed other polymers and were selected for subsequent modifications including (i) incorporation of hybrid carbon nanoparticles, i.e., graphene, activated carbon, and carbon black into the polymer prior to fiber fabrication, and (ii) surface modification by dip coating with polyhydroxy modifiers including graphene oxide, tannin, dopamine, hesperidin, and heparin. These novel fibrous sorbents were comparable to commercial C18 sorbent and provided excellent analyte recoveries of 70–112% even from the protein-containing matrices.

SIMULTANEOUS REMOVAL OF ACIDIC AND NEUTRAL POLLUTANTS FROM WATER USING MIXED-MODE RESINS

Polycyclic aromatic hydrocarbons and endocrine-disrupting phenols are both ubiquitous pollutants in the environment. Human activities through urbanisation and rapid industrialisation are at the forefront of global environmental pollution. Therefore, removing pollutants in miscellaneous characteristics is important to eliminate the stage-by-stage reduction of pollutants, especially from wastewater, for a cost-effective and time-effective treatment. A simple preliminary study was conducted for the concurrent removal of acidic 2, 4, 6-trichlorophenol (2, 4, 6-TCP) and neutral fluorene (FLU) from water by mixed-mode resins that consist of Anion Exchange Chromatography (AEC) and reversed-phase C18 sorbents. The one-variable-at-time approach was applied in the optimisation of the removal process, where sorbent dosage, exposing time, stirring speed, and sample pH were investigated to enhance the removal efficiency. Under the optimal conditions, 20 mg of each AEC and C18 successfully removed 74.8% of 2, 4, 6-TCP and 96.5% of FLU from the water sample spiked with 50 mg/L of 2, 4, 6-TCP and 0.5 mg/L of FLU that was pre-modified to pH 9 and agitated at 600 rpm for 10 min. The AEC and C18 achieved a removal capacity of 37.4 mg/g for 2, 4, 6-TCP and 0.48 mg/g for FLU, respectively, upon treating 20 mL of the water sample. The mixed-mode resins combine the capabilities of two different retention mechanisms and allow for the simultaneous removal of a broad range of compounds from environmental samples.

Development, validation, and implementation of an ultratrace analysis method for the determination of moenomycin A, in aquatic animal products.

Moenomycin A, an antimicrobial growth promoter widely used as an additive in aquaculture feedstuffs, has been restricted for use in the European Union and China due to its potential risk of promoting resistant strains of pathogenic bacteria and causing residues in aquatic animal products. Although methods for analyzing moenomycin A in feedstuffs have been developed, no established method exists for aquatic matrices. In this study, we present, for the first time, a sensitive and validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of moenomycin A in aquatic animal products. Samples were extracted using methanol and purified with the QuEChERS method employing C18 sorbent. The aliquot was dried under a nitrogen stream, reconstituted with methanol-water solvent, and analyzed by HPLC-MS/MS. The developed method exhibited good linearity (r2 > 0.995) over a wide concentration range (1-100μg/L) and a low limit of detection (1µg/kg). Average recoveries ranged between 70 and 110% at spiked concentrations of 1, 50, and 100μg/kg, with associated intra- and inter-day relative standard deviations of 1.25 to 7.32% (n = 6) and 2.91 to 10.08% (n = 3), for different representative aquatic animal production, respectively. To the best of our knowledge, this is the first reported HPLC-MS/MS method for the quantification of moenomycin A in aquatic animal products. The new approach was effectively employed in the analysis of moenomycin A across various aquatic samples.

