Detection of banned antibacterial growth promoter in animal feed by enzyme-linked immunosorbent assay: Method validation according to the Commission Decision 2002/657/EC criteria

An enzyme-linked immunosorbent assay (ELISA) test has been applied for the qualitative screening analysis of virginiamycin and bacitracin in feedingstuffs at level of 1 mg/kg. The ELISA validation study was performed according to the Commission Decision 2002/657/EC criteria established for qualitative screening methods in food. In this regard, the following parameters were determined: detection capability (CCβ), specificity and ruggedness. The resulted CCβ values were <1 ppm for both molecules and no interferences from matrix effects were observed.Slight variations of some critical factors in the sample pre-treatment and clean up were deliberately introduced for ruggedness evaluation and they did not result in any negative effect on the detection of virginiamycin, while ruggedness evaluation on the detection of bacitracin showed some critical factors. The proposed method is suitable for qualitative screening analysis of virginiamycin and bacitracin in conformity with the current EC performance requirements.     

Multiclass determination of 27 antibiotics in honey

A multiclass approach for the screening and confirmation of antimicrobial substances in honey has been developed and validated according to Commission Decision 2002/657/EC. A total of 27 basic drugs belonging to sulfonamide, nitroimidazole and quinolone families were determined. Sample preparation consisted in an acidic hydrolysis of honey followed by a double purification step (defatting and strong cation exchange solid-phase extraction). Instrumental determination was performed by liquid chromatography tandem mass spectrometry (LC–MS/MS) operating in positive electrospray ionization mode. Chromatographic separation was performed on a Poroshell 120 EC-C18 column (100 × 3.0 mm, 2.7 μm) using a gradient with acetonitrile and water both containing 0.1% of formic acid. The method was validated in the range 0.1–10 μg kg⁻¹ evaluating selectivity, linearity, precision, trueness, matrix effect, decision limits and detection capabilities. Satisfactory performances were obtained for all the analytes, although important differences were observed in function of the honey type.The procedure was applied to the analysis of 74 honey samples of different botanical origins and geographical provenience collected from the Italian market. In nine honeys (12%) trace levels of sulfonamides were confirmed. The found levels (lower than 2 μg kg⁻¹) do not raise concerns with respect to the public health.     

Development and validation of a new qualitative ELISA screening for multiresidue detection of sulfonamides in food and feed

An indirect competitive enzyme-linked immunosorbent assay (ELISA) to screen sulfonamide residues in food (muscle, eggs, milk and honey) and feed has been developed and validated according to Commission Decision 2002/657/EC. The immunoreagents were appropriately produced to detect a wide range of sulfonamide antibiotic congeners, obtaining half-maximum inhibition concentration (IC₅₀) values below 10 μg L⁻¹ for 11 sulfonamides widely used in veterinary practices. Taking into account the complexity of involved matrices, specific sample preparation protocols have been optimised combining high method throughput with low detectable concentrations. Accordingly, depending on the congener, the obtained detection capabilities (CCβs) were lower or equal to 20 μg kg⁻¹ (muscle, eggs and milk), 10 μg kg⁻¹ (honey) and 2 mg kg⁻¹ (feed). Finally the developed qualitative test was applied to real samples collected within the official monitoring programmes: results exceeding the established screening cut-off were re-analysed with a suitable confirmatory method. The presence of one or more sulfonamides was found in all the suspect screening samples thus demonstrating that the proposed ELISA can be successfully applied in class-specific detection of sulfonamides in food and feed.     

Analysis of tetracyclines in chicken tissues and dung using LC–MS coupled with ultrasound-assisted enzymatic hydrolysis

The accurate measurement of tetracycline antibiotics (TCs) in complex matrices related to chicken raising is important for food control. It was experimentally demonstrated that conventional acid deproteination methods led to high losses of TCs because TCs were strongly bounded to protein aggregates. To eliminate this effect, an ultrasound-assisted enzymatic hydrolysis method was developed to break the three-dimensional structures of proteins and release the bound TCs. This not only significantly improved the recovery of TCs but also shortened the pretreatment time from 960 to 6 min. By combining this new deproteination method and a solid phase extraction clean-up, a suitable sample preparation was achieved for the analysis of TCs with LC–MS/MS. The established LC–MS/MS analysis of TCs provided good linear ranges in the order of 20–1000 μg L⁻¹ with the limits of detection ranging from 1.05 to 3.50 μg L⁻¹ for the tested TCs. The new method yielded recoveries of TCs in spiked chicken-related samples as high as 89.1%–102.4%, being much higher than those (23.5%–36.2%) obtained using the acid deproteination process. When this method was used to analyze five practical samples of manures, it gave residual concentrations of 0.9–4.2 and 1.3–4.0 mg kg⁻¹ for oxytetracycline and chlortetracycline, respectively.     

