Aluminium In Natural Waters Research Articles

A green procedure for the determination of bioavailable forms of aluminum in natural waters by electrothermal atomic absorption spectroscopy combined with microextraction technique.

Aluminum is a prevalent element in nature, but bioavailable forms of aluminum are toxic to plants, animals, and humans. The present study is dedicated to the development of an ecologically friendly, fast, simple, reliable, sensitive, and accurate improved procedure for the determination of subtrace concentrations of bioavailable forms of aluminum in natural waters. The procedure includes the separation and pre-concentration of bioavailable forms of aluminum using vortex-assisted liquid-liquid microextraction (VALLME) of ionic associates with salicylaldehyde 4-picolinhydrazone (SAPH) and sodium dodecyl sulfate (DDSNa) by isoamylacetate (200μl) and direct electrothermal atomic absorption spectroscopy (ETAAS). The SAPH reagent interacts only with water-soluble forms of aluminum. SAPH is used for the pre-concentration of bioavailable forms of aluminum as well as a chemical modifier; it increases the absorbance and the precision of the analytical signal of aluminum. The calibration curve shows the linear dependence in the range of 0.05-86μg⋅L-1 of the aluminum concentration (R2 = 0.992), with the limit of detection at 0.015μg⋅L-1 and the limit of quantification at 0.05μg⋅L-1. The accuracy of the proposed procedure for bioavailable forms of aluminum determination was verified on model solutions and against a reference method on natural samples of river and lake waters (RSD 3.2-5.2%, recovery 97.1-103.4%).

Determination of Bioavailable Aluminum in Natural Waters in the Presence of Suspended Solids.

Analyses of natural waters frequently show elevated levels of total aluminum (Al) attributable to acid extraction of Al from the total suspended solids (TSS) minerals. Hence, there is a need for an analytical method that measures only bioavailable Al. Natural waters high in TSS were collected to study the chronic effects of Al on Ceriodaphnia dubia. In the collected waters TSS ranged from 30 to 411 mg/L; total Al concentrations ranged from 2.0 to 44.8 mg/L. The TSS in natural waters inhibited reproduction of C. dubia up to 40% in comparison to the same filtered waters. This inhibition did not correlate with the concentration of TSS or total Al; it was attributed to nutritional deficiency and was prevented by increasing the food supply. To demonstrate that toxicity can be measured in natural waters, samples with elevated TSS were spiked with soluble Al, and survival and reproduction were measured in chronic studies performed at pH 6.3 and 8.0. To properly characterize the Al concentrations in the toxicity studies, a method was needed that could discriminate bioavailable Al from mineral forms of Al. An extraction method at pH 4 for bioavailable Al was developed and evaluated using C. dubia chronic toxicity studies in the presence of TSS. It is concluded that the proposed method is better able to discriminate chronic toxicity effects attributable to bioavailable Al from mineralized nontoxic forms of Al compared with existing methods using total or total recoverable Al (i.e., extraction at pH ≤ 1.5). We propose that this new method be used when assessing the potential for Al in natural surface waters to cause toxicity. Environ Toxicol Chem 2019;38:1668–1681. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

High-throughput deposition of chemical reagents via pen-plotting technique for microfluidic paper-based analytical devices

The deposition of chemical reagent inks on paper is a crucial step in the development and fabrication of microfluidic paper-based analytical devices (μPADs). A pen-plotting approach, delivering chemical ink deposition using technical pens filled with reagents and inserted into a desktop electronic plotter, is shown herein to be a versatile, low-cost, simple, rapid, reproducible, and high-throughput solution. The volume of the deposited ink was quantified gravimetrically, confirming that nanoliter volumes of reagents can be deposited reproducibly (e.g. 7.55 ± 0.37 nL/mm for a plotting speed of 10 cm/s) in detection zones of μPADs, typically spatially defined using wax printing. This approach was further investigated with regard to deposition of reagents in different geometrical forms (circular and linear), so demonstrating its applicability for preparation of μPADs with flexible design and application. By adjusting the plotting speed for linear deposition, lines with a relatively large range of widths (≈628–1192 μm) were created. Circular deposition was also demonstrated via delivery of reagents within wax printed circular fluidic barriers of a range of diameters (inner diameter = 1.5–7 mm). These capabilities were practically demonstrated via the fabrication of μPADs, based upon differing detection principles for determination of aluminum in natural waters using Morin as the fluorescent reagent. Traditional μPADs based on digital image colorimetry (DIC) were produced using circular deposition, whilst distance-based μPADs exploited linear deposition. Both types of μPADs developed using this method showed excellent precision for determination of trace concentrations of aluminium (average RSDs = 3.38% and 6.45%, and LODs = 0.5 ng (0.25 ppm) and 2 ng (0.5 ppm), for traditional and distance-based detection, respectively).

