Royal Decree 575/1996, 28 March, Laying Down New Official Methods Of Analysis Of Fertilizers.

Original Language Title: Real Decreto 575/1996, de 28 de marzo, por el que se aprueban nuevos métodos oficiales de análisis de fertilizantes.

Read the untranslated law here: https://www.global-regulation.com/law/spain/1460338/real-decreto-575-1996%252c-de-28-de-marzo%252c-por-el-que-se-aprueban-nuevos-mtodos-oficiales-de-anlisis-de-fertilizantes.html

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The full integration of Spain into the European Community requires the harmonization of national legislation with Community legislation.


The transposition of Directive 95/8/EC of 10 April, the Commission, on methods of analysis for fertilizers, which involves the incorporation to the internal regulations of new Community methods that allow to check their conditions of quality and composition, as well as to remove technical barriers to trade in the sector is therefore required. New methods are added to the existing official methods, approved by orders of 30 November 1976, on July 31, 1979, on September 17, 1981, 1 December 1981 and July 18, 1989 and by the Royal Decrees 1163 / 1991, 22 July, and 2490 / 1994 of 23 December.


The content of this standard is run under cover of the provisions in article 40.2 of the Act 14/1986 of 25 April, General health, and article 149.1.13. 2nd and 16th of the Constitution, concerning the basis and coordination of the general planning of economic activity and bases and general coordination of the health.


In the processing of this Royal Decree have been consulted entities and organizations affected by it and the report of the Interministerial Commission for food management has been issued.


In his virtue, a proposal of the Ministers of agriculture, fisheries and food, economy and finance, industry and energy, of health and of trade and tourism, according to the Council of State, and after deliberation by the Council of Ministers at its meeting of March 28, 1996, D I S P O N G O : Article 1. Object.


Methods of analysis of fertilizers listed in the annex are approved as official.


Article 2. The so-called official methods.


When there are no official methods for certain analysis of fertilizers, and until they are approved, may be used as laid down in national regulations or those international recognized methods.


Sole additional provision. Basic character.


The provisions of this Royal Decree has the character of basic State legislation under cover of the provisions in article 40.2 of the Act 14/1986 of 25 April, General health, and article 149.1.13. 2nd and 16th of the Constitution, relating to the bases and coordination of the general planning of economic activity and the bases and general coordination of the health.


First final provision. Schools of development.


It empowers the Ministers of agriculture, fisheries and food, finance and economy, industry and energy, health and consumption and trade and tourism to dictate, in the field of their respective competencies, the provisions necessary for the implementation and application of the provisions of this Royal Decree.


Second final provision. Entry into force.


This Royal Decree shall enter into force the day following its publication in the "Official Gazette".


Given in Madrid on March 28, 1996.


JUAN CARLOS R.


The Minister of the Presidency, ALFREDO PEREZ RUBALCABA to N E X or index 22 (b). Quantitative determination of boron in fertiliser extracts of content exceeding 10 per 100 by means of acidimetric titration.


23 (e). Trace elements in content exceeding 10 per 100.


23 (f). Extraction of water-soluble trace elements.


23 (g). Removal of organic compounds in fertiliser extracts content exceeding 10 per 100.


23 (h). Quantitative determination of trace elements in content exceeding 10 per 100 in fertiliser extracts by spectrometry of atomic absorption (general procedure).


29 (b). Determination of zinc content exceeding 10 per 100 in fertiliser extracts by atomic absorption spectrometry.


30 (c). Quantitative determination of copper in fertiliser extracts content exceeding 10 per 100 by volume.


32 (b). Determination of iron in fertilizer extracts content exceeding 10 per 100 by atomic absorption spectrometry.


33 (b). Determination of manganese content exceeding 10 per 100 in fertiliser extracts by titration as permanganate.


35 (b). Quantitative determination of molybdenum content exceeding 10 per 100 in fertilizer extracts by the gravimetric method with 8-hydroxyquinoline.


37 (b). Determination of cobalt in fertiliser extracts of content exceeding 10 per 100 by the gravimetric method with 1-nitroso-2-naphthol.


METODO 22 (b) 22 (b) quantitative determination of boron in fertiliser extracts of content exceeding 10 per 100 by means of acidimetric titration.


22 (b).1 principle.


This document describes a method for the determination of boron in fertiliser extracts.


This procedure is applicable to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f), for which the order of 14 June 1991, on fertilizers and related products, the Declaration of the content of total boron and/or of the water-soluble boron content.


