固相微萃取法在禁用偶氮染料检测中的应用初探

将固相微萃取技术应用于出口染色纺织品及皮革制品中禁用偶氮染料检验,偶染料经连二亚硫酸钠还原成芳胺后,用固相微萃取技术萃取富集后,用ＧＣ－ＭＳ分析。实验了萃取方式、萃取纤维、pＨ值、浓度、温度、萃取时间及色谱条件等因素对萃取与测定的影响。     

Extraction and recovery of azo dyes into an ionic liquid

The azo dyes are commonly used in the leather and textile industries as they are quite versatile in nature. However, they are neither totally utilised during the process, nor are they recovered at the end of the process. In fact, in the leather industry, typically about 10–15% of the dye is discharged with the effluent creating both environmental and economic issues. Hence, there is a need to remove the residual dye from the large volume of aqueous effluent. In this study, for the first time, azo dyes employed in the leather industry have been successfully extracted into a neutral ionic liquid, with an extraction efficiency of 98%, potentially providing a method of minimizing pollution of waste-waters. The extraction of the dye into the ionic liquid also provides a potential analytical approach to determination of these dyes.     

Fast throughput, highly sensitive determination of allergenic disperse dyes in textile products by use of sample composition

A simple, highly sensitive and fast procedure for the control of allergenic disperse dyes in textile products was optimized. The method is based on ultrasound assisted extraction of textile samples with 20 mL of methanol under controlled conditions (15 min, 70 °C) followed by separation and analysis by LC-MS-MS. The sample preparation process was optimized by means of a surface response experimental design and provided quantitative recoveries of dyes, much better than the poor recoveries provided by current standard procedures. The chromatographic separation was optimized by means of computer-assisted method development by use of a special chemometric tool developed specifically for LC-MS systems, as previously reported by the authors. The result is a rapid chromatographic procedure that enables accurate quantification, at very low concentrations, of all 23 allergenic and/or carcinogenic disperse dyes considered. Matrix effects in the LC-MS procedure were studied. Under the experimental conditions, both conventional and strategic sample composition are proposed as efficient procedures that reduce the costs and work involved in the control of allergenic dyes in finished textile products. The benefits of strategic sample composition are demonstrated by means of an example case study, and the pros and cons of preparing the composite samples from sample extracts or directly from textile products are discussed.     

Polypyrrole‐magnetite dispersive micro‐solid‐phase extraction combined with ultraviolet‐visible spectrophotometry for the determination of rhodamine 6G and crystal violet in textile wastewater

Polypyrrole‐magnetite dispersive micro‐solid‐phase extraction method combined with ultraviolet‐visible spectrophotometry was developed for the determination of selected cationic dyes in textile wastewater. Polypyrrole‐magnetite was used as adsorbent due to its thermal stability, magnetic properties, and ability to adsorb Rhodamine 6G and crystal violet. Dispersive micro‐solid‐phase extraction parameters were optimized, including sample pH, adsorbent amount, extraction time, and desorption solvent. The optimum polypyrrole‐magnetite dispersive micro‐solid phase‐extraction conditions were sample pH 8, 60 mg polypyrrole‐magnetite adsorbent, 5 min of extraction time, and acetonitrile as the desorption solvent. Under the optimized conditions, the polypyrrole‐magnetite dispersive micro‐solid‐phase extraction with ultraviolet‐visible method showed good linearity in the range of 0.05–7 mg/L (R ² > 0.9980). The method also showed a good limit of detection for the dyes (0.05 mg/L) and good analyte recoveries (97.4–111.3%) with relative standard deviations < 10%. The method was successfully applied to the analysis of dyes in textile wastewater samples where the concentration found was 1.03 mg (RSD ±7.9%) and 1.13 mg/L (RSD ± 4.6%) for Rhodamine 6G and crystal violet, respectively. It can be concluded that this method can be adopted for the rapid extraction and determination of dyes at trace concentration levels.     

