Eriochrome Cyanine Research Articles

Spectro-ellipsometric studies of activated sol–gel thin films to detect Cu2+ ions in aqueous solutions

Abstract Thickness, refractive index n and extinction coefficient k of eriochrome cyanine R (ECR) dye doped mesostructured silica film (ECRMSSF) dip-coated on silicon wafers without prior removal of surfactant have been determined in the visible range of the spectrum by spectroscopic-ellipsometry (SE). ECRMSSF was used as sensing detection layer of Cu 2+ in aqueous solutions of known pH. The dependence of optical parameters on the pH range of the aqueous phase (pH=6–8) was investigated. The detection reversibility of ECRMSSF was demonstrated. An electron paramagnetic resonance spectrum demonstrated the complexation of Cu 2+ by the entrapped ECR.

Optimization of a mouse locomotor rating system to evaluate compression-induced spinal cord injury: correlation of locomotor and morphological injury indices

Due to the usefulness of mouse genetics, there is a need to improve procedures for producing and assessing spinal cord injury (SCI) in mice. The authors describe an improved locomotor scoring system for evaluating SCI. The modified Basso-Beattie-Bresnahan (mBBB) scoring system for mice is compared with existing procedures as well as histological SCI criteria. Mice were subjected to SCI by placing a weight on the cord at T-12 for 5 to 15 minutes after laminectomy to produce spinal cord ischemia. Injury was assessed using mBBB scoring that incorporates elements of the rat BBB and the mouse motor function scoring systems that are best suited for precisely assessing mouse SCI. The mBBB score was found to be more discriminating than the inclined plane test, and in the authors' laboratory it had a significantly lower coefficient of variation than the Basso mouse scale score. The mBBB score is well correlated with sparing of white matter as assessed by eriochrome cyanine staining of myelin. Weight placement at T-12 in the mouse causes reproducible SCI. A new mBBB scoring system is useful for accurately assessing locomotor dysfunction following SCI in mice and is well correlated with histological assessment of spinal cord white matter.

Validation of an Alt locus for aluminium tolerance scored with eriochrome cyanine R staining method in barley cultivar Honen (Hordeum vulgare L.)

Aluminium (Al) phytotoxicity is one of the major constraints for barley (Hordeum vulgare L.) production on acid soils. Genetic variation for Al tolerance is present in barley germplasm. Previous studies have shown that Al tolerance in cv. Dayton and WB229 is controlled by a single locus on 4H. The present study was conducted to investigate the genetic control of Al tolerance in Japanese barley cv. Honen, and validate the linkage relationship between the Al tolerance locus and the molecular markers established previously. An F3 progeny representing 94 F2s from the cross of F6ant28B48-16 (Al sensitive) × Honen (Al tolerant) was evaluated for Al tolerance by staining roots with eriochrome cyanine R. A single Al tolerance locus Alt was validated on the long arm of chromosome 4H in Honen. Single sequence repeat (SSR) markers Bmag353 and HVM68 flanked the Alt locus at a distance of 1.6 ± 0.9 and 5.1 ± 1.7 cM, respectively. Our results have shown that the linkage between SSR markers and the Al tolerance locus can be used to characterise the ‘unknown source’ for Al tolerance.

Determination of Aluminum Traces in Hemodialysis and Tap Water Using Standard Method's Procedure Modified and Flow Injection Ionic Exchange Preconcentration

A procedure for the spectrophotometric determination of aluminum traces in water using a flow injection (FI) preconcentration system has been proposed. The flow system was made up of a peristaltic pump, an injector‐commutator, and a minicolumn filled with 300.0 mg of Amberlite IR‐120 cationic exchange resin. After the preconcentration step, aluminum was eluted by a 4.0 mol l−1 HCl solution. In a second stage, out of the flow system, the eluate was neutralized with a 4.0 mol l−1 NaOH solution. The aluminum was submitted to the reaction with eriochrome cyanine to form a chelate in solution buffered to pH 5.85, according to the Standard Method's procedure with some modifications, and this was followed by spectrophotometric detection. Chemical and flow variables were studied in the preconcentration system. The precision of the proposed method was calculated for a solution containing 46.8 µg l−1 of Al(III), when 40.0 ml of solution were preconcentrated (n=7), and their respective relative standard deviation (RSD) was 1.8%. The detection limit obtained was 1.7 µg l−1 of Al(III) (sample volume=40.0 ml). The proposed method was successful in determining aluminum in water certified reference material.

