Different Concentrations Of EDTA Research Articles

Biosorption of Zn by dried biomass of Euglena gracilis from aqueous solutions

The aim of this work was to evaluate the possibility to utilize the dried biomass of Euglena gracilis var. bacillaris as a biosorbent applied for the removal of Zn from aqueous solutions. For these purposes, experiments involving solutions spiked by 65ZnCl2 were carried out under the conditions of batch systems. The prepared biosorbent in the form of dried biomass of E. gracilis (< 300 μm) was characterized in terms of the presence of functional groups (COOH, PO3H2, OH, and NH2), the concentration of binding sites cAn and the value of pHzpc = 6.6 using the modelling program ProtoFit. From the kinetics of Zn biosorption, it can be assumed that the Zn removal was a rapid process, in which the concentration equilibrium [Zn]solution : [Zn]biosorbent was stabilized in the first 5 min of interaction. In individual experiments, the effect of solution pH, initial biosorbent or Zn concentration were evaluated. Based on the MINEQL+ speciation modelling program, we predicted the decrease in the abundance of free Zn2+ cations in the presence of different concentrations of EDTA as a complexing agent in the solution. It was found that the Zn biosorption decreased linearly with the decreasing the proportion of Zn2+ in solution. The biosorption data expressed as equilibrium values of the remaining Zn concentration in solution Ceq (µmol.dm-3) and equilibrium values of specific adsorption Qeq (µmol.g-1; d.w.) were well fitted to the Langmuir model of adsorption isotherm in comparison with the Freundlich model. The maximum adsorption capacity of the dried biomass of E. gracilis for the biosorption of Zn reached the value Qmax = 0.53 ± 0.05 mmol.g-1or 34.7 ± 3.4 mg.g-1 (d.w.), respectively.

Effect of different levels of EDTA on phytoextraction of heavy metal and growth of Brassica juncea L.

Heavy metal pollution of soil is a major concern due to its non-biodegradable nature, bioaccumulation, and persistence in the environment. To explore the probable function of EDTA in ameliorating heavy metal toxicity and achieve the sustainable development goal (SDG), Brassica juncea L. seedlings were treated with different concentrations of EDTA (0, 1.0, 2.0, 3.0, and 4.0 mM Kg-1) in heavy metal-polluted soil. Plant samples were collected 60 days after sowing; photosynthetic pigments, H2O2, monoaldehyde (MDA), antioxidant enzymes, and ascorbic acid content, as well as plant biomass, were estimated in plants. Soil and plant samples were also examined for the concentrations of Cd, Cr, Pb, and Hg. Moreover, values of the phytoremediation factor were utilized to assess the accumulation capacity of heavy metals by B. juncea under EDTA treatments. In the absence of EDTA, B. juncea seedlings accrued heavy metals in their roots and shoots in a concentration-dependent manner. However, the highest biomass of plants (roots and shoots) was recorded with the application of 2 mM kg-1 EDTA. Moreover, high levels (above 3 mM kg-1) of EDTA concentration have reduced the biomass of plants (roots and shoots), photosynthetic area, and chlorophyll content. The effect of EDTA levels on photosynthetic pigments (chlorophyll a and b) revealed that with an increment in EDTA concentration, accumulation of heavy metals was also increased in the plant, subsequently decreasing the chlorophyll a and b concentration in the plant. TLF was found to be in the order Pb> Hg> Zn> and >Ni, while TF was found to be in the order Hg>Zn>Ni>Pb, and the best dose was 3 mM kg-1 EDTA for Hg and 4 mM kg-1 for Pb, Ni, and Zn. Furthermore, hyperaccumulation of heavy metals enhanced the generation of hydrogen peroxide (H2O2), superoxide anions (O2•-), and lipid peroxidation. It also interrupts mechanisms of the antioxidant defense system. Furthermore, heavy metal stress reduced plant growth, biomass, and chlorophyll (chl) content. These findings suggest that the exogenous addition of EDTA to the heavy metal-treated seedlings increases the bioavailability of heavy metals for phytoextraction and decreases heavy metal-induced oxidative injuries by restricting heavy metal uptake and components of their antioxidant defense systems.

Cyanide-Free Copper-Silver Electroplated Coatings on Carbon Steel Exposed to 5% NaClO Bleacher.

