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To obtain antibodies to develop an enzyme-linked immunosorbent assay (ELISA) for the analysis of Sudan red I, haptens were designed and synthesized via four different strategies: (i) attachment of a spacer at the para position of the benzene ring, (ii) attachment of a spacer at the naphthol part, (iii) attachment of a spacer at the hydroxyl group of the Sudan red I molecule, and (iv) use of a fragment of the target molecule. A total of 10 haptens were used to generate immunogens, coating antigens, and polyclonal antibodies. One of the heterologous ELISAs developed exhibited an IC(50) of 1.6 ng/ml, a limit of detection (LOD) of 0.03 ng/ml, and a dynamic range between 0.1 and 14 ng/ml. The assay had 13% cross-reactivity with Para red and negligible cross-reactivity with other structure-related compounds. This ELISA was much more specific than those published previously. This assay was used to determine Sudan red I residues in tomato sauce and chili powder samples after simple pretreatment. The results were validated by comparison with high-performance liquid chromatography (HPLC). The average recoveries of Sudan red I by ELISA and HPLC were in ranges of 70-97% and 82-114%, respectively, indicating suitability of the developed ELISA for screening of Sudan red I in foods., (Copyright 2010 Elsevier Inc. All rights reserved.)

Azo compounds are widely used in polymerization as an initiator for chain polymerization reactions. Although they have excellent initiating properties, the thermal instability and associated risk of ignition and explosion cannot be ignored. This paper aimed to decode the thermal behavior and evaluation thermal hazards of two water-soluble azo initiators 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AIBA) and 2,2′-azobis(2-(2-imidazoline-2-yl) propane) dihydrochloride (AIBI). Thermogravimetric analysis and adiabatic experiments were used to investigate the decomposition process of these two azos under atmospheric and adiabatic conditions. The apparent activation energy (Ea) and time to maximum rate under adiabatic conditions (TMRad) were obtained based on above experiments. Decomposition products and mechanisms of AIBA and AIBI were preliminarily studied using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer system. Results showed that most decomposition products of AIBA and AIBI still existed in the form of organic compounds under nitrogen conditions. Furthermore, the leakage of pyrolysis gas (such as ammonia) should be prevented from causing environmental pollution. [ABSTRACT FROM AUTHOR]

Azo compounds (azos) are widely used as radical initiators in the polymerization industry. Nonetheless, due to the azo group molecular structure, azos gravitate toward thermal decomposition and lead to thermal runaway accidents. In this paper, the thermal decomposition behaviors of 2-(1-cyano-1-methylethyl)azocarboxamide (CABN) under the dynamic and adiabatic environments were investigated using differential scanning calorimetry and accelerating rate calorimeter. Several safety assessment parameters such as time to maximum rate under adiabatic condition (TMRad), temperature of no return, and self-accelerating decomposition (SADT) temperature were calculated based on thermokinetic analysis as well as curve fitting. The results indicated that CABN decomposes at low temperatures (90.0–100.0 °C) and releases huge volumes of gaseous products, which may set off a fire, deflagration, or even explosion if the decomposition occurs uncontrolled in a confined space. Compared with commonly used azos, the shorter TMRad, lower SADT, and more heat from thermal decomposition reflect the potential thermal explosion hazards of CABN. To investigate emergency response procedure in terms of industrial applications, the oxygen-balance method was further used to evaluate the explosion hazard of CABN, and several recommendations on alleviating the thermal hazards of CABN were established to prevent catastrophic accidents. [ABSTRACT FROM AUTHOR]

Azo compounds, which are commonly used in radical polymerization reactions, readily demonstrate their self-reactive properties. Because of their sensitive thermal decomposition properties, azo compounds have been responsible for many accidents. To avoid unexpected thermal decomposition in the workplace, information about the thermal stability and other properties of azo compounds should be provided to on-site personnel in industries that use these materials. In this study, the target substance, 2,2'-azobis-(2,4-dimethylvaleronitrile) (ABVN), is shown to have a higher reactivity than other azo compounds, and its thermal decomposition characteristics are discussed based on a literature review and results from differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC). A thermokinetic analysis of ABVN is conducted using DSC and ARC data. The results can provide process-control data and explain the effects of thermal runway for ABVN. In addition, based on applied numerical methods, critical runaway temperatures, stable temperatures, and the required heat dissipation rate for the prevention of the thermal runaway reactions are calculated using a process deviation analysis. The results show that the reactant quantities and the process parameters must be strictly controlled to achieve the desired reaction. [ABSTRACT FROM AUTHOR]

• Used the results of laboratory scale analysis to confirm thermal hazards in plant. • The kinetics of two azo compounds by thermal analysis was investigated. • Kinetic-based simulations were applied for evaluation of SADT for two azos. • Kinetic model on process condition was determined based on adiabatic data. • Thermal stability, such as TMR ad and SADT have been found using analytical models. As a key initiator of polymerization, azo compounds (azos) can supply abundant energy to the polymerization process. Although polymerization can be implemented more smoothly and the product can be modified, the use of azos also increases the probability of process hazards caused by high heat accumulation and release. To preserve the thermal safety of using azo initiators in the synthesis process, the frequently used azo initiators dimethyl 2,2′-azobis(2-methyl propionate) (AIBME) and 2,2′-azobis(2,4-dimethylvaleronitrile) (ABVN) were chosen for investigation. Under process conditions, initiators are essential for evolving and monitoring chemical reactions on both the laboratory scale and process environment. The assessment, control, and mitigation of reaction hazards are primarily based on kinetic models, which are used to estimate multiple critical safety parameters, such as TMR ad in process safety and TCL and SADT in storage and transportation operation. The data from the adiabatic calorimeter correspond to real process situations are combined with the nonlinear adiabatic kinetic model, which is rarely applied to analyze the thermal hazard properties of azos. The results indicated that the kinetic model of azos in the actual process, the thermal hazard characteristics, and simulation of the runaway mode of azos in setting boundary conditions should also be investigated. [ABSTRACT FROM AUTHOR]

Azo compounds (azos) are vital basic initiators used in chemical plants that also possess thermally active properties. Azos may trigger serious accidents because of their intense exothermicity. We applied a specific method to characterize the reaction kinetics of azos using data from differential scanning calorimetry (DSC). Specifically, this method was used to analyse the thermal decomposition of 2,2-azobis(2-methylbutyronitrile) (AMBN). The exothermic peak temperature, exothermic final temperature, and heat of decomposition were determined. The data obtained from the experiments were utilized to predict the self-accelerating decomposition temperature, control temperature, and emergency temperature. Experiments conducted to explore the runaway phenomenon of AMBN during the overall decomposition process interfered with the thermal analysis studies. We utilized a process simulation model to mimic the decomposition of AMBN, ensuring that the simulation results were realistic and practical. The results are worthy of being applied to thermal analysis, for example, for application in proactive loss prevention. [ABSTRACT FROM AUTHOR]