Hydroxylated polycyclic aromatic hydrocarbons are metabolites of persistent organic pollutants which are formed during the bioactivation process of biological matrices and whose toxicity is being ...studied. The aim of this work was the development of a novel analytical method for the determination of these metabolites in human tissues, known to have bioaccumulated their parent compounds. Samples were treated by salting‐out assisted liquid‐liquid extraction and the extracts were analyzed by ultra‐high performance liquid chromatography coupled to mass spectrometry with a hybrid quadrupole‐time‐of‐flight analyzer. The proposed method achieved limits of detection in the 0.15–9.0 ng/g range for the five target analytes (1‐hydroxynaphthalene, 1‐hydroxypyrene, 2‐hydroxynaphthalene, 7‐hydroxybenzoapyrene, and 9‐hydroxyphenanthrene). The quantification was achieved by matrix‐matched calibration using 2,2´‐biphenol as internal standard. For all compounds, relative standard deviation, calculated for six successive analyses, was below 12.1%, demonstrating good precision for the developed method. None of the target compounds was detected in the 34 studied samples. Moreover, an untargeted approach was applied to study the presence of other metabolites in the samples, as well as their conjugated forms and related compounds. For this objective, a homemade mass spectrometry database covering 81 compounds was created and none of them was detected in the samples.
The determination of 15 pyrethroids in soil and water samples was carried out by gas chromatography with mass spectrometry. Compounds were extracted from the soil samples (4 g) using solid–liquid ...extraction and then salting‐out assisted liquid–liquid extraction. The acetonitrile phase obtained (0.8 mL) was used as a dispersant solvent, to which 75 μL of chloroform was added as an extractant solvent, submitting the mixture to dispersive liquid–liquid microextraction. For the analysis of water samples (40 mL), magnetic solid‐phase extraction was performed using nanocomposites of magnetic nanoparticles and multiwalled carbon nanotubes as sorbent material (10 mg). The mixture was shaken for 45 min at room temperature before separation with a magnet and desorption with 3 mL of acetone using ultrasounds for 5 min. The solvent was evaporated and reconstituted with 100 μL acetonitrile before injection. Matrix‐matched calibration is recommended for quantification of soil samples, while water samples can be quantified by standards calibration. The limits of detection were in the range of 0.03–0.5 ng/g (soil) and 0.09–0.24 ng/mL (water), depending on the analyte. The analyzed environmental samples did not contain the studied pyrethroids, at least above the corresponding limits of detection.
An analytical procedure is proposed for determining three cyanotoxins (microcystin RR, microcystin LR, and nodularin) and two phycotoxins (domoic and okadaic acids) in seawater and algae-based food ...supplements. The toxins were first isolated by a salting out liquid extraction procedure. Since the concentration expected in the samples was very low, a dispersive liquid-liquid microextraction procedure was included for preconcentration. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (80 mg) was used as green extractant solvent and acetonitrile as disperser solvent (0.5 mL) for a 10 mL sample volume at pH 1.5, following the principles of green analytical chemistry. Liquid chromatography with electrospray ionization and quadrupole time of flight-mass spectrometry (LC-Q-TOF-MS) was used. The selectivity of the detection system, based on accurate mass measurements, allowed the toxins to be unequivocally identified. Mass spectra for quadrupole time of flight-mass spectrometry (Q-TOF-MS) and Q-TOF-MS/MS were recorded in the positive ion mode and quantification was based on the protonated molecule. Retention times ranged between 6.2 and 17.9 min using a mobile phase composed by a mixture of methanol and formic acid (0.1%). None of the target toxins were detected in any of the seawater samples analyzed, above their corresponding detection limits. However, microcystin LR was detected in the blue green alga sample.