Polar pesticides in food of animal origin: interlaboratory validation to evaluate method fitness-for-purpose of official control

The present work reports on the design, execution and evaluation of results of an interlaboratory validation study aimed at verifying the fitness-for-purpose of a LC-MS/MS method for the detection of polar pesticides in food of animal origin in official control and monitoring programmes. To this scope, five participant laboratories, with relevant expertise, were recruited. After passing a pre-trial test, the participants were asked to analyse test samples of bovine fat, chicken eggs and cow’s milk, contaminated with 11 polar pesticides (group A: Aminomethyl phosphonic acid (AMPA), cyanuric acid, ethephon, glyphosate, fosetyl aluminium, 2-hydroxyethyphosphonic acid (HEPA), maleic hydrazide, N-acetyl-glyphosate, group B: N-acetyl glufosinate (NAG), 3-methylphosphinicopropionic acid (MPP) and glufosinate ammonium) at two different levels (0.05 and 0.25 mg/kg−1 and 0.01 and 0.05 mg/kg−1 for group A and B respectively. The method was based on acidified methanol/water extraction followed by dSPE clean up with C18 sorbent. For LC-MS/MS analysis isotopically labelled standards were used for all targeted analytes. With a couple of exceptions, average recoveries ranged from 85% to 110%, with repeatability (RSDr) ranging from 3% to 25%, and reproducibility (RSD R ) from 4% to 26%. The assessment by different laboratories provided also insights on key factors impacting method performance characteristics and its implementation by new users.

A modified micro-solid phase extraction device for in-port elution and injection into portable liquid chromatography: A proof-of-concept study

A micro-solid phase extraction (micro-SPE) device packed with a C18 sorbent (10 mg) has been developed for the enrichment and purification of organic water pollutants prior to their analysis using a portable liquid chromatograph with a dual UV detector. To this end, the sorbent was immobilized at the inlet of a 4 mm syringe filter (0.20 µm), which was modified to reduce its internal volume. The filter was coupled to the needle of the chromatograph. After loading the sample and cleaning the sorbent for analyte purification, the device was installed into the injection port of the chromatograph, and the target compounds were desorbed and transferred directly to the chromatographic column with a small volume of organic solvent. Under optimized conditions, sample volumes as large as 50 mL could be processed with the micro-SPE device, while the analytes were desorbed with only 60 µL of methanol. As a result, efficient preconcentration could be reached, as demonstrated for different water contaminants, namely aclonifen, bifenox, tritosulfuron, triflusulfuron-methyl and caffeine. The proposed micro-SPE device was applied to the analysis of different types of water (river, well, sea, ditch and wastewater). The recoveries of the target compounds in samples ranged from 76 % to 109 %, which allowed their detection at low to sub µg/L levels. All operations were carried out manually, and thus, no additional laboratory instruments such as centrifuges, stirrers or evaporators were required. This proof-of-concept study shows that the proposed micro-SPE approach can be considered a reliable and effective option for the on-site analysis of pollutants in environmental water samples by portable liquid chromatography.

Quantitative and qualitative comparison of marine dissolved organic nitrogen recovery using solid phase extraction

AbstractMarine dissolved organic carbon and nitrogen (DOC and DON) are major global carbon and nutrient reservoirs, and their characterization relies on extraction methods for preconcentration and salt removal. Existing methods optimize for capturing and describing DOC. Here, we report an optimized analytical strategy to recover marine DON for subsequent molecular characterization. Retention efficiencies between 5% and 95% are reported for seven solid phase extraction (SPE) sorbents, with PPL recovering 23% of marine DON compared to 95% recovered with C18. Additional comparisons of the effect of varying sample volumes and elution speed, and the resulting molecular composition of DON extracts, were investigated using C18 and PPL sorbents. Sample volumes > 200 mL decreased DON retention efficiency independent of SPE sorbent, and gravity elution recovered 1.7‐ to 4.2‐fold more DON compared to vacuum elution. Characterization of extracted DON by negative‐ion electrospray ionization Fourier transform‐ion cyclotron resonance mass spectrometry (FT‐ICR MS) highlights compositional differences between DON species recovered by each method. DON isolated with optimized methods includes low molecular weight (< 600 Da) peptide‐like compounds with low O:C ratios (0.2 to 0.5) that are not detected by other SPE sorbents (e.g., PPL). The majority of additional DON isolated with this approach was undetectable by direct infusion negative mode FT‐ICR MS analysis.

