SPE Cartridges Research Articles

Determination of anabasine, anatabine, and nicotine biomarkers in wastewater by enhanced direct injection LC-MS/MS and evaluation of their in-sewer stability

Wastewater-based epidemiology (WBE) has been used to estimate tobacco use in the population. However, the increased use of nicotine replacement therapies and e-cigarettes contributes to the load of nicotine metabolites in wastewater, causing over-estimation of tobacco use if nicotine metabolites were used in WBE back-estimation. This study aims to develop a rapid method for determining the tobacco-specific biomarkers, anabasine and anatabine, in wastewater and to evaluate their in-sewer stability for better estimation of tobacco use by WBE. An enhanced direct injection LC-MS/MS was developed to quantify anabasine and anatabine as well as nicotine biomarkers (nicotine, cotinine and hydroxycotinine). The method was optimal when wastewater was filtered through 0.2 μm RC syringe filters and a pre-conditioned SPE cartridge (Oasis HLB 1 cc, 30 mg) before 50 μL was injected into the LC-MS/MS system. Limits of quantification varied between 2.7 and 54.9 ng/L with recoveries from 76% to 103% for all five compounds. In sewer reactors, anabasine and anatabine were less stable than cotinine and hydroxycotinine. They were more stable in the gravity sewer reactor with <20% loss in 12 h than in the rising main sewer reactor with ~30% loss in the same period. We then applied the new method to 42 daily wastewater influent samples collected from an Australian wastewater treatment plant. The five biomarkers were detected in all samples with concentrations ranging from 9.2 to 7430 ng/L. All five compounds were positively correlated with one another. Our results suggested a high throughput analytical method for feasible application in anabasine and anatabine as biomarkers of tobacco use in routine wastewater monitoring.

Investigation on the Contents of Acrylamide in Baked and Fried foods

The current work aims to develop a method for the determination of acrylamide in baked and fried foods using high performance liquid chromatography-mass spectrometry (UPLC-MS/MS). In this study, the extraction of acrylamide was using water and then cleaned up on a HLB and MCX SPE cartridge, followed by separating on a [Waters ACQUITY UPLC BEH C18 (100 mm×2.1 mm, 1.7 μm)] column using acetonitrile and 0.1% formic acid as mobile phase. Thereafter, the concentration of acrylamide was determined in multiple reaction monitoring mode, usingD3-acrylamide as internal standard. It was found that the proposed calibration curve was linear in the range of 0.1 to 100 μg/L with a correlation coefficient greater than 0.99 indicating a very good linearity. The limit of detection (LOD) was 5.0 μg/kg and the quantitative limit (LOQ) was 10.0 μg/kg. The average recovery at three spiked levels (5, 20 and 100 μg/kg) of roasted coffee and deep-fried dough sticks was ranged from 88.0 % to 106 % with RSD smaller than 6%. The method was also tested by analysing acrylamide in baked and fried food samples (biscuits, roasted coffee, cake, fried potato, potato chips and deep-fried dough sticks). The acrylamide concentrations were found between 28 μg/kg and 635 μg/kg in those samples. Taken together, the developed method has superior for determination of acrylamide in baked and fried foods samples, which is of simplicity, high accuracy and good stability.

Solid-Phase Extraction Combined with Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry for the Determination of 5 Trace Nitro-Polycyclic Aromatic Hydrocarbons in Barbecued Foods.

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are the derivatives of polycyclic aromatic hydrocarbon which are direct mutagens and carcinogens to human. Nitro-PAHs can be produced in the process of food barbecuing/grilling. At present, there are few studies for the determination of nitro-PAHs in food. To assess the effect of barbecued food to human health, we have established a method for the determination of 5 nitro-PAHs in barbecued foods. The target nitro-PAHs were extracted with the mixture of methanol/acetone and then purified with an HLB SPE cartridge and finally analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry. Two pairs of target multiple reaction monitoring (MRM) ion pairs have been successfully identified for the target nitro-PAHs, and confirmed by high-resolution mass spectrometry to explore their formation mechanism. The method had linear ranges of 2.0-500 µg/L (except 1-nitronaphthalene 20-5000 µg/L) with the correlation coefficients greater than 0.995. The extraction recoveries were between 70.1% and 85.6% with the relative standard deviations less than 10.0%. The limits of detection of the method were less than 0.60 µg/L (except 1-nitronaphthalene 6.0 µg/L). The method has been successfully applied to the analysis of 5 nitro-PAHs in barbecued foods. 1-nitronaphthalene, 1,8-dinitropyrene , 1-nitropyrene were detected in some charcoal grilled samples with the contents of 1.35-12.9 µg/kg. 1,8-Dinitropyrene was detected in some oil-fried samples with the contents of 2.12-5.12 µg/kg. This work presents an ultra-high-performanceliquid chromatography-tandem mass spectrometry method for the determination of 5 nitro-PAHs in barbecued foods for the first time. The method has been successfully applied to the analysis of 5 nitro-PAHs in various barbecued foods and the nitro-PAHs were detected in some barbecued food samples. The mechanism of mass spectrometric decomposition of nitro-PAHs was investigated as well.

