Sudan Dyes In Food Samples Research Articles

Novel Cu2+-based immobilized metal affinity magnetic nanoparticles for fast magnetic solid-phase extraction of trace Sudan dyes in food samples

A novel type of Cu2+-based immobilized metal affinity magnetic nanoparticles (MHNTs@PDA@Cu2+) was designed and synthesized by a facile and green strategy, and served as an adsorbent for magnetic solid-phase extraction (MSPE) of trace Sudan dyes in foodstuffs. Owing to π-π stacking, hydrogen bonding, hydrophobic and Cu2+-azo coordination, MHNTs@PDA@Cu2+ possesses superior affinity and very fast adsorption capability to Sudan dyes (adsorption time of 1 min). The main parameters influencing the extraction efficiency of MSPE were investigated and optimized. By coupling MHNTs@PDA@Cu2+-based MSPE with HPLC-UV, a simple, fast and sensitive method for the determination of trace Sudan dyes in food samples were developed. Good linearity (R2 ≥ 0.9937) and low limits of detection (0.06–0.10 μg L−1) were obtained. The method was successfully applied to determine Sudan dyes in juice, soy sauce and red wine, and the recoveries for the spiked samples ranged from 78.1% to 112.4% with RSD less than 9.0%.

New approach applying a pet fish air pump in liquid-phase microextraction for the determination of Sudan dyes in food samples by HPLC.

A new approach applying a pet fish air pump is introduced to develop an extraction method, namely, air-pump-enhanced emulsion, followed by salt-assisted emulsion breaking based on solidified floating organic drop microextraction for the extraction and preconcentration of Sudan I-IV before high-performance liquid chromatography. The applicability of this method was successfully demonstrated by determination of these dyes in four chili products that include chili powder, chili oil, chili sauce, and chili paste. An enrichment factor of 62 was obtained only with a sample solution of 5mL. A linear range of 0.5-2500ng/mL was obtained with a limit of detection of 0.16-0.24ng/mL and recovery of 90-110%. This method is superior to other liquid-liquid extraction methods, as is simple, rapid, environmental friendly, and its phase separation needs no centrifugation. It also needs no disperser solvent and requires less organic solvent, and satisfies the criteria to be called as a green extraction. Therefore, this facile extraction method can be successfully applied in the determination of Sudan dyes in food samples.

Magnetic/non-magnetic argan press cake nanocellulose for the selective extraction of sudan dyes in food samples prior to the determination by capillary liquid chromatograpy

Two methods for the determination of Sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples, by solid phase extraction - capillary liquid chromatography, are proposed. Both methods use nanocellulose (NC) extracted from bleached argan press cake (APC), as a nano-adsorbent recycled from an agricultural waste material. One of the methods involves the dispersion of NC in food sample extracts, along with the waste and eluents being separated by centrifugation. In the other method, NC was modified by magnetic iron nanoparticles before using it in the extraction of Sudan dyes. The use of a magnetic component in the extraction process allows magnetic separation to replace the centrifugation step in a convenient and economical way. The two proposed methods allows the determination of Sudan dye amounts at the 0.25–2.00µgL−1 concentration range. The limit of detections, limit of quantifications and standard deviations achieved were lower than 0.1µgL−1, 0.20µgL−1 and 3.46% respectively, when using NC as a nano-adsorbent, and lower than 0.07µgL−1, 0.23µgL−1 and 2.62%, respectively, with the magnetic nanocellulose (MNC) was used. Both methods were applied to the determination of Sudan dyes in barbeque and ketchup sauce samples, obtaining recoveries between 93.4% and 109.6%.

Measurement uncertainty assessment of magnesium trisilicate column for determination of Sudan colorants in food by HPLC using C8 column.

This study aimed to conduct measurement uncertainty assessment of a new method for determination of Sudan colorants (Sudan I, II, III and IV) in food by high performance liquid chromatography (HPLC). Samples were extracted with organic solvents (hexane, 20% acetone) and first purified by magnesium trisilicate (2MgO·3SiO2). The Sudan colorants (Sudan I-IV) were also initially separated on C8 by gradient elution using acetonitrile and 0.1% (v/v) formic acid aqueous solution as the mobile phases and detected with diode-array detector (DAD). The uncertainty of mathematical model of Sudan I, II, III and IV is based on EURACHEM guidelines. The sources and components of uncertainty were calculated. The experiment gave a good linear relationship over the concentration from 0.4 to 4.0 μg/mL and spiked recoveries were from 74.0% to 97.5%. The limits of determination (LOD) were 48, 61, 36, 58 μg/kg for the four analytes, respectively. The total uncertainty of Sudan colorants (Sudan I, II, III and IV) was 810±30.8, 790±28.4, 750±27.0, 730±50.0 μg/kg, respectively. The recovery uncertainty was the most significant factor contributing to the total uncertainty. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in food samples. The sources of uncertainty have been identified and uncertainty components have been simplified and considered.

