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PubMed1999

Experimental staining of the anterior lens capsule in albino rabbits.

PURPOSE: To study the value and safety of staining the anterior lens capsule in albino rabbits. SETTING: Ophthalmology Department, Cairo University, and Ophthalmic Pathology Department, Research Institute of Ophthalmology, Cairo, Egypt. METHODS: The experiment was divided into 3 stages. First, the capacity of different concentrations of crystal violet solution to stain the anterior lens capsule of postmortem albino rabbit eyes was tested. The toxicity of different concentrations of the dye (2% to 0.25%) was then tested to determine the highest concentration that was nontoxic to the cornea and trabecular meshwork. The third step was to detect possible toxicity of lower concentrations (0.1% to 0.05%). Different dye concentrations were injected into the anterior chamber of the rabbit eyes. The eyes were examined after 1 and 3 days, 1 week, and 1 month using light microscopy and scanning and transmission electron microscopy. RESULTS: Different concentrations of crystal violet stained the anterior lens capsule, allowing for easy capsulorhexis. The use of the 2% and 1% concentrations was accompanied with irreversible damage to all corneal layers. The use of the 0.5% concentration caused damage to stromal keratocytes and endothelium. The use of the 0.25% concentration did not damage any corneal layer or the trabecular meshwork. Lower concentrations of 0.1% and 0.05% also stained the capsule, providing good visibility for successful capsulorhexis, and were less toxic to the corneal endothelium. CONCLUSION: Staining the anterior lens capsule with 0.25% to 0.05% concentrations of crystal violet solution caused no injury to the cornea or trabecular meshwork in albino rabbit eyes.

Animals↗
PubMedDate not supplied

Sentinel node detection in breast carcinoma.

AIMS AND BACKGROUND: The standard procedure for the evaluation of axillary nodal involvement in patients with breast cancer is still complete lymph node dissection. However, about 70% of patients are found to be free of metastatic disease while axillary node dissection may cause significant morbidity. Lymphatic mapping and sentinel lymph node (SLN) biopsy are changing this situation. METHODS AND STUDY DESIGN: In a period of 18 months we studied 201 patients with breast cancer, excluding patients with palpable axillary nodes, tumors > 2.5 cm in diameter, multifocal or multicentric cancer, pregnant patients and patients over 80 years of age. Before surgery 99mTc-labeled colloid and vital blue dye were injected into the breast to identify the SLN. In lymph nodes dissected during surgery the metastatic status was examined by sections at reduced intervals. Only patients with SLNs that were histologically positive for metastases underwent axillary dissection. RESULTS: We localized one or more SLNs in 194 of 201 (96.5%) patients; when both techniques were utilized the success rate was 100%. Histologically, 21% of patient showed SLN metastases (7.8% micrometastases) and 68% of these had metastases also in other axillary nodes. None of the patients with negative SLNs developed metastases during follow-up. CONCLUSIONS: At present there is no definite evidence that negative SLN biopsy is invariably correlated with negative axillary status; however, our study and those of others demonstrate that SLN biopsy is an accurate method of axillary staging.

Aged↗
PubMed1992

Plaque quantitation through protein measurement.

This study was undertaken to establish whether the quantitation of dental plaque protein by a dye-binding method (Coomassie G-250) may be used as an index of the amount of dental plaque sampled. Ten sites were sampled in 34 children on 5 occasions at 4 month intervals. The mean protein concentration in 1391 plaque samples was 6.9 +/- 4.1 micrograms (micrograms) (mean +/- standard deviation). A three-way analysis of variance showed that the plaque protein concentration was similar at the different sampling sites in the same child (p = 0.14), but statistically significant differences were observed with respect to time of sampling (F = 36.24; p = 0.0001) and individual sampled (F = 5.69; p = 0.0001). These observations indicate that plaque bacterial counts may be expressed as units of protein concentration and this method may be useful to relate the number of viable bacteria to an estimate of the amount of plaque collected. This ratio allows standardisation for any variation in the amount of plaque collected.