The Borate ion forms with mannitol a mannitoboric complex is formed by the following reaction: CH (OH) + HBO 1 CHOB + HO the complex is titrated with a solution of sodium hydroxide until a pH of 6.3.


22 (b).2 Material and devices.


22 (b). 2.1 pH electrode glass 22 (b). 22 (b) magnetic stirrer 2.2.2. 3 beaker 400 ml with teflon rod.


22 (b).3 reagents.


22 (b). 3.1-methyl red indicator solution. In a 100 ml graduated flask, dissolve 0,1 g of (Chinese) methyl red in 50 ml of ethanol to 95 per 100. Make up to volume with water. Homogenize.


22 (b). 3.2 diluted hydrochloric acid solution, about 0,5 M. mix 1 volume of hydrochloric acid (HCl, d = 1,18 g/ml) with 20 volumes of water.


22 (b). 3.3 solution of sodium hydroxide, approximately 0.5 M. It must be free of carbon dioxide. In a graduated 1 litre flask containing about 800 ml of boiled water, dissolve 20 g of sodium hydroxide (NaOH) in. When the solution has cooled, make up to volume with boiled water. Homogenize.


22 (b). 3 4 standard sodium hydroxide solution, about 0,025 M. It must be free of carbon dioxide. Dilute the 0,5 M sodium hydroxide solution 20 times (22 (b). 3.3) with boiled water and mix thoroughly. Be determined its value expressed in B (see item 22 (b). 4.4).


22 (b). 3.5 (100 lg/ml B) boron calibration solution. In a 1000 ml volumetric flask dissolve water 0,5719 g of boric acid (HBO), weighed with a precision of 0.1 mg. make up to volume with water and mix thoroughly. Go to a plastic jar to keep in the fridge.


22 (b). d-mannitol (CHO) 22 (b) powder 3.6.3. 7 sodium chloride (NaCl).


22 (b).4 procedure.


22 (b). 4.1-preparation of the test solution. Dissolution of boron. See 23 methods (e) and 23 (f) and, where appropriate, 23 (g).


22 (b). 4.2 test. In the beaker 400 ml (23 (b). 2.3), introduce an aliquot portion (a) taken from the summary (22 (b). 4.1) and containing between 2 and 4 mg of boron (B). Add 150 ml of water.


Add several drops of methyl red indicator solution (22 (b). 3.1).


In the case of extraction with method 23 (f) acidify by adding 0,5 M hydrochloric acid (22 (b). 3.2) until you turn the indicator and then add a 0.5 ml of 0,5 M hydrochloric acid (22 (b). 3.2). Add 3 g of sodium chloride (22 (b). 3.7) and bring to the boil to eliminate carbon dioxide. Leave to cool. Put the beaker on the magnetic stirrer (22 (b). 2.2) and insert the pH meter electrodes (22 (b). 2.1) that there will be calibrated before. Adjust the pH to 6.3 exactly, first with the sodium hydroxide solution 0.5 M and then with the 0,025 M. add 20 g of d-mannitol solution (22 (b). 3.6), dissolve completely and mix thoroughly. Titrate with the 0,025 M sodium hydroxide solution (22 (b). 3.4) until the pH of 6.3 (for at least 1 minute stability).


Let X the volume required.


22 (b). 4.3 test blank. Run a test in the same conditions since the dissolution, omitting only the fertilizer. Let X the volume required.


22 (b). 4. boron (B) of the sodium hydroxide solution 4 value (22 (b). 3.4). A pipette 20 ml (2,0 mg of boron (B) equivalents) of the calibration solution (22 (b). 3.5) and pour it into a glass beaker 400 ml; Add a few drops of the methyl red solution (22 (b). 3.1). Add 3 g of sodium chloride (22 (b). 3.7) and hydrochloric acid solution (22 (b). 3.2) until you turn the indicator solution (22 (b). 3.1). Make up the volume to approximately 150 ml and bring slowly to a boil to remove carbon dioxide. Leave to cool. Put the beaker on the magnetic stirrer (22 (b). 2.2) and insert the pH meter electrodes (22 (b). 2.1), which will be calibrated before. Adjust the pH to 6.3 exactly, first with the sodium hydroxide solution 0.5 M and then with the 0,025 M. add 20 g of d-mannitol solution (22 (b). 3.6) completely dissolve and mix. Titrate with the 0,025 M sodium hydroxide solution (22 (b). 3.4) until the pH of 6.3 (for at least 1 minute stability). Let V the volume required.