In-line micro-matrix solid-phase dispersion extraction for simultaneous separation and extraction of Sudan dyes in different spices

A novel, simple, fast, and miniaturized method, termed in-line micro-matrix solid-phase dispersion (in-line MMSPD), coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction and determination of Sudan dyes (i.e. Sudan I–IV, Sudan orange G, Sudan black B, and Sudan red G) with the aid of an experimental design strategy. In this method, a matrix solid-phase dispersion (MSPD) column including a suitable mixture of polar sorbents was inserted in the mobile phase pathway, and while the interfering compounds were retained, the analytes were eluted and entered into the analytical column. In this way, the extraction, elution, and separation of the analytes were performed sequentially. Under the optimal experimental conditions (including the amount of sample, 0.0426g; amount of dispersant phase, 0.0216g of florisil, 0.0227g of silica, 0.0141g of alumina; and blending time, 112s), the limits of detection (LODs), limits of quantification, linear dynamic ranges, and recoveries were obtained to be 0.3–15.3μgkg−1, 1–50μgkg−1, 50–28,000μgkg−1, and 94.5–99.1%, respectively. The results obtained showed that determination of the selected Sudan dyes in food samples using an enough sensitive and a simple analytically validated method like in-line MMSPD may offer a suitable screening method, which could be useful for food analysis and adulteration.

A hydrazone covalent organic polymer based micro-solid phase extraction for online analysis of trace Sudan dyes in food samples

Covalent organic polymers (COPs) connected by covalent bonds are a new class of porous network materials with large surface area and potential superiority in sample pretreatment. In this study, a new hydrazone linked covalent organic polymer (HL-COP) adsorbent was well-designed and synthesized based on a simple Schiff-base reaction. The condensation of 1,4-phthalaldehyde and 1,3,5-benzenetricarbohydrazide as organic building blocks led to the synthesis of HL-COP with uniform particle size and good adsorption performance. This HL-COP adsorbent with high hydrophobic property and rich stacking π electrons contained abundant phenyl rings and imine (CN) groups throughout the entire molecular framework. The adsorption mechanism was explored and discussed based on π–π affinity, hydrophobic effect, hydrogen bonding and electron–donor–acceptor (EDA) interaction, which contributed to its strong recognition affinity to target compounds. Enrichment factors were 305–757 for six Sudan dyes by HL-COP micro-solid phase extraction (μ-SPE), indicating its remarkable preconcentration ability. Furthermore, the adsorption amounts by HL-COP μ-SPE were 1.0–11.0 folds as those by three commonly used commercial adsorbents. Then, HL-COP was applied as adsorbent of online μ-SPE coupled with high performance liquid chromatography (HPLC) for enrichment and analysis of trace Sudan dyes in food samples with detection limit of 0.03–0.15μg/L. The method was successfully applied for online analysis of chilli powder and sausage samples. Sudan II and Sudan III in one positive chilli powder sample were actually found and determined with concentrations of 8.3 and 6.8μg/kg, respectively. The recoveries of chilli powder and sausage samples were in range of 75.8–108.2% and 73.8–112.6% with relative standard deviations of 1.2–8.5% and 1.9–9.4% (n=5), respectively. The proposed method was accurate, reliable and convenient for the online simultaneous analysis of trace Sudan dyes in food samples.

Production of the Polyclonal Antibody against Sudan 3 and Immunoassay of Sudan Dyes in Food Samples

In this study, 4-aminophenylacetic acid was covalently coupled to aniline to synthesize an intermediate hapten and the intermediate hapten was coupled to β-naphthol to synthesize a tentative hapten of Sudan 3. The hapten was coupled to bovine serum albumin as the immunogen to produce the polyclonal antibody. The obtained antibody was highly specific to Sudan 3, Sudan 1, and Para red, but showed relative low binding ability to Sudan 2, Sudan 4, and Sudan red G. After evaluation of different coating antigens, a heterologous indirect competitive immunoassay was developed to multidetermine the six red dyes in food samples. The cross reactivities to the six analytes were in a range of 21-105%, and the limits of detection were in a range of 0.1-0.8 ng/mL depending on the compound. Intra- and interassay recoveries from the standard fortified blank samples were in a range of 74.5-96.3% with coefficients of variation lower than 15.1%.

Production of the monoclonal antibody against Sudan 2 for immunoassay of Sudan dyes in egg

Many methods have been reported to determine the residues of Sudan dyes in food samples. Among the reported methods, enzyme-linked immunosorbent assay (ELISA) was a frequently used practical screen tool. In this study, a novel hapten of Sudan 2 was synthesized by coupling 4-amino-3-methylbenzoic acid to β-naphthol, and the monoclonal antibody against Sudan 2 was produced. The obtained antibody can recognize Sudan 1, 2, 3, and 4, Sudan red G, and Para red simultaneously. After evaluation of different coating antigens, a heterologous indirect competitive ELISA was then developed to determine the six Sudan dyes in egg. The cross-reactivities for the six analytes were in a range of 63% to 100%, and the limits of detection were in a range of 0.2 to 0.5ng/g, depending on the compound. Intra- and interassay recoveries from the standard fortified blank eggs were in a range of 71.7% to 97.6% with coefficients of variation lower than 17.1%.

