Solid-phase Extraction Liquid Chromatography Research Articles

Determination of Sedative and Anesthetic Drug Residues in Aquatic Food Products Using Solid Phase Extraction (SPE) and Liquid Chromatography–Tandem Mass Spectrometry (LC–MS/MS)

The residues of sedative and anesthetic drugs in aquatic products are an important factor affecting food safety. In order to screen the residues of sedative and anesthesia drugs in aquatic products, a rapid and sensitive method was established using solid phase extraction (SPE) and high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). The samples were extracted by 80% aqueous acetonitrile by an alumina column and separated by a C18 column. The mass spectra were determined in positive ion mode. The standard curves were matrix matched and quantified by the external standard method. The results showed that the linear ranges of the drugs in aquatic products were from 0.5 to 100 μg kg−1. The correlation coefficient (R 2) was greater than 0.990 and the detection limits were between 0.001 and 0.322 μg kg−1. The average recovery rate and relative standard deviation were between 78.64% and 112.15% and from 0.41%-8.26%. Overall, the developed method showed promising results for the simultaneous qualitative and quantitative determination of the drug residues in aquatic products.

Determination of calcium β-hydroxy-β-methyl butyrate content in milk and dairy products by solid-phase extraction and high performance liquid chromatography

In this paper, an analytical method based on solid-phase extraction (SPE) purification and high-performance liquid chromatography method (HPLC) was developed for the first time to determine the content of calcium β-hydroxy-β-methyl butyrate (CaHMB) in milk and dairy products. The quantitative detection was performed by HPLC with diode array detector (DAD) under external standard method. The limit of quantification (LOQ), calculated as 10 times the standard deviation, was 0.10 g/100 g. The average recoveries were in the range of 92.40–103.00 %, with relative standard deviations (RSDs) of 1.25–3.77 %, measured at three concentration levels. The real sample analysis results showed that CaHMB was detected in infant formula, formulated milk powder, and milkshake samples, the contents of which were in the range of 0.60–8.66 g/100 g, respectively. The developed method features good purification effect, good separation specificity, good repeatability, accuracy and reliability, and can meet the content determination of CaHMB in milk and dairy products.

Sorption of Polycyclic Aromatic Sulfur Heterocycles (PASH) on Nylon Microplastics at Environmentally Relevant Concentrations.

Microplastics have garnered an infamous reputation as a sorbate for many concerning environmental pollutants and as a delivery vehicle for the aquatic food chain through the ingestion of these contaminated small particulates. While sorption mechanisms have been extensively studied for polycyclic aromatic hydrocarbons, polycyclic aromatic sulfur heterocycles (PASHs) have not been investigated, partly due to their low concentrations in aquatic ecosystems. Herein, an analytical methodology is presented for the analysis of dibenzothiophene, benzo[b]naphtho[1,2-b]thiophene, benzo[b]naphtho[2,1-b]thiophene, benzo[b]naphtho[2,3-b]thiophene, chryseno[4,5-bcd]thiophene and dinaphtho[1,2-b:1',2'-d]thiophene at relevant environmental concentrations based on solid phase extraction and high-performance liquid chromatography. The sorption uptake behavior and the sorption kinetics of the three benzo[b]napthothiophene isomers were then investigated on nylon microplastics to provide original information on their environmental fate and avoid human contamination through the food chain. The obtained information might also prove relevant to the development of successful remediation approaches for aquatic ecosystems.

Optimizing solid phase extraction and HPLC-MS/MS parameters for reliable quantification of COVID-19 pharmaceuticals in Mexico City’s wastewater: A design of experiments approach

