Carbon Black Solid-phase Extraction Research Articles

Untargeted Analysis of Short-Chain Peptides in Urine Samples Short Peptides Analysis.

Short-chain peptides have attracted increasing attention in different research fields, including biomarker discovery, but also a well-known analytical challenge in complex matrices due to their low abundance compared to other molecules, which can cause extensive ion suppression during mass spectrometric acquisition. Moreover, there is a lack of analytical workflows for their comprehensive characterization since ordinary peptidomics strategies cannot identify them. In this context, an enrichment strategy was introduced and developed to isolate and clean up short-chain peptides by graphitized carbon black solid phase extraction. For better coverage of peptide polarity, urine samples were analyzed by ultrahigh performance liquid chromatography by reversed-phase and hydrophilic interaction liquid chromatography. High-resolution mass spectrometry allowed the detection of the eluting peptides by data-dependent mode using a suspect screening strategy with an inclusion list; peptides were identified by a semiautomated workflow implemented on Compound Discoverer. The complementarity of the orthogonal separation strategy was confirmed by peptide identification, resulting in 101 peptides identified from the RP runs, and 111 peptides from the HILIC runs, with 60 common identifications.

Untargeted metabolomics of prostate cancer zwitterionic and positively charged compounds in urine

Prostate cancer, a leading cause of cancer-related deaths worldwide, principally occurs in over 50-year-old men. Nowadays there is urgency to discover biomarkers alternative to prostate-specific antigen, as it cannot discriminate patients with benign prostatic hyperplasia from clinically significant forms of prostatic cancer. In the present paper, 32 benign prostatic hyperplasia and 41 prostatic cancer urine samples were collected and analyzed. Polar and positively charged metabolites were therein investigated using an analytical platform comprising an up to 40-fold analyte enrichment step by graphitized carbon black solid-phase extraction, HILIC separation, and untargeted high-resolution mass spectrometry analysis. These classes of compounds are often neglected in common metabolomics experiments even though previous studies reported their significance in cancer biomarker discovery. The complex metabolomics big datasets, generated by the UHPLC-HRMS, were analyzed with the ROIMCR procedure, based on the selection of the MS regions of interest data and their analysis by the Multivariate Curve-Resolution Alternating Least Squares chemometrics method. This approach allowed the resolution and tentative identification of the metabolites differentially expressed by the two data sets. Among these, amino acids and carnitine derivatives were tentatively identified highlighting the importance of the proposed methodology for cancer biomarker research.

First determination of extracellular paralytic shellfish poisoning toxins in the culture medium of toxigenic dinoflagellates by HILIC–HRMS

Paralytic shellfish poisoning (PSP) toxins have received considerable attention in recent years because of their adverse effects on marine breeding industries and human health. In this study, a reliable method for the analysis of extracellular PSP toxins in the culture medium of marine toxic dinoflagellates was developed for the first time using graphitized carbon black–solid-phase extraction and hydrophilic interaction liquid chromatography–high-resolution mass spectrometry. The limit of quantification of typical PSP toxins in algal culture medium ranged from 0.072 μg/L to 0.151 μg/L under optimal conditions. Satisfactory absolute recoveries (87.5%–102.4%), precision (relative standard deviation ≤ 7.6%), and linearity (R2 ≥ 0.9998) were also achieved. In addition, the proposed method was applied to screen and determine the extracellular PSP toxins of two typical toxigenic dinoflagellates, Alexandrium minutum and Alexandrium tamarense. The total concentrations of the extracellular PSP toxins in A. minutum and A. tamarense over the whole growth period were within 2.0–735.5 and 2.0–19.2 μg/L, respectively. The concentrations of extracellular PSP toxins varied remarkably in the different growth stages of A. minutum and A. tamarense, and the contents of some extracellular PSP toxins were substantially higher than those of intracellular PSP toxins. Therefore, the extracellular PSP toxins released by toxigenic red tide algae cannot be ignored, and their environmental fate, bioavailability, and potential harm to aquatic environment need to be investigated in future studies.

New insights in hemp chemical composition: a comprehensive polar lipidome characterization by combining solid phase enrichment, high-resolution mass spectrometry, and cheminformatics.