Spectroscopic studies and evanescent optical fibre wave sensing of Cu2+ based on activated mesostructured silica matrix

This paper report on the synthesis and test of eriochrome cyanine R (ECR) doped mesostructured silica films as Cu2+ sensing without prior removal of the surfactant. ECR activated mesostructured silica (via sol-gel technique) coated optical fibre core were used to Cu2+ sensing by evanescent wave method. The sol was prepared via acidic hydrolysis-condensation of tetraethoxysilane (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB:C16H33NCH3Br) as the structure-directing agent. Spectrophotometric investigations using doped sol-gel thin films dip-coated on glass slides were reported. Heat treatment temperature effect (optimum temperature 150°C), absorption dependence on the pH of the aqueous phase (pH = 8 seems to be the optimal absorption pH), sensitivity, reversibility and response range (0.05 mmol/l) were reported.

Direct, Sensitive Determination of Trace Amounts of Dissolved Ferric Iron in Natural Water by Light Absorption Ratio Variation Spectrometry

The chromophore eriochrome cyanine R (ECR) was used to sensitively coordinate Al(II) and Fe(II) in the presence of cetylpyridinium chloride (CPC) at pH 4.8. Trace amounts of Fe(III) can displace Al(III) from the Al(ECR)(CPC) ternary complex to form the Fe(ECR)(CPC) complex. The composition of the complexes was determined by the break point approach. The competitive displacement complexation was sensitive and highly selective, even if no masking reagent was added. An ongoing novel spectrophotometry, named the light-absorption ratio variation approach, was applied to the direct determination of Fe(III) in natural water with recovery between 92.5 and 106%. The detection limit was only 9 ng/mL Fe(III).

Aluminium Tolerance of Four Bean (<i>Phaseolus vulgaris</i> L.) Varieties

Four bean (Phaseolus vulgaris) varieties (‘Rosecoco'– GLP 2, ‘Mwitemania'– GLP X 92, ‘Mwezi Moja' – GLP 1004, and French bean – ‘Amy') locally obtained from seed merchants in Kenya were investigated for their aluminium tolerance under two techniques of screening, namely root elongation and staining. Using hydroponic system, 3-day old seedlings were subjected to aluminium treatments of 0, 3, 5, 10, 20 and 50 µM, followed by subsequent root elongation studies and staining by Eriochrome cyanine R. The two techniques in combination produced the following increasing order of aluminium tolerance: French bean < Mwezi moja < Mwitemania < Rosecoco. Root elongation produced superior differential rating in assessing for aluminium toxicity in the beans. On the other hand, Eriochrome cyanine R staining lacked clear differentiation especially where there were marginal differences of Al tolerance. It follows that, screening for aluminium tolerance in common beans can preferably be accomplished through the staining technique procedure and only be followed by root elongation method under circumstances of ambiguity or where difference in tolerance are inseparable through the former. Journal of Agriculture, Science and Technology Vol.4(1) 2002: 52-65

Flow injection spectrophotometric determination of Al in hemodialysis solutions

A flow analysis (FA) system with spectrophotometric detection for Al determination in hemodialysis solutions was developed. The method was based on the reaction of Al with eriochrome cyanine R (ECR). The complex formed associated with cetyltrimethylammonium bromide (CTAB) — a cationic surfactant, which showed enough sensitivity to execute the direct analyte determination. All interferences were eliminated with the matrix matching calibration. The system presented the following analytic parameters: sensitivity ( m) of 8.10 × 10 −4 L μg −1, limit of detection (LOD) of 3.24 μg L −1 (3 σ), linear correlation coefficient of 0.9966 and linear range response from 10.8 to 650 μg L −1. The accuracy of the proposed method was checked by comparison with electrothermal atomic absorption spectrometry (ET-AAS) method. There were no differences among the results obtained from both methods, at a confidence level of 95% (paired t-test). Recovery tests were also made, values obtained were from 90.4 to 109 of recovery for Al-spiked samples.

Simultaneous preconcentration flotation-separation and spectrophotometric determination of thorium, lanthanum and yttrium in some geological and enviromental samples

The extraction and preconcentration of a metal complex via surfactant-mediated phase separation was studied. A sensitive, selective and low-cost methodology for the determination of micro amounts of thorium, lanthanum and yttrium ions, using Eriochrome Cyanine R (ECR) with a flotation step prior to spectrophotometric determination was developed. The precipitate in the scum layer was quantitatively collected, stripped with 4 ml of 3% HCl and measured spectrophotometrically at 540 nm for Th(IV) and at 650 nm for both La(III) and Y(III). The stripping of Th(IV), La(III) and Y(III) from the scum layer was carried out in one step with different mineral acids. The stripping efficiency was found to be quantitative in the case of HCl. An excess amount of ECR was used to eliminate the interfering effects of various foreign species. The proposed procedure was applied to the determination of Th(IV), La(III) and Y(III) spiked in natural water samples and in some ore samples. Additionally, the mechanism of flotation of the metal chelate was proposed to be due to a physical interaction between the metal chelate and the oleic acid surfactant through the Van der Waals force.

