Graphene and graphene like 2D graphitic carbon nitride: Electrochemical detection of food colorants and toxic substances in environment

Excessive consumption of substances such as food colorants, exposure to doses of metal ions, antibiotic residues and pesticides residues above maximum tolerance limit have a detrimental effect on human health. Hence in detecting these harmful substances, the development of sensitive, selective and convenient analytical tools is an essential step. Graphene and graphene like 2D graphitic carbon nitride have shown great promise in the development of electrochemical sensors for determining the levels of these substances in different samples. In this paper, graphene and graphene like 2D graphitic carbon nitride applications on the determination of various food colorants in foods and drinks such as azo dyes (tartrazine, allura red, amaranth, carmine and sunset yellow); metal ions contaminants, antibiotic and pesticide residues in the environment are reviewed.     

Towards a comprehensive exploitation of agrofood residues: Olive tree – olive oil as example

A comprehensive use of residues from the agrofood industry requires development of a number of steps – discussed in this article taking as a model the olive tree – olive oil binomial – consisting of: (i) extraction, identification and quantitation of valuable products (with isolation of individual compounds, if required); (ii) assessment of beneficial effects (which could be made mainly through metabolomics); (iii) improvement of cultivation varieties (through cross-breeding or other agricultural resources); (iv) commercialization as nutraceuticals, food supplements, pharmaceuticals or even as antibacterial and antifoam agents in water treatment plants; (v) use of the final residues to produce compost, foodstuffs, biogas or heat (after checking the characteristics of these residues which can be very different from those of the original residue). This working scheme may be applied to any other system to break the traditional one cultivation–one commercial product scheme.     

Automatic Headspace Sampling for Determination of Ethylene Dibromide Residues in Cereals

Abstract

The possibility was investigated to apply a commercially available automatic head-space sampler in trace analysis of ethylene dibromide (EDB, 1,2-dibromoethane), in cereals.

Samples of rice and wheat flour were thermostatted in closed vials at 70[ddot]C for 30min. The top gas was then automatically introduced into a gas chromatograph equipped with an electron capture detector. Quantitation was performed using external standards (untreated samples spiked with solutions of EDB in N,N′-dimethylacetamide).

The relative standard deviation of the method was 3.4% for rice and 4.5% for wheat flour, at a residue level of 0.008 mg/kg. The detection limit was 0.001 mg/kg (the official EC residue tolerance is 0.01 mg/kg).

Preliminary experiments with other fumigants were carried out as well.

The headspace technique in question has the following advantages over other methods for determining EDB residues in cereals: 1. No sample pre-treatment like extraction, steam distillation, purge and trap etc.; 2. Automated sample handling; 3. “Clean” chromatograms.     

Simultaneous determination of trifloxystrobin and trifloxystrobin acid residue in rice and soil by a modified quick,easy, cheap,effective, rugged,and safe method using ultra high performance liquid chromatography with tandem mass spectrometry

A sensitive analytical method for the simultaneous determination of trifloxystrobin and its metabolite trifloxystrobin acid in rice including straw, bran, brown rice and soil was developed by using ultra high performance liquid chromatography coupled with tandem mass spectrometry. The fungicide trifloxystrobin and its metabolite trifloxystrobin acid were extracted using acetonitrile with 1% formic acid v/v and subsequently cleaned up by primary secondary amine, octadecylsilane or graphitized carbon black prior to ultra high performance liquid chromatography coupled with tandem mass spectrometry. The determination of two target compounds was achieved in less than 3 min using an electrospray ionization source in positive mode. The limits of detection were below 0.22 μg/kg and the limits of quantification did not exceed 0.74 μg/kg in all matrices, which were much lower than the maximum residue levels established by the Codex Alimentarius Commission. The overall average recoveries in four matrix at three levels (0.1, 1.0 and 5.0 mg/kg) ranged from 74.2 to 107.4% with a relative standard deviations of less than 7.8% (n = 5) for both analytes. The method was demonstrated to be convenient and reliable for the routine monitoring of trifloxystrobin and its metabolite. The developed method was validated and applied for the analysis of degradation study samples.     

反相液相色谱-串联质谱法检测猪肝中26种β2-受体激动剂类药物残留

建立了一种猪肝中26种β2-受体激动剂药物残留的反相液相色谱-串联质谱(HPLC-MS/MS)检测方法。样品经β-葡萄糖苷酸酶/芳基硫酸酯酶酶解12 h后,加入HClO4调至pH 1,去除蛋白,残渣经过0.1 mol/L HClO4再次提取后,合并提取液,调节混合提取液至pH 4,过混合阳离子(MCX)固相萃取柱净化。采用0.1%甲酸(A)和0.1%甲酸-乙腈(B)作为流动相进行梯度洗脱,质谱(ESI+)采用多离子检测模式(MRM)对β2-受体激动剂的定量离子和定性离子进行监测,本方法在15 min内完成26种目标化合物的分离分析。26种β2-受体激动剂在5、10和20μg/L添加水平的回收率为64.0%~112.7%,相对标准偏差小于15.2%,方法检出限为0.15~1.35μg/kg。     