Carry out a blank test in the same way, substituting the calibration solution and 20 ml of water. Let V the volume required.


The equivalence in boron (F) of the standard NaOH solution (22 (b). 3.4) is as follows: F (in mg/ml) = 2 /(V-V) correspondence of 1 ml of exactly 0,025 M 0,27025 mg B. is sodium hydroxide solution


22 (b).5 calculations.



The percentage of boron (B) of the fertiliser is: B (%) = (X - X) X F X V 10 X X M be: B (%) = the percentage of boron in the fertiliser.


X = the volume of the 0,025 M sodium hydroxide solution (22 (b). 3.4) necessary in the test (22 (b). 4.2), in ml.


X = the volume of the 0,025 M sodium hydroxide solution (22 (b). 3.4) in the blank (22 (b). 4.3), in ml.


F = boron (B) equivalence of the 0,025 M sodium hydroxide solution (22 (b). 3.4) in mg/ml.


V = the volume of the extract obtained according to method 23 (e) or 23 (f), in ml.


a = volume of the aliquot (22 (b). 4.2).


M = the mass of the test sample of fertiliser taken 23 method (e) or 23 (f), in grams.


22 (b).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.5.


II. METODO 23 (e) 23 (e) trace elements in content exceeding 10 per 100 extraction of total trace elements 23 (e).1 principle.


Dissolution in dilute hydrochloric acid and boiling.


Note: The extraction is empirical and may not be quantitative, according to the product or other components of the fertilizer. In particular, in the case of certain manganese oxides, the extracted quantities can be much lower than all of the manganese content in the product. It is the responsibility of the fertilizer manufacturers to ensure that the declared content actually corresponds to the quantity extracted under the conditions of the method pertaining.


The present document establishes the method of extracting the following trace elements: total boron, total cobalt, total copper, total iron, total manganese, total molybdenum and total zinc.


The aim is to carry a minimum number of extractions, making use, wherever possible, the same extract to determine the total of each of the aforementioned trace elements content.


This method concerning the EEC fertilizers referred to in the order of 14 June 1991, on fertilizers and related, products containing one or more of the following trace elements: boron, cobalt, copper, iron, manganese, molybdenum and zinc. Applies to each of the trace elements whose declared contents are greater than 10 per 100.


23 (e).2 Material and devices.


23 (e). 2.1 plate adjustable temperature heating.


23 (e). 2.2 pH meter.


Note: If expected the quantitative determination of boron present in the extract, use of borosilicate glass should be discarded. The use of teflon or silica, will be more convenient since the extraction is by boiling. If detergents containing borates for washing glassware are used, these should be clarified carefully.


23 (e).3 reagents.


23 (e). 3.1 dilute solution of hydrochloric acid (HCl), about 6 m mix 1 volume of hydrochloric acid (p = 1,18 g/mg) with 1 volume of water.


23 (e). 3.2 concentrated ammonia solution (NH OH, p = 0,9 g/ml).


23 (e).4 procedure.


23 (e). 4.1 sample preparation. See method number 1 (order of 18 July 1989, which approve the official methods of analysis of fertilizers) 23 (e). 4.2 sampling. Weigh an amount of payment of 1 or 2 g depending on the declared content of element in the product. The following table should be used to obtain a final solution which, once diluted suitably, place in the span of each method. The samples shall be weighed with a precision of 1 mg.


Declared content of the trace element in the fertiliser (%). «/ 10 t R 25 /» 25 sample mass (g). / 2 / 1 mass of the element in the sample (mg). «/ T 200 R 500 /» 250 volume of extract V (ml). / 500 / 500 concentration of the element in the extract (mg/l). «/ T 400 R 1,000 /» 500 enter the sample in a beaker of 250 milliliters.


23 (e). 4.3 dissolution. If necessary moisten the sample with a little water; Add diluted hydrochloric acid (23 (e). 3.1) in small fractions and with caution, at a rate of 10 millilitres per gram of fertiliser used; then add about 50 ml of water. Cover the beaker with a watch glass and mix. Boil for 30 minutes on the heating plate. Allow to cool, stirring occasionally. Transfer quantitatively to a 500 ml graduated flask. Make up to volume with water. Homogenize. Pass through a dry filter into a dry container. Discard the first portion of the filtrate. The extract must be perfectly clear.


Proceed as quickly as possible to the determination on aliquot parts of filtrate clear. If it is not, cover the container.


Remark: Extracts the boron content must be determined in which will be a pH between 4 and 6 with concentrated ammonia (23 (e). 3.2).