The chemical composition of Cannabis sativa L. has been extensively investigated for several years; nevertheless, a detailed lipidome characterization is completely lacking in the literature. To achieve this goal, an extraction and enrichment procedure was developed for the characterization of phospholipids and sulfolipids. Firstly, a study on the solid-liquid extraction was performed, to maximize the recovery of the considered lipids; the best procedure consisted of a simple extraction with a mixture of methanol and chloroform (1:1, v/v). The hemp extracts were analyzed by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry and lipids were tentatively identified by Lipostar. To improve the number of identifications, an enrichment method, based on graphitized carbon black solid phase extraction, was evaluated to fractionate phospholipids and sulfolipids into separate eluates. Recovery and matrix effects of the procedure were determined on a mixture of standard lipids, containing representative compounds for each considered lipid class. The optimized method allowed the tentative identification of 189 lipids, including 51 phospholipids and 80 sulfolipids, in the first and second fractions, respectively. The detection of only 6 sulfolipids in the first fraction and 9 phospholipids in the second fraction proved the efficacy of the fractionation method, which also allowed the number of lipid identifications to be increased compared to the same procedure without enrichment, which scored 100 lipids. Finally, a semi-quantitative analysis permitted the hemp polar lipidome to be characterized. The results of this study allow knowledge of the hemp chemical composition to be improved with a detailed description of its phospho- and sulfolipid profiles. Graphical abstract.

Enrichment procedure based on graphitized carbon black and liquid chromatography-high resolution mass spectrometry for elucidating sulfolipids composition of microalgae

Microalgae have recently become a popular functional food due to their health benefits. Sulfolipids, a class of substances abundant in this matrix, have been reported to have interesting bioactivities, such as anti-carcinogenic activity. However, despite the potential interest in sulfolipids, a dedicated analytical method for their characterization is currently lacking but would significantly increase the coverage of sulfolipids with respect to the direct lipidomic analysis. To achieve this goal, in this work a procedure, based on graphitized carbon black solid phase extraction, was developed for clean-up and enrichment of sulfolipids (sulfoquinovosyldiacylglycerols and sulfoquinovosylmonoacylglycerols) and it was applied to spirulina (Arthrospira platensis) microalgae. A careful study of the solid phase extraction conditions was performed, first to maximize the recovery of reference standards, then to increase the total number of identified sulfolipids from the spirulina lipid extract. All samples were analysed by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry and lipids were tentatively identified by Lipostar, for a reliable lipid structure assignment. The developed method was compared to the direct lipidomic analysis without enrichment, to establish the enrichment efficiency in terms of number of identifications. From the comparison, the enrichment procedure proved better and allowed the tentative identification of 199 sulfolipids, which is the largest number reported so far for the Arthrospira platensis species. The described method was validated in terms of precision, accuracy, recovery, limit of quantitation and detection for two sulfolipids. Finally, a relative lipid quantitation based on peak area was carried out on the microalgae sample, which indicated nine abundant sulfolipids as representing ca. 60% of sulfolipids in spirulina microalgae.

Application and enantioselective residue determination of chiral pesticide penconazole in grape, tea, aquatic vegetables and soil by ultra performance liquid chromatography-tandem mass spectrometry

