Titan Yellow Research Articles

One-Step Synthesis of Hierarchical Flower-like SnO2/BiOCOOH Microspheres with Enhanced Light Response for the Removal of Pollutants.

The low separation rate of electron-hole pairs in single-component photocatalysts severely limits their applications for wastewater treatment. For this study, SnO2/BiOCOOH photocatalysts in flower-like microspheres were controllably synthesized via a one-step hydrothermal method and were characterized by various advanced techniques. These SnO2/BiOCOOH nanocomposites demonstrated excellent photocatalytic activities for the degradation of rhodamine B (RhB), titan yellow, and levofloxacin hydrochloride (LVF). Specifically, 98.5% of RhB, 80% of titan yellow, and 85% of LVF were degraded under 5 W LED (λ = 365 nm) light irradiation within 30, 40, and 60 min, respectively. Radical trapping experiments and electron spin resonance results indicated that h+ was the dominant active radical, whereas ·O2- and ·OH played an auxiliary role in the photocatalytic system. Subsequently, a potential photocatalytic mechanism was proposed based on the experimental results.

Preparation of supported chitosan adsorbent with high adsorption capacity for Titan Yellow removal

The supported chitosan (CS) adsorbent (FZCS) was successfully prepared by load CS on the BSCS supporter in this work. The adsorbent was characterized by elemental analysis, FT-IR, XRD, TGA, SEM and N2 adsorption-desorption techniques. The results showed the FZCS sorbent displayed the high removal rate (97.95%) for Titan Yellow (TY) anionic dye in aqueous solutions owing to its properties combining amino active functional amino group from the CS itself and higher specific surface area and mesoporous structure from the BSCS support. Isotherm data conform to the Langmuir isothermal model with a maximum adsorption capacity of 120.48 mg/g at 30 °C, suggesting monolayer adsorption of TY on the FZCS sorbent. The data were very well fitted to the pseudo-second-order kinetics. The adsorption capacity of FZCS could maintain about 70% after six cycles. The research indicated that FZCS would be a promising, eco-friendly and effective sorbent for anionic dye wastewater treatment in the near future.

Derivative spectrophotometry and multivariate optimization for simultaneous removal of Titan yellow and Bromophenol blue dyes using polyaniline@SiO2 nanocomposite

In the present study, the performance of PAN@SiO2 nanocomposites as an adsorbent to remove Bromophenol blue (BPB) and Titan yellow (TY), was considered in single- and binary-component solutions. PAN@SiO2 nanocomposites were characterized through diverse techniques such as FE-SEN, XRD, FTIR, and EDX. Derivative spectrophotometry (DS) was developed to determine TY and BPB in two-compound mixtures employing ‘zero-crossing’ technique. In fact, useful parameters such as the amount of sorbent, pH, and the initial concentration of each dye were optimized using a four-factor central composite design (CCD) to maximize the percentage removal of TY and BPB dyes from aqueous solution simultaneously. The optimum operation conditions were pH of 3, initial concentration of 202 mg/L for BPB, 218 mg/L for TY and an adsorbent dose of 0.048 g. Under optimal condition, the maximum removal percents of 95% and 84% were obtained for both TY and BPB, respectively. The adsorption kinetics of both TY and BPB dyes were best correlated to the pseudo 2nd order model. The Langmuir isotherm model was appropriate for elucidating the dye adsorption process in single and binary solutions. The maximum uptake capacity (qmax) of TY and BPB was 141.5 mg/g and 129.6 mg/g for the single solution and 129 mg/g and 109 mg/g for the binary solution, respectively. The thermodynamic calculations demonstrated that the adsorption of TY and BPB dyes onto PAN@SiO2 was endothermic and spontaneous.