23 (e). 4.4-determination. The determination of each trace element shall be carried out on the aliquot portions indicated in the method for each trace elements.


Methods 22 (b), 37 (b), 33 (b) and 35 (b) cannot be used to determine elements present in form chelated or complexed. In such cases, you should follow the method 23 (g) prior to the determination.


This treatment may not be necessary in the determinations by atomic absorption spectrophotometry (methods 32 (b) and 29 (b)).


23 (e).5 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L 86, on April 2, 1995. 10.1 method.


III. METODO 23 (f) 23 (f) extraction of water-soluble trace elements.


23 (f).1 principle.


Extraction of trace elements is done by shaking the fertilizer in water at a temperature of 20 ± 2 ° C.


Note: The extraction is empirical and may not be quantitative.


This document sets the extraction method of forms soluble in water of the following trace elements: boron, cobalt, iron, manganese, molybdenum and zinc. The aim is to carry a minimum number of extractions, making use, whenever possible, the same extract to determine the content of each of these trace elements.


This method applies to the EEC fertilizers referred to in the order of 14 June 1991, on fertilizers and related, products containing one or more of the following trace elements: boron, cobalt, copper, iron, manganese, molybdenum and zinc. Applies to each of the trace elements whose declared contents are greater than 10 per 100.


23 (f).2 Material and devices.


23 (f). 2.1 Rotator set at 35 or 40 revolutions per minute, approximately.


Note: If expected the quantitative determination of boron present in the extract, the use of borosilicate should be discarded. Teflon or silica is preferable for this extraction. If detergents containing borates for washing glassware are used, these should be clarified carefully.


23 (f).3 reagents.


23 (f). 3.1 dilute solution of hydrochloric acid (HCl), about 6 m mix 1 volume of hydrochloric acid (q: 1,18 g/ml) with 1 volume of water.


23 (f).4 procedure.


23 (f). 4.1 sample preparation. See method number 1 (order of 18 July 1989, which approve the official methods of analysis of fertilizers).


23 (f). 4.2 sampling. Take a quantity of fertiliser of 1 or 2 g depending on the declared content of element in the product. The following table should be used to obtain a final solution which, once diluted suitably, place in the span of each method. The samples shall be weighed with a precision of 1 mg.


Declared content of the trace element in the fertiliser (%). «/ 10 t R 25 /» 25 sample mass (g). / 2 / 1 mass of the element in the sample (mg). «/ T 200 R 500 /» 250 volume of extract V (ml). / 500 / 500 concentration of the element in the extract (mg/l). «/ T 400 R 1,000 /» 500 place the sample in a 500 ml flask.


23 (f). 4.3 dissolution. Add about 400 ml of water. Stopper the flask carefully. Shake vigorously by hand to get a good dispersion of the product. Place the flask on the shaker (23 (f). 2.1). Have the appliance in operation for thirty minutes. Make up to volume with water. Homogenize. Filter immediately into a clean, dry flask. Stopper the flask. Proceed to the determination immediately after filtering.


Note: If a progressive turbidity of extract, make another extraction according to (23 (f). 4.2) and (23 (f). 4.3) in a flask of volume V. filter into a volumetric flask of volume W previously dry, which has have spilled 5 ml of dilute hydrochloric acid (23 (f). 3.1). Stop the filtration at the time at which the diffuser line is reached. Homogenize.


Under these conditions the value of V which figure in the calculations section is: V = V X W W - 5 dilutions included in the calculations section depend on this value of V 23 (f). 4.4-determination. The determination of each trace element shall be carried out on the aliquot portions indicated in the method for each trace elements.


Methods 22 (b), 37 (b), 30 (c), 33 (b) and 35 (b) cannot be used for certain elements in the form chelated or complexed. In such cases, you should follow the method 23 (g) before each measurement.


This treatment may not be necessary in the determinations by atomic absorption spectrophotometry (methods 32 (b) and 29 (b)).


23 (f).5 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L 86, of 20 April 1995. Method 10.2.


IV. 23 METODO (g)



23 (g) removal of the organic compounds in fertiliser extracts content exceeding 10 per 100.


23 (g).1 principle.


The organic compounds in an aliquot of the extract are oxidized with hydrogen peroxide.


This method applies to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f) for which the order of 14 June 1991, on fertilizers and related products, establishes the quantitative determination of the total element and/or water-soluble element.


The presence of organic matter in small amounts rarely affect determinations by atomic absorption spectrometry.


23 (g).2 Material and devices.


23 (g). 2.1 plate adjustable temperature heating.