Through the COVID-19 health crisis, a plethora of new medications, along with some discontinued pharmaceuticals, were directly tested on population to assess their efficacy in symptom management. Consequently, residues from these treatments were systematically disposed into sewage systems, presenting a novel contamination challenge in urban centers. To effectively address this issue by environmental authorities, the presence of these pollutants in wastewater must be accurately quantified. Herein, we conducted a meticulous study to validate an analytical method based on solid-phase extraction (SPE) and high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) to detect six pharmaceuticals (metformin, famotidine, indomethacin, dexamethasone, azithromycin, and ivermectin) in wastewater. Using a Plackett-Burman design (PBD), the eight parameters significantly impacting on the HPLC-MS/MS technique were established based on the analytical signal of the six analytes. Subsequently, in conjunction with a Box-Behnken design (BBD), optimal analysis conditions were determined as follows: injection volume: 10 µL, column temperature: 20 °C, capillary voltage: 4100 V, drying gas temperature and flow rate of 350 °C and 7 L min−1 respectively, nebulizer pressure: 15 psi, concentration of formic acid and ammonium acetate in the mobile phase of 0.1 % and 10 mmol/L, respectively. SPE was optimized through a univariable experimental design. OASIS HLB cartridges exhibited the highest extraction efficiency compared to highly polar and non-polar adsorbents. The optimal sample loading conditions were set as 250.0 mL of water sample at pH = 9.0. The washing conditions were 5.0 mL of a 95:5 water:methanol solution, while elution conditions were optimal using 6.0 mL of a 98:2 methanol:formic acid solution. After evaporating the eluate to dryness and reconstituting in 1.0 mL of a 98:2 methanol:formic acid solution, a concentration factor of 250 was achieved. The analytical method was validated using for matrices, namely, raw and treated wastewater, wastewater percolated through soil and groundwater. Acceptable levels of precision and accuracy were achieved for all analytes in the tested matrices. Using the validated method, the six pharmaceuticals were quantified in environmental samples, revealing high levels of metformin, dexamethasone, and azithromycin in Mexico City’s sewage. Highly polar compounds displayed mobility through environment as they were present in effluent samples, percolated wastewater, and groundwater.

Ionic liquid-functionalized mesoporous multipod silica for simultaneously effective extraction of aflatoxin B1 and its two precursors from grain

BackgroundAflatoxin B1 (AFB1) and its precursors contaminate food and agricultural products, posing a significant risk to food safety and human health, but simultaneous and effective extraction and determination of AFB1 and its precursors with varied structures is still a challenging task. ResultsIn this study, a bisimidazolium-type ionic liquid functionalized mesoporous multipod silica (SiO2@mPMO-IL(im)2) was fabricated to extract AFB1 and its two precursors, i.e., averantin and sterigmatocystin. The SiO2@mPMO-IL(im)2 could simultaneously extract three targets with varied structures based on the multipods, mesopores, and multifunctional groups. The density functional theory calculations further verified the multiple interactions between SiO2@mPMO-IL(im)2 and targets. The fabricated SiO2@mPMO-IL(im)2 could effectively extract and determine three targets in grains by combing with dispersive solid-phase extraction and high-performance liquid chromatography. Good linearity (r2 > 0.9978), low LODs (0.9–1.5 μg kg−1) and LOQs (3.0–4.5 μg kg−1), satisfactory spiked recoveries (92.5%–106.8%) and high precisions (RSD<6.4%) were observed. Significance and noveltyThis work demonstrates the feasibility of SiO2@mPMO-IL(im)2 for simultaneous and effective extraction of toxins with varied structures and provides a promising sample preparation for the analysis of AFB1 and its precursors in grain samples.

Determination of lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) and domoic acid in mussels by solid-phase extraction and reversed-phase liquid chromatography with tandem mass spectrometry

An accurate and efficient method was developed for the determination of azaspiracid shellfish toxins (azaspiracids-1, -2, and -3), neurotoxic shellfish toxins (brevetoxins-2 and -3), diarrhetic shellfish toxins (okadaic acid and dinophysistoxins-1 and -2), and the amnesic shellfish toxin (domoic acid) in mussels (Mytilus galloprovincialis). Lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) were extracted with 0.5 % acetic acid in methanol under heating at 60°C to improve the extraction efficiency of okadaic acid group toxins and then cleaned up with a C18 solid-phase extraction cartridge. Domoic acid was extracted with 50 % aqueous methanol and then cleaned up with a graphitized carbon solid-phase extraction cartridge. Lipophilic marine biotoxins and domoic acid were quantified by reversed-phase liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The developed method had insignificant matrix effects for the nine analytes and good recoveries in the range of 79.0 % to 97.6 % at three spiking levels for all analytes except brevetoxin-2 (43.8–49.8 %). The developed method was further validated by analyzing mussel tissue certified reference materials, and good agreement was observed between certified and determined values.

WLIP, WLIPβ, and WLIPγ Produced from Pseudomonas canadensis Q3-1 via Precursor-Directed Biosynthesis and Their Roles on Biocontrol of Phytophthora Blight in Peppers.