Analysis of Variance↗
PubMed1990

Essential problems in quantification of proteins following colloidal staining with coomassie brilliant blue dyes in polyacrylamide gels, and their solution.

Quantitative determination of stained proteins following polyacrylamide gel electrophoresis (PAGE) is of increasing interest especially since computer-aided densitometers have become available as well as recipes for sensitive and background-free staining with Coomassie Brilliant Blue dyes. However, avoidance of separation artifacts is not the only essential prerequisite for quantitative evaluation. The local particle density of a protein in a given gel is of critical importance since it determines its stainability. Depending on local protein concentration, the dye binding to the same amount of a given protein differs considerably. Since the stainability of proteins using colloidal staining procedures, as with Coomassie Brilliant Blue dyes, is time-dependent and, in addition, also dependent on the pore size of a given polyacrylamide gel used for PAGE, calibration curves for quantitative determinations have to be prepared in polyacrylamide gels of the same composition as used for PAGE. Staining conditions also have to be identical for calibration gels and gels under analysis. If, however, a set of calibration curves is prepared for different staining times, it is possible to calculate a generalized calibration curve, allowing for quantitative evaluation with flexible staining time. Furthermore, and in consequence of the implications due to particle density, quantitative determination via densitometry is only possible by determining the protein amount of each single measuring point (pixel) via its absorbance on the basis of a calibration curve. Since the particle density is inherent in a calibration curve, the final summation of the protein amount per pixel will give values close to reality.

Calibration↗
PubMed2005

Sentinel node localization in breast cancer using intradermal dye injection: results, influencing factors and learning curve.

To evaluate the identification rate, false negative rate, concordance, negative predictive value of sentinel node localization in breast cancer using intradermal isosulfan blue injection whether this is accurate enough for surgical approach in breast cancer surgery and whether there is a significant learning curve for this technique. Factors affecting the outcomes of the procedure are also determined. From August 2002 to September 2003, 66 cases of stage 0-IIIB operable breast cancer patients underwent sentinel lymph node biopsy before standard breast cancer operation. Overall, identification rate was 80.3%, false negative rate was 10.6%, concordance was 86.8%, negative predictive value was 83.3%, sentinel node was the only node that was positive in 45.5%, and mean operative time was 55.1 minutes. Factors found to lower sentinel node identification rate are neoadjuvant chemotherapy and large tumor (T3-4) while previous excision was not found to affect the identification rate. There is significant learning curve in this technique and this should be performed at least 40-45 cases in the learning phase to accomplish a high identification rate and lower false negative rate before implicating into clinical practice.

Adolescent↗
PubMed2002

Comparison of microleakage of three acid-base luting cements versus one resin-bonded cement for Class V direct composite inlays.

STATEMENT OF PROBLEM: Demineralized dentin beneath set cement may adversely affect microleakage under fixed restorations. PURPOSE: Microleakage of direct composite inlays cemented with acid-base cements and a methyl methacrylate resin cement were evaluated to determine their effect on the integrity of the underlying hybridized dentin. MATERIALS AND METHODS: Sixty Class V box preparations (3 mm x 3 mm x 1.5 mm) were precisely prepared in previously frozen bovine teeth with one margin in enamel and another margin in dentin. Direct composite inlays (EPIC-TMPT) for each preparation were divided into 4 groups of 15 specimens each and cemented with 3 acid-base cements (control group): Elite, Ketac-Cem, Hy-Bond Carbo-Cem, and 1 adhesive resin cement: C&B Metabond. All specimens were stored in distilled water for 24 hours at 37 degrees C before immersion in 0.5% basic fuchsin for 24 hours. The dye penetration was measured on the sectioned specimens at the tooth-cement interface of enamel and cementum margins and recorded with graded criteria under light microscopy (Olympus Vanox-T) at original magnification x 50, 100, and 200. A Kruskal-Wallis and the Mann-Whitney test at P<.05 were used to analyze leakage score. RESULTS: All cementum margins of the 3 acid-base cements tested demonstrated significantly higher leakage scores than cementum margins for inlays cemented with the resin cement tested(P<.01). No leakage along the tooth-cement interface was found for inlays retained with the adhesive resin cement. CONCLUSIONS: Within the limitations of this study, the 3 acid-base cements tested exhibited greater microleakage at the cementum margins than did the adhesive resin cement that was tested.