Penconazole is a typical triazole fungicide with wide use on fruits, vegetables, and tea plants to control powdery mildew. In the present study, an efficient graphite carbon black solid phase extraction (GCB-SPE) purification combined with chiral ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for determination of penconazole enantiomers in different complex matrices, including grape, tea, soil, lotus root, lotus leaf, lotus seed and hulls. The method was then applied to investigate the enantioselective dissipation of penconazole enantiomers in a real field experiment of grape and soil. As a result, a satisfactory separation of penconazole enantiomers on a chiral Lux Cellulose-2 column (150 mm × 2 mm i.d., 3 µm) was obtained with 0.1% formic acid in methanol and 10 mmol L−1 ammonium acetate in water (75/25, v/v) as mobile phase at 0.25 mL min−1. The enantiomer (+)-penconazole was firstly eluted, and (-)-penconazole was then eluted. The method showed reliable performances in linearity, recovery and precision, the recoveries of (+)-penconazole and (-)-penconazole in all of six matrices were between 70.5% and 121.0% with the relative standard deviations (RSDs) ranging from 0.8% to 23.6% at the low, medium and high spiked levels. The limits of quantitation (LOQs) of this method were lower than 0.0025 mg kg−1 in grape, soil and lotus root, 0.005 mg kg−1 in lotus leaf, lotus seed meat and lotus seed shell, and 0.0125 mg kg−1 in tea. Results of field trials indicated that (-)-penconazole degraded faster than its (+)-isomer in grape. While only a moderate stereoselectivity was observed in soil, with (-)-penconazole preferential degraded. The proposed method could be used to investigate enantioselective environmental behavior of penconazole enantiomers in complex matrices. And results in this study could provide useful information on realistic risk assessment of penconazole in grape.

High performance liquid chromatography tandem mass spectrometry determination of perfluorinated acids in cow milk

A new and sensitive liquid chromatography/electrospray-tandem mass spectrometric (LC/ESI–MS/MS) method for the determination of 12 perfluorinated compounds (PFCs) in cow milk is described. Milk samples were extracted with acetone and cleaned-up by a graphitized carbon black solid-phase extraction cartridge, optimizing the entire procedure by using a screening experimental design. LC/ESI–MS/MS was performed in negative ion mode using multiple reaction monitoring mode. The performance of the method was evaluated under the optimized conditions in terms of matrix effects, range of linearity, accuracy, and repeatability. For all compounds, linearity in matrix was observed in the range LOQ–10μgL−1, and coefficients of determination R2 ranged from 0.9982 to 0.9999. The analytical recoveries, relative to the isotopic internal standard, measured at 10 and 50ngL−1 were in the range of 91–105%, with relative standard deviations below 6% and method detection limit, based on the blank value +3 times the standard deviation of the blank, ranged from 0.5 to 3ngL−1. The final method developed was used to determine the concentration of PFCs in 15 retail milk samples. None of these compounds were detected in cow milk analyzed samples.

Validation of a Solid-Phase Extraction and Ultra-Performance Liquid Chromatographic Tandem Mass Spectrometric Method for the Detection of 16 Glucocorticoids in Pig Tissues

A sensitive analytical method has been developed and validated for simultaneous determination of 16 glucocorticoid (fluorometholone, flumethasone, triamcinolone, aldosterone, clobetasol propionate, methylprednisolone, fluocinolone acetonide, hydrocortisone, prednisone, dexamethasone, beclomethasone, prednisolone, budesonide, triamcinolone acetonide, fludrocortisone acetate, and cortisone) residues in pig tissues (muscle, liver, and kidney). These biosamples were hydrolyzed with beta-glucuronidase/arylsulfatase enzyme and passed through a Supelclean ENVI-Carb graphitized carbon black solid-phase extraction cartridge, followed by further purification using aminopropyl cartridges. Analytes were separated on an ultra-performance liquid chromatography BEH C18 column followed by tandem mass spectrometry (MS) with an electrospray ion source. The MS data acquisition was performed in the negative multireaction monitoring mode by a time-scheduled multireaction monitoring program. The assay for the 16 glucocorticoids were linear over the range of 1-250 microg/L for pork, liver, and kidney, with correlation coefficient >0.99. Estimated detection limits for the target analytes ranged from 0.03 to 0.30 microg/kg, and limits of quantitation ranged from 0.10 to 1.00 microg/kg. Recoveries of the glucocorticoids (spiked at levels of 0.4 and 2.0 microg/kg) ranged from 81.0 to 112.3%, with relative standard deviations between 2.6 and 16.6%.