23 (g).3 reagents.


23 (g). 3.1 diluted hydrochloric acid solution, about 0,5 M.


Mix 1 volume of hydrochloric acid (HCl, q = 1,18) with 20 volumes of water.


23 (g). 3.2 solution of hydrogen peroxide (HO, q = 1.1), free from trace elements 100 30.


23 (g).4 procedure.


23 (g). 4.1 sample preparation. Take 25 ml of the extraction solution following method 23 (e) or 23 (f) and place it in a beaker of 100 ml. If it's the extraction 23 (f), add 5 ml of hydrochloric acid solution (23 (g). 3.1).


Then add 5 ml of hydrogen peroxide solution (23 (g) 3.2). Cover with a watch glass. Let rust cold for about an hour and then gradually boil and keep boiling for half an hour. If necessary, add other 5 ml of hydrogen peroxide to the warm solution and proceed the Elimination of organic compounds.


Then eliminate the excess of boiling hydrogen peroxide. Allow to cool and transfer quantitatively into a volumetric flask of 50 ml. make up to volume with water. Homogenize. Filter if necessary.


There will be this dilution to 50 by 100 when taking aliquot and to calculate the percentage of trace element of the product.


23 (g).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L 86, of 20 April 1995. Method 10.3.


V. method 23 (h) 23 (h) quantitative determination of trace elements in content exceeding 10 per 100 in fertiliser extracts by atomic absorption spectrometry. (General procedure).


23 (h).1 principle.


After a possible treatment of the extract, to reduce or eliminate interfering chemical substances, is diluted so that its concentration is placed in the area of optimal response of the spectrometer for a wavelength adapted to the element in question.


This method applies to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f) for which the order of 14 June 1991, on fertilizers and related products, a declaration of total and/or water-soluble iron or zinc content.


Special adaptations of this procedure to each trace element are specified in the methods for the element in question.


The presence of organic matter in small amounts usually does not affect determinations by atomic absorption spectrometry.


23 (h).2 Material and devices.


23 (h). 2.1 Atomic Absorption Spectrometer fitted with sources emitting characteristics of radiation of the elements studied lines.


For use, the analyst shall follow the instructions of the manufacturer of the device and should be familiar with its use.


The appliance must be allowed to correct the Fund's flame, if it were necessary (for example, Zn). Gases used are air and acetylene.


23 (h).3 reagents.


23 (h). 3.1 hydrochloric acid solution approximately 6 m mix 1 volume of hydrochloric acid (q = 1,18 g/ml) with 1 volume of water.


23 (h). 3.2 hydrochloric acid solution approximately 0,5 m mix 1 volume of hydrochloric acid (q = 1,18 g/ml) with 20 volumes of water.


23 (h). 3.3 lanthanum salt solutions (10 g of the per litre). This reagent is used for the quantitative determination of iron and zinc. You can prepare in two ways: to) with oxide of lanthanum dissolved in hydrochloric acid (23 (h). 3.1). In a 1 litre volumetric flask, place 11,73 g of lanthanum (LaO) oxide in 150 ml of water and then add 120 ml of 6 M hydrochloric acid (23 (h). 3.1). Leave it to dissolve and make up to volume with water. Homogenize. This solution in hydrochloric acid concentration is 0.5 M, approximately.


(b) with solutions of lanthanum nitrate, sulphate, or chloride. In a 1 litre graduated flask, dissolve 26,7 g of lanthanum heptahydrate chloride (amounts · 7HO) or 31,2 g of lanthanum hexahydrate (the (non) · 6HO) nitrate or 26,2 g of lanthanum nonahydrate sulphate (the (OS) · 9HO) in 150 ml of water; Add 85 ml of 6M hydrochloric acid (23 (h). 3.1). Leave it to dissolve and make up to volume with water. This solution in hydrochloric acid concentration is 0.5 M, approximately.


23 (h). 3.4 solutions pattern. See methods of quantitative determination of each trace element for its preparation.


23 (h) 4 procedure.


23 (h). 4.1-preparation of the test solution.


23 (h). 4.1. 1 dissolution of the elements to be determined. See 23 methods (e) and 23 (f) and, where applicable, 23 (g).


23 (h). 4.1. 2 preparation of the test solution. Dilute an aliquot portion of the extract obtained using methods 23 (e), 23 (f) or 23 (g) with water or HCL (23 (h). 3.1) or (23 (h). 3.2) so that pattern is obtained, in the final solution for measurement, a concentration of the element in question appropriate to the used range of solutions (23 (h). 4.3) and a concentration of hydrochloric acid of not less than 0.5 M but not more than 2.5 M. This operation may require one or more successive dilutions.