Animals↗
PubMed1998

Mechanism of electroporative dye uptake by mouse B cells.

The color change of electroporated intact immunoglobulin G receptor (Fc gammaR-) mouse B cells (line IIA1.6) after direct electroporative transfer of the dye SERVA blue G (Mr 854) into the cell interior is shown to be dominantly due to diffusion of the dye after the electric field pulse. Hence the dye transport is described by Fick's first law, where, as a novelty, time-integrated flow coefficients are introduced. The chemical-kinetic analysis uses three different pore states (P) in the reaction cascade (C <==> P1 <==> P2 <==> P3), to model the sigmoid kinetics of pore formation as well as the biphasic pore resealing. The rate coefficient for pore formation k(p) is dependent on the external electric field strength E and pulse duration tE. At E = 2.1 kV cm(-1) and tE = 200 micros, k(p) = (2.4 +/- 0.2) x 10(3) s(-1) at T = 293 K; the respective (field-dependent) flow coefficient and permeability coefficient are k(f)0 = (1.0 +/- 0.1) x 10(-2) s(-1) and P0 = 2 cm s(-1), respectively. The maximum value of the fractional surface area of the dye-conductive pores is 0.035 +/- 0.003%, and the maximum pore number is Np = (1.5 +/- 0.1) x 10(5) per average cell. The diffusion coefficient for SERVA blue G, D = 10(-6) cm2 s(-1), is slightly smaller than that of free dye diffusion, indicating transient interaction of the dye with the pore lipids during translocation. The mean radii of the three pore states are r(P1) = 0.7 +/- 0.1 nm, r(P2) = 1.0 +/- 0.1 nm, and r(P3) = 1.2 +/- 0.1 nm, respectively. The resealing rate coefficients are k(-2) = (4.0 +/- 0.5) x 10(-2) s(-1) and k(-3) = (4.5 +/- 0.5) x 10)(-3) s(-1), independent of E. At zero field, the equilibrium constant of the pore states (P) relative to closed membrane states (C) is K(p)0 = [(P)]/[C] = 0.02 +/- 0.002, indicating 2.0 +/- 0.2% water associated with the lipid membrane. Finally, the results of SERVA blue G cell coloring and the new analytical framework may also serve as a guideline for the optimization of the electroporative delivery of drugs that are similar in structure to SERVA blue G, for instance, bleomycin, which has been used successfully in the new discipline of electrochemotherapy.

Animals↗
PubMed2005

The current status of sentinel lymph node mapping in non-small cell lung cancer.

Sentinel lymph node (SLN) mapping has become a common procedure in the treatment of breast cancer and malignant melanoma. Its primary benefit is that it enables surgeons to avoid nontherapeutic lymph node dissection and the complications that follow. There are also several studies of the use of SLN mapping in the treatment of non-small cell lung cancer (NSCLC) reported in the English literature, and all present evidence for the existence of SLNs in NSCLC. Nevertheless, SLN mapping is not widely used in the treatment of NSCLC for several reasons: first, special precautions are required to minimize exposure when radioisotopes are used as tracers; second, it is difficult to detect the blue dyes used as tracers within anthoracotic thoracic lymph nodes; and third, major complications comparable to the arm edema seen in breast cancer or the lymphedema and nerve injury seen in melanoma are not seen with mediastinal lymph node dissection (MLND). To address these issues, new techniques are being developed by groups at several institutes, including our own. We believe that SLN mapping will enable surgeons to more precisely stage NSCLC, after which more sensitive techniques can be employed on a limited amount of tissue to detect occult micrometastatic disease with less cost and effort. SLN mapping can also be applied to video-assisted thoracic surgery (VATS) for NSCLC, enabling surgeons to avoid nontherapeutic and technically difficult MLND often necessary with traditional open surgery. For all of these reasons, we think that SLN mapping will be useful in the treatment of NSCLC, and that further development aimed at making SLN mapping a practical surgical procedure is warranted.