Selective method for quantitative determination of glyphosate, aminomethylphosphonic acid, and glufosinate in animal products using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)

Glyphosate and glufosinate are broad-range, non-selective herbicides that contaminate plant products used in fattening farm animals which in turn bears the risks of contamination of the whole food chain. The goal of this study is to develop a selective procedure for the chromato-mass spectrometric determination of glyphosate, aminomethylphosphonic acid (glyphosate metabolite) and glufosinate in meat, offal and milk. The limit of quantitative determination of glyphosate and glufosinate in meat and offal is 0.05 mg/kg, aminomethylphosphonic acid is 0.4 mg/kg; the limit of quantitative determination of glyphosate and glufosinate in milk is 0.02 mg/kg, aminomethylphosphonic acid is 0.05 mg/kg. The compounds to be determined are extracted from the objects under study with a solution of sulfbsalicylic acid, the primary purification of the extracts is carried out using a reverse-phase C18 sorbent, the compounds to be determined are derivatized using 9-fluorenylmethoxycarbonyl chloride, and the final purification of the derivatives is carried out on a sorbent exhibiting weak cation exchange properties. The purified extract is concentrated, diluted with a mixture of methanol and acetic acid in water, centrifuged and then used for analysis. Chromatographic separation is performed on a column with a reversed-phase C18 sorbent. Tandem mass-spectrometry is used for detection of the compounds under study. The calibration dependences for the determined compounds are linear, the correlation coefficient (K) > 0.99. The validation of the procedure showed that the relative expanded uncertainty in the lower range of the determined contents ranged from 27 to 41% for glyphosate, from 25 to 29% for aminomethylphosphonic acid, and from 25 to 34% for glufbsinate, depending on the type of object of analysis. The obtained values of the limit of quantitative determination are consistent with the temporary maximum allowable levels set in SanPiN 1.2.3685-21.

Development and Validation of a Residue Analysis Method for Ethylene Oxide and 2-Chloroethanol in Foods by Gas Chromatography Tandem Mass Spectrometry

A selective and sensitive method is reported for the residue analysis of ethylene oxide (EO) in diverse matrices, namely sesame, cumin, wheat, tea, spices, herbs, dehydrated fruits, food additives, grapes, and tomatoes. The study modified the European Union reference method (EN 15662) by performing the sample extraction (with acetonitrile) at <10 °C, cleanup through dispersive-solid phase extraction with C18 and primary secondary amine sorbents, and analysis using gas chromatography tandem mass spectrometry with selected reaction monitoring. Injections were performed through a programmable temperature vaporizer port. The sample preparation process provided a limit of quantification of 10 ng/g for both EO and 2-CE and effectively minimized matrix effects. Recoveries of both EO and 2-CE ranged from 74 to 120% at 10, 20, and 50 ng/g with precision RSDs of <12%, satisfying the SANTE/11312/2021 guidelines of analytical method validation. The HorRat (Horwitz ratio) values of 0.31–0.40 indicated high interlaboratory (n = 6 laboratories) method reproducibility. The results of incurred residues in sesame (0.055–0.1 mg/kg), cumin (0.008–0.013 mg/kg), and coriander (0.01–0.025 mg/kg) demonstrated satisfactory extraction efficiency and precision (RSDs < 10%) in test results. The method is highly suitable for regulatory analysis of EO in diverse food matrices.

Determination of Pesticides in Dead Honeybees

Pesticide residues were analyzed in dead honeybees by gas chromatography-tandem mass spectrometry (GC-MS/MS). Sample preparation using QuEChERS was followed by purification on a mixture of PSA and C18 sorbents. The extraction efficiency of &gt; 80% was obtained for all analytes and pesticides were quantified in the range of 5-1000 ng/g. This method was used for investigating incidents of honeybees poisoning by pesticides. Fipronil was detected in all of the investigated samples originating from different regions of Russia. Additionally, τ-fluvalinate was detected in three samples.