This work deals with the development of cyanide-free copper-silver electroplated coatings on AISI-1075 steel and its corrosion behavior under a 5% NaClO solution (commercial household bleach). A cyanide-free bath based on sodium thiosulfate was employed to obtain the silver coatings using current densities from 0.2 to 5.0 mA/cm2 and different concentrations of EDTA (additive). The evolution of the open circuit potential with time showed that silver is anodic with respect to copper, so there were no intense attacks in the silver pores. Adhesion measurements were made on both coatings by the tape test. The behavior against corrosion was evaluated by polarization resistance (Rp) in samples with the best coating adhesion. The best results were obtained with a silver coating of about 20 μm in thickness deposited on copper coating previously polished with colloidal silica. The best performance was attributed to the formation of AgCl as demonstrated by x-ray diffraction and scanning electron microscopy.

The investigation of adsorption desulphurization performance using bimetallic Cu[sbnd]Ce and Ni[sbnd]Ce mesoporous Y zeolites: Modification of Y zeolite by H4EDTA-NaOH sequential treatment

The microporous structure of Y zeolite strongly affects the function of adsorption desulphurization, especially when resistant compounds are present in fuel. The goal of this paper was to enhance a novel, hierarchically structured bimetal Y zeolite and to investigate the adsorption desulphurization performance from different model fuels that included toluene as a competitor. Mesoporosity was introduced in Y zeolite by the dealumination-desilication process with different concentrations of EDTA and NaOH to improve the pore structure. The synthesized samples were characterized by means of XRD, BET, FE-SEM, FT-IR, EDX and UV techniques. In the following, bimetallic CuCe and NiCe were impregnated on parent Y zeolite and mesoporous samples to increase the adsorption capacity. The prepared meso-CuCe and meso-NiCe were characterized and measured in the term of adsorption desulphurization with different model fuels contained thiophene and dibenzothiophene. The results showed that meso-NiCe increased the adsorption capacity of thiophene and dibenzothiophene up to 24.4 and 27.5 mg/g, respectively, which were almost 4.1 times more than the parent Y zeolite and after two cycles of regeneration by thermal method, the adsorption capacity hardly decreased. In addition, effect of toluene, initial concentration, time, and temperature were investigated on the adsorption capacity of the adsorbents.

Effect of the application of different concentrations of EDTA on the adhesion of fiber posts using self-adhesive cements.

The purpose of this study was to analyze the effect of the application of different concentrations of EDTA on the adhesion of fiber posts to root dentin using self-adhesive resin cements. After endodontic treatment, 78 single roots were randomly divided into six groups (n = 13) according to the combination of the following factors: surface dentin treatment - control (distilled water), 17% EDTA and 24% EDTA; and self-adhesive resin cement - RelyX U200 (RX); and Multilink Speed (ML). After fiber post cementation, six slices were obtained for each root. Ten roots of each group were used for bond strength (BS) and three for microhardness (MH) evaluations. Data obtained from BS and MH tests for each resin cement were subjected to two-way ANOVA (surface treatment vs. root region) and to a post-hoc Tukey's test (α = 0.05). The lowest BS value was observed in the 24% EDTA group for RX cement, whereas the highest values for ML cement were observed for the control group in the middle and apical regions. In the MH test, the lowest value for RX was observed for 24% EDTA in the cervical region, whereas and the highest value for the ML cement was observed in the control group. Regarding both self-adhesive resin cements tested, the application of 24% EDTA was not able to improve the adhesion of fiber posts to root canal.

Outcome of Different Processing Methods on Mechanical and Physicochemical Properties of Human Dentin as a Potential Natural Scaffold