Carcinoma, Non-Small-Cell Lung↗
PubMed2005

Adverse drug reactions during lymphatic mapping and sentinel lymph node biopsy for solid neoplasms.

Currently, 1 per cent isosulfan blue dye and technetium-99-labeled sulfur colloid (SC) are used in lymphatic mapping (LM). Several reports have suggested that the incidence of adverse drug reactions (ADRs) during LM is high. We report our experience with LM for solid neoplasms in order to determine the incidence and risk factors for development of ADRs. Seven hundred fifty-three patients (90% women, mean age 57) underwent LM with blue dye alone or in combination with SC from 1998 to 2004. The most common malignancy was breast cancer (83%). One hundred ten patients (14%) had injection of both mapping agents. Most patients (87%) underwent intraparenchymal injection of LM agent. Eight patients (1.1%) had an ADR during LM; none had prior exposure to LM. Of these, 7 had limited reactions (mostly blue hives) that quickly resolved. One patient (0.1%) developed anaphylaxis. The ADR incidence in patients with a sulfa allergy was not significantly different than that in patients without a sulfa allergy (3.4 vs 1%, P = 0.12). No risk factors for development of ADR were identified. Overall, the incidence of ADR during LM is low. Patients with sulfa allergies and prior exposure to LM did not demonstrate an increased incidence of ADR. Anaphylaxis, though rare, can occur during LM.

Adolescent↗
PubMed1975

The interaction of apurinic acid aldehyde groups with pararosaniline in the Feulgen-Schiff and related staining procedures.

The equilibrium reactions involved in the formation of the apurinic acid (APA)-Schiff chromophores in the staining phase of the Feulgen-Schiff reaction do not allow a quantitative conversion of APA to these chromophores. By modification of the sulfite and dye concentrations and the pH of the staining reagents, or by using better solvents for pararosaniline like acetic acid or dimethylsulfoxide (DMSO) a shift of these equilibria was attempted in order to obtain a higher amount of APA-bound dye. A 40% higher absorbance, when compared with the normal Schiff-staining, was obtained in model films by staining with a saturated solution of pararosaniline in a 1:1 v/v mixture of DMSO and SO2-water, followed by rinsing in SO2-water. A doubling of the absorbance resulted in the same objects when a saturated solution of pararosaniline in a 2 M acetic acid/acetate buffer of pH 4.45 was used for staining, followed by a short rinse in SO2-water. Amino groups (as found in histones) are shown to compete with the amino groups of pararosaniline for the APA aldehydes. This effect, although causing lower staining intensities, is shown not to be the explanation for the differences in stain content found between more and less compact forms of chromatin. Depending on the pH, and dye and sulfite concentrations of the staining reagents, the following components are considered as possible contributors to the mixture of chromophores (Duijndam et al., 1973 b) formed between APA and Schiff's reagent or its modifications: 1. An acid labile component with a wavelength of maximal absorbance (lambda max) near 510 nm; its structure is probably the azomethine--CH=N--; 2. A relatively acid stable component with a high value of molecular absorbance (epsilon), an lambda max near 570 nm and possibly having an enamine structure--CH=CH--NH--; 3. A component with intermediate acid stability, low epsilon, and lambda max near 540 nm, and which is probably an alkylsulfonic acid --CH(SO3H)--NH--compound. Small differences in the staining conditions in the histochemical application of the Feulgen-Schiff reaction may cause a shift in the ratio between especially components 2 and 3, resulting in variations in stain content and in lambda max.