Determination of Aluminum in Natural Waters by Flow Injection Analysis with Spectrophotometric Detection

ABSTRACTA rapid flow injection analysis method is reported for the on-line determination of trace aluminum in natural water. The parameters for the formation of complex of aluminum with chrome azurol S were optimized in the presence of cetyltrimethylammonium bromide. Aluminum reacted with reagents to form the complex and was detected in a 30 mm flow cell with detection at 620 nm and a reference wavelength of 700 nm. The parameters were optimized based on a univariate experimental design. Potential interferences from concomitant ions were also evaluated. The method provided high sensitivity with a limit of detection of 20.1 nmol L−1. The linear dynamic range was from 50 to 5000 nmol L−1. The upper limit of the calibration curve was extended to 20 µmol L−1 using a less sensitive detection wavelength. The recoveries were between 97.4 and 103.4%, and the relative standard deviation was 0.64% (n = 8) for river water fortified with 200–1000 nmol L−1 aluminum. The sample throughput exceeded 50 h−1. The results from the flow injection method were in agreement with analysis by inductively coupled plasma mass spectrometry. The procedure was used to analyze aluminum in drinking water, rainwater, and Jiulong Jiang River water.

Алюминий в природных водах Верхней Оби

Алюминий в природных водах Верхней Оби

Aluminium heterogeneous speciation in natural waters

The presence of aluminium in natural waters is of major concern at present because of the potential threat for the health of a number of species, including humans. In natural water, aluminium exists in different forms depending on the concentrations of various other species, organic matter, the types of minerals, the pH, etc. The aluminium species in the natural water – gibbsite system is considered in this work. The main approaches for estimating of the individual concentrations of the aluminium species involve the use of reliable thermodynamic data, together with experimental measurements of free or total concentrations of major components. The new type of diagrams based on graphical and computerized methods, which quantitatively describe the distribution of soluble and insoluble, inorganic, and organic, and monomeric and polymeric aluminium species in heterogeneous aquatic systems is presented. This approach utilizes thermodynamic relationships coupled with original mass balance constraints, where the mineral phases are explicitly expressed. The factors influencing the distribution of soluble and insoluble aluminium species in aquatic systems were analyzed. The new type of developed diagrams may be used to interpret data obtained within the framework of water-quality monitoring programs.

Toxicity of aluminium in natural waters controlled by type rather than quantity of natural organic matter

Extension of the conditions under which Al toxicity is tested is required. Environmentally representative preparation of waters is used in investigating roles of alginate (AA) and humic acids (HA) in partitioning of Al (0.5mgL−1), subsequent uptake and accumulation by and toxicity to Lymnaea stagnalis. HA and AA did not alter precipitation of Al(OH)3, but altered subsequent behaviour of Al. High (40mgL−1) HA concentrations, and to a lesser extent AA, prevented settling and availability for benthic grazing but made deposited Al more likely to be ingested. HA detoxified but AA increased toxicity relative to Al alone. Low concentration (4mgL−1) AA and HA do not change partitioning but increase uptake; they both detoxify, but AA less than HA. The study shows OC:Al ratio is critical in predicting Al behaviour in natural waters, also uptake is mediated by snail behaviour, not solely a function of concentration and form of Al. Therefore, predicting Al behaviour will be subject to errors in determining relevant water composition and response of biota to the new speciation. However, with respect to toxicity, rather than other aspects of Al behaviour, different ratios of HA and Al are insignificant compared to whether AA is present rather than HA.