Comprehensive assessment of different extraction methodologies for optimization and validation of an analytical multi-method for determination of emerging and regulated mycotoxins in maize by UHPLC-MS/MS

A multi-analyte method for identification and quantification of 23 regulated and emerging mycotoxins was developed in maize samples by ultra high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Several extraction methodologies were evaluated, including solid-liquid extraction (SLE), solid-phase extraction (SPE), and modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) protocols. The final method consisting of an extraction by QuEChERS using C18 sorbents, was in-house validated in terms of linearity, repeatability, reproducibility, recovery, Limits of Detection (LOD) and Limits of Quantification (LOQ). Acceptable performance characteristics were obtained according to specific and general European regulations for regulated and emerging mycotoxins, respectively. The developed method proved to be specific and selective for all mycotoxins, with LODs and LOQs lower than 21.10 and 37.49 ng g−1, respectively; and recoveries ranging from 55.25 to 129.48% with precisions, expressed as relative standard deviations, below 15.03%. The method was successfully applied to real maize samples.

Green capsule phase microextraction employing hydrophobic monolithic sol-gel octadecyl siloxane platforms for the monitoring of organophosphorus pesticides in environmental water samples

In this study, a novel, facile and green capsule phase microextraction (CPME) method is presented for the extraction and preconcentration of organophosphorus pesticides (i.e., chlorpyrifos, disulfoton, ethoprophos, fenchlorphos, prothiofos, and parathion-methyl) from environmental water samples. Monolithic sol-gel octadecyl siloxane (sol-gel C18) sorbent encapsulated within porous polypropylene capsules was synthesized, characterized, and evaluated for its efficiency towards the adsorption of the target organophosphorus pesticides. CPME was combined with gas chromatography-mass spectrometry (GC-MS) for the monitoring of the target analytes. The method was optimized to ensure high method sensitivity and it was fully validated. The limits of detection of the CPME-GC-MS method for the OPPs were 0.02–0.15 ng mL−1. The relative standard deviations were 1.5–8.7% for intra-day study and 5.4–9.6% for inter-day study, demonstrating satisfactory precision. Moreover, good method accuracy was obtained, since the relative recoveries were within the range 92.6–107.0% and 90.8–107.6% for intra-day and inter-day (c = 5.00 and 20.0 ng mL−1), respectively. The absence of interferences in the blank samples demonstrates that the proposed method is selective. The sol-gel C18 sorbent encapsulated CPME media could be reused for at least 25 adsorption/desorption cycles. In addition, the methodology presents advantageous features in comparison to existing methods. The final protocol was used for analyzing four different water sample types (i.e., lake water, river water, pond water and tap water sample).

Evaluation of a septumless mini-cartridge for automated solid-phase extraction cleanup in gas chromatographic analysis of >250 pesticides and environmental contaminants in fatty and nonfatty foods

The QuEChERSER mega-method has recently been introduced to quantify and identify a wide range of chemical residues (pesticides, veterinary drugs, environmental contaminants, among others) in nearly all types of foods. The approach calls for taking a small amount of the initial extract to cover analytes amenable to liquid chromatography, and the remainder is salted out for analysis by gas chromatography (GC), both with mass spectrometry (MS) based detection. In the case of GC-MS(/MS), the extract undergoes automated robotic mini-cartridge solid-phase extraction (SPE) cleanup in a technique known as µSPE or instrument-top sample preparation (ITSP). In 2022, a septumless mini-cartridge for µSPE was introduced to improve upon the ITSP design. The new design houses a bed of 20 mg anhydrous MgSO4, 12 mg each of C18 and primary secondary amine sorbents, and 1 mg of graphitized carbon black, the latter substituting for CarbonX used in the ITSP product. The septumless µSPE mini-cartridge employs a different gripping mechanism with the syringe needle that allows leak-free operation at higher flow rates (e.g. 10 µL/s), whereas the ITSP design is limited to 2 µL/s. Based on cleanup and analyte elution profiles, the extract load volume and flow rate was increased in µSPE for QuEChERSER from 300 µL at 2 µL/s to 500 µL at 5 µL/s, which improved accuracy of results, sped the cleanup step, and obviated the need for micro-vial inserts in the receiving vials. The new design also reduced both the amount and consistency of dead (void) volumes in the mini-cartridges from 83 ± 14 µL to 52 ± 7 µL for 200-600 µL load volumes. Normalization of peak areas to internal standards led to recoveries between 80 and 120% with typical RSDs <5% in low-pressure GC-MS/MS of 227-242 out of 252 pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, and polycyclic aromatic hydrocarbons in hemp powder, spinach, whole milk, egg, avocado, and lamb meat.