Forensic analysis of anthraquinone,azo, and metal complex acid dyes from nylon fibers by micro-extraction and capillary electrophoresis

The extraction and separation of dyes present on textile fibers offers the possibility of enhanced discrimination between forensic trace fiber evidence. An automated liquid sample handling workstation was programmed to deliver varying solvent combinations to acid-dyed nylon samples, and the resulting extracts were analyzed by an ultraviolet/visible microplate reader to evaluate extraction efficiencies at different experimental conditions. Combinatorial experiments using three-component mixture designs varied three solvents (water, pyridine, and aqueous ammonia) and were employed at different extraction temperatures for various extraction durations. The extraction efficiency as a function of the three solvents (pyridine/ammonia/water) was modeled and used to define optimum conditions for the extraction of three subclasses of acid dyes (anthraquinone, azo, and metal complex) from nylon fibers. The capillary electrophoresis analysis of acid dye extracts is demonstrated using an electrolyte solution of 15 mM ammonium acetate in acetonitrile/water (40:60, v/v) at pH 9.3. Excellent separations and discriminating diode array spectra are obtained even for dyes of similar color. Figure Capillary electropherogram of three acid dyes extracted from nylon 6,6 thread     

Standard additio--a way of improving quantification of banned azo dyes in leather

An analytical procedure based on supercritical-fluid extraction and microwave-assisted extraction was applied on six different real leather samples for the determination of banned azo dyes. Determination of the dyes was performed indirectly by measuring their corresponding harmful aromatic amines, formed after reduction. A comparative study between external standard calibration and standard addition using both the dyes as well as the corresponding amines showed that the latter quantification method provided the highest accuracy.     

液液萃取-分散液液微萃取-气相色谱-质谱联用测定纺织废水中痕量禁用偶氮染料

建立了液液萃取-分散液液微萃取-气相色谱-质谱联用技术测定纺织废水中痕量偶氮染料的方法。废水中的偶氮染料在碱性条件下经连二亚硫酸钠还原成芳香胺后,先用叔丁基甲醚液液萃取、盐酸反萃进行预浓缩及净化;再以乙腈-氯苯体系进行分散液液微萃取,气相色谱-质谱测定。对前处理条件进行了优化,考察了酸碱度及盐效应对芳香胺萃取效率的影响,结果表明：液液萃取过程中加入30 g NaCl,分散液液微萃取过程中加入1 mL 5 mol/L的NaOH调节体系至碱性才能达到较好的萃取效率。在优化的实验条件下,21种目标物均呈现良好的线性关系,其中13种芳香胺的线性范围为0.05~10 μg/L,7种芳香胺的线性范围为0.05~5 μg/L,2,4-二氨基苯甲醚的线性范围为20~100 μg/L,相关系数为0.996~0.999。20种芳香胺的检出限可达0.05 μg/L,2,4-二氨基苯甲醚检出限为20 μg/L。印染、机织、印花等实际废水加标试验表明,方法的回收率为75.6%~115.1%。该方法富集倍数高,检出限低,适用于纺织废水中痕量禁用偶氮染料的检测。     

High-performance liquid chromatographic determination of some anthraquinone and naphthoquinone dyes occurring in historical textiles

A reversed-phase HPLC method has been developed for identification and quantitation of nine natural quinone dyes and applied to historical textile fibres. A Purospher RP18e column was used with a convex gradient of methanol in a mobile phase of 0.1 M aqueous citrate buffer (pH 2.5) and spectrophotometric diode-array detection at 270 nm. For identification of alizarin, purpurin and xanthopurpurin, occurring together in the madder plant, an isocratic method was used with a methanol-0.2 M acetate buffer (pH 4.3) (75:25) as the mobile phase. After an acid extraction of textile fibres and the analysis of the extracts, alizarin and purpurin were identified and quantitated in three fibres.     