An Electrochemical Sol–Gel Sensor for Determining Iron by Stripping Voltammetry

Electrochemical sensors were developed based on thick-film carbon-containing electrodes coated with thin xerogel films fabricated by the sol–gel technology. The effect of the composition of a hydrolyzed mixture and the types of carbon-containing inks and a support on the properties of sol–gel electrodes was studied. Conditions for preparing sol–gel film sensors modified with 1,10-phenanthroline, 2,2′-dipyridyl, Chrome Azurol S, and Eriochrome Cyanine were chosen, and the electrochemical properties of these sensors were studied. Optimum conditions are found for determining total iron by stripping voltammetry (SVA) using sol–gel sensors modified with 1,10-phenanthroline and 2,2′-dipyridyl. The detection limit for iron(II, III) was found to be 0.02 mg/L at an accumulation time of 60 s. The sol–gel sensors were used in the analysis of natural waters.

The adaptation of a piezo-optical gas sensing system to detect copper ions in aqueous solution

A piezo-optical gas sensing system has been adapted to detect copper(II) ions in aqueous solution at pH 6.5 by using a thin polymer-bound film of powdered sol–gel silica doped with eriochrome cyanine R (ECR). Effects of varying ECR concentration, immersion time in the test solution, drying time and copper(II) concentration have been studied. The system permits rapid and inexpensive field measurements of copper(II) concentrations between 0.01 mM (0.6 ppm) and 0.5 mM (30 ppm) in water at pH 6.5, to an accuracy better than ±20%.

Effects of matrix variations on pH and Cu2+sensing properties of sol–gel entrapped Eriochrome Cyanine R

Eriochrome Cyanine R has been entrapped in a range of acid- and base-catalysed silica sol–gel matrices using various values of the water ∶ alkoxide ratio (R) and total precursor volume and incorporating varying amounts of the organic modifier methyltriethoxysilane (MTES). Diffuse reflectance spectra of thin films of polyisobutylene-bound finely-ground samples of these carefully aged materials have been measured as a function of time in solutions of various pH and Cu2+ concentration. Effects of pore size distribution and organic modification on these sensing properties have been interpreted in terms of data from nitrogen adsorption porosimetry and EXAFS. Optimum sensitivity to low Cu2+concentrations is achieved for gels incorporating 10% MTES, and the use of the polymer-bound ground samples increases response speed by a factor of 300 relative to bulk monolith sol–gel samples with elimination of cracking effects.

Identification of Aluminum Resistant Genotypes Among Madeiran Regional Wheats

Forty‐eight genotypes representing wheat diversity from the Island of Madeira were screened for resistance to aluminum (Al) in nutrient solution. Seeds of wheat used in the experiments were obtained from local farmers. The soil pH and content of ionic Al of plots cultivated with wheat were analyzed. The pH of topsoils varied between 3.83 and 6.59. The amount of ionic Al in soil samples varied between 0.38 and 1.36 cmol Al3 + per kg of soil and was positively correlated with the altitude of a plot. Eriochrome cyanine staining was used to evaluate the effect of Al ions on the root elongation. Seventy‐two hour exposure of 3‐day‐old seedlings to 100 and 200 µM Al in nutrient solution revealed a high number of Al resistant genotypes among wheat germplasm. After withdrawal of Al stress, survival and root regrowth was observed in 28 and 23 genotypes screened at 100 and 200 µM Al in nutrient solution, respectively. Enhanced resistance to Al among Madeiran genotypes was associated with the amount of ionic Al in the soils. Complexity and various patterns of responses of tested cultivars to Al stress may suggest that Madeiran germplasm could be a valuable source of genes controlling Al resistance for conventional breeding programs and for studies of molecular bases of mechanisms of Al resistance.

A new optical sensing reaction for nitric oxide

Based on the reaction between the Cu(II) complex of Eriochrome cyanine R (ECR) and nitric oxide (NO) in phosphate buffer (pH 7.4), a new colorimetric method for the determination of NO concentration has been developed. The linear calibration range for NO was 0–60 μM with a detection limit of 1.24 μM. This reaction was then used as the basis in the development of a fibre optic chemical sensor for NO gas. The copper complex was incorporated into silicone rubber membranes and exposed to NO gas after incubating the films in phosphate buffer (pH 7.4). A linear calibration for NO gas between 0 and 6 ppm was obtained with a detection limit of 0.227 ppm (1 μM ≃ 0.031 ppm NO in solution). The sensor response was shown to be reproducible and reversible (2.77%, R.S.D., n=4) upon exposure to aqueous phosphate buffer (pH 7.4). The sensor response was also found to be pH independent between 7 and 10.