Dentin has been considered a promising scaffold for bone regeneration. This study investigated the effects of two different demineralization and deproteinization methods on the mechanical and physicochemical properties of dentin as a potential scaffold for tissue engineering approaches. Eighty dentin discs were divided into five groups according to the treatment process: control (C), no treatment; DEM1, complete demineralization with HCl; DEM2, partial demineralization with different concentrations of EDTA; DEP1, complete deproteinization using NaOCl solution; and DEP2, partial deproteinization by boiling water. The treated dentin discs were characterized using ATR-FTIR and SEM. The compressive strength, elastic modulus, and microhardness values of all C and treated samples were measured. They were analyzed using one-way ANOVA, Kruskal-Wallis, and Weibull analysis. FTIR showed significantly reduced mineral/matrix ratio in demineralized groups (DEM1 and 2) (p < 0.001), while increase of mineral/matrix ratio in DEP1 was not significant (p = 0.31). SEM observations revealed open dentinal tubules in DEM1 group and lower amounts in the other groups. The C showed the highest compressive strength (78.18 ± 16.19 MPa), and the DEM1 showed the lowest (0.84 ± 0.32 MPa). The treated groups showed lower Weibull moduli (m), when compared with the C group. The DEP2 (642 ± 318.9) and DEM1 (2.9 ± 1.37) groups showed the highest and lowest modulus of elasticity, respectively. DEM1 showed the least hardness values (10.27 ± 3.09) compared to the other groups (p < 0.001). Based on the results, the DEM1 showed confirmed demineralization and lowest mechanical properties. The highest mechanical properties belonged to DEM2 and DEP2 groups which both were partially treated. Depending on the purpose of the regeneration, the dentin processing method can be selected. Whenever the high mechanical properties are more important in scaffold selection, DEM2 and DEP2 are the best choices. This study investigated the effects of two different demineralization and deproteinization methods including DEM1, demineralization with HCl; DEM2, demineralization with EDTA; DEP1, deproteinization using NaOCl solution; and DEP2, deproteinization by boiling water on the mechanical and physicochemical properties of dentin as a potential scaffold. Based on the results, the DEM1 showed confirmed demineralization and lowest mechanical properties. The highest mechanical properties belonged to DEM2 and DEP2 groups which both were partially treated. Depending on the purpose of the regeneration, the dentin processing method can be selected. Whenever the high mechanical properties are more important in scaffold selection, DEM2 and DEP2 are the best choices. Future studies should be conducted to assess the osteoinductive/osteoconductive potential of these scaffolds and also cell growth and proliferation on the prepared scaffolds using mentioned protocols.

Enhanced photocatalytic activity of BiVO4 powders synthesized in presence of EDTA for the decolorization of rhodamine B from aqueous solution.

Bismuth vanadate (BiVO4) powders were successfully synthesized in presence of EDTA via microwave irradiation and used as photocatalysts in the oxidation reaction of rhodamine B (rhB) under visible light. Different concentrations of EDTA (0.5 to 10%) to chelate Bi3+ ions were employed on the BiVO4 synthesis. Under the presence of EDTA, a monoclinic crystalline structure was obtained, whereas a mixture of monoclinic and tetragonal phases was observed in the absence of EDTA. In addition, the use of different EDTA concentrations promoted the formation the different shapes of particles. The BiVO4 sample synthesized with low concentration of EDTA (0.5%) exhibited about 85% of rhB decolorization in 300min at pH7.5. Therefore, this high efficiency can be attributed to a combination of intrinsic properties such as the morphology type and monoclinic structure of BiVO4 particles.

Can EDTA Change MRSA into MSSA? A Future Prospective!

In the present era we are left behind with limited options for the treatment of serious infections caused by multidrug resistant S.aureus, most remarkably nosocomially acquired Methicillin resistant S.aureus (MRSA). The problem increases more when these strains easily become multidrug resistant (MDR) due to biofilm formation. Those staphylococcal species that are vancomycin and linezolid resistant are also resistant to other antistaphylococcal agents which call for an urgent intervention to develop newer antimicrobial agents. The present study was undertaken with the aim to evaluate the antibiofilm effect of EDTA against the biofilm forming MRSA isolates, isolated from different clinical infections. The biofilms formed on polystyrene microtitre plates by the MRSA strains were treated by different concentrations of EDTA to find out its anti-biofilm activity. Further simultaneously the antibiotic susceptibility pattern was noted down to check whether the MRSA strains become MSSA (Methicillin sensitive S.aureus). Our data demonstrates that EDTA at 4mM concentration inhibits biofilm of MRSA and at 20 mM have an ability to reduce and dissociate the biofilm membrane, allowing the antibiotics to enter and convert MRSA strains into MSSA. These findings suggest that commercially available EDTA could be used in future to control MRSA and its biofilm- related infections.