Combination of Sea Sand Disruption Method and Ion-Pair Solid-Phase Extraction for Effective Isolation and Purification of Chlorogenic Acid from Plants Prior to the HPLC Determination.

Chlorogenic acid (CQA) is one of phenolics commonly found in higher plants, possessing numerous health-promoting effects on humans. Unfortunately, it is easily degraded/transformed into other substances during extraction. Therefore, its reliable analysis requires a special approach that does not involve high temperatures. This paper presents a very simple method of CQA isolation using the sea sand disruption method with subsequent purification of the extract using the ion-pair solid-phase extraction process, followed by HPLC–DAD detection. It was found that control of the ion pairing reagent concentration and sample pH is crucial to improve purification, and that the best results, with recovery exceeding 98%, were obtained for 0.05 M tetrabutylammonium bisulfate at pH 7 when the ion pairs were formed directly in the extract and eluted from the C18 sorbent using an acidified methanol–water mixture. The practical potential of the developed procedure was verified by using it for CQA isolation from different plants. The approach represents one of the contemporary analytical trends and current advances in the solid phase extraction, in which several sorption extraction techniques are combined to ensure high-quality analytical results.

Rapid determination of 103 common veterinary drug residues in milk and dairy products by ultra performance liquid chromatography tandem mass spectrometry.

A multi-residue method has been developed for the identification and quantification of 103 common veterinary drug residues in milk and dairy Products. This method was based on QuEChERS with dispersive solid-phase where C18 sorbent and anhydrous sodium sulfate were used to sample purification. After evaporation and reconstitution, the samples were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry. The mean recovery results were all higher than 60% except ampicillin, pipemidic acid, enoxacin, and estriol, and the relative standard deviation was <20.0%. The limit of quantification ranged between 0.1 and 5 μg/kg for milk and between 0.5 and 25 μg/kg for milk powder. It was successfully used to detect residues of veterinary drug in real samples. This study proposes a simple and fast analytical method for monitoring multi-class veterinary drug residues to ensure food safety.

Determination of five nitroimidazoles and six benzodiazepines in aquatic products using ultra-high performance liquid chromatography-tandem mass spectrometry coupled with dispersive solid-phase extraction

建立了分散固相萃取-超高效液相色谱-串联质谱法同时测定水产品中5种硝基咪唑类和6种苯二氮卓类药物残留的方法。样品用1%(v/v)氨水乙腈提取,提取液经十八烷基键合硅胶(C18)和N-丙基乙二胺(PSA)吸附剂净化,在45 ℃下用氮气吹至近干,用1 mL甲醇-水(1:9, v/v)溶液复溶,过0.22 μm尼龙-66滤膜后用超高效液相色谱-串联质谱测定。目标化合物采用Kinetex F5色谱柱(100 mm×3.0 mm, 2.6 μm)分离,以0.1%(v/v)甲酸水溶液和甲醇作为流动相进行梯度洗脱,在电喷雾离子源(ESI)、正离子扫描和多反应监测(MRM)模式下进行测定,基质匹配外标法定量。结果表明,5种硝基咪唑类和6种苯二氮卓类药物在8.5 min内完成色谱分离分析,目标物在0.5~20 μg/L范围内线性关系良好,相关系数均大于0.995,检出限和定量限分别为0.2~0.5 μg/kg和0.5~1.0 μg/kg。以草鱼、对虾和大黄鱼为样品基质,在3个不同的添加水平下,5种硝基咪唑类和6种苯二氮卓类药物的平均回收率为73.2%~110.6%,相对标准偏差(RSD)小于15%。本研究建立的方法具有简单、快速、灵敏度高和成本低等优势,可用于水产品中5种硝基咪唑类和6种苯二氮卓类药物的快速检测。该方法的建立为我国水产品质量安全相关监管部门同时监控水产品中硝基咪唑类和苯二氮卓类药物残留提供了技术支持。