Screening of salbutamol residues in swine meat and animal feed by an enzyme immunoassay in Taiwan

An ELISA was developed for routine examination for extensive monitoring and screening programs for the residues of salbutamol in swine serum, animal feed, meat, and meat-related products destined for human consumption in Taiwan. Objectives of the study were to investigate the use of a new immunoassay for the detection of salbutamol residues in swine meat and animal feed samples, and to compare with a commercial kit in field test screens. A fast, simple and reliable sample preparation method for the determination of salbutamol was established. Field trials with 222 swine meat and 120 animal feed samples that were taken from local meat markets, auction markets and feed mills. The application and the results of two ELISA kits (a homemade and a commercial kit) for the screening of salbutamol were presented. Adopting 2 μg kg⁻¹ salbutamol as a cut-off value for swine meat, the commercial β-agonist ELISA had a sensitivity of 85.3% and a specificity of 95.2% versus GC-MS at a cut-off of 2 μg kg⁻¹. The homemade salbutamol ELISA had a sensitivity of 100% and a specificity of 90.9% and gave no false-negative rate results. Furthermore, adopting 20 μg kg⁻¹ salbutamol as a cut-off value for animal feed, both the commercial and homemade ELISA showed 100% sensitivity and 100% specificity of the assays. In conclusion, a sensitive, specific salbutamol polyclonal antibody-based ELISA has been developed that could serve as a rapid screening assay, and the detection of positive samples at the place of sampling can result in more effective control of the illegal use of β-agonists.     

Multi-residue confirmatory method for the determination of twelve coccidiostats in chicken liver using liquid chromatography tandem mass spectrometry

The confirmatory LC-MS/MS method for the determination of residues for twelve coccidiostats including ionophore antibiotics (lasalocid, maduramycin, monensin, narasin, salinomycin, semduramycin) and chemical coccidiostats (clazuril, decoquinate, diclazuril, halofuginone, nicarbazin and robenidine) in poultry liver has been developed. The sample preparation was based on extraction with acetonitrile, defatting with Alumina columns and clean-up on Oasis HLB spe. The separation of analytes was performed on PhenylHexyl column with a gradient of acetonitrile, methanol and the ammonium formate pH 4.0. For all analytes, at least 2 diagnostic fragmentation ions were monitored. The validation, performed according to the CD 2002/657/EC, proved the suitability of the method for the confirmatory analysis of the coccidiostats. For lasalocid, however, low reproducibility was observed and the proper quantification could not be performed with this method.     

The Cardbox/Cardview Database for residues in live animals and their products

The growing interest of the public opinion in environmental problems has resulted in the establishment of national and international norms and regulations. Among others, the protection of human health requires the constant monitoring of several groups of potentially toxic substances as well as of their residues in live animals and their products. For this reason in recent years the European Commission decided to establish four Community Reference Laboratories (CRLs) for the analysis of residues in products of animal origin. The current mandate and operative conditions of the CRLs are described in the Council Directive 96/23/EC of 29 April 1996, which has the goal of promoting and supporting the harmonization of approaches among National Reference Laboratories (NRLs). In this context the CRL at the Istituto Superiore di Sanità of Rome is responsible for chemical elements, organochlorine compounds (including PCBs), carbamates, pyrethroids and organophosphorus compounds. The supply of updated information on the literature of relevance to the tasks of the NRLs is one of the duties of the Rome CRL. To this end, the so-called Cardbox Database has been set up, which for the time being is fully operative for chemical elements and organochlorine compounds.     

Validation of a high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of tetracyclines residues in bovine milk

A high-performance liquid chromatography-fluorescence detection method was optimized and validated to determine tetracyclines residues in bovine milk. Post-column derivatization using metal complexation in non-aqueous reagent increased the fluorescence of chelates by a factor up to 2.54 compared to water (signal-to-noise ratio enhancement). Overall recoveries ranged from 61 to 115%, with RSD_r from 5 to 15% (n = 54). Detection limits ranged from 5 to 35 μg kg⁻¹. Limits of quantification were established at 50 μg kg⁻¹. Decision limits (CCα) were 109, 108 and 124 μg kg⁻¹ and detection capabilities (CCβ) 119, 117 and 161 μg kg⁻¹ for oxytetracycline, tetracycline and chlortetracycline, respectively. The method was applied successfully in a national monitoring program.     

Residues of a Pfaff system relative to an invariant subscheme

In this paper we give a purely algebraic construction of the theory of residues of a Pfaff system relative to an invariant subscheme. This construction is valid over an arbitrary base scheme of any characteristic.