Acetates↗
PubMed2000

Practical guidelines for optimal gamma probe detection of sentinel lymph nodes in breast cancer: results of a multi-institutional study. For the University of Louisville Breast Cancer Study Group.

INTRODUCTION: Multiple radioactive lymph nodes are often removed during the course of sentinel lymph node (SLN) biopsy for breast cancer when both blue dye and radioactive colloid injection are used. Some of the less radioactive lymph nodes are second echelon nodes, not true SLNs. The purpose of this analysis was to determine whether harvesting these less radioactive nodes, in addition to the "hottest" SLNs, reduces the false-negative rate. METHODS: Patients were enrolled in this multicenter (121 surgeons) prospective, institutional review board-approved study after informed consent was obtained. Patients with clinical stage T1-2, N0, M0 invasive breast cancer were eligible. This analysis includes all patients who underwent axillary SLN biopsy with the use of an injection of both isosulfan blue dye and radioactive colloid. The protocol specified that all blue nodes and all nodes with 10% or more of the ex vivo count of the hottest node should be removed and designated SLNs. All patients underwent completion level I/II axillary dissection. RESULTS: SLNs were identified in 672 of 758 patients (89%). Of the patients with SLNs identified, 403 patients (60%) had more than 1 SLN removed (mean, 1.96 SLN/patient) and 207 patients (31%) had nodal metastases. The use of filtered or unfiltered technetium sulfur colloid had no impact on the number of SLNs identified. Overall, 33% of histologically positive SLNs had no evidence of blue dye staining. Of those patients with multiple SLNs removed, histologically positive SLNs were found in 130 patients. In 15 of these 130 patients (11.5%), the hottest SLN was negative when a less radioactive node was positive for tumor. If only the hottest node had been removed, the false-negative rate would have been 13.0% versus 5.8% when all nodes with 10% or more of the ex vivo count of the hottest node were removed (P =.01). CONCLUSIONS: These data support the policy that all blue nodes and all nodes with 10% or more of the ex vivo count of the hottest SLN should be harvested for optimal nodal staging.

Biopsy↗
PubMed1994

Intraoperative lymphatic mapping for vulvar cancer.

OBJECTIVE: To determine the feasibility of intraoperative lymphatic mapping in patients with vulvar cancer. METHODS: Isosulfan blue was injected intradermally at the junction of tumor and normal skin in nine patients. We then attempted to identify the dye in the superficial lymphatic channels and in a superficial groin lymph node. RESULTS: The sentinel node was identified in seven of 12 groins in seven of the nine subjects studied. Six of the successful cases had unilateral lesions. The cases in which a sentinel node was not identified were both patients with midline lesions, including one whose scar was injected following a prior wide local excision of a perineal tumor and one who appeared to have direct drainage to the deep pelvic nodes. There were no technique-related complications. In no case was there a positive non-sentinel node in the presence of a negative sentinel node. CONCLUSION: Intraoperative lymphatic mapping is technically feasible in patients with vulvar cancer, particularly those with unilateral disease. Further experience is needed to evaluate the reliability of the technique in identification of groin node metastases.

Carcinoma, Squamous Cell↗
PubMed2004

Influence of the thickness of mineral trioxide aggregate on sealing ability of root-end fillings in vitro.

The purpose of this study was to compare the ability of different thicknesses of mineral trioxide aggregate (MTA) to prevent apical leakage through the use of a protein-dye complex with Coomassie Brilliant Blue G. Sixty-four teeth were divided into 4 groups, then filled with MTA to depths of 1, 2, 3, or 4 mm. Two teeth served as the positive controls. Another 2 teeth served as the negative controls. Root-filled teeth were mounted in an apparatus and then challenged with protein solution. The evaluation was conduced at 24-hour intervals for 60 days. The 1-mm-thick MTA was the least effective in preventing apical leakage (P <.05). No significance difference was found between 2- and 3-mm-thick MTA (P >.05). Four-millimeter-thick MTA was significantly more effective than the other thicknesses tested (P <.05). The results of this study suggest that the thickness of 4 mm is most adequate for the use of MTA as a root-end filling material.