A rapid and simple procedure is reported for the determination of six ethylene glycol ethers in cleaning products and detergents using gas chromatography with mass spectrometry. The analytes were ...extracted from 2.0 g samples in acetonitrile (3 mL) and the extract was submitted to a clean‐up step by QuEChERS method, using a mixture containing 0.3 g magnesium sulfate, 0.15 g primary/secondary amine, and 0.05 g C18. The clean acetonitrile extract (1 μL) was injected into the chromatographic system. No matrix effect was observed, so the quantification of the samples was carried out against external standards. Detection limits were in the range 3.0–27 ng/g for the six ethylene glycol ethers. The recoveries obtained, using the optimized procedure, were in the 89.4–118% range, with relative standard deviations lower than 14%. Twenty‐three different household cleaning products, including glass cleaner, degreaser, floor, softeners, and clothes and dishwashing detergents, were analyzed. Large interindividual variations were observed between samples and compounds.
-Nucleobases, nucleosides and nucleotides are determined in food yeasts-Hydrophilic interaction liquid chromatography using a zwitterionic phase is applied-High-resolution mass spectrometry based on ...quadrupole and time-of-flight is used-Sample treatment is based on the lysis of yeast using an homogenizer-Pellet and supernatant were differentiated with low speed centrifugation
Hydrophilic interaction liquid chromatography using a zwitterionic phase, coupled with high-resolution mass spectrometry based on quadrupole and time-of-flight mass analyser (HILIC-Q-TOF-MS) is applied for the determination of four nucleobases (adenine, thymine, guanine and uracil), five nucleosides (adenosine, 5´-methyluridine, guanosine, cytidine and uridine) and five nucleotides (cytidine 5´-monophosphate, uridine 5´-monophosphate, adenosine 5´-monophosphate, inosine 5´-monophosphate and guanosine 5´-monophosphate) in food yeasts. Sample treatment based on the lysis of yeast using an ultra-turrax homogenizer allows the pellet and supernatant to be differentiated with low-speed centrifugation (1000 g). The pellet contains the nucleus (nuclear fraction), while the supernatant contains, among others, the organelles present in the cytoplasm (cytoplasmatic fraction). Both fractions were treated with perchloric acid in order to extract nucleobases, nucleosides and nucleotides and analysed by HILIC-Q-TOF-MS. The method was validated following international guidelines and detection limits were in the 2.5–22 ng mL−1 range (62–550 ng g−1, for 200 mg yeast). Five different Saccharomyces cerevisiae food yeasts were analysed and nucleotide concentrations of 0.6–570 µg g−1 and 5.6–924 µg g−1 were found in the nuclear and cytoplasmatic fractions of all samples. Nucleosides and nucleobases were not found in any sample.
Graphical Abstract
Display omitted .
Pteridines are a group of compounds synthesised by many living organisms that are involved in the metabolism of many cofactors and vitamins. Their concentration in biological fluids may be altered by ...various pathologies such as cancer or inflammatory bowel disease, urine being the main route of excretion. In this study, three lumazines and ten pterins were analysed in their native oxidation state using high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Their high concentration in urine samples and their good ionisation behaviour allow the use of the dilute-and-shoot method by simple filtration of the urine prior to chromatographic analysis. The final method offers excellent linearity, sensitivity and precision parameters, and a total of 135 urine samples were analysed from patients with some relevant information such as faecal calprotectin (FCP) levels, common diseases such as diabetes, hypertension and dyslipidaemia and immunological diseases such as inflammatory bowel disease (IBD). The pteridine profile was related to FCP levels without showing any correlation. In addition, pteridine levels were compared between healthy subjects and IBD, diabetic, hypertensive and dyslipidaemic patients, and significant differences were found between the two groups for some of the pteridines.
Nitrosamines (NAs), which are catalogued as carcinogenic compounds, may be present in meat products due to the conversion of nitrites and as result of migration from elastic rubber nettings used. A ...method based on ultrasonic assisted extraction coupled with dispersive liquid–liquid microextraction as sample treatment and gas chromatography-mass spectrometry as separation and detection technique was proposed for the determination of twelve NAs in cooked ham samples. The method was validated by evaluating linearity (0.5–1000 ng g−1), matrix effect, sensitivity (detection limits were between 0.15 and 1.4 ng g−1) and precision, which was below 12%. Five NAs were found in the samples with levels ranging from not quantifiable to 40 ng g−1. The effect of the elastic rubber nettings on the nitrosamine content of meat was evaluated by comparing the levels found in products made with several plastics or thread in the presence of additives.