Purification, Sequencing, and Biochemical Characterization of a Novel Calcium-Independent α-Amylase AmyTVE from Thermoactinomyces vulgaris

α-Amylase from Thermoactinomyces vulgaris was highly purified 48.9-fold by ammonium sulfate precipitation, gel filtration on Sephadex G-50 column, and ion exchange chromatography column of DEAE-cellulose. The molecular weight of the enzyme was estimated to be 135 and 145 kDa by SDS-PAGE. Its high molecular weight is due to high glycosylation. The purified amylase exhibited maximal activity at pH 6.0 to 7.0 and was stable in the range of pH 4.0 to 9.0. The optimum temperature for its activity was 50 °C. The enzyme half-life time was 120 min at 50 °C, suggesting intermediate temperature stable α-amylase. The enzyme was sensitive to different metal ions, including NaCl, CoCl(2), and CaCl(2), and to different concentrations of EDTA. The enzyme activity was inhibited in the presence of 1 mM CaCl(2), suggesting that it is a calcium-independent α-amylase. The TLC showed that the amylase hydrolyzed starch to produce large maltooligosaccharides as the main products. A 1.1-kb DNA fragment of the putative α-amylase gene (amy TVE) from T. vulgaris was amplified by using two specific newly designed primers. Sequencing analysis showed 56.2 % similarity to other Thermoactinomyces α-amylases with two conserved active sites confirming its function.

Genotyping of urinary samples stored with EDTA for forensic applications

Individual identification of urinary samples is necessary when sample switching or handling are suspected during a judicial process. To improve the rate of successful genotyping of urinary samples, we examined the stability of DNA in urinary samples stored for up to 30 days. Urinary samples from 20 healthy individuals (10 males and 10 females) were stored at -80°C with different concentrations of EDTA (0, 10 and 40 mM). Urinary DNA was extracted at days 0, 3, 9, and 30 after collection. The Quantifiler Human DNA Quantification Kit was used for measuring DNA concentration. Twenty STR loci were co-amplified using amelogenin-specific PCR with the Goldeneye 20A Kit. Significant differences in DNA concentration were observed between samples from females and males. In the case of female urinary DNA preservation with 10 and 40 mM EDTA the mean detection rate reached 0.95 after up to 30 days; for the male urinary samples, the mean detection rate of urinary DNA preserved with 40 mM EDTA was significantly higher than with 10 mM. We concluded that 40 mM EDTA is the best concentration for preservation of the DNA in urinary samples.

Properties of a lipase produced by Beauveria bassiana: purification and biochemical studies

Lipases are some of the crucial enzymes during the fungal penetrating process of the insect integument. Due to the importance and lack of information on the microbial lipases of Beauveria bassiana, investigations were carried out to purify and biochemically characterize these enzymes. The results obtained on growth medium demonstrated the highest activity of lipase 6 days after inoculation while the pH of the medium was 7.1. After three purification steps, the purified enzyme was 9.91-fold with specific activity of 20816 U/mg protein, recovery of 25% and molecular weight of 25 kDa. The purified lipase had the optimal pH and temperature at 7 and 35°C and was stable for 36–72 h under those conditions. Ca2 + significantly increased the enzyme activity and NaCl decreased it at all the tested concentrations. In addition, Mn2 + had no effect on enzyme activity but Mg2 + and Zn2 + increased it only at the highest concentration used. Three out of the four inhibitors used, significantly decreased the purified lipase activity so that most inhibition and changes in the enzyme kinetic parameters were obtained by using different concentrations of EDTA. Knowledge of enzymology provides important information for the development of fungi as microbial pest control agents opening new avenues for study of the role of enzymes in virulence.

Malachite Green Adsorption onto Chitosan Coated Bentonite Beads: Isotherms, Kinetics and Mechanism

AbstractThe removal of Malachite green (MG) from aqueous solutions by cross‐linked chitosan coated bentonite (CCB) beads was investigated and the CCB beads were characterized by Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X‐ray diffraction (XRD) analysis. Solubility and swelling tests were performed in order to determine the stability of the CCB beads in acidic solution, basic solution and distilled water. The amount of MG adsorbed was shown to be influenced by the initial pH of the solution, contact time and the initial MG concentration. A kinetic study indicated that a pseudo‐second‐order model agreed well with the experimental data. From the Langmuir isotherm model, the maximum adsorption capacity of MG was found to be 435.0 mg g–1. Desorption tests were carried out at different concentrations of EDTA, H2SO4 and NaOH. However, all desorbing solutions showed zero recovery of MG at all concentrations.