Determination of 400 pesticide residues in green tea leaves by UPLC-MS/MS and GC-MS/MS combined with QuEChERS extraction and mixed-mode SPE clean-up method

Maximum residue limits (MRLs) for pesticides have been established in teas for quality control and protection of consumer health in many countries and regions, including Europe. It is, however, challenging to quantify multi-pesticide residues at low concentrations in complex matrices, such as tea. In this study, highly sensitive, efficient, and rugged analytical methods were adapted for simultaneous determination of 400 pesticide residues in green tea products using ultra performance liquid and gas chromatography coupled to tandem mass spectroscopy (UPLC-MS/MS and GC-MS/MS). Matrix effects were minimized by combining QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction and mixed-mode SPE clean-up with different sorbents in sample preparation. A C18 SPE cartridge paired with SPE GCB/PSA proved to be the most effective clean-up method and enabled 225 pesticide residues to be quantified, based on solvent calibration curves (154 residues using UPLC-MS/MS and 71 residues using GC-MS/MS). The analytical methods were validated fully in accordance with the SANTE/11945/2015. LOQs for most pesticides (386/400 or 96.5%) were below 10 µg/kg, i.e., less than the EU MRL (5–70 mg/kg). Thus, these approaches can be applied for routine analysis of multi-pesticide residues in green tea.

Determination of CHLORPYRIFOS by GC/ECD in water and its sorption mechanism study in a RHODIC FERRALSOL.

The validation of chromatographic methods is a costly process, however necessary, especially with regard to the validation of methods that accurately determine concentrations of pesticides in different environmental compartments. This research aimed at the development and validation of a simple and fast method for the determination of chlorpyrifos concentrations in water by means of a gas chromatograph with electron capture detection (GC/ECD), and to investigate chlorpyrifos dynamics of adsorption in a Rhodic Ferralsol in Southern Brazilian conditions. The developed chromatographic method was based in EPA 8141 method. Parameters to be checked for method validation were: Selectivity/specificity, linearity, precision, accuracy, robustness, limit of detection (LOD) and limit of quantitation (LOQ). Were employed the following methodologies for the validation process: ANVISA Resolution 899, DOQ-CGCRE-008 and FDA Bioanalytical Method Validation Guide. Also, through laboratory tests, the sorption dynamics of chlorpyrifos in Rhodic Ferralsol was evaluated. Thus, the soil was contaminated with increasing concentrations of chlorpyrifos, which were subjected to solid-liquid extraction with SPE cartridge Chromabond® C18 ec. The obtained results were submitted to the models of Langmuir, Freundlich, Dubinin-Radushkevich and Sips. By this method, chlorpyrifos peaks are obtained at 16.9min, demonstrating practicality and low cost. This method exhibits precision and sensitivity, with satisfactory LQ and LQ values. The models of Langmuir, Freundlich, Dubinin-Radushkevich and Sips suggest the occurrence of simultaneous adsorption in mono and multilayer of chlorpyrifos in Rhodic Ferralsol colloids, as well as the predominance of a chemical, high energy binding process (irreversible). However, the chemisorption of chlorpyrifos is more related to the good fit found for Dubinin-Radushkevich sorption energy values (9.861 and 11.079 KJ mol-1) and Qm values estimated by Langmuir (485.55 and 389.61μgg-1 for linear and nonlinear model).