The present work is focused on the development of an analytical platform to elucidate the metabolic pathway of PTSO from onion, an organosulfur compound well-known for its functional and ...technological properties and its potential application in animal and human nutrition. This analytical platform consisted of the use of gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography quadrupole with time-of-flight MS (UHPLC-Q-TOF-MS) in order to monitor volatile and non-volatile compounds derived from the PTSO. For the extraction of the compounds of interest, two different sample treatments were developed: liquid-liquid extraction (LLE) and salting-out assisted liquid-liquid extraction (SALLE) for GC-MS and UHPLC-Q-TOF-MS analysis, respectively. Once the analytical platform was optimised and validated, an in vivo study was planned to elucidate PTSO metabolisation, revealing the presence of dipropyl disulfide (DPDS) in liver samples with concentrations between 0.11 and 0.61 µg g
. The DPDS maximum concentration in the liver was observed at 0.5 h after the intake. DPDS was also present in all plasma samples with concentrations between 2.1 and 2.4 µg mL
. In regard to PTSO, it was only found in plasma at times above 5 h (0.18 µg mL
). Both PTSO and DPDS were excreted via urine 24 h after ingestion.
•In situ acetylation of the alkylphenols provided a good GC separation.•Magnetic nanoparticles functionalized with oleic acid efficiently preconcentrate the APs.•Most of the baby food samples ...analyzed were free from the studied APs.
Magnetic solid phase extraction (MSPE) with cobalt ferrite nanoparticles coated with oleic acid is described for the determination of alkylphenols (APs), 4-tert-butylphenol (TBP), 4-pentylphenol (PP), 4-hexylphenol (HP), 4-tert-octylphenol (TOP), 4-n-octylphenol (OP) and 4-nonylphenol (NP) in baby foods using gas chromatography with mass spectrometry (GC–MS). Prior to MSPE, the sample was treated with trichloroacetic acid, and the APs derivatized with acetic anhydride. Parameters affecting the extraction efficiency: amount of magnetic nanoparticles, extraction time and desorption conditions, were optimized. The enriched phase obtained was evaporated to dryness and the residue reconstituted in 50μL of methanol, 1μL of which was injected into the GC–MS. Samples were quantified applying matrix-matched calibration and using 2-chloro-5-bromoanisole as surrogate standard. The analysis of 0.5g of sample provided detection limits in the 0.4–1.7ngg−1 range. Some samples contained APs at levels of between 3ngg−1 for HP and 122ngg−1 for TOP.
Ranitidine drug products were recently recalled because they contained carcinogenic nitrosamines (NAs), such as N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA). This episode emphasises ...the importance of developing analytical methods to determine NAs in this type of product. This study describes the development and validation of an analytical method for the determination of nine NAs (NDMA, N-nitrosomethylethylamine (NEMA), NDEA, N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR) N-nitrosodi-n-propylamine (NDPA) N-nitrosopiperidine (NPIP), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPhA)) in ranitidine drug samples using a combination of microextraction and gas chromatography-mass spectrometry. The procedure involved the dissolution of 1 g of sample in 10 mL of water. For the dispersive liquid-liquid microextraction, 0.5 g of NaCl was added to this aqueous solution, followed by a mixture containing 0.5 mL methanol as dispersant and 150 μL chloroform as extractant solvent. The recovered organic phase was injected into the GC-MS system and a 20 min oven programme was applied. Quantification limits were in the 0.21–21 ng g−1 range, corresponding the lower limit to NDPhA and the higher to NDMA. Relative standard deviations lower than 12% were achieved in all cases, which indicates the adequate precision of the method. Seven pharmaceutical products containing two different amounts of ranitidine (150 and 300 mg) were analysed. None of the samples contained NEMA, NDEA, NPYR, NMOR, NDPA or NPIP, while NDMA, NDBA and NDPhA were found in three products.
Display omitted
•Nitrosamines are determined as impurities in ranitidine pharmaceutical products.•DLLME coupled with GC-MS provides high sensitivity and rapid sample preparation.•Three of seven commercial pharmaceuticals were contaminated with NDMA, NDBA or NDPhA.
PDF