A review of analytical techniques for determination of Sudan I–IV dyes in food matrixes

Sudan dyes are a family of lipophilic azo dyes, extensively used in industrial and scientific applications but banned for use as food colorants due to their carcinogenicity. Due to the continuing illicit use of Sudan dyes as food colorants their determination in different food matrices – especially in different chilli and tomato sauces and related products – has during the recent years received increasing attention all over the world. This paper critically reviews the published determination methods of Sudan I–IV dyes. LC–UV–vis and LC–MS are the dominating methods for analysis of Sudan I–IV dyes. Sudan dyes are usually found in food at mg kg⁻¹ levels at which it may be necessary to use a preconcentration step in order to attain the desired detection limits. Liquid–solid extraction is the dominating sample preparation procedure. In recent years it has been supplemented by ultrasonic-assisted extraction and pressurized liquid extraction. Various solid phase extraction types have been used for sample cleanup. The large majority of works use conventional C18 columns and conventional LC eluents. Traditionally the UV–vis absorbance detection has been the most frequently used. In the recent years MS detection is applied more and more often as it offers more reliable identification possibilities.     

A Novel Kinetic Approach for Photocatalytic Degradation of Azo Dye with CdS and Ag/CdS Nanoparticles Fixed on a Cement Bed in a Continuous‐Flow Photoreactor

Azo dyes are one of the synthetic dyes that have been used in many textile industries. Azo dye and their intermediate products are toxic, carcinogenic, and mutagenic to aquatic life. Removal of azo dyes is one of the main challenges before releasing the wastes discharged by textile industries. Photocatalytic degradation of azo dyes by nanoparticles is one of the environment‐friendly methods used for the removal of dyes from textile effluents. Therefore, this study focused on degradation of azo dye, Direct Red 264. Photocatalytic degradation of DR 264 azo dye was investigated using CdS and Ag/CdS nanoparticles immobilized on a cement bed in a continuous‐flow photoreactor under UV‐C exposure. The effect of the parameters of type and mass of catalyst, temperature, flow rate, dye concentration, and light intensity were evaluated for azo dye removal. Under optimal conditions, photocatalytic degradation of DR 264 azo dye using Ag/CdS nanoparticles immobilized on a cement bed in a continuous‐flow photoreactor obtained an efficiency of 99.99%. A developed kinetic model was proposed based on the intrinsic elementary reactions. The proposed model is in a good agreement with the Langmuir–Hinshelwood (L–H) equation. The pseudo–steady‐state approximation has considered for the concentration of hydroxyl radicals associated with the L–H model under certain conditions and explains consistently the dependence of the apparent kinetic parameter, k_obs (the reaction rate constant), and K_R (the adsorption equilibrium constant) with the light intensity. Based on the model, k_obs for Ag/CdS was greater than the CdS nanoparticles.     

Selective on-line immunoextraction coupled to liquid chromatography for the trace determination of benzidine, congeners and related azo dyes in surface water and industrial effluents.

A new extraction immunosorbent involving antigen-antibody interactions was coupled on-line to liquid chromatography for the selective extraction in aqueous samples of benzidine and congeners, widely used as intermediate compounds in the manufacturing of dyes and pigments. Due to the cross-reactivity of the antibodies for analytes with chemical structures closely related to that of the analyte used for immunization, the immunoextraction sorbent was shown to be able to extract aminoazobenzene and related azo dyes with good recoveries. The on-line coupling was optimized for the trace determination of benzidine, dichlorobenzidine, aminoazobenzene and some azo dyes with detection limits in the range 0.1 to 1 microgram/l. The high selectivity of the immunoextraction was shown by comparing the analysis of an industrial textile effluent obtained using precolumns packed either with a non-selective polymeric sorbent or with the anti-benzidine immunosorbent. In such complex samples, extraction and clean-up are achieved in the same step.     

