Method for determination of iron (iii) and aluminium (iii) in acidic solutions


(57) Abstract:

Usage: continuous flow analysis and simultaneous automated determination of iron content 3+and aluminum 3+in acidic solutions, an extract from the soil, dissolved rocks. The inventive sample is injected into a stream of nitric acid, add in a stream kylinalove orange and photometrically detect iron content 3+. After that, the stream is heated to 60 to 70°C and photometrically detect the total aluminium content 3+and iron 3+. 1 Il. table 2.

The invention relates to analytical chemistry (continuous flow analysis) and can be used for efficient, automated determination of iron and aluminum in various objects, mass tests for iron (III) and aluminium (III) is determined by their prevalence; everywhere such analyses are conducted, for example, in geological service. With special attention paid to performance definitions, as well as the simplicity and availability of methods.

Closest to the invention to the technical essence and the achieved result is a flow-injection method for determining getproviders in this case separately, in two stages using two independent flow systems. Determination of iron is carried out by detection of its own colour chloride complexes, which determines a very low sensitivity. Aluminum is determined by the color of its complexes with selenology orange (KO). The method consists in following the flow of the medium (0.1 M Hcl) Inuktitut the analyzed sample, containing in addition to aluminum (III) ions Na, K, CA, q, Fe, Mn, Pb, Zn and others, to him for the recovery of iron (III) to iron (II) add the flow of 0.1% ascorbic acid (And). Iron (II) does not form colored compounds with K, in contrast to iron (III). After adding to the stream flows the following components: AK, K. Oh, disodium salt ethylenediaminetetraacetic acid (EDTA), he passes the mixing spiral, heated to 70-140aboutC. Then adds a stream photometric reagent KOH buffer (pH 3-6). Thus all ions of the sample form colored complexes with the reagent. Then to eliminate the interfering effect of Fe (III), Mn (II), Zn (II) and other ions add to the flow of 0.02 M EDTA, damaging the painted compounds of all ions, except aluminum (III). Next, the flow enters the flow cell of the photometer, where at 506 nm is recorded signal is ptx2">

The purpose of the invention increase the detection sensitivity.

The proposed method allows the determination of aluminium (III) and iron (III) using the same running system.

The proposed method is that the sample is injected into the flow of 0.1-1 M nitric acid, add in a stream TO, photometrically detect the content of iron (III). After that, the stream is heated on 60-70aboutAnd photometrically detect the total content of aluminium (III) and iron (III) in this thread.

The difference of the proposed method is that the content of iron (III) in the flow detected after introducing the flow of acid and KOH, after which the stream is heated to 60-70oAnd detects the total content of iron (III) and aluminium (III) in this thread. When choosing acid was guided by its availability, purity and complexing properties. The use of hydrochloric and phosphoric acids in the proposed method is impossible due to the formation with ion iron (III) stable complex compounds. Insufficient purity sulfuric acid also excludes its application. In the proposed method from the available acid should be used nitrogen, in the range of concentrations 0,WMD already at the first detection records the total content of iron (III) and aluminium (III). Solutions of greater concentration can not be applied due TO protonation and rapid failure of the communications flow system. Before the second detection it is necessary to heat flow up to 60-70oC. At a lower temperature does not result in formation of colored compounds of aluminium (III) with KO. Heated to high temperatures is impractical due to the lack of a stronger effect. In the proposed method twice in succession, photomatrixovina spend in one dual beam flow-through photometer, in which the flow sequentially proceeds through two flow-through cuvette. The first one detects the content of iron (III), and the second the total content of iron (III) and aluminium (III).

For implementing the method used high-speed flow analyzer, consisting of a sampler, peristaltic pump, analytical unit, dual beam flow detector and recorder.

The drawing shows an analytical unit that implements the proposed method.

The analytical unit is a system of flexible tubes, the mixing spirals and other devices. After switching on the probe sampler automatically takes samples of h the ski unit and is mixed with a flow of 1 M nitric acid 3, 4 and segmented air flow 5 tube passes through the mixing helix 6, and enters the first flow cell of the photometer 7. On the ribbon diagram is logged peak, the height of which corresponds to the content of iron (III). After that, in order to accelerate the formation of complexes of aluminium (III) with CO, the flow passes through a water bath 60-70o9, the mixing helix 10 and after removal of air bubbles with the help of Dibbler 11, the flow enters the second cell the flow-through photometer 12, when this occurs, the second peak from the same sample, and its height is proportional to the total content of aluminum and iron. The second peak at diagrames the ribbon looks like a negative.

The proposed method is illustrated by the following examples using the specified schema.

P R I m e R 1. The sample containing 7 to 10-6M iron (III) and 1 to 10-5M aluminum (III), placed in a Cup sampler, of which over 30 with a flexible tube I. providing speed 0,287 ml/min, get into the flow system. Then the tube serves wash solution (water) within 130 C. After that, the transmitter automatically switches to the selection of the next sample.

At the same time as three other Tr is 87) and air (0,226). United, segmented air stream is mixed with a break in the helix 6 and enters the first cell 7 photometer. After exiting the cuvette flow is a water bath (60aboutC) another helix 9, and enters the second cell 10 photometer.

The content of iron (III) and aluminium (III) is determined by the heights of the positive and negative peaks on a pre-constructed in identical conditions, the calibration graphs. Performance is 14 samplers 1 h

To improve the performance of the method proposed to use variable time washing the rest, as described above). For this purpose between each of the three neighboring samples used washing time is 60 s, and between triples 130 C. This leads to increased productivity determine the two components up to 32 pravovogo in 1 hour

P R I m m e R 2. Determination of Fe (III) and aluminium (III) is carried out, as described in example 1, changing only the concentration of nitric acid up to 1.0 M and temperatures up to 70aboutC. the Results are similar and are given in table. 1.

P R I m e R 3. Estimation of iron (III) and aluminium (III) at a concentration of nitric acid 0.5 M and a temperature of 65about(The rest as in example 1). R is requently found in various objects of cations and anions. Criterion interfering influence served as the analytical output signal within the confidence interval.

The selectivity of the developed method is quite high, which determines the possibility of its use in the analysis of the different objects, for example, soil extracts, the main of rocks.

P R I m e R 4. Using the proposed system was the analysis of a standard sample of the basic rocks (si-1) after acid dissection and appropriate dilution and acid extracts of samples of soils (SDPS-1 and SCT-1). The results are shown in table. 2.

Thus, the described method allows the simultaneous selective determination of Fe (III) and aluminium (III) using a simple flow-through system that includes one input and one detector, and the use of available reagents. In addition, the proposed method extends the capabilities of high-speed flow analyzer PFa-300, designed for one-component definitions.

METHOD for determination of IRON (III) AND ALUMINIUM (III) IN ACIDIC SOLUTIONS, including the introduction of the sample into the flow of the acid adding flow kylinalove orange, heating, photomatrixovina iron (III) and aluminium the Oia kylinalove orange detects iron (III), the stream is heated to 60-70oAnd detects the total content of iron (III) and aluminium (III).


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