Aluminum Compounds↗
PubMed2004

Toxicological effects of malachite green.

This review summarises the wide range of toxicological effects of malachite green (MG), a triarylmethane dye on various fish species and certain mammals. MG is widely used in aquaculture as a parasiticide and in food, health, textile and other industries for one or the other purposes. It controls fungal attacks, protozoan infections and some other diseases caused by helminths on a wide variety of fish and other aquatic organisms. However, the dye has generated much concern regarding its use, due to its reported toxic effects. The toxicity of this dye increases with exposure time, temperature and concentration. It has been reported to cause carcinogenesis, mutagenesis, chromosomal fractures, teratogenecity and respiratory toxicity. Histopathological effects of MG include multi-organ tissue injury. Significant alterations occur in biochemical parameters of blood in MG exposed fish. Residues of MG and its reduced form, leucomalachite green have been reported from serum, liver, kidney, muscles and other tissues as also from eggs and fry. Toxicity occurs in some mammals, including organ damage, mutagenic, carcinogenic and developmental abnormalities. However, despite the large amount of data on its toxic effects, MG is still used as a parasiticide in aquaculture and other industries. It is concluded that the potential of alternative parasiticides, like humic acid, chlorine dioxide and Pyceze, should be explored to replace MG. Until then, MG should be used with extreme care at suitable concentrations and at times when the temperature is low. Removal of residual MG in treatment ponds should also be considered.

Aniline Compounds↗
PubMedDate not supplied

Amalgam repair: evaluation of bond strength and microleakage.

This study evaluated the tensile bond strength of "repaired" amalgams and compared the degree of microleakage. Amalgam (Cavex avalloy) was condensed into plastic tubes (3 mm in diameter, 10 mm in height) to the half-length. After storage in water at 37 degrees C for two days, the remaining parts of tubes were filled with amalgam (A), cavity varnish (CV)+A, Liner Bond 2V (LB2V)+A, 3M Opal Luting Cement (3MOLC)+A, Panavia F(PF)+A, Metabond(MB)+A, Fuji BondLC(FB)+A, HytacOSB(HOSB)+Hytac Aplitip (H), Liner Bond2V+Clearfil AP-X(CAP). The bond strengths for 15 samples of each restoration group were determined. For the microleakage study, MOD cavities of 90 extracted human premolars were used. The distal half of cavities were filled with amalgam. After storage in water at 37 degrees C for two days, the mesial half of the cavities were filled to simulate a clinical repair. The "repair" was placed using the procedures applied in the bond strength study. The teeth were stained with basic fuchsine (0.5%), sectioned and evaluated for dye penetration. In both parts of study, the data were analyzed by ANOVA and Duncan's multiple range tests. Bond strength values (MPa) were: A+PF+A 3.84+/-1.08, A+LB2V+A 3.15+/-0.97, A+LB2V+CAP 3.05+/-0.53, A+MB+A 2.86+/-0.88, A+HOSB+H 2.58+/-0.51, A+3MOLC+A 2.11+/-0.75, A+FB+A 0.68+/-0.59. The repaired A+A and A+CV+A groups were separated before testing. The A+PF+A group showed the highest bond strength (p<0.05). Microleakage in the cervical margins of repaired restorations was lower in the amalgam groups than microleakage in the resin composite and compomer groups. PF, MB, 3MOLC and FB performed better at the amalgam "repair" interface. The A+LB2V+A group showed no microleakage at both the occlusal and gingival test regions.

Analysis of Variance↗
PubMed1992

In-gel digestion of proteins for internal sequence analysis after one- or two-dimensional gel electrophoresis.