Dummy molecularly imprinted polymer (DMIP) as a sorbent for bisphenol S and bisphenol F extraction from food samples

Dummy molecularly imprinted polymer (DMIP) was prepared towards bisphenol S and bisphenol F employing bisphenol A as a dummy template. Liquid chromatography with UV and fluorescence detection (LC-UV/FLD) was used for the separation and quantification of these analytes. The maximum adsorption capacity of DMIP was 20.9 mg g−1 and 18.6 mg g−1 for BPS and BPF, respectively. By applying solid phase extraction with DMIP prior to LC-UV/FLD, the limits of detections achieved in food samples can be lowered to 0.5 ng g−1 for BPF and 5 ng g−1 for BPS. Only 5 mg of DMIP sorbent was sufficient to achieve good recoveries (71–113%) and precision (RSD 0.1–3.2%, n = 3) for analyzed liquid food samples spiked at two concentration levels 0.25 mg L − 1 and 0.40 mg L − 1. For preconcentrated pineapple extract spiked with 0.5 mg•L − 1 of both analytes, also very good recovery was obtained (89% for BPS and 99% for BPF), significantly higher than for conventional SPE cartridges such as Oasis HLB and Affinimip®. The analytical characterization of the proposed method makes it suitable for monitoring programs, intended for the assessment of human exposure to bisphenol S in food samples, without using much expensive mass spectrometry detection.

Determination of tylosin in milk samples by poly(ethylene terephthalate)‐based molecularly imprinted polymer

AbstractPoly(ethylene terephthalate)‐based molecularly imprinted polymers (MIPs) were synthesized, and their recognition capability was evaluated. Adsorption isotherm was described by the Langmuir model and the maximum adsorption capacity of MIPTy reached 172.4 mg g−1 in water at pH 6.2. A recognition coefficient of 1.17 was obtained. A solid‐phase extraction cartridge was manufactured and its behavior was evaluated for tylosin extraction from aqueous and milk samples. An off‐line SPE‐UV method was applied. An acceptable linearity was obtained in the range of 1–20 μg ml−1 and the average recovery at three spike levels in milk samples was higher than 92%. The limit of quantification was 2.6 × 10−2 μg ml−1. The manufactured SPE cartridge has a great potential for clean‐up processes in complex media. The cartridge offers a fast and sensitive option to the existing sorbents for extracting this drug from milk samples.

Graphene oxide/polydimethylsiloxane-coated stainless steel mesh for use in solid-phase extraction cartridges and extraction of polycyclic aromatic hydrocarbons.

The stainless steel mesh, in the form of the disk, was coated with graphene oxide and poly(dimethylsiloxane) (GO-PDMS) by sol-gel technique. The coated stainless steel meshes are loaded in the mini-column as solid-phase extraction cartridge for the fast isolation and preconcentration of polycyclic aromatic hydrocarbons (PAHs) from real water samples. The extracted PAHs (naphthalene, acenaphthene, acenaphthylene, anthracene, benz[a]anthracene, fluorene, and pyrene) were quantified by gas chromatography-mass spectrometry. The operation parameters affecting the extraction efficiency including sample volume, desorption conditions, and ionic strength were investigated. At optimized conditions, the linearity of this method is obtained from 0.001 to 20ngmL-1 with 0.2 to 1.0pgmL-1 limit of detection. For 5 replicates at 3 spiking levels (0.1, 1, and 10ngmL-1), the relative standard deviations between 4.0 and 6.3% were achieved. Theabsolute extraction recovery varied from 89.1 to 94.7%. The enrichment factors were in the range of 2227-2367. Themethod has been employed in the determinationof PAHs in the real water samples including well water, tap water, river water, and wastewater. Relative recoveries are between 95.2 and 100.9%. Graphical abstractSchematic representation of the SPE procedure using the self-assembly SPE cartridge.

Development of a mesoporous silica based solid-phase extraction and ultra-performance liquid chromatography-MS/MS method for quantifying lignans in Justicia procumbens.

Justicia procumbens is a food and medicine homologous variety, popularly used for making vegetable soups. In this study, a novel mesoporous silica was synthesized and used as the sorbent of SPE for the purification of lignans from J. procumbens. A laboratory-made SPE cartridge was packed with 100mg of mesoporous silica, which was washed with 10% methanol and eluted using 0.8mL acetonitrile after sample loading. Afterward, the extract was analyzed by ultra-performance liquid chromatography (UPLC) and MS/MS. All the lignans were efficiently separated in 6min with the noise level in the range of 50-150cps. 6'-Hydroxy justicidin B, 6'-hydroxy justicidin A, justicidin B, chinensinaphthol methyl ether, justicidin C, and neojusticdin A were identified to be the dominant molecular species in J. procumbens with contents of 0.065-0.37mg/g in three tested sample batches from different geographic origins. In conclusion, the proposed mesoporous silica based SPE UPLC-MS/MS method is efficient in linearity (R2 = 0.9989-0.9996), sensitivity (LOD ≤0.13 μg/kg and LOQ ≤0.42μg/kg), precision (RSDintra-day ≤3.12 and RSDinter-day ≤4.56), and recovery (83.42-96.11%, RSD ≤2.88%).