A sensitive HPLC-MS/MS screening method for the simultaneous detection of lupine,pea, and soy proteins in meat products

The use of vegetable proteins in various types of meat products is common practice. In order to control food specifications, also with regard to food fraud and allergenic potential, a reliable detection of these additives is required. Here, a sensitive screening method for the simultaneous detection of lupine (Lupinus angustifolius), pea (Pisum sativum), and soy (Glycine maxima) in meat products applying High Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS) has been developed. After protein extraction and tryptic digestion, 3 to 4 marker peptides for each plant species were measured by HPLC-MS/MS. For matrix calibration, emulsion-type sausages with 0, 1, 6, 32, 160, 800, and 4000 mg/kg raw legume protein isolates/legume flour were produced. The mentioned legumes were detectable in sausages with concentrations of 6 mg/kg legume protein isolates/legume flour or greater. High correlation coefficients (R² > 0.999) between the peak areas of the mass transitions of the marker peptides and the contents of legume proteins in the meat products were obtained. The limits of detection (LODs) of the method were about 5 mg/kg meat product for pea protein, 4 mg/kg meat product for soy protein, and 2 mg/kg meat product for lupine protein. No false-positive or false-negative results were recorded. The applicability of the described method was tested by analyzing commercial meat products with and without added legume proteins.     

Determination of methenamine residues in edible animal tissues by HPLC-MS/MS using a modified QuEChERS method: Validation and pilot survey in actual samples

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was developed for the determination of methenamine in edible animal tissues by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Samples were extracted with acetonitrile, and cleaned with anhydrous sodium sulfate and primary secondary amine (PSA) sorbent. An isotope dilution mass spectrometry technique was applied to compensate for matrix effect. The separation was performed on a HILIC column, and the mobile phase composed of acetonitrile-0.1% of formic acid and 5.0 mmol/L of ammonium acetate in water. The method showed a linear relationship in the range of 1.0–20.0 μg/L for methenamine, and the determination coefficients (R²) ranged from 0.9939 to 0.9995. The limit of detection (LOD) and quantification (LOQ) for methenamine in animal tissues sample was 1.5 μg/kg and 5.0 μg/kg, respectively. The average recoveries were 86.7–109.5% at spiked levels of 5.0, 25.0, 100.0 μg/kg. The intra-day precision ranged from 2.6 to 7.0%, and the inter-day precision ranged from 4.9 to 11.3%. The validated method was successfully applied to determination of methenamine in swinish muscle, kidney and liver.     

Determination of fumonisin B1 in bovine milk by LC–MS/MS

The aim of the present work was to develop a sensitive and selective method for identification and quantification of fumonisin B1 (FB1) in bovine milk. FB1 was isolated by immunoaffinity column and was detected using liquid chromatography coupled with tandem mass spectrometry in positive electrospray ionization (ESI+).The LOQ of the method was 0.1 μg/kg that was lower than the others reported in the literature. The high coefficient of determination (R² > 0.99) obtained in the range of 0.1–10.0 μg/kg, the good recovery (84%) and relative standard deviation (7%) of the proposed method ensure correct fumonisin detection in milk even at relatively low concentrations.The developed method was applied on different commercial samples in order to test its efficacy. FB1 was found above the LOQ in eight out of 10 samples analysed and the average level of contamination found was 0.26 μg/kg.     

The rapid selecting of precursor ions and product ions of thirty-four kinds of pesticide for content determination by GC–EI/MS/MS

Pesticide residues caused great threat to human body health, and all countries protected the health of human body by specifying its upper limit. However, pesticide residues were generally very low, similar to trace analysis and as low as millionth or less, the content determination of pesticide residues was a troublesome problem. With the application and promotion of tandem mass spectrometry, it was able to do trace analysis. GC–EI/MS/MS was a common method for the determination of pesticide residues. The multiple reaction monitoring (MRM) mode was the most common quantitative method used in GC–EI/MS/MS. It has the characteristics of high sensitivity, good reproducibility, high accuracy, strong anti-interference and high ion flux. Multiple-twin precursor ions, product ions and collision energy of thirty-four pesticides were provided for MRM. It could play an important role in developing MRM method for the quantifying of 34 kinds of pesticide. Meanwhile, the development of MRM method for the quantifying of other compounds could also refer to this paper.     