White line-inducing principle (WLIP, 1), together with two new cyclic lipopeptides (CLPs) WLIPβ (2) and WLIPγ (3), were characterized from the supernatant of Pseudomonas canadensis Q3-1 via precursor-directed biosynthesis (PDB) in the current study. They were purified from the supernatant of P. canadensis Q3-1 by solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC), and their structures were mainly determined via bioinformatic analyses, spectrometric and spectroscopic techniques, as well as single crystal X-ray diffraction (XRD). These WLIPs share (R)-3-hydroxydecanoic acid (HDA), but they differ from each other in the composition of peptidic sequences. In addition, these CLPs showed biocontrol activities against Phytophthora blight (caused by Phytophthora capsici) in peppers. Collectively, this study has shown that PDB could be used for generating new CLPs in Pseudomonas spp. Moreover, we have confirmed that WLIP, WLIPβ, and WLIPγ could be used as lead agrochemicals to control Phytophthora blight in peppers.

Highly selective analysis of glipizide as an antidiabetic drug in urine samples using HPLC-DAD technique via magnetic nanocomposites (Fe3O4@SiO2@tryptophan)

The extraction of endogenous compounds and drugs from complex biological matrices such as bio fluids and solid tissues necessitates an appropriate analytical approach that allows for qualitative and quantitative analysis because of the very low concentrations of the target species. This present work surveys the universe to isolate, purify, and immobilize an antidiabetic drugs such as glipizide biomolecules in urine samples using a magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC-DAD). To accomplish this purpose, a synthesis strategy of silica-coated magnetic nanoparticles functionalized with Tryptophan which is known as an amino acid to be applied as sorbent for (MSPE) is elaborated and analyzed. The structural and optical properties of the new magnetic nanocomposite have been investigated using Scanning electron microscope (SEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transformation infrared (FTIR) techniques. In addition, HPLC analysis was carried out for the detection and determination of glipizide concentration in urine samples after magnetic solid phase extraction. After MSPE, the linear range for glipizide molecules (R2 > 0.9942) was obtained in the range of 15.00–900.00 ng mL−1. The calculations yielded a limit of detection (LOD) of 4.38 ng mL−1 and a limit of quantification (LOQ) of 14.71 ng mL−1. Additionally, the relative standard deviation (RSDs %) was found to be below 3.8 %. Furthermore, the recovery values for synthetic urine were 96.5 %, 96.6 %, and 102.5 %, and for human urine were 104.5 %, 106.1 %, and 97.1 %. These findings indicate that the combined use of MSPE with HPLC-DAD is an effective and valuable approach for accurately determining the concentration of glipizide in human urine samples.

Determination of 55 Veterinary Antibiotics in Chicken Manure Using Ultra-High-Performance Liquid Chromatography – Tandem Mass Spectrometry (UPLC-MS/MS)

A highly efficient method for the detection and quantification of 55 veterinary antibiotics (VAs) in chicken manure belonging to six drug classes using solid-phase extraction (SPE) and ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) was developed. The mixture of EDTA–McIlvaine buffer (pH 3.0) and the organic extractant (methanol–acetonitrile, 1:3, v/v) was used to isolate the target VAs from freeze-dried chicken manure. The extract was purified by a hydrophile–lipophile balance cartridge. All antibiotics showed excellent linear relationships in the range between 1 and 100 µg/kg with the coefficients of determination of the standard curves above 0.990. The recoveries of antibiotics were between 35.66% and 103.54% using matrix-matched calibration for quantification. The limits of detection and quantification were from 0.01 to 1.59 µg/kg and 0.04 to 4.76 µg/kg, respectively. The method was demployed to determine VAs in chicken manure from 12 farms, revealing contamination in all samples. A total of 13 VAs belonging to six classes were detected with concentrations up to 41.47 mg/kg. The presence of high concentrations of antibiotic residues in poultry manure poses a potential risk for environmental contamination. This work has identified significant differences in the types of VAs compared to literature reports. Additionally, it detected pleuromutilin antibiotics in chicken manure for the first time.

Thyroid Hormone Metabolites Quantified in Pup and Adult Rat Cerebellum, Cortex and Whole-Brain Samples Using an Automated Online SPE-LC-MS/MS Method.