Enhanced photocatalytic and electrochemical performance of TiO2-Fe2O3 nanocomposite: Its applications in dye decolorization and as supercapacitors

This work reveals a green combustion route for the synthesis of TiO2, Fe2O3 and TiO2-Fe2O3 nanocomposites as photocatalysts for decolorization of Titan Yellow (TY) and Methyl Orange (MO) dyes at room temperature in aqueous solution concentration of 20 ppm under UV-light irradiation. We observed that the TiO2-Fe2O3 nanocomposite shows superior photocatalytic activity for TY dye compared to pure TiO2 and Fe2O3. Rate constant (k) values of TiO2, Fe2O3 and TiO2–Fe2O3 for TY and MO are 0.0194, 0.0159, 0.04396 and 0.00931, 0.00772 0.0119 kmin−1 respectively. The surface area and pore volume of TiO2-Fe2O3 nanocomposite were found to be 71.56 m2/g and 0.076 cm3/g, respectively as revealed by BET studies. From the Barrett–Joyner–Halenda (BJH) plot, the mean pore diameter of TiO2-Fe2O3 nanoparticles was found to be 2.43 nm. Further, the TiO2-Fe2O3 nanocomposite showed good electrochemical behavior as an electrode material for supercapacitors when compared to pure TiO2 and Fe2O3 nanoparticles resulted in stable electrochemical performance with nearly 100% coulombic efficiency at a scan rate of 10 mV/s for 1000 cycles. Interestingly, the novelty of this work is that the designed supercapacitors showed stable electrochemical performance even at 1000th cycle, which might be useful for rechargeable supercapacitor applications. The electrochemical properties of the nanocomposites were compared by the data obtained by cyclic voltammograms, charge-discharge tests and electrochemical impedance spectroscopic studies. These results demonstrated that the TiO2-Fe2O3 nanocomposite showed stable performance compared to TiO2 and Fe2O3 nanoparticles at current density of 5 Ag−1.

Bio-Waste Aloe vera Leaves as an Efficient Adsorbent for Titan Yellow from Wastewater: Structuring of a Novel Adsorbent Using Plackett-Burman Factorial Design

Titan yellow (TY), a triazene azo dye, was removed from contaminated wastewater samples using a green adsorbent recycled from Aloe vera leaves (AV) waste. Two adsorbents were developed—air-dried Aloe vera (ADAV) and thermally treated Aloe vera (TTAV). Adsorption efficacy of both adsorbents was assessed in terms of percent removal (%R) of TY and adsorption capacity (qe). ADAV had a better performance compared to TTAV. Plackett–Burman design (PBD) was exploited to establish the experimental pattern of the study. Four variables were studied: pH, adsorbent dose (AD), dye concentration (DC), and stirring time (ST). Analysis of variance (ANOVA) at 95.0 confidence interval (CI), control, and quality charts helped establish regression model(s). Characterization of both adsorbents was performed using FT-IR/Raman spectroscopy together with TGA/dTGA and SEM/energy dispersive X-ray spectroscopy (EDX) analyses. Textural properties were determined using nitrogen adsorption isotherms at 77 K. Results showed that the surface areas of ADAV and TTAV300 were 3.940 and 7.076 m2/g, respectively. Raman analysis showed that the TTAV had clear D- and G-bands. Equilibrium studies revealed that data were well fitted to Freundlich isotherm with a maximum adsorption capacity of 55.25 mg/g using Langmuir equation, and the adsorption was physisorption. Adsorption followed a pseudo-second order that occurred in two steps—diffusion and then adsorption.

The Kinetics and Equilibrium Thermodynamics Study on the Removal of Direct Blue and Titan Yellow Dyes from Aqueous Media by Modified Rice Husk Char

Abstract The use of indigenous natural materials and their modification toward fruitful application is one of the important subjects. Thermal modification of Rice Husk at 400 oC resulted into Rice Husk Char (RHC) which was chemically modified with KOH and was labeled as KOH Modified Rice Husk Char (KMRHC). Both RHC and KMRHC were characterized by using, Fourier transformed infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-rays (EDX) and X-ray diffraction (XRD) before and after their use as adsorbents. The prepared material was applied for the removal of toxic dyes, Direct Blue (DB) and Titan Yellow (TY) from aqueous media. The maximum adsorption capacity of DB and TY dyes on KMRHC were inspected as 30.9 mg/g and 28.6 mg/g, respectively at pH 4 using initial dye concentrations of 80 mg/L containing 2500 mg/L of the adsorbent dose with agitation speed of 240 rpm at 303 K. At the same experimental conditions the highest percentage removal of DB and TY on the adsorbent were observed as 96.6% and 89.3%, respectively. Thermodynamics studies of the adsorption of DB and TY dyes on KMRHC inferred for exothermic and spontaneous process. The value of ΔS is negative which suggested that randomness decreases at the interface of adsorbent-adsorbate during the adsorption. The kinetics study indicated that the experimental data of the adsorption process for both dyes, best fits to pseudo-second order kinetic model. The equilibrium data was tested on Langmuir, Freundlich and Temkin adsorption isotherm models. It was observed that the data are best fit to the Langmuir isotherm model (R2 > 0.99), which suggested that the adsorption process is dominated by chemisorption approach. The overall results suggest that various parameters of the adsorption process were not only affected by the variation in experimental conditions but also by the chemical structure of the adsorbate molecules for the same adsorbent.