Molecular Characterization of Hydrotreated Atmospheric Residue Derived from Arabian Heavy Crude by GC FI/FD TOF MS and APPI FT-ICR MS

High resolution mass spectrometry in combination with distillation and SARA fractionation provides us an opportunity for in-depth understanding about the hydrotreating process at the molecular level. In this study, the atmospheric residue derived from Arabian heavy crude and its hydrotreated products were initially subjected to distillation and SARA fractionation. The saturates were characterized by GC FI/FD TOF MS. The aromatics and resins were characterized by APPI FT-ICR MS. Compositional changes of different compounds (paraffins, naphthenes, aromatic hydrocarbons, and heteroatomic compounds) contained in different distillates (vacuum gas oil, vacuum residue) were obtained. More detailed knowledge about the hydrotreating process was achieved.     

GC/MS分析油酸乙二醇单酯的组成

用硅胶玻璃色谱柱吸附样品,采用溶剂梯度洗脱的方法从油酸乙二醇酯添加剂中分离出油酸乙二醇单酯,再用ＧＣ／ＭＳ详细地分析了油酸乙二醇单酯的组成和结构,并通过油酸乙二醇单酯的结构推断出油酸原料中所含酸的种类,从ＧＣ／ＭＳ分析领域给出了分析油酸乙二醇单酯的较好方法     

Determination of difenoconazole residue in tomato during home canning by UPLC-MS/MS

The effects of different steps in canned tomato paste production on difenoconazole levels were investigated. And residues were determined by using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after each stage including washing, peeling, homogenization, simmering and sterilization. Results showed that washing and peeling process reduced the amount of residue by 99%, whereas homogenization, simmering, and sterilization process had little effects on the removal of difenoconazole residue. Difenoconazole mostly remained in tomato skin, therefore, washing and peeling significantly reduced difenoconazole, especially peeling resulted in nearly 94.6% difenoconazole removal from tomatoes, with the processing factor of peeling at < 0.05.     

Study on the fast pyrolysis of oil sludge by PY-GC/MS

Oil sludge is an organic solid waste produced in oilfield exploitation, transportation, and petroleum refineries. Pyrolysis is one of the most effective ways to reduce oil sludge and realize energy re-utilization. In the present work, the amounts and distributions of pyrolysis products at different reaction time and with different amounts of NiO catalyst were investigated with PY-GC/MS. The results suggest that the degree of the pyrolysis reaction increased and more macromolecules were degraded into smaller hydrocarbons as the reaction time prolonged. The addition of NiO catalyst effectively promoted the conversion of aromatic and paraffin products, and increased the production of small molecule olefins.     

Analytical Profile of Organo-nitrogen Compounds in Gulf Coast Refined Fuels by GC/MS

This study examines the composition of two samples of crude fuels originating from the Gulf Coastal areas of the United States. Both nitrogen-containing basic compounds as well as non-basic hydrocarbon compounds were evaluated for presence and relative amount in these two samples. The extractions of the basic nitrogenous compounds were achieved with weak acid extractions. The basic nitrogenous compounds, due to emulsification, formed two distinct fractions. The nitrogenous based-compounds were comprised of pyridines, quinolines, tetrahydroquinolines, indoles, and carbazoles to varying amounts. The hydrocarbon content in each of the two fuels analyzed was found to contain mostly naphthols.     

Analytical Profile of Organo-nitrogen Compounds in Gulf Coast Refined Fuels by GC/MS

Abstract

This study examines the composition of two samples of crude fuels originating from the Gulf Coastal areas of the United States. Both nitrogen-containing basic compounds as well as non-basic hydrocarbon compounds were evaluated for presence and relative amount in these two samples. The extractions of the basic nitrogenous compounds were achieved with weak acid extractions. The basic nitrogenous compounds, due to emulsification, formed two distinct fractions. The nitrogenous based-compounds were comprised of pyridines, quinolines, tetrahydroquinolines, indoles, and carbazoles to varying amounts. The hydrocarbon content in each of the two fuels analyzed was found to contain mostly naphthols.     