Combination of ionic liquid-based dispersive liquid–liquid micro-extraction with stopped-flow spectrofluorometry for the pre-concentration and determination of aluminum in natural waters, fruit juice and food samples

In this research, we combined ionic liquid-based dispersive liquid-liquid micro-extraction (IL-based DLLME) with stopped-flow spectrofluorometry (SFS) to evaluate the concentration of aluminum in different real samples at trace level. 1-Hexylpyridinium hexafluorophosphate [Hpy][PF(6)] ionic liquid and 8-hydroxyquinoline (oxine), which forms a highly fluorescent complex with Al(3+), were chosen as the extraction solvent and chelating agent, respectively. The hydrophobic Al-oxine complex was extracted into the [Hpy][PF(6)] and separated from the aqueous phase. Then, the concentration of the enriched aluminum in the sediment phase was determined by SFS. Some effective parameters that influence the SFS signals and the micro-extraction efficiency, such as the suction and sending time, the concentration of the chelating agent, pH, the amount of the ionic liquid, the type of disperser solvent and diluting agent, ionic strength, extraction time, equilibration temperature and centrifugation time were investigated and optimized. In the optimum experimental conditions, the limit of detection (3s) and enrichment factor were 0.05microgL(-1) and 100, respectively. The relative standard deviation (RSD) for six replicate determinations of 6microgL(-1) Al was 1.7%. The calibration graph using the pre-concentration system was linear in the range of 0.06-15microgL(-1) with a correlation coefficient of 0.9989. The developed method was validated by the analysis of certified reference materials and applied successfully to the determination of aluminum in several water, fruit juice and food samples.

Aluminum in Natural Waters: Content, Forms of Migration, Toxicity

Aluminum in Natural Waters: Content, Forms of Migration, Toxicity

8-Hydroxyquinoline–chloroform single drop microextraction and electrothermal vaporization ICP-MS for the fractionation of aluminium in natural waters and drinks

A new method of cycle-flow single drop microextraction (SDME) combined with electrothermal vaporization (ETV)-ICP-MS was proposed for the fractionation of aluminium with 8-hydroxyquinoline (8-HQ) as extractant. Several factors affecting the separation of aluminium species, such as sample flow rate, microdrop volume, pH and extraction time were investigated, and the optimized microextraction conditions were established. The experimental results indicated that in a pH range of 5.0–7.5 labile monomeric Al species (free Al (Al3+, AlOH2+, and Al(OH)2+)) could be extracted by the 8-HQ–chloroform microdrop while non-labile monomeric Al species (Al–citrate, Al–SO4, Al–F, Al–EDTA, Al–humic) directly passed through the microdrop. Labile aluminium in the post-extraction organic phase was directly determined by ETV-ICP-MS. The total Al was determined using pneumatic nebulization (PN)-ICP-MS. The non-labile aluminium was obtained by subtraction of labile aluminium from the total aluminium. Under the optimized conditions, the detection limit of the method was 3.3 pg mL−1 and the relative standard deviation for 1 ng mL−1 of Al was 10%. After 8 min of extraction, the enrichment factor was 210. The proposed method has been successfully applied to the determination of Al species in natural water, coffee and tea infusions. The results were comparable with that obtained by the 8-HQ loaded silanized silica gel microcolumn system and conventional liquid–liquid extraction system.

Fractionation of aluminum in natural waters by fluorometry based on the competitive complexation

A novel strategy for the speciation of aluminum has been developed by fluorometry using selective analytical reagents under different pH conditions, which is based on the measurement of the complexation ability of Al for analytical reagents and native organic matters. With Eriochrome Blue Black R, labile monomeric Al and total monomeric Al fractions are determined at pH 4.5 and pH 8.0, respectively. With morin only the labile monomeric Al is determined at pH 4.0, while with 8-hydroxyquinoline the total monomeric Al is determined at pH 5.5. So, acid soluble Al fraction is obtained indirectly. This method is successfully applied to the fractionation of Al in natural waters. The results well agree with those obtained by Driscoll’s 8-hydroxyquinoline/cation-exchange protocol. This fluorometric method possesses some advantages such as high sensitivity, easy manipulation, no separation step and less time-consuming.

Morin applied in speciation of aluminium in natural waters and biological samples by reversed-phase high-performance liquid chromatography with fluorescence detection.

A reversed-phase high-performance liquid chromatographic method with fluorescence detection for the determination of labile monomeric aluminium has been developed through pre-column complexation using morin as the analytical reagent. The highly fluorescent aluminium-morin complex (excitation wavelength 418 nm, emission wavelength 490 nm) was separated on a Spherisorb ODS 2 column with an eluent consisting of 30% methanol and 70% water (pH 1.0 with perchloric acid). The most remarkable point of this protocol was that only the most toxic aluminium species, that is, free aqua-aluminium ion and its monomeric hydroxo complex ions, selectively respond among various aluminium complexes. This strategy has been successfully applied to direct fractionation of the toxic aluminium in natural waters and biological samples without any pretreatment.