Self-assembly of positively charged SiO2/Y2O3 composite nanofiber membranes with plum-flower-like structures for the removal of water contaminants

Abstract Water contaminants, especially bacterial and viral contaminants, have substantially negative impacts on human health because of their wide variety and incredibly small sizes. To develop a nanofiber filter with a high adsorption capacity, a positively charged SiO2/Y2O3 composite membrane with a plum-flower-like structure was prepared by self-assembly and heat treatment. The effects of the hydrothermal temperature and reaction time on the morphology of the composite nanofiber membrane (NFM) were investigated. In the composite NFM, the Y2O3 nanoflowers were tightly bound to the SiO2 nanofiber support. The possible formation mechanism of the composite NFM with a plum-flower-like structure is discussed. The results indicated that the Y2O3 nanoparticles were attached to the SiO2 nanofiber support via a Y-Si-O chemical bond. The surface charge of the composite NFM and its adsorption properties toward water contaminants were characterized. The isoelectric points (IEP) of the composite NFM calcinated under a N2(96%)/H2(4%) atmosphere was 9.23. The maximum bacterial retention was close to 100% and the log reduction values (LRV) of the bacteria were 6. Viral contaminants were simulated using a small molecule with two negative charges, titan yellow, with a maximum saturated adsorption capacity and removal rate of the plum-flower-like NFM for titan yellow were 87.96 mg/cm3 and 99.999%, respectively. After reusing a membrane five times, the composite NFM retained a removal rate of 95.641%. This positively charged SiO2/Y2O3 composite NFM with a plum-flower-like structure has broad application prospects in the fields of contaminant removal and virus filtration.

Tamarindus indica mediated biosynthesis of nano TiO2 and its application in photocatalytic degradation of Titan yellow

Present article reports for the first time a simple, eco-friendly synthesis of nano TiO2 semiconductor photocatalyst mediated by ethanolic Tamarindus indica leaf extract using titanium isopropoxide as precursor. XRD of the obtained product confirms the synthesis of anatase titania. Presence of aggregates of near spherical particles of size range 20–40 nm was revealed by SEM and TEM images. Purity of synthesised titania was verified by EDX and the surface area of the product determined by BET was 75 m2/g. The band gap estimated by UV spectroscopy was 3.21 eV. The photocatalytic activity of synthesised nano TiO2 was tested on photodegradation of Titan yellow dye by heterogeneous semiconductor photocatalysis process. The effect of TiO2 loading (0.25–1.0 g/l), initial concentration of Titan yellow (10–40 ppm), pH (3, 5, 7, 9 and 11) of the dye on photodegradation was studied in presence of UV light of 125 W. The percent degradation observed for 10 ppm dye at nano TiO2 loading of 0.75 g/l at pH 7.0 was 95% in 120 min. Effect of various light source and irradiation time were also studied. The degradation data was best fitted by Langmuir Hinshelwood kinetics with apparent rate constant of 0.015 min−1. The photo degradation follows the pseudo first order kinetics.

Comparison of magnetic Fe3O4/chitosan and arginine-modified magnetic Fe3O4/chitosan nanoparticles in simultaneous multidye removal: Experimental design and multicomponent analysis