Synthese de substances macromoleculaires renfermant des motifs monomeres derives de colorants—XVIII: Synthese d'oligoamides colores par structure

Oligoamides with amino end-groups have been reacted with acid chlorides of azo or quinophthalic dyes. Oligoamides with 4-nitro phenyl end-groups have been reduced to oligoamides with aminophenyl end-groups; they have been diazotized and coupled with β naphthol. Due to their low thermal stability, oligoamides containing azo groups cannot be spun; on the other hand, oligoamides with quinophthalic groups can be used as macromolecular dyes for polyamides. Coloured fibres have excellent mechanical properties and the dye cannot be extracted by solvent.     

Photobleaching as a useful technique in reducing of fluorescence in Raman spectra of blue automobile paint samples

The usefulness of the photo-beaching technique in reducing the fluorescence background in Raman spectra of automotive paints was studied. The method was applied to group of 20 blue solid and metallic paints, in which pigment identification with the use of a green laser (514.5 nm) was not possible due to strong fluorescence. The samples were irradiated by high laser power for a long period of time before acquiring spectra. The process of bleaching was studied in detail based on two samples. Then the procedure was applied to all samples before acquiring spectra. Due to irradiation fluorescence originating from the background decreased, whereas Raman scattering features of samples stayed unchanged. The applied procedure satisfactorily quenched fluorescence in 90% of examined samples and made pigment identification possible.     

Determination of textile dyes by means of non-aqueous capillary electrophoresis with electrochemical detection

Eight textile dye compounds including five cationic dyes, namely, basic blue 41, basic blue 9, basic green 4, basic violet 16 and basic violet 3, and three anionic dyes, acid green 25, acid red 1 and acid blue 324, were separated and detected by non-aqueous capillary electrophoresis (NACE) with electrochemical detection. Simultaneous separations of acid and basic dyes were performed using an acetonitrile-based buffer. Particular attention was paid to the determination of basic textile dyes. The optimized electrophoresis buffer for the separation of basic dyes was a solvent mixture of acetonitrile/methanol (75:25, v/v) containing 1 M acetic acid and 10 mM sodium acetate. The limits of detection for the basic dyes were in the range of 0.1–0.7 μg mL⁻¹. An appropriate solid-phase extraction procedure was developed for the pre-treatment of aqueous samples with different matrices. This analytical approach was successfully applied to various water samples including river and lake water which were spiked with textile dyes.     

Optimization of an analytical procedure for the determination of banned azo dyes in leather

The possibility of improving an existing method, based on supercritical-fluid extraction (SFE) and microwave-assisted extraction (MAE), for the determination of banned azo dyes in leather has been studied. Thus, optimization of experimental conditions in different steps (degreasing, reduction, and extraction) of the analytical procedure was performed. The influence of different variables (reaction time, temperature, and concentration of reducing agent) on the reduction process was evaluated by use of a factorial design. It was found that the concentration of the reducing agent and the interaction between time and temperature were the most influential variables. Consequently, by applying a higher temperature, the reaction time could be halved. The use of acidified water as extraction solvent in MAE was also investigated. Usually 1 mol L^–1 HCl was superior to methanol and buffer in terms of extraction efficiency. In conclusion, the present method gave significantly higher recoveries in comparison with the original method. All dyes were determined indirectly by measuring their corresponding harmful amines, formed after reduction by use of sodium dithionite.     

Analysis of electrochemical degradation products of sulphonated azo dyes using high-performance liquid chromatography/tandem mass spectrometry

Electrochemical treatment of wastewaters containing azo dyes in the textile industry is a promising approach for their degradation. The monitoring of the course of the decomposition of azo dyes in wastewaters is essential due to the environmental impact of their degradation products. In this work, aqueous solutions of a simple azo dye with a low molecular weight (C.I. Acid Yellow 9) and more complex commercial dye (C.I. Reactive Black 5) were electrochemically treated in a laboratory-scale electrolytic cell in sodium chloride or ammonium acetate as supporting electrolytes. Ion-pairing reversed-phase high-performance liquid chromatography coupled with negative-ion electrospray ionization mass spectrometry is applied for the identification of electrochemical degradation products. In addition to simple inorganic salts, the formation of aromatic degradation products obtained due to the cleavage of azo bonds and further degradation reactions is shown, as well as chlorination where sodium chloride is the supporting electrolyte. Degradation mechanisms are suggested for the treatment with sodium chloride as the supporting electrolyte.     