Changes in thyroid hormone (TH) levels in rat brain at early developmental stages are correlated with adverse effects on offspring development. To characterize the ability of substances to interfere with the TH concentrations in, e.g., rat brain, it is essential to know the mean TH concentrations in this tissue under control conditions. In this publication, an online solid-phase extraction (SPE) liquid chromatography (LC) tandem mass spectrometry (MS/MS) method was validated and used to measure TH metabolites (T4, T3, rT3, T2 and T1) in the brains of untreated rats. Data on TH concentrations in the whole brain and separate data from the cerebellum and the cortex are shown. The corresponding samples were gathered from young rats at postnatal days (PND) 4 and 21/22 and from adult rats. The results show inter alia the high accuracy and precision of the method, and LOQs of 0.02 ng/mL were determined for T1, T2 and rT3 and of 0.15 ng/mL for T3 and T4. Technical variability is low, as shown by the relative standard deviations of 7.5-20%. For our rat model, we found that T4, T3 and T2 concentrations rise from PND4 to PND21, whereas the rT3 concentration decreases; as well as there is no statistical difference between TH concentrations in the male and female rat brain. This method is suitable to analyze TH metabolites in the brain and build up a database of historical TH concentrations in control rats. Together, this yields a robust diagnostic tool to detect potentially adverse disturbances of TH homeostasis in the most vulnerable anatomic structure.

Determination of Phenylethanolamine A Residues in Milk by Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry

A method was established for the determination of phenethanolamine A residue in milk by solid phase extraction, liquid chromatography-tandem mass spectrometry. The samples were extracted with ammonium acetate buffer solution under the condition of enzymatic hydrolysis and purified by MCX solid phase extraction column. The eluent was blown dry with nitrogen at 45℃ and dissolved with 1.0 mL 0.1% formic acid solution. The samples were isolated by Poroshell 120EC-C18, 100 mm ×3.0 mm (i.d.), 2.7 μm column, and then determined by mass spectrometry in multiple reaction monitoring mode, and quantified by internal standard method. The results showed that phenethanolamine A had good linear relationship in the concentration range of 0.5-50.0 μg/L, the correlation coefficient r=0.9984, the limit of detection was 0.17 μg/kg, and the limit of quantitation was 0.57 μg/kg. The average recovery was 98.3-108.7% and the precision was 2.4-3.7% at different supplemental levels. The established method can purify the samples effectively, improve the detection efficiency, and is suitable for the detection of phenethanolamine A residue in milk.

A Review of Global Occurrence of Emerging Pollutants in Wastewater: Present Status, Source/Pathway, Extraction and Detection Techniques

The occurrence of emerging pollutants (EPs) is constantly reported around the world. Despite this, due to their large number, only a few of these compounds have been toxicologically evaluated. In this paper, the literature on EPs found in wastewater was reviewed from 1998 to 2021, with a focus on their occurrence, extraction, and detection methods. Pesticides, microplastics, pharmaceuticals and personal care products, per and polyfluoroalkyl substances were studied for their presence in wastewater in Africa, Oceania, North America, Asia, Europe and South America. The highest concentration of pesticides in wastewater was recorded in Africa (Cameroun) at concentration ranging from 2 to 2993 ng/L whilst the least was recorded in Europe (Spain) at concentrations ranging from 0.02 to 1.94 ng/L; Pharmaceuticals and personal care products had the highest concentration in Africa (Egypt) at 70.6 to 119.4 mg/L whilst the least concentration was found at 0.1 to 646 ng/L in Africa (Tunisia); Per and polyfluoroalkyl substances had the highest concentration in Asia (Thailand) at 662 to 1383 ng/L while the least concentration was found to be in the range 0.2 to 48.6 ng/L in Europe (Denmark); Microplastics were also recorded in this study to have the highest concentration in the range 28.4 to 79.9 particles/L in Asia (China) and the least concentration in the range 0.0008 particles/L in North America (USA). Reliable analytical extraction and detection methods were the solid phase extraction and high-performance liquid chromatography coupled to different detectors respectively, and they were employed for the pesticides, pharmaceuticals and personal care products, per and polyfluoroalkyl substances only whilst the extraction and detection methods employed for the microplastics were filtration and digestion techniques followed by the FT-IR detection method. EPs were more prevalent in the African continent as a result of various socio-economic issues that led to poor sanitation systems and drastic shortages in wastewater treatment plants in many regions, making it difficult to tackle the problem of emerging pollutants.

Occurrence of sulfonamides and tetracyclines in the coastal areas of the Yangtze River (China) Estuary.