In this study, multidye biosorption of Titan yellow (TY), Fuchsine acid (FA) and Indigo carmine (IC) in ternary mixture onto magnetic Fe3O4/chitosan nanoparticles (MFe3O4/CS NPs) and arginine-modified MFe3O4/CS NPs was investigated. Simultaneous determination of TY, IC, and FA in ternary solutions was performed by principal component-wavelet neural network (PC-WNN). Characterizations of the synthesized particles were performed by scanning electron microscopy (SEM), elemental analysis (EDAX), thermo-gravimetric analysis (TGA), vibrating sample magnetometer (VSM), Fourier transform infrared (FT-IR) spectroscopy and BET surface area analysis. Result VSM indicate the saturation magnetization values of bare Fe3O4 and arginine-modified magnetic chitosan nanoparticles were about 55.00, 23.04 emu/g, respectively. Also result of BET analysis showed chitosan, MFe3O4/CSNPs, and arginine-modified are nonporous and specific surface area for arginine-modified is more than chitosan, MFe3O4/CSNPs. Response surface methodology (RSM) with Box-Behnken design was used to optimize experimental parameters (biosorbent dose, pH, and time). At optimum conditions, maximum total biosorption capacity of MFe3O4/CSNPs and arginine-modified MFe3O4/CSNPs for anionic dyes was 0.385 and 0.681 mmol g−1, respectively. Arginine-modified magnetic Fe3O4/CSNPs biosorption capacity was twice better than that of magnetic Fe3O4/CSNPs. The biosorption processes were kinetically followed by a pseudo-second order model. Fourteen isotherms were also fitted to biosorption equilibrium data.

Multi-functional Zn 2 TiO 4 :Sm 3+ nanopowders: Excellent performance as an electrochemical sensor and an UV photocatalyst

Abstract Zn2TiO4:Sm3+ (1–9 mol %) nano powders (NPs) were prepared by a facile solution combustion route using oxalyl dihydrazide (ODH) as a fuel. The obtained product was characterized by Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–Visible studies. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements were performed using a carbon paste electrode. CV results indicated the reversibility of the electrode reaction, whereas EIS measurements revealed a reduction in the charge transfer resistance with increase in the double layer capacitance of the electrode. The prepared electrodes also exhibited high sensitivity for detection of paracetamol. The photocatalytic degradation of Zn2TiO4:Sm3+ on Titan yellow (TY) dye was evaluated under UV light irradiation. The catalyst showed an excellent photocatalytic activity (PCA) for the degradation of TY dye due to reduction of photo generated electron–hole pair recombination, thereby enhancing absorption. The high electrode reversibility and excellent catalytic activity of Zn2TiO4:Sm3+ make it promising for multifunctional applications.

Fabrication of porous ceramics with double-pore structure by stepwise freeze casting using water/diphenyl methane emulsion

Porous alumina with double-pore structure was fabricated by stepwise freeze casting using water/diphenyl methane (DPM) emulsion as freezing medium. The effects of DPM content in the alumina slurry on the pore structure, mechanical properties, and specific surface area of porous ceramics were investigated. The porosity of porous ceramics was not significantly affected by DPM content in the alumina slurry due to their same solid contents. The lamellar pore size decreased, and the spherical pore size increased in porous alumina with increasing DPM content in the slurry. Closed spherical pores were formed in lamellar pore walls when the DPM content was 10vol%. The compressive strength slightly increased, and the specific surface area decreased in the samples with DPM compared with those in porous ceramics with pure water as freezing medium. The specific surface area of porous alumina was 0.566m2/g, and the interception rate for titan yellow was 44.16% when the DPM content reached 25vol% because the large spherical pore was connected to the outside. Hence, the fabricated porous alumina with DPM exhibited potential as adsorption and filtration materials.

Silver ions as em marker of congo red ligation sites in amyloids and amyloid-like aggregates.

Congo red (CR) is a known selective amyloid ligand. The focus of our work is identification (by EM imaging) of dye binding sites and their distribution in amyloids and amyloid-like aggregates formed in vitro. In order to produce the required contrast, CR has been indirectly combined with metal via including Titan yellow (TY) by intercalation which exhibits a relatively strong affinity for silver ions. The resulting combined ligand retains its ability to bind to proteins (which it owes to CR) and can easily be detected in EM studies thanks to TY. We have found, however, that in protein aggregates where unfolding is stabilized by aggregation and therefore is irreversible, TY alone may serve as both, the ligand and the metal carrier. The formation of ordered structures in amyloids was studied using IgG light chains with amyloidogenic properties, converted into amyloids by shaking. The resulting EM images were subjected to interpretation on the basis of the authors' earlier research on the CR/light chain complexation process. Our results indicate that dimeric light chains, which are the subject of our study, produce amyloids or amyloid-like complexes with chain-like properties and strong helicalization tendencies. Cursory analysis suggests that the edge polypeptide loops belonging to unstable light chains form intermolecular bridges which promote creation of loose gel deposits, or are otherwise engaged in the swapping processes leading to higher structural ordering.