Typical indoor concentrations and mass flow of cyclic volatile methylsiloxanes (cVMSs) in Dalian, China

Cyclic volatile methylsiloxaes (cVMSs), namely hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), were studied for a typical indoor environment of male and female dormitories in the campus of Dalian Maritime University (DMU) in China. An empty, frit-fitted SPE cartridge was placed on top of an Isolute ENV + cartridge, sampling cVMSs in particulate and gas phases, respectively. The highest concentration of D3, D4, D5, and D6 was 190, 460, 37,000, and 670 ng m−3, respectively. All cVMSs, especially D5, were higher in female dormitories than that in male dormitories. Emission rate from different sources of cVMSs in dormitories was calculated from a survey of the use of personal care products (PCPs) by students living in the dormitory during the sampling period. The mean emission rate (ER, mg·d−1) of D4 and D5 in male dormitories was 0.12 ± 0.01 and 0.49 ± 0.03 mg d−1, respectively, and that in female dormitories was 0.21 ± 0.05 and 46 ± 17 mg d−1, respectively. Then, we modified an existing mass balance model to predict the indoor air levels of D4 and D5 in both male and female dormitories based on the usage of PCPs. There was a good agreement for D4 and D5 concentrations in female dormitories between modeled and measured concentrations with the ratio of predicted to measured values to be 1.5 and 1.2, respectively, which indicated that use of PCPs was the main source of cVMSs in university dormitories.

SPE cartridges with a 3D graphene framework for extraction of triclosan in environmental water

Graphene framework obtained with a simple methodology as a high efficient sorbent in SPE cartridges for extraction of triclosan.

Rapid SPE – LC MS/MS analysis for atrazine, its by-products, simazine and S metolachlor in groundwater samples

A rapid analysis of pesticides using on-line Solid phase extraction LC MS/MS (Agilent Technology) was performed using only 2-mL water samples. SPE cartridge PLRP-s was used for the pre-concentration sample with methanol elution in back flush. Sensitive transitions and mass spectrometry conditions were optimized by direct infusion of individual standard solutions in a positive electrospray mode. Water samples were spiked with internal standards to compensate the matrix effect. The limit of quantification was calculated to be 20 ng L−1 using the standard deviation of blank analysis injected ten times and uncertainties were estimated at less than 20% on concentrations. This method was validated to study leaching water samples for which only small quantities of water were available.•Only 2 mL water sample was used.•Samples were filtered at 0.2 µm and spiked with individual standard.•Compounds were separated in an 18.5-min elution time using the dynamic MRM program.

Optimization of SPE method for the extraction of 12 neurotransmitters from sheep brain

Abstract The present paper presents our attempts concerning the development of an extraction method for catecholamines. In order to achieve the extraction of all the selected solutes using a single SPE cartridge, several types of support were tested, among them: cation exchange supports, hydrophilic-lipophilic supports, C18 supports and PGC supports. As unfortunately none of the supports tested offered us the possibility of carrying out the extraction of 12 catecholamines from our standard mixture, we chose to use a coupling of two different cartridges: Oasis HLB and PGC which together ensure the extraction of all the compounds of the mixture with good extraction yields and with simple protocols. The selected cartridges were successfully tested for the extraction of a sample spiked from sheep brain with the 12 catecholamines in our mixture. The SPE method that we have developed allows the purification of the samples (a significant part of the components of the matrix is eliminated during this step) and also a preconcentration of the samples.

A New LC-MS/MS Method for Simultaneous and Quantitative Detection of Bisphenol-A and Steroids in Target Tissues: A Power Tool to Characterize the Interference of Bisphenol-A Exposure on Steroid Levels.