The evaluation of structural changes in wool fibre keratin treated with azo dyes by Fourier Transform Infrared Spectroscopy

Fourier Transform Infrared Spectroscopy spectroscopy is a useful technique for the analysis of structural changes in wool fibres at the molecular and supermolecular levels. Ecological requirements the textile industry has to meet oblige manufacturers to use ecological dyes in the process of fibre dyeing. These dyes should not split into the forbidden, carcinogenic aromatic amines (e.g. benzidine) while used. Wool was dyed with an azo dye, then underwent a chemical reaction. Changes were observed in the region of Amide A, Amide B, Amide I and II, dipolar ions amino acids, and the fingerprint region.     

Extraction-chromatographic determination of sulfonated azo dyes in aqueous solutions

The extraction of sulfonated azo dyes E102, E110, E122, E124, and E129 from aqueous solutions using hydrophilic solvents and their mixtures in the presence of a salting-out agent (ammonium sulphate) has been studied. Some regularities of extraction have been revealed. The composition of the mobile phase has been optimized and a procedure has been proposed for the identification and determination of the dyes in aqueous solutions by thin-layer chromatography in concentrations of 0.1–0.01 μg/L. An office scanner and a personal computer have been used to process the results of the separate determination of the dyes.     

Characterization of sulfonated azo dyes and aromatic amines by pyrolysis gas chromatography/mass spectrometry

Sixteen sulfonated and unsulfonated azo dyes as well as eleven sulfonated and unsulfonated aromatic amines were analyzed and qualitatively characterized by means of pyrolysis gas chromatography/mass spectrometry at different temperatures. Aniline and aminonaphthalene were found to be the dominant pyrolysis products of sulfonated aromatic amines and dyes. Azo dye and dye class specific key compounds such as benzidine, vinyl-p-base and 4-aminoazobenzene could be identified by pyrolysis gas chromatography/mass spectrometry of commercial acid, cationic, direct, reactive and solvent dyes. 500 degrees C was the optimal pyrolysis temperature for most of the pyrolyzed compounds. The method was applied to a dried sample of a textile wastewater concentrate from a dyeing process. Reactive azo dyes of the group of Remazol dyes and anthraquinone dyes could be identified as the major compounds of the sample. The finding of caprolactam (a printing additive) suggests that the wastewater contained effluent from a process of heat-activated printing with reactive dyes. p-Chloraniline, a banned aromatic amine, was identified. Chemical reduction of the wastewater sample prior to pyrolysis resulted in the release of volatile aromatic amines and aided the classification of several products of pyrolysis.     

Electrically enhanced liquid‐phase microextraction of three textile azo dyes from wastewater and plant samples

An electromembrane extraction procedure coupled with HPLC and visible detection was applied for the extraction of three textile azo dyes as organic salts. The extraction parameters such as extraction time, applied voltage, pH range, and concentration of salt added were optimized. A driving force of 60 V was applied to extract the analytes through 2‐nitrophenyl octyl ether, used as the supported liquid membrane, into a neutral aqueous solution. This method required 20 min extraction time from a neutral sample solution. The proposed microextraction technique provided good linearity with correlation coefficients from 0.996 to 0.998 over a concentration range of 1.0–1000.0 ng/mL. The LODs of dyes were 0.30–0.75 ng/mL, while the reproducibility ranged from 6.7 to 12.9% (n = 6). Also, enrichment factors of 96–162 that corresponded to the recoveries ranging from 48 to 81% were achieved. Finally, the application of this new method was demonstrated on wastewater samples and some plants grown in contaminated environments. Excellent selectivity was obtained as no interfering peaks were detected.