The effect of different concentrations of EDTA on instrumented root canal walls

The purpose of this study was to investigate smear layer removal and erosive capacity of different concentrations of EDTA on instrumented root canal walls. Forty single-rooted teeth were instrumented using step-back technique and 2.5% NaOCl. The teeth were randomly divided into 4 groups, and final flushes were preformed with different concentrations of EDTA (15%, 10%, 5%, and 1%). All specimens were prepared for scanning electron microscope evaluation. The results showed that there was no significant difference on the smear layer removal between different concentrations of EDTA (P = .1959). Only coronal versus apical thirds showed significant difference regarding presence of smear layer (P = .0176). Whereas 15%, 10%, and 5% EDTA solutions demonstrated similar erosion patterns on the root canal walls (P > .05), 1% EDTA caused restricted erosion (P < .0001). There was no significant difference among the regions in terms of erosion (P = .6399). Lower concentrations of EDTA can be recommended for clinical usage to avoid excessive erosion of root canal dentin.

Preparation, Characterization, and Environmental Application of Crosslinked Chitosan-Coated Bentonite for Tartrazine Adsorption from Aqueous Solutions

The preparation, characterization, and environmental application of crosslinked chitosan-coated bentonite (CCB) beads for tartrazine adsorption have been investigated. CCB beads were characterized by using Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) surface area and Barrett–Joyner–Halenda (BJH) pore size distribution analyses were also determined. The values of pH of the aqueous slurry and pH of zero point charge (pHZPC) were almost equal. The adsorption at equilibrium of tartrazine was found to be a function of pH of the solution, stirring rate, contact time, and tartrazine concentration. The optimum conditions for tartrazine adsorption were pH 2.5, stirring rate of 400 rpm and contact time of 80 min. Pseudo-first-order and pseudo-second-order models were used to analyze the kinetics of adsorption with the latter found to agree well with the kinetics data, suggesting that the rate determining step may be chemisorption. The two most common isotherm models, Langmuir and Freundlich, were used to describe the adsorption equilibrium data. On the basis of Langmuir isotherm model, the maximum adsorption capacities were determined to be 250.0, 277.8, and 294.1 mg g−1 at 300, 310, and 320 K, respectively. Desorption studies were carried out at different concentrations of EDTA, H2SO4, and NaOH. All desorbing solutions showed poor recovery of tartrazine.

Comparison of Extracellular and Intracellular Potency of Botulinum Neurotoxins

Levels of botulinum neurotoxin (BoNT) proteolytic activity were compared using a cell-free assay and living neurons to measure extracellular and intracellular enzymatic activity. Within the cell-free reaction model, BoNT serotypes A and E (BoNT/A and BoNT/E, respectively) were reversibly inhibited by chelating Zn2+ with N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN). BoNT/E required relatively long incubation with TPEN to achieve total inhibition, whereas BoNT/A was inhibited immediately upon mixing. When naïve Zn2+-containing BoNTs were applied to cultured neurons, the cellular action of each BoNT was rapidly inhibited by subsequent addition of TPEN, which is membrane permeable. Excess Zn2+ added to the culture medium several hours after poisoning fully restored intracellular toxin activity. Unlike TPEN, EDTA irreversibly inhibited both BoNT/A and -E within the cell-free in vitro reaction. Excess Zn2+ did not reactivate the EDTA-treated toxins. However, application of EDTA-treated BoNT/A or -E to cultured neurons demonstrated normal toxin action in terms of both blocking neurotransmission and SNAP-25 proteolysis. Different concentrations of EDTA produced toxin preparations with incrementally reduced in vitro proteolytic activities, which, when applied to living neurons showed undiminished cellular potency. This suggests that EDTA renders the BoNT proteolytic domain conformationally inactive when tested with the cell-free reaction, but this change is corrected during entry into neurons. The effect of EDTA is unrelated to Zn2+ because TPEN could be applied to living cells before or after poisoning to produce rapid and reversible inhibition of both BoNTs. Therefore, bound Zn2+ is not required for toxin entry into neurons, and removal of Zn2+ from cytosolic BoNTs does not irreversibly alter toxin structure or function. We conclude that EDTA directly alters both BoNTs in a manner that is independent of Zn2+.

Comparative evaluation of the effect of two different concentrations of EDTA at two different PH and time periods on root dentin

The aim of the study was to evaluate the effects of two different concentrations of EDTA at two different pH values for lmin & 10 min applications respectively on root dentin. 54 human maxillary incisors instrumented to size 60 to apical foramen were sectioned at the middle third (8mm sections) longitudinally into two equal mesial and distal halves. The sectioned specimens were irrigated for I and 10 min respectively using EDTA of concentrations 17% & 10% at 7.5 and 9 pH. The amount of demineralization and removal of smear layer was evaluated by phosphorus liberation, surface roughness studies and SEM analysis. Optimum results were obtained with EDTA at 10% concentration at 9 pH for 1 min.