Bisphenol A (BPA), an endocrine disruptor, may affect in situ steroidogenesis and alter steroids levels. The present work proposes a liquid chromatography tandem mass spectrometry method to simultaneously quantify BPA, 17β-Estradiol and testosterone in two target tissues: testis and visceral fat mass. Analytes were isolated and lipophilic impurities removed by two serial steps: liquid-liquid and solid phase extraction. All compounds were separated in a single gradient run by Kinetex F5 column and detected via multiple reaction monitoring using a triple quadrupole with a TurboIon electrospray source in both negative and positive modes. The method is selective and very sensitive. In the investigated concentration range, the linearity of the detector response is verified in both tissues. The use of specific SPE cartridges for affinity chromatography purification allows obtaining high percentages of process efficiency (68.0–83.3% for testicular tissue; 63.7–70.7% for visceral fat mass). Good repeatability and reproducibility was observed. The validated method can be efficiently applied for direct biological monitoring in testis and visceral fat mass from mice exposed to BPA. The quantification of compounds in a single assay could be achieved without a loss of sensitivity.

An amino-functionalized zirconium-based metal-organic framework of type UiO-66-NH2 covered with a molecularly imprinted polymer as a sorbent for the extraction of aflatoxins AFB1, AFB2, AFG1 and AFG2 from grain.

A surface imprinted polymer of type UiO-66-NH2@MIP was prepared by combining molecular imprinted polymers (MIPs) and an amino-functionalized zirconium-based metal-organic framework. Quercetin is used as the virtual template, UiO-66-NH2 acts as the carrier to which the monomer acrylamide can be copolymerized. The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It was used as a sorbent in a solid-phase extraction column. The extraction conditions were optimized. The adsorption capacities for aflatoxins AFB1, AFB2, AFG1 and AFG2 by this SPE and by the commercial SPE were compared. The method was successfully applied to quantify the aflatoxins in grain. Figures of merit include (a) good linearity (range from 0.20-45μg·kg-1) with R2 (range from 0.9986-0.9994), (b) low detection limits (90-130ng·kg-1), (c) acceptable reproducibility (1.0-5.9%; for n= 6), and (d) relatively satisfactory recovery rates (74.3-98.6%). The new sorbent has good selectivity and reusability. Graphical abstractUiO-66-NH2@MIPs were synthesized with modified UIO-66-NH2 as core and quercetin as pseudo template. A cartridge was prepared with the polymers as the sorbent, and its performance was compared with different commercial SPE cartridges.

Distribution of Antibiotic Residues in Non-medicated Poultry Feeds by High-Performance Liquid Chromatography with Diode-array Detection

This paper reports on the determination and distribution of antibiotic drugs in poultry feeds mainly the layers and growers mash obtained from Ogun state in Nigeria. Pulverized feed samples were initially treated with phosphate buffer adjusted to pH 7 and the analytes extracted in an SPE cartridge with ammonium hydroxide and methanol. The extract reconstituted in phosphate buffer was determined with high-performance liquid chromatography-diode array detection (HPLC–DAD). The analytical column was an XTerra MS C18 column, (4.6 mm x 100 mm, 3.5 µm) with mobile phases consisting of ultrapure water and acetonitrile mixed with 0.1% HCOOH in gradient elution mode. Data acquisition was achieved with AgilentChemStation Version B.040.01 SP1 while the analytes were completely separated under 10 minutes with good resolution and symmetric peaks. The high correlation coefficient (R2) values (> 0.998, excluding sulfadimethoxine) indicate a good correlation between analyte concentration and peak areas. Limit of detection (LOD) and quantitation (LOQ) was between 5.37 and 55.42 ng/g, and 17.91 and 184.74 ng/g, respectively. All the drugs exhibited high mean concentration values in the two feed types, and there was no significant difference between their means (p < 0.05). The results clearly showed that feed millers fortify their feeds with antibiotics mainly sulfonamides in varying amounts without declaring same, thus compromising security of poultry birds and human consumers.

Tandem Cation/Anion Exchange SPE Cartridge Method for Sample Desalting for HPLC Analysis of Soluble Dietary Fiber: Development and Inter-laboratory Validation.

In HPLC analyses of soluble dietary fiber, desalting processes using open, mixed-bed ion-exchange columns are time-consuming and labor-intensive. We developed and validated a simple desalting method using tandem cation/anion exchange SPE cartridges. We found that combining Bond Elut Jr SCX (upstream) and Bond Elut PSA (downstream) cartridges provided adequate desalting of test solutions. The developed method was then validated in an inter-laboratory study. Five test samples were prepared by mixing food matrixes with purified soluble dietary fiber and treated to generate solutions to test the desalting process. These solutions were then analyzed by eight different laboratories. The results demonstrated that the developed method is simple and reliable for desalting samples containing 140 to 945 mg/100 mL of soluble dietary fiber in preparation for HPLC analysis of soluble dietary fiber.