Characterization of n-alkanes and n-alkylbenzenes from different sediments by Py-GC/MS

Sediments from a selection of source were systematically pyrolysed in two kinds of experiments (single stage and multi-stage) using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) in order to investigate the n-alkanes and n-alkylbenzenes obtained in pyrolysate volatiles. Our results show that the n-alkanes can be detected by Py-GC/MS, this may be related to the high molecular cleavage of the diverse organic matter constituents under the thermal conditions. And n-alkylbenzenes were also detected, probably produced in connection with n-alkanes, or products of their subsequent evolution. In addition, both sets of experimental results suggested that organic matter adsorbed in modern sediments differs from that in source rocks where organic matter is bound in kerogen, thus the primary stage of products in modern sediments is earlier than that in source rocks.     

GC/MS法测定工业污水中有机物

采用液-液萃取法对炼油废水中有机物样品进行处理，对分离条件做了探讨。用GC／MS法进行测定并定性分析。     

芳烃生产新工艺中原料和产物的GC／MS分析

利用ＧＣ／ＭＳ联用法对芳烃生产新工艺中的原料和产物进行了分析，其中原料定出２６个组份，产物定出２４个组份，并用面积归一化法对原料和产物中的各个组份的含量进行了定量计算，为芳烃生产新工艺中的新型芳构化催化剂ＡＦ－５的推广运用提供了科学依据。     

Rapid identification of Tetragenococcus halophilus and Tetragenococcus muriaticus,important species in the production of salted and fermented foods,by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)

Tetragenococcus halophilus and Tetragenococcus muriaticus are moderately halophilic lactic acid bacteria, characteristically grouped as tetrads arrangement of cocci, are found in fermentation period of various salted and fermented foods, such as soy sauce and fish sauce. T. halophilus may be one of the most important contributor to the salted and fermented products. In this study, a MALDI-TOF MS method was developed for the rapid identification of T. halophilus and T. muriaticus. Before the MS analysis, the cells were washed with ethanol and treated with formic acid, then ionized with a matrix: α-cyano-4-hydroxycinnamic acid. The MS peak similarity in each of eleven stock strains of the same species was higher than 78%, and the similarity of the two different species was about 36%. The similarity between the two Tetragenococcus and other lactic acid cocci (LAC) including Tetragenococcus koreensis and Tetragenococcus solitarius, was only 24% and less. The MALDI-TOF MS results were obtained in 30 min, from colonies grown on agar plates for viable counts. The MALDI-TOF MS method is a very rapid, simple and accurate method for discrimination of T. halophilus from T. muriaticus and other LAC, and therefore will be useful for quality control in production of salted and fermented food.     

Coupling SPE on-line pre-enrichment with HPLC and MS/MS for the sensitive detection of multiple allergens in wine

Mass spectrometry (MS) represents an essential tool in proteomics studies, in the last years also exploited for monitoring allergens contamination in food products. Milk and egg are renowned allergens often used as fining agents to promote clarification of wines, therefore any residual amount in the end-products could represent a menace for allergic individuals. In view of this, it is of paramount importance to have at disposal sensitive analytical methods able to detect traces of milk and egg allergens in food. In this work we describe the upgrade and the optimization of an analytical workflow based on the use of a pre-enrichment column coupled with HPLC separation and MS/MS detection for the selective and sensitive detection of milk and egg allergens in white wine. Two different sample pre-treatments based on the use of mass cut-off filters or size exclusion cartridges were evaluated and compared, before tryptic digestion and LC-SRM-MS/MS analysis of the resulting peptides mixture. The devised UF based method coupled with peptide on-line pre-enrichment enabled to reach the lowest LODs down at 0.036 μg/mL and 0.05 μg/mL for egg and milk allergens respectively, proving to be the most sensitive strategy for monitoring allergens contamination in wine.     

A Study on NMR and GC/MS Spectra of the Isomers of Linear Hexyl Naphthalene

The GC/MS and NMR analysis of the reaction products of naphthalene with 1-bromohexane were reported. The products obtained were suggested to have six isomers of linear hexylnaphthalene and the structure of each isomer was determined by GC/MS and NMR spectra. For the first time, the unique chemical shift data were obtained. The content of each isomer calculated by ¹H NMR and ¹³C NMR spectra was consistent with that by GC/MS spectra, which confirmed the accuracy of NMR data.