Antibiotics have attracted global attention due to the ecological risks to environment. In this paper, solid-phase extraction and ultra-performance liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS) were utilized to analyze the fugitive characteristics of 10 antibiotics of sulfonamides (sulfadiazine, sulfamethazine, sulfadimidine, sulfathiazole, sulfapyridine, sulfamethoxazole) and tetracyclines (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in the coastal waters and surfece sediments of the Yangtze River Estuary and the ecological risks of antibiotics in water were estimated using ecological risk assessment method. The results have showed that 7 of the 10 antibiotics were detected in the water, with total concentrations ranging from 0.652 to 434.47ng/L. 8 antibiotics were detected in the sediment, with total concentrations ranging from 0.091 to 499.23ng/g. The main antibiotic species detected in the sediment and water varied seasonally. Higher concentrations in spatially distributed areas where rivers meet and where human activities have a more significant impact. The ecological risks were found to be higher in spring and autumn than those in winter and summer. Spatial variation in individual microbial communities was not evident in the sediments. The relationship between antibiotics and microorganisms in the environment was predominantly positive. Physical and chemical factors were significantly correlated for both antibiotics and microbial communities. This study can provide research ideas for other types of antibiotics and provide a basis for the prevention of antimicrobial resistance (AMR).

Synergistic enhancement of glucagon-like peptide-1 release by γ-aminobutyric acid and L-phenylalanine in enteroendocrine cells-searching active ingredients in a water extract of corn zein protein.

This study investigated the glucagon-like peptide-1 (GLP-1)-releasing activity of an aqueous extract (ZeinS) from corn zein protein and aimed to identify the active compounds responsible for this activity. Glucagon-like peptide-1-releasing activity was evaluated using a murine enteroendocrine cell line (GLUTag). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed on purified fractions of ZeinS to identify active molecules. ZeinS stimulated more GLP-1 secretion from GLUTag cells compared to zein hydrolysate. Fractions displaying biological activity were determined by solid-phase extraction and high-performance liquid chromatography (HPLC) fractionation. Subsequent LC-MS/MS analysis identified several amino acids in the active fractions of ZeinS. In particular, γ-aminobutyric acid (GABA) exhibited significant GLP-1-releasing activity both alone and synergistically with L-phenylalanine (Phe). Moreover, ZeinS-induced GLP-1 secretion was attenuated by antagonists for the GABA receptor and calcium sensing receptor. These results demonstrate that GABA and Phe identified in ZeinS synergistically stimulate GLP-1 secretion in enteroendocrine cells.

Determination of Benzimidazoles in Chicken and Egg Samples by Urea-Based Covalent Organic Polymer (UCOP) Pipette Tip–Solid-Phase Extraction (PT–SPE) and High-Performance Liquid Chromatography–Tandem Mass Spectrometry (HPLC–MS)

A urea-based covalent organic polymer (UCOP), was synthesized using 1,4-phenylene diisocyanate (PPDI) and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) trianiline (TTTA) and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nitrogen adsorption-desorption isotherm analysis. The prepared material was employed as an adsorbent for pipette tip–solid-phase extraction (PT–SPE) for benzimidazoles before high-performance liquid chromatography–tandem mass spectrometry analysis (HPLC–MS). The parameters affecting the isolation efficiency, including salt concentration, sample pH, mass of adsorbent, and types and volumes of eluent, were optimized. Using these conditions, PT–SPE provided good linearity from 0.1 to 10 μg kg−1 with low limits of detections (LODs) of 0.02 μg kg−1 together with good precision (relative standard deviations from 4.2 to 8.3%) and accuracy (recoveries from 76.2 to 84.8%). The results demonstrate that the urea-based covalent organic polymer has the potential for the enrichment of trace benzimidazoles.

Simultaneous determination of paracetamol and diclofenac in wastewater by high-performance liquid chromatography method

In this study, a simple, selective, and accurate analysis method was developed for the simultaneous determination of anti-inflammatory drugs (paracetamol and diclofenac) existing inlet and outlet of the wastewater treatment system. This method used solid-phase extraction (SPE) and reversed-phase high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). Separation was performed using an HSR C18 column (250 mm × 4.6 mm; 5 µm) with a mobile phase consisting of acetonitrile: sodium dihydrogen orthophosphate in the ratio 60:40 v/v. The flow rate was 1 ml/min, and PDA was detected at 243 nm with paracetamol and 276 nm with diclofenac. The duration of paracetamol and diclofenac was 2.39 and 4.39 min, respectively. The developed method was validated in terms of accuracy, precision, and linearity for two drugs found in the range of 0.01 - 1 µg/ml, and 0.02 - 1 µg/ml for paracetamol, and diclofenac, respectively. The limits of detection for paracetamol and diclofenac were 0.003 µg/ml and 0.006 µg/ml, respectively, whereas the limits of quantification were 0.01 µg /ml and 0.02 µg/ml, respectively. The recoveries for paracetamol and diclofenac were greater than 95 %. The described method also has been applied to determine paracetamol and diclofenac simultaneously in the wastewater of the treatment system.