HPLC-MS/MS multiclass determination of steroid hormones in environmental waters after preconcentration on the carbonaceous sorbent HA-C@silica

In this study, a sensitive and multiclass method has been developed for analysis of three families of steroid hormones, i.e. progestins, oestrogens, androgens, by SPE-HPLC-ESI-MS/MS. The extraction efficiency of thermally condensed humic acids onto silica sorbent (HA-C@silica), here for the first time studied for multiclass enrichment of these sex hormones, was tested in different environmental waters (tap and river water, urban wastewater treatment plant effluent) spiked at the nanograms per litre levels (5–1000 ng L−1). Quantitative adsorption was achieved using 200 mg sorbent for preconcentration of 250–1000 mL sample, at the native pH (pH = 6.5–7.7). Elution was performed by two sequential fractions (methanol followed by acetonitrile), obtaining in all the matrices investigated satisfactory recoveries (71% to 124% for river waters and 71–113% for urban wastewater treatment plant effluent) and RSDs below 15% (n = 3). The high enrichment factors (up to 4000) coupled with high-performance liquid chromatography tandem mass spectrometry quantification (MRM mode) provided low limits of detection and quantification (a few ng L−1), that are suitable for environmental monitoring. Most of the analytes were detected in river water and in wastewater effluent samples (in the ng L−1 concentration range), attesting their environmental diffusion. The proposed method was extended to a fourth class, Glucocorticoids, achieving good results in river samples, by the same SPE cartridge and chromatographic run.

Targeting esterified oxylipins by LC–MS - Effect of sample preparation on oxylipin pattern

A major part of oxygenated metabolites of polyunsaturated fatty acids – i.e. eicosanoids and other oxylipins – in biological samples is found in the esterified form. Yet, their biological role is only poorly understood. For quantification of esterified oxylipins in biological samples current protocols mostly apply alkaline hydrolysis with or without prior lipid extraction to release oxylipins into their free form which can be subsequently quantified via liquid chromatography-mass spectrometry.Herein, a detailed protocol for precise and reproducible quantification of esterified oxylipins in plasma is presented comprising i) extraction of lipids and removal of proteins with iso-propanol, ii) base hydrolysis with potassium hydroxide to saponify lipids and iii) solid phase extraction of the liberated oxylipins on C8/anion exchange mixed mode material. Unequal extraction of internal standards and lipid classes during lipid extraction before hydrolysis led to distorted concentrations, emphasizing that the choice of solvent used in this step is important to minimize discrimination. Regarding the hydrolysis conditions, at least 30 min incubation at 60 °C is required with 0.1 M KOH in sample. Drying of the SPE cartridges is a critical parameter since autoxidation processes of PUFA, which are present in high concentrations after cleavage, lead to artificial formation of epoxy fatty acids. With the developed protocol, inter-day, intra-day and inter-operator variance was <21% for most oxylipins including hydroxy-, dihydroxy-, and epoxy-PUFA. The applicability of the developed methodology is demonstrated by investigating the changes in the oxylipin pattern following omega-3 fatty acid feeding to rats.

Evaluation of three-way fluorescence data-based for simultaneous determination of polycyclic aromatic hydrocarbons in tea infusion samples at sub-ppb levels by second-order multivariate calibration

In this work, two fast and low solvent-consumption analytical methods were evaluated for the determination of the eight polycyclic aromatic hydrocarbons (PAHs), commonly named PAH8, in tea infusion samples by second-order multivariate calibration. The analytical performance of the excitation-emission matrix fluorescence (EEMF) and retention time-emission spectra matrices (RTEFM) data was compared, and these methods were applied to the analysis of real samples. Better figures of merit were obtained with EEMF (detection limit: 0.05–0.22 μg L−1; analytical sensitivity: 14.8–68.9) than with those of RTEFM (detection limit: 1.5–12.1 μg L−1; analytical sensitivity: 0.4–4.9). However, in the analysis of tea infusion samples, the method based on RTEFM showed a lower prediction error (4.0–9.7%) and better accuracy than did the reference method. Finally, the proposed methods were applied to real tea infusions obtained from green and black tea samples containing PAHs at ng L−1 levels, including a preconcentration step on a C-18 SPE cartridge, demonstrating the analytical potential of these methods.