Determination of the residues of 50 anabolic hormones in muscle, milk and liver by very-high-pressure liquid chromatography–electrospray ionization tandem mass spectrometry

A sensitive and specific method for determination of the residues of 50 anabolic hormones in muscle (pork, beef, shrimp), milk and pig liver was developed. Analytes were separated and acquired by liquid chromatography coupled with an electrospray ionization tandem mass spectrometer (LC–ESI–MS/MS). Target compounds were simultaneously extracted with methanol after enzyme hydrolysis, and purified using a graphitized carbon-black solid-phase extraction (SPE) and followed by NH 2 SPE cartridge. Limits of quantification were 0.04–2.0 μg kg −1; average recoveries were 76.9–121.3%; and the relative standard deviation was 2.4–21.2%. This method has been successfully applied in real samples.

Determination of cyanuric acid residues in catfish, trout, tilapia, salmon and shrimp by liquid chromatography–tandem mass spectrometry

In May 2007, investigators discovered that waste material from the pet food manufacturing process contaminated with melamine (MEL) and/or cyanuric acid (CYA) had been added to hog and chicken feeds. At this time, investigators also learned that adulterated wheat gluten had been used in the manufacture of aquaculture feeds. Concern that the contaminated feed had been used in aquaculture and could enter the human food supply prompted the development of a method for the determination of CYA residues in the edible tissues of fish and shrimp. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) was employed as a sensitive technique for the analysis of CYA in catfish, tilapia, salmon, trout and shrimp tissue. CYA was extracted from ground fish or shrimp with an acetic acid solution, defatted with hexane, and isolated with a graphitic carbon black solid-phase extraction column. Residues were separated from matrix components using a porous graphitic carbon LC column, and then analyzed with electrospray ionization in negative ion mode on a triple quadrupole mass spectrometer. Selective reaction monitoring was performed on the [M−H] − m/ z 128 ion resulting in the product ions m/ z 85 and 42. Recoveries from catfish, tilapia and trout fortified with 10–100 μg kg −1 of CYA averaged 67% with a relative standard deviation (R.S.D.) of 18% ( n = 107). The average method detection limit (MDL) for catfish, tilapia and trout is 3.5 μg kg −1. An internal standard, 13C 3-labeled CYA, was used in the salmon and shrimp extractions. Average recovery of CYA from salmon was 91% (R.S.D. = 15%, n = 18) with an MDL of 7.4 μg kg −1. Average recovery of CYA from shrimp was 85% (R.S.D. = 10%, n = 13) with an MDL of 3.5 μg kg −1.

Determination of organochlorine pesticides in sediment using graphitized carbon black solid-phase extraction and gas chromatography/mass spectrometry

An analytical method for the determination of organochlorine pesticides (OCPs) in sediment samples involves ultrasonic extraction, solid-phase extraction (SPE), gas-chromatography (GC)/electron-capture detection (ECD), and GC/mass spectrometry (MS). OCPs were extracted from sediment samples by ultrasonication in mixtures of n-hexane and acetone. Several SPE sorbents [Florisil, silica gel, C18, Oasis HLB, and graphitized carbon black (GCB)] were evaluated as means of preliminary purification. GCB SPE cartridges successfully removed major contaminants such as non-polar hydrocarbons when eluted with an acetone–acetonitrile mixture. After purification, the extract was preferentially screened using GC/ECD and confirmed and quantified using GC/MS. The percentage recovery of samples spiked with 10 or 100 ng/g OCP ranged from 73.9% to 106.0% with a relative standard deviation of 0.4–5.7%. Detection limits ranged from 0.002 to 0.005 ng/g for GC/ECD and from 0.03 to 0.50 ng/g for GC/MS detection. The linear dynamic range extended from 0.2 to 20 ng/g, with a correlation coefficient ( R 2) greater than 0.995. The method was validated using a standard reference material (SRM 1941b) and spiked sediment samples. Real sediment samples collected from a river near a Korean industrial area exhibited low levels of several OCPs when analyzed using this method.