Removal of Titan yellow dye from aqueous solution by polyaniline/Fe3O4 nanocomposite.

The efficiency of polyaniline/Fe 3 O 4 (PANI/Fe 3 O 4 ) nanocomposite (NC) as an adsorbent was investigated in the removal of Titan yellow (TY) dye from aqueous solution. The PANI/Fe 3 O 4 was synthesized by polymerization of aniline in H 2 SO 4 medium in the presence of Fe 3 O 4 nanoparticles with ammonium persulfate as an oxidant. The NC formed was characterized by SEM and FT-IR methods. The dye removal process was studied under various conditions and was found that the adsorption activity of the PANI/Fe 3 O 4 NC was greater than that of the bare PANI and Fe 3 O 4 nanoparticles. Adsorption kinetics fitted with pseudo-first-order kinetic model.

Synthesis of maghemite nanoparticles and its application for removal of Titan yellow from aqueous solutions using full factorial design

In this paper, batch adsorption experiments were carried out to investigate the maximum adsorption conditions of the anionic dye Titan yellow on maghemite nanoparticles (γ-Fe2O3). The γ-Fe2O3 nanoparticles were synthesized by co-precipitation method, and the γ-Fe2O3 nanoparticles structure was performed by transmission electronic microscopy, scanning electron microscope, XRD, and Brunauer–Emmett–Teller. The prepared magnetic adsorbent was well dispersed in water and easily separated magnetically from the medium after loaded with adsorbate. The main goal of this study was to analyze the role of experimental factors on the removal of Titan yellow from aqueous solution using full factorial design. The main and interactive effects of four most important variables like pH of the solution, dosage of adsorbent, initial concentration of dye, and contact time were investigated through the model equations designed by a two-level full factorial design. The results were statistically analyzed using the analysis of variance to define important experimental factors and their levels. A regression model that considers the significant main and interaction effects was suggested and fitted the experimental data very well. The optimized conditions for dye removal were at initial pH 6.0, 0.35g L−1 of adsorbent, 30.0 mg L−1 dye, and 25.0 min adsorption time. The adsorption capacity was evaluated using both the Langmuir and Freundlich adsorption isotherm models. The maximum predicted adsorption capacities for Titan yellow was obtained as 839.421 mg g−1. Furthermore, the kinetic of Titan yellow adsorption on γ-Fe2O3 nanoparticles was analyzed using pseudo-first- and second-order kinetic models and the results showed that the removal was mainly a pseudo-second-order process.

Determination of magnesium by the solution scanometric method in a coloured titan yellow magnesium hydroxide complex form

In this work, the magnesium content was determined by the solution scanometric method using titan yellow (TY) as a complexing agent in alkaline media. This method is based on scanning a solution containing the pink-coloured product of the combination of TY and the magnesium hydroxide complex. Hydroxylamine hydrochloride (HA) and starch were utilised as colour stabilizers and protective colloids, respectively. After the cells containing the sample solution were scanned, the colour of each cell was analysed with software written in Visual Basic (VB 6) in terms of the red, green and blue values. The parameters used for optimisation include the reaction time and the concentration of TY, sodium hydroxide, starch and HA. The system had a wide linear range between 0.070 and 30.000μgmL−1 concentrations of magnesium, with a detection limit of 0.058μgmL−1 and a relative standard deviation of 1.90% for the G colour value. In addition, the effects of some foreign species were investigated. The method was successfully applied for the determination of magnesium in almond gum and three water samples.