Determination of the speciation of aluminum(III) in natural waters by adsorption stripping voltammetry and complexation with AlIII–solochrome violet RS

A sensitive electrochemical procedure is proposed for the determination of the speciation of aluminum in natural waters using solochrome violet RS (SVRS) as analytical agent. The method is based on the different affinity of AlIII for SVRS and natural organic matter (NOM) present in natural waters at two pHs: pH 5.2 and 8.5. The Labile monomeric Al fraction (mainly inorganic Al) is determined at pH 5.2 condition (accumulation time: 60s, accumulation potential: −0.33V, SVRS concentration: 1.0×10−6moldm−3 and NH4Ac–HClO4 concentration: 0.17moldm−3), while the total monomeric Al fraction is determined at pH 8.5 condition (accumulation time: 30s; accumulation potential: −0.47V; SVRS concentration: 3.0×10−6moldm−3 and NH4Ac–NH3·H2O concentration: 0.17moldm−3). This sensitive and simple speciation method is successfully applied to the speciation of Al in natural water samples. Five fractions are measured: (i) labile monomeric Al (Ali); (ii) total monomeric Al (Ala); (iii) acid reactive Al (Alr); (iv) non-labile monomeric Al (Alo); (v) acid soluble Al (Als). The results are satisfactorily in agreement with those of the 8-hydroxyquinoline extraction/ion exchange method. The proposed method possesses the distinct advantages of speed, convenience, simple instrumentation, and freedom from toxic solvents. The principle for speciation of Al by electrochemical method is discussed.

FRACTIONATION OF ALUMINUM IN NATURAL WATERS BY CATION-EXCHANGE RESIN COUPLED WITH CHLOROFORM EXTRACTION/8-HYDROXYLQUINOLINE FLUORIMETRIC DETERMINATION

This paper reports a new and sensitive technique for the fractionation of aqueous aluminum in natural waters by cation-exchange resin, coupled with chloroform extraction/8-hydroxyquinoline fluorimetric determination. Four fractions of aluminum, including total reactive-AlT, total monomeric-Ala, labile monomeric- Ali (inorganic form), and non-labile monomeric (organic form) Alo can be determined directly by the proposed method. The acidic soluble Alr was calculated as the difference between total reactive AlT and total monomeric Al (AlT-Ala). Compared with the widely used Driscoll's method (MIBK extraction-GF/AAS), the proposed method possesses some distinct advantages: 1. the toxic forms of aluminum (labile monomeric Al) retained by the resin can be determined directly by fluorimetry. 2. the sensitivity and precision of this method are better than those of Driscoll's. 3. hazardous organic solvent MIBK is no longer used. Application of this method to fractionate aluminum to fifty natural water samples, collected from different areas in China, has been carried out. The results obtained by this method are compared with those by Driscoll's and are found to be in good agreement.

Speciation of aluminium(III) in natural waters using differential pulse voltammetry with a pyrocatechol violet-modified electrode.

A differential pulse voltammetric (DPV) procedure is proposed for the speciation of aluminium in natural waters using Pyrocatechol Violet chemically modified electrodes (PCV-CMEs). This novel speciation idea is based on the selective determination of different AlIII forms under two pH conditions. The labile monomeric Al fraction (mainly inorganic Al) is analysed at pH 4.8 (0.20 mol dm(-3) NaOAc-HOAc) and the total monomeric Al fraction is analysed at pH 8.5 (0.20 mol dm(-3) NH3.H2O-NH4Cl). The difference is thought to be caused by the weak competition ability of PCV to sequester AlIII from AlIII-natural organic matter complexes. This sensitive and simple speciation method has been applied successfully to aluminium speciation in natural waters sampled from different regions of China. Five fractions are measured directly or indirectly: (i) labile monomeric Al; (ii) total monomeric Al; (iii) acid reactive Al; (iv) non-labile monomeric Al; and (v) acid soluble Al. The results are in satisfactory agreement with those obtained by Driscoll's 8-hydroxyquinoline extraction-ion exchange method.