The analysis of alkylphenol ethoxysulphonate surfactants by high-performance liquid chromatography, liquid chromatography–electrospray ionisation–mass spectrometry and matrix-assisted laser desorption ionisation–mass spectrometry

Commercial nonylphenol ethoxysulphonate and octylphenol ethoxysulphonate surfactant formulations, used for enhanced oil recovery, have been analysed by high-performance liquid chromatography (LC), liquid chromatography–electrospray ionisation–mass spectrometry (LC–ESI–MS) and matrix-assisted laser desorption ionisation–mass spectrometry (MALDI–MS). Mixed-mode C18/SAX and C8/SAX columns were used for both liquid chromatography and liquid chromatography–mass spectrometry analyses. Matrix-assisted laser desorption ionisation–mass spectra were obtained using either α-cyano-4-hydroxycinnamic acid or 2,5-dihydroxybenzoic acid as matrix with the addition of lithium chloride to simplify the mass spectra obtained. Data obtained from each method indicate that the nonylphenol ethoxysulphonate formulation has an ethoxymer (EO) chain length ranging from 2 to 13 EO units with an average of 6.26. This is in broad agreement with earlier studies, although the range was reported as 2–15. However, the data obtained suggest that the octylphenol ethoxysulphonate formulation has an ethoxymer chain length ranging from 1 to 8 EO units with an average chain length of 3.67. This is in contrast to earlier studies carried out by LC only, which suggested that the chain length ranged from 2 to 6 EO units with an average of 3.6. A method for the extraction of alkylphenol ethoxysulphonates from sea water using graphitised carbon black solid-phase extraction cartridges has also been developed.

Extraction and isolation of linear alkylbenzenesulfonate and its sulfophenylcarboxylic acid metabolites from fish samples.

Linear alkylbenzenesulfonate (LAS) is the most widely used synthetic surfactant. In fish, assessment of the environmental risk and investigation of the biotransformation behavior of LAS require compound-specific methods for extraction and isolation of LAS and its biotransformation products, sulfophenylcarboxylic acids (SPC). Matrix solid-phase dispersion (MSPD) extraction with subsequent ion-pair liquid-liquid (IP-LL) partitioning of the extract was a time-efficient sample preparation method for analysis of LAS. The recovery of parent LAS from spiked fish exceeded 70%, and the limit of quantitation ranged around 0.2 mg.kg-1 corresponding to 0.6 mumol.kg-1. In a simultaneous determination of LAS and SPC in fish, the analytes were MSPD extracted in different fractions. The target compounds were separated from the sample matrix by protein precipitation and subsequent isolation of (a) SPC by graphitized carbon black solid-phase extraction of the supernatant and (b) parent LAS by IP-LL partitioning of the pellet obtained after protein precipitation. The recoveries of the model compounds C12-2-LAS and C4-3-SPC were 84 +/- 6 and 65 +/- 11%, respectively. The use of C3-3-SPC as an internal standard corrected for the loss of the biotransformation product during sample workup. The suitability of both methods was demonstrated by analyzing fish containing LAS and SPC incurred during aqueous exposure.

Rapid screening for organochlorine and organophosphorus pesticides in milk using C18 and graphitized carbon black solid phase extraction cleanup

A rapid, multiresidue, solid phase extraction (SPE) technique for the isolation and gas chromatographic determination of organochlorine and moderately polar organophosphorus pesticide residues in milk is described. Milk is sonicated with an acetonitrile‐acetone‐methanol mixture and centrifuged. The supernatant is subjected to a cleanup using both C18 and graphitized carbon black SPE columns. The pesticide residues are determined by gas chromatography with electron capture and flame photometric detection. The method required minimal volumes of solvent and resulted in the production of minimal volumes of hazardous waste.

Determination of Nonylphenol and Octylphenol Ethoxylates in Effluent by Liquid Chromatography with Fluorescence Detection

Abstract A robust liquid chromatographic (LC) method with fluorescence detection is described for the simultaneous determination of the nonionic surfactants nonylphenol ethoxylates (NPEO) and octylphenol ethoxylates (OPEO) in effluent samples from sewerage treatment plants. The cleanup procedure uses graphitized carbon black solid-phase extraction cartridges. A subsequent derivatization step removes matrix interferences that are no longer fluorescent after acetylation. The efficiency of the method is monitored by inclusion of a surrogate compound designed and synthesized specifically for this purpose. The limit of reporting for the method is 5 μg/L for 100 mL effluent samples. Studies on confirmation of identity of NPEO and OPEO by electrospray LC/mass spectrometry are described.