Preconcentration and determination of ultra-trace amounts of U(VI) and Th(IV) using titan yellow-impregnated Amberlite XAD-7 resin

A simple and sensitive method for the determination of ultra trace amounts of U(VI) and Th(IV) ions by spectrophotometric method after solid-phase extraction on a new extractant-impregnated resin (EIR) has been reported. The new EIR was synthesised by impregnating a weakly polar polymeric adsorbent, Amberlite XAD-7, with titan yellow (TY) as extractant. The analytical method is based on the simultaneous adsorption of analyte ions in a mini-column packed with TY/XAD-7 and performing sequential elution with 0.5% (w/v) Na2CO3 for uranium and 2.0 M HCl for thorium. The influences of the analytical parameters including pH, salting out agent and sample volume were investigated. The interference effects of foreign ions on the retention of the analyte ions were also explored. The limits of detection for U(VI) and Th(IV) were as low as 50 and 25 ng L−1, respectively. Relative standard deviations (n = 7) for U(VI) and Th(IV) were 3.1% and 2.9%, respectively. The method was successfully applied to the determination of ultra trace amounts of U(VI) and Th(IV) in different real matrices including industrial wastewater samples and environmental waters. The proposed method was validated using three certified reference materials and the results were in good agreement with the certified values.

ADSORPTION STUDIES OF SOME DYES ON ACACIA CONCINNA POWDER

The low cost activated carbon from Acacia Concinna was processed by treating with 2% HCl and 2% NaOH. The treated Acacia Concinna (Shikakai powder) was then roasted to get activated carbon. The influence of parameters like pH, concentration, dose and contact time were studied on adsorption of activated carbon for Congo red, Rhodamine-B, Crysoidine, Bismark brown and Titan yellow. The adsorption capacity of activated carbon was found to be 97, 98, 95, 98 and 96% respectively at pH 2 and contact time 24-48 hrs for all the dyes. The effect of concentration indicated that, as concentration increases adsorption decreases, hence increase in dose amount increases the adsorption. The data obtained through batch adsorption study was applied for Langmuir, Freundlich and Dubinin-Radushkevich(D-R) isotherms. The curve was linear for all the three isotherms and correlation coefficient (R 2 ) was 0.92, 0.970 and 0.977 respectively indicating that the developed model was favourable.

The use of Titan yellow dye as a metal ion binding marker for studies on the formation of specific complexes by supramolecular Congo red

Abstract Congo red (CR) and other self-assembling compounds creating supramolecular structures of rod- or ribbon-like architecture form specific complexes with cellulose and also with many proteins, including antibodies bound to the antigen and amyloids in particular. The mechanism of complexation and structure of these complexes are still poorly recognized despite the importance of the problem for medicine. This work proposes the progress in electron microscopy studies of amyloid-dye complexes by labeling supramolecular ligand CR with silver ions as a marker. Silver ions are introduced to CR carried by the strongly binding silver dye Titan yellow, which in addition form comicellar structures with CR. Silver carried by self-assembled dye molecules forms in the resulting metal nanoparticles, making the specific amyloid ligand CR perceptible in EM studies.

Highly sensitive and selective determination methyldopa in the presence of ascorbic acid using OPPy/TY/Au modified electrode

An enzymeless biosensor, based on electrodeposition of overoxidized polypyrrole (OPPY) onto gold electrode and modified with titan yellow (TY), was investigated in this study. OPPY/TY/Au showed electrocatalytic activity for the oxidation of methyldopa (MDA) in acetate buffer solution. The electrochemical performance of the modified electrodes was investigated by differential pulse voltammetric (DPV) method. The resulting biosensor exhibited excellent performance for MDA determination with a wide linear range (50nM to 20μM), a highly reproducible response (RSD of 2.3%), low percentage of the interferences and long-term stability. The calculated detection limit was 17nM. In order to verify the reliability of the biosensor, it was applied to the determination of MDA in human serum and pharmaceutical samples.

Retention behaviour of Hg(II) and Pb(II) ions on a chemically modified, strongly basic anion-exchange resin: Effect of acid mixed with surfactant on the distribution coefficients of metal ions

Summary Titan yellow has been adsorbed on a strongly basic anion-exchange resin. The effects of concentration, pH, time, and temperature on adsorption of the dye by the resin have been studied. The effects of surfactants on the distribution coefficients of metal ions were also studied. On the basis of distribution coefficients several binary separations of analytical importance (Zn(II) from Hg(II), Zn(II) from Pb(II), Cu(II) from Pb(II), Cd(II) from Pb(II), and Cu(II) from Hg(II) have been achieved on a column containing the Titan yellow-modified resin. Hg(II) and Pb(II) were selectively analysed in synthetic mixtures.