Major and trace metal extraction from soil by EDTA: Equilibrium and kinetic studies

EDTA, a powerful chelating agent, is used extensively in soil sciences to determine the bioavailability of trace metals and their possible decontamination from polluted soils. Because of its non-selective nature, the co-dissolution of major elements also occurs, in addition to the extraction of trace metal ions. In this work, the reactivity of trace and major elements (Pb, Cu, Cd, Al, Fe, Ca and Mg) with different concentrations of EDTA was studied in eight soil samples (Burgundy, France). The limit between lack and excess of EDTA with respect to total metal extracted, determined after 24 h of reaction for different types of soil varied from 0.002 to 0.05 M, respectively. For calcareous samples the amount of Pb, Cu and Cd extracted by EDTA was reduced to 50% of that extracted in non-calcareous soils. From the kinetic point of view, the extraction behavior of major elements seemed to depend heavily on excess or lack of EDTA and the soil Ca content. For a lack of EDTA, different competitive behaviors were revealed for the major elements (Al, Ca, Fe and Mg) towards the reagent, depending on the soil matrix. According to these experimental results, the mass balance between the reagent and cations in any EDTA–soil media is strongly controlled by major metal extraction. When choosing the reagent concentration needed to extract the trace metals efficiently, all the extractable metal present in the concerned sample must be taken into account.

Iron-chelation properties of phenolic acids bearing catechol and galloyl groups

In this study, the capacity of seven phenolic acids and hydroxytyrosol for complex formation with iron was quantified. A metal-chelation mechanism was described by means of spectrophotometry and calculating the binding constants of the complexes. The influence of phosphate buffer, Hepes buffer, Tris buffer and water on this mechanism was investigated. UV–Vis absorption spectroscopy showed that the absorption of phenolic acids changes upon the addition of Fe 2+, which resulted in several shifts of their spectra. These batochromic shifts were analyzed and evaluated by calculating binding constants. Furthermore, in the presence of different concentrations of EDTA (0–1 mM), a reduction of the constants was observed. However, not all of the phenolic compounds assessed here showed complex formation, those not bearing catechol or galloyl moiety like vanillic acid, syringic acid and ferulic acid, did not show any complex formation in our study. The ability of the phenolic compounds which chelate iron have been ranked in line with the binding constants in ascending order rendering the protocatechuic acid (1.43 M −1) the weakest chelator, followed by hydroxytyrosol (2.66 M −1), gallic acid (4.78 M −1), caffeic acid (8.12 M −1) and chlorogenic acid (20.13 M −1) as the strongest chelator.

Role of divalent metal ions in serum complement activity of the American alligator ( Alligator mississippiensis)

Treatment of alligator serum with different concentrations of EDTA resulted in a concentration-dependent inhibition of serum-mediated sheep red blood cell (SRBC) hemolysis. This inhibition of serum-dependent hemolysis was observed for other chelators of divalent metal ions, such as phosphate and citrate. Treatment of alligator serum with 5 mM EDTA completely inhibited SRBC hemolysis, which could be totally restored by the addition of 5 mM Ca 2+ or Mg 2+, but not Cu 2+ or Ba 2+. These data indicate a specific need for Ca 2+ and/or Mg 2+ in the serum-mediated hemolysis of SRBCs. Kinetic analyses revealed that the addition of 30 mM EDTA 1 min after incubation of SRBCs with serum resulted in only 30% inhibition of hemolytic activity. However, addition of EDTA as early as 3 min post-incubation resulted in complete SRBC hemolysis. Pretreatment of serum with EDTA inhibited the hemolytic activity, but the activity could be restored in a time-dependent manner by the addition of Ca 2+or Mg 2+. These data indicate that, as in human serum, the need for divalent metal ions occurs early in the alligator serum complement cascade.

Effect of EDTA on the light scatter in KDP crystal

KDP crystals with different concentrations of EDTA in solution were grown. Light scatter was detected with ultramicroscopic method. It has been proven that light scatter in KDP crystal aggravates with the increasing concentration of EDTA in the growth solution. The increase with light scatter occurs since EDTA inhibits the growth of KDP crystal at high concentration, which results in the formation of mother liquid inclusions, which in turn causes light scatter. The density, size and shape of light scatter are varied within different sectors of the KDP crystal. The mechanism of the effect is discussed.