Porous polymer monoliths with complementary retention mechanisms for online solid-phase extraction liquid chromatography to determine lysozyme in egg white

Porous polymer monoliths with complementary retention mechanisms for online solid-phase extraction liquid chromatography to determine lysozyme in egg white

Development and Validation of a SPE-HPLC Method for Quantification of Rhein, Emodin, Chrysophanol and Physcion in Rhamnus petiolaris Boiss. & Balansa.

Anthraquinones exhibit a significant group of natural and synthetic quinone derivatives because of their biological activities and industrial applications. Rhamnaceae is one of the families known to contain different kinds of anthraquinones. In this study, it was aimed to quantify rhein, emodin, chrysophanol and physcion in fruits of Rhamnus petiolaris Boiss. & Balansa belonging to Rhamnaceae by solid phase extraction and high performance liquid chromatography with ultraviolet detection. The anthraquinones were separated using a C18 analytical column. Gradient elution was performed using a mobile phase consisted of 0.1% o-phosphoric acid solution and methanol. Analytes were detected at 254nm. Calibration curves were prepared in the range of 0.25-5.00μg/mL for rhein, chrysophanol, physcion, 1.00-50.00μg/mL for emodin. Limits of detection and quantification were between 0.07-0.11 and 0.20-0.34μg/mL, respectively. Relative standard deviations were ≤ 5.78% in repeatability and intermediate precision studies. Accuracy was determined as relative mean error (8.17-12.06%). Extraction was achieved by maceration with acetone and ethanol, followed by hydrophilic-lipophilic balance solid phase extraction. Recoveries were between 96.2 and 109.6%. The developed and validated method was successfully performed to quantify rhein, emodin, chrysophanol and physcion in R. petiolaris fruit extracts. Only physcion was not detected above limit of detection.

Hybrid Targeted/Untargeted Screening Method for the Determination of Wildfire and Water-Soluble Organic Tracers in Ice Cores and Snow.

Wildfires can influence the earth's radiative forcing through the emission of biomass-burning aerosols. To better constrain the impacts of wildfires on climate and understand their evolution under future climate scenarios, reconstructing their chemical nature, assessing their past variability, and evaluating their influence on the atmospheric composition are essential. Ice cores are unique to perform such reconstructions representing archives not only of past biomass-burning events but also of concurrent climate and environmental changes. Here, we present a novel methodology for the quantification of five biomass-burning proxies (syringic acid, vanillic acid, vanillin, syringaldehyde, and p-hydroxybenzoic acid) and one biogenic emission proxy (pinic acid) using solid phase extraction (SPE) and ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry. This method was also optimized for untargeted screening analysis to gain a broader knowledge about the chemical composition of organic aerosols in ice and snow samples. The method provides low detection limits (0.003-0.012 ng g-1), high recoveries (74 ± 10%), and excellent reproducibility, allowing the quantification of the six proxies and the identification of 313 different molecules, mainly constituted by carbon, hydrogen, and oxygen. The effectiveness of two different sample storage strategies, i.e., re-freezing of previously molten ice samples and freezing of previously loaded SPE cartridges, was also assessed, showing that the latter approach provides more reproducible results.

Application of solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) and comparison of both detection techniques (DAD and FLD) to analyse nesfatin-1 in fetal bovine serum samples

AbstractIn this study, we propose a simple, cost-effective, and sensitive high-performance liquid chromatography with both detection techniques such as diode-array detection and fluorescence detection (HPLC-DAD-FLD) for the determination of nesfatin-1 in fetal bovine serum samples. The limit of detection (LOD) and limit of quantification (LOQ) for nesfatin-1 were set at satisfactory values in the range 0.22–0.35 mg mL−1 and in the range 0.67–1.05 mg mL−1, respectively (at two different wavelengths (DAD) and at four different wavelengths (FLD)). Analyte concentrations were determined as the average value from fetal bovine serum matrix samples. The preliminary results show that the SPE procedure on Isolute Si-TsOH (SCX-3) could be used for further nesfatin-1 analyses in human serum samples. Both the SPE technique, chromatographic analysis with gradient elution mode and detection technique are fast and convenient.