Indirect A.C. Oscillopolarographic Determination of Total Monomeric and Acid-Reactive Aluminum in Natural Waters by Using Pyrocatechol Violet

ABSTRACT Indirect determination of total monomelic and acid-reactive aluminum in natural waters by a.c. oscillopolarography in the presence of pyrocatechol violet (PCV) is presented in this paper. In 0.5 mol 1−1 NH4Ac buffer solution (pH 6.4) containing l×lO−3 mol 1−1 PCV, PCV yields two incisions on the a.c oscillogram at the potentials of - 0.80 and - 1.20 V, respectively. The incision depth declines when adding aluminum in the solution. The decreases of incision depth (Ep = -1.20 V) has a linear relationship with increasing Al concentrations (4×10−7 - 4×10−6 mol 1−). It is the basis for indirect quantitative analysis. The relative standard deviation is 8.3% for 1×10−6 mol 1−1 Al (n = 10) and the detection limit is 2 × 10−7 mol 1−1. The proposed method has been applied to determine total and acid-reactive Al in natural waters and the results are compared with Driscoll's 8-HQ-MIBK-GF/AAS and PCV colorimetric methods.

Fluorimetric determination of dissolved aluminium in natural waters after liquid–liquid extraction into n-hexanol

A sensitive and selective extraction-fluorimetric method for the determination of trace amount of dissolved aluminium in natural waters is developed in this study. Aluminium–lumogallion complex (Al–LMG) is extracted into n-hexanol, and the fluorescence can be enhanced substantially up to 20-fold. Compared to other publications in the literature, the method reported here is free from matrix effects, and the interference from iron and fluoride has been minimised successfully by Be 2+ and o-phenanthroline, respectively. The detection limit of dissolved Al is 0.25 nM, which is one order of magnitude lower than the traditional fluorescence techniques, with a precision of 5% at an Al level of 40 nM and 6.7% at an Al level of 1.0 nM in routine analyses. The inter-calibration with electro-thermal atomic absorption spectrometry (ETAAS) technique for a variety of natural water samples shows a difference of 5–10%. The analysis of international SRM 1643C reference material by the method developed here provides a result consistent with the certified value. The successful inter-laboratory calibration practice demonstrates again the merit of present analytical procedure for the determination of Al in environmental and marine sciences.

Trace analysis of aluminum in natural waters with rubeanic acid by adsorption chronopotentiometry

The determination of trace levels of aluminum in natural waters with rubeanic acid (RA) by adsorption chronopotentiometry is developed in this paper. Optimum experimental conditions include an accumulation potential of −0.40 V, accumulation time of 60 s, and a RA concentration of 6×10 −6 M in 0.2 M NaAc–HAc buffer solution (pH 4.6). The response is linear over the 1×10 −8∼4×10 −7 M concentration range. The detection limit is 5.6×10 −9 M and the relative S.D. (at the 3×10 −7 M level) is 2.6%. Possible interferences are evaluated. The method has been applied to the determination of trace levels of Al in various real samples. Direct determination of toxic forms of Al in surface waters by this technique is also explored.

Direct Determination of Labile Monomeric Aluminum in Natural Waters By A.C. Oscillopolarography in the Presence of Rubeanic Acid

ABSTRACT A simple and sensitive electrochemical method for the direct determination of labile (monomeric inorganic Al speciation) Al concentration in natural waters is developed in this paper. It is based on the use of a.c. oscillopolarography in the presence of rubeanic acid (RA). The optimal experimental conditions are: 1 mol/L NaAc-HAc buffer (pH 5.4) and a RA concentration of 6x10−4 mol/L. The response is linear over the 2x10−7 to 2x10−6 mol/L concentration range. The detection limit is 1x10−7 mol/L and the relative standard deviation (at the 1.2 x 10−6 mol/L level) is 5.5%. The method has been applied to the direct determination of labile monomeric Al concentrations in various natural samples. The results were verified by the classic ion exchange method.

Measurement of dissolved aluminium in waters: use of the tangential flow filtration technology

A comparison of tangential or cross flow filtration (TFF) and dead-end filtration (DEF) is presented with respect to the separation of particulate and dissolved forms of aluminium in natural and potable waters (from the Melbourne area, Australia) and synthetic suspensions of alumina in waters. It was found that 34 and 87% of the aluminium transmitted through 0.45 μm filters in DEF mode were not transmitted through 0.2 and 0.003 μm filters, respectively, both being operated in TFF mode. Spectroscopic and particle size analysis of suspended matter in a typical water sample from the Yarra River indicated the presence of quartz and aluminium bearing clay minerals with a modal size of 0.2 μm—below the pore size of filters (0.45 μm) commonly used to define dissolved and particulate forms of many elements. Results indicate that TFF produces filtrates whose composition is less dependent on the nature and concentration of solids in the sample being processed, and that the use of filters of 0.003 μm pore size effectively prevents particulate and colloidal forms passing into filtrates from their samples. Such filtrates therefore more accurately reflect the concentration of dissolved species of aluminium in natural waters.