Exchangeable aluminum evaluation in acid soils

One of the main factors limiting agricultural production in tropical climate regions is mainly related to the presence of exchangeable aluminum (Al3+) in highly weathered acid soils. Four methods of Al3+ determination extracted with neutral 1 mol L¹ KCl solution were evaluated: three colorimetric methods (aluminon plus ascorbic acid, and eriochrome cyanine R by FIA) and the usual titrimetric method with back-titration. Surface samples from 20 soils of different Brazilian regions, with active acidity (0.01 mol L¹ CaCl2 pH) ranging from very high to medium (3.82 to 5.52), were used. The variance analysis revealed significant interaction among Al3+ determination methods and soil. Mean methods comparisons within each soil (Tukey, P &lt; 0.05) indicated that, for most of the soils, the methods differed among each other, although there were high correlations between the obtained values. Al3+ values determined for soil samples by titration varied between 0.15 and 14.71 mmol c dm³. The colorimetric methods showed higher values than the titration method, mainly for those with aluminon (up to 18.75 mmol c dm-3). The Al3+ contents of colorimetric methods correlated quadraticaly with the titration values, for the soil samples with Al3+ &gt; 10 mmol c dm³. Among colorimetric methods, in operational terms, the eriochrome with FIA method presented analytical performance up to 50 samples per hour, easiness and sensibility for routine Al analysis in soil samples. However, due to the specificity, the titration/back-titration method should be used, despite the moroseness, when the Al3+ ions are the objective.

Study of the Sorption Properties of Cellulose Acetate Modified with Aluminon and Eriochrome Cyanine R

Study of the Sorption Properties of Cellulose Acetate Modified with Aluminon and Eriochrome Cyanine R

Extraction-Spectrophotometric Method for Determination of Fluoride in the Range of Microgram per Liter in Natural Waters

In this study a new extraction–spectrophotometric method for the determination of fluoride ion in natural waters has been presented by use of octyl chemically bonded solid phase extraction (SPE) cartridge. In this method at first aluminium–oxinate chelate is adsorbed on SPE cartridge, then the water sample (containing fluoride ion) is passed through the SPE device. The excess of oxine on the sorbent is washed with acetate buffer and finally the residual of aluminium–oxinate chelate on the sorbent is eluted by ethanol and its absorbance is read at 375 nm. The decrease of adsorbed aluminium–oxinate chelate on sorbent is proportional to the fluoride ion concentration in the water samples. The detection limit of this method is 80 ng/ml and the linear dynamic range is between 0.1–2 µg/ml. Sensitivity of the method is excellent and absorbance variation for each µg/ml fluoride ion is 0.6 (approximately equal to Eriochrome cyanine R-zirconium standard method and ten times better than the Alizarin complexon standard method). Results of this method have good agreement with the Eriochrome cyanine R-zirconium standard method. Also this method has less interferences as compared with SPADNS standard method.

USE OF ERIOCHROME CYANINE R FOR SEPARATION-FLOTATION AND MICRODETERMINATION OF HAFNIUM AND ZIRCONIUM IN REAL SAMPLES

Eriochrome cyanine R (ECR) is investigated as a collector for separation and flotation of hafnium from zirconium through the use of an oleic acid surfactant. Selective separation of Zr(IV) is achieved at pH 2 with maximum efficiency, whereas Hf(IV) is completely separated at pH 7.0–7.5. Excess ECR is used to avoid interferences from foreign ions without any effect on the separation efficiency. The procedure is successfully applied to the determination of Zr(IV) and Hf(IV) in real samples. A flotation mechanism is proposed.

Direct determination of traces of beryllium with eriochrome cyanine R by diffuse reflection spectroscopy using chromaticity functions.

Chromaton-N-super and Silasorb C18 (SMT C18) were compared as solid supports for the direct determination of the immobilized beryllium complexes with eriochrome cyanine R by diffuse reflection spectroscopy. The advantage of Silasorb C18 was shown. A detection limit of 0.0002 microg mL(-1) could be reached in a 100-mL sample. The method was used for the analysis of real water samples.

Spectrophotometric flow-batch determination of aluminum in plant tissues exploiting a feedback mechanism

The feasibility of flow-batch systems to carry out procedures exploiting feedback mechanisms is discussed, and a flow-batch analyzer is proposed for spectrophotometric determination of aluminum in plant digests. As eriochrome cyanine R (ECR) was used as chromogenic reagent and considering the pronounced pH dependence of absorbance of the Al-ECR, in-line individual pH conditioning was performed. For pH matching, the m-cresol purple indicator was monitored in order to reach the required acidity for every assayed sample. The proposed system handles about 15 samples per hour, requires only 60 μg ECR per determination, and yields reproducible results (R.S.D.<1.0%). A quadratic correlation ( r>0.999, n=6) was achieved within 0.25 and 6.00 mg l −1 Al (dry basis). Results are in agreement with inductively coupled plasma atomic emission spectrometry.