Determination of sudan dyes in food samples using supercritical fluid extraction–capillary liquid chromatography

Determination of sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples has been developed by several and different methods. However, sample treatment continues being the most important problem to determine these compounds in real samples. A rapid, sensitive and selective method for the extraction, separation and quantification of sudan dyes in commercial food samples has been developed. The method is based on the combination of a supercritical fluid extraction (SFE) procedure, followed by the analysis of the extracted plug by capillary liquid chromatography (CLC) with diode array detection (DAD). The entire procedure was optimized for the extraction of the samples, separation and detection of the analytes. For the SFE, the effect of CO2 flow rate, extraction pressure, extraction temperature, equilibration and extraction time and methanol modifier content were studied. Linear responses in the range from 50 to 1000ngmL−1 with average relative standard deviation lower than 11.6, and detection limits ranging from 23.2 to 42.0ngmL−1 were obtained for the different sudan dyes. The recoveries were in the range of 91–109% for dyes powder samples.

Determination of banned Sudan dyes in food samples by molecularly imprinted solid phase extraction‐high performance liquid chromatography

A method for molecularly imprinted SPE of banned Sudan azo-dyes from food samples was investigated. The molecularly imprinted polymer was obtained by suspension polymerization using 1-(4-chlorophenyl)azonaphthalen-2-ol as the mimic template. The molecular recognition properties of imprinted beads were evaluated for use as a SPE sorbent, in order to develop a selective extraction protocol for the Sudan class of dyes. The optimized extraction protocol resulted in a reliable molecularly imprinted SPE (MISPE) method suitable for HPLC analysis. It was selective for the main analyte, Sudan I, and the related azo-dyes Sudan II, III, IV, Sudan Red B, and Sudan Red 7B, while the permitted azo-dyes Allura Red AC, Neococcin, and Sunset Yellow FCF were not extracted. The method was tested for Sudan I, II, III, and IV in five different food samples (hot chilli pepper, hot chilli tomato sauce, sausage, tomato sauce, and hard boiled egg yolk) at three concentration levels (15, 100, and 300 microg/g). It demonstrated itself to be insensitive to the presence of different complex matrices, precise, accurate, and with good recovery rates (85-101%). The LOD and LOQ were satisfactory for most analytical determinations.

Comparison of dual solvent-stir bars microextraction and U-shaped hollow fiber–liquid phase microextraction for the analysis of Sudan dyes in food samples by high-performance liquid chromatography–ultraviolet/mass spectrometry

Two sample preparation methods, dual solvent-stir bars microextraction (DSSBME) and U-shaped hollow fiber–liquid phase microextraction (U-shaped HF–LPME), are proposed and critically compared for high-performance liquid chromatography (HPLC)–ultraviolet (UV)/mass spectrometry (MS) analysis of Sudan dyes in this paper. In DSSBME, the organic solvent was confined to a pair of hollow fiber membrane fixed on a stir bar, which can stir by itself, while the hollow fiber in U-shaped HF–LPME was fixed by two microsyringes. The significant factors affecting the microextraction of Sudan dyes in both microextraction techniques have been examined and no obvious difference in the effect of extraction solvent, pH and salt concentration on the extraction efficiency of Sudan dyes was observed except extraction time and stirring speed. Both microextraction techniques were similar in terms of analytical performance from aqueous solutions (LODs ranged from 0.09 to 0.95 μg L −1 by HPLC–UV and 2.5–6.2 μg L −1 by HPLC–MS; the absolute LODs ranged from 0.9 to 11.25 pg by HPLC–UV and 5–21.2 pg by HPLC–MS), however, DSSBME was more stable (lower stirring speed required), less sample consuming and much shorter time required to reach extraction equilibrium; while U-shaped HF–LPME was easier to operate and no more special device required. The two microextraction techniques combined with HPLC–UV/MS were successfully applied to the analysis of real samples including strawberry sauce, capsicum oil, salted egg, and two kinds of chilli sauce. Although the LODs of HPLC–UV are lower than that of HPLC–MS by a factor of 10 in this work, the absolute LODs for both HPLC–UV and HPLC–MS are comparable. HPLC–UV cannot identify the suspicious peaks at the same retention time as that of Sudan II and III in salted egg, while HPLC–MS can give exact information of Sudan I–IV in real sample analysis and is more reliable. The sensitivity of HPLC–MS is enough for real sample analysis.