We examined the different steps necessary for the enzymatic digestion of proteins in the polyacrylamide matrix after gel electrophoresis. As a result, we developed an improved method for obtaining peptides for internal sequence analysis from 1-2 micrograms of in-gel-digested proteins. The long washing-lyophilization-equilibration steps necessary to eliminate the dye, sodium dodecyl sulfate, and other gel-associated contaminants that perturb protein digestion in Coomassie blue-stained gels have been replaced by washing for 40 min with 50% acetonitrile, drying for 10 min at room temperature, and then rehydrating with a protease solution. The washing and drying steps result in a substantial reduction of the gel slice volume that, when next swollen in the protease solution, readily absorbs the enzyme, facilitating digestion. The Coomassie blue staining procedure has also been modified by reducing acetic acid and methanol concentrations in the staining solution and by eliminating acetic acid in the destaining solution. The peptides resulting from the in-gel digestion are easily recovered by passive elution, in excellent yields for structural characterization. This simple and rapid method has been successfully applied for the internal sequence analysis of membrane proteins from the rat mitochondria resolved in preparative two-dimensional gel electrophoresis.

Amino Acid Sequence↗
PubMed2005

Adsorption kinetics of malachite green onto activated carbon prepared from Tunçbilek lignite.

Adsorbent (T3K618) has been prepared from Tunçbilek lignite by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N2 adsorption isotherm. The N2 adsorption isotherm of malachite green on T3K618 is type I. The BET surface area of the adsorbent which was primarily contributed by micropores was determined 1000 m2/g. T3K618 was used to adsorb malachite green (MG) from an aqueous solution in a batch reactor. The effects of initial dye concentration, agitation time, initial pH and adsorption temperature have been studied. It was also found that the adsorption isotherm followed both Freundlich and Dubinin-Radushkevich models. However, the Freundlich gave a better fit to all adsorption isotherms than the Dubinin-Radushkevich. The kinetics of adsorption of MG has been tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Results show that the adsorption of MG from aqueous solution onto micropores T3K618 proceeds according to the pseudo-second-order model. The intraparticle diffusion of MG molecules within the carbon particles was identified to be the rate-limiting step. The adsorption of the MG was endothermic (DeltaH degrees = 6.55-62.37 kJ/mol) and was accompanied by an increase in entropy (DeltaS degrees = 74-223 J/mol K) and a decrease in mean value of Gibbs energy (DeltaG degrees = -6.48 to -10.32 kJ/mol) in the temperature range of 20-50 degrees C.

Adsorption↗
PubMed2006

Spectrophotometric determination of trace arsenic in water samples using a nanoparticle of ethyl violet with a molybdate-iodine tetrachloride complex as a probe for molybdoarsenate.

A new spectrophotometric method was developed for the determination of low ppb levels of arsenic in water. We found that Ethyl Violet with molybdate-iodine tetrachloride complex forms nanoparticles under acidic conditions, which provide a sensitive probe for molybdoarsenate. The nanoparticles form stable particles with a diameter micrometers in size in the presence of heteropolyacid, and the resulting particles give a purple color to the apparently homogeneous solution, the intensity of which depends on the arsenic concentration. The nanoparticle itself is unstable due to conversion of the dye to a colorless carbinol species under acidic conditions without heteropolyacid. Although triphenylmethane dyes have been the subject of a number of investigations, there do not appear to be any reports on the dye particles for trace determination. The calibration curve is linear up to 20 microg L-1 arsenic, and the detection limit is 0.5 microg L-1 (6.6 x 10(-9) mol L-1). The coefficient of variation for spectrophotometry at 10 microg L-1 is 5.8% (n = 8). Furthermore, it is possible to detect concentrations as low as 1 microg L-1 arsenic visually using this method. The interferences from phosphorus and silica were eliminated using an anion exchange column and sodium fluoride as a masking agent, respectively. The proposed method has been successfully applied to water samples in abandoned mine water, groundwater, and river water. There was good agreement between the results obtained by the proposed method and those by hydride generation atomic absorption spectrometry. Since this method is specific for As(V), it is applicable to the speciation of arsenic oxidation states. Our method has enormous practical potential for simple and field detection of arsenic, requiring no complex apparatus or skilled laboratory support.

Arsenates↗