The final solution must be obtained by placing an aliquot of the diluted extract in a 100 ml volumetric flask, being (a) the volume in ml of the aliquot. Add 10 ml of the chosen lanthanum salt solution (23 (h). 3.3). Make up to volume with the 0,5 M hydrochloric acid solution (23 (h). 3.2) and mix thoroughly. D is the dilution factor.


23 (h). 4.2 preparation of the blank solution. Prepare a blank solution following the entire process from the extraction stage, omitting only the test sample of fertiliser.


23 (h). 4.3 preparation solutions pattern starting from the solution prepared work pattern as described for each trace element, prepare in 100 ml volumetric flasks a series of, as minimum, five solutions pattern of increasing concentration corresponding to the optimal measuring of the device area. If necessary, adjust the concentration of hydrochloric acid for approaching as close as possible to the diluted problem solution (23 (h). 4.1. 2). For the determination of iron or zinc, add 10 ml of the same lanthanum salt solution (23 (h). 3.3) who has been employed in 23 (h). 4.1.2. Make up to volume with the 0,5 M hydrochloric acid solution (23 (h) 3.2) and mix.


23 (h). 4.4-measurements. Prepare the spectrometer (23 (h). 2.1) for the determination and adjust wavelength value required in the method of the element that is going to determine.


Spray three times in succession solutions pattern (23 (h). 4.3), the test solution (23 (h). 4.1. 2) and the blank solution (23 (h). 4.2), noting each result; to thoroughly wash the appliance with distilled water between each measurement.


Represent the curve pattern putting in ordinate value average of the results of each of the pattern measurements (23 (h). 4.3) read the spectrometer and abscissas the corresponding concentration of the element to be determined, expressed in lg/ml.


From this curve, determine the concentrations of this element in the solution problem X (23 (h). 4.1. 2). These concentrations are expressed in lg/ml.


23 (h).5 calculations.


The percentage of the element (E) in the fertiliser is equal a: E (%) of the fertilizer = (X - X) X V X D M X 10 if it has followed the 23 method (g): E (%) of the fertilizer = (X - X) X V X M X 10 being 2D: E = the quantity of the element determined, expressed as a percentage of the fertiliser.


X = the concentration of the test solution (23 (h). 4.1. 2) lg/ml.


X = the concentration of the blank solution (23 (h). 4.2) lg/ml.


V = the volume of the extract obtained according to method 23 (e) or 23 (f), in ml.


D = the factor corresponding to the dilution carried out in (23 (h). 4.1. 2).


M = the mass of the sample taken in accordance with method 23 (e) or 23 (f), in grams.


D: dilution factor calculation if (a), (a), (a),... (a) and (a) are the aliquot and (v), (v), (v),... (v) and 100 volumes corresponding to the respective dilutions, the dilution D factor will be equal a: v / v / v / 100 D = / / X / / X... X / / X / to / to / to / to (/) / (/) / (/) / (/) / 23 (h).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.4.


VI. 29 METODO (b) 29 (b) quantitative determination of zinc content exceeding 10 per 100 in fertiliser extracts by atomic absorption spectrometry.


29 (b).1 principle.


Once treated and diluted extracts properly, zinc is determined by atomic absorption spectrometry.


This method applies to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f) for which the order of 14 June 1991, on fertilizers and related products, the Declaration of the content of zinc.


29 (b).2 Material and devices 29 (b). 2.1-Atomic Absorption Spectrometer: see paragraph 23 (h). 2. The appliance must be fitted with a source of radiation characteristic of zinc (213.8 nm) and a background corrector.


29 (b).3 reagents.



29 (b). 3.1 approximately 6 m hydrochloric acid solution see paragraph 23 (h). 3.1.


29 (b). 3.2 approximately 0,5 m hydrochloric acid solution see paragraph 23 (h). 3.2.


29 (b). 3.3 lanthanum salt solutions (10 g of the per litre). See paragraph 23 (h). 3.3.


29 (b). 3.4 solutions pattern of zinc.


29 (b). 3.4. 1 solution zinc (1,000 lg/ml) stock. In a 1000 ml volumetric flask, dissolve 1 g of zinc powder or plates, heavy with an accuracy of 0,1 mg in 25 ml of concentrated 6 M hydrochloric acid (29 (b). 3.1). After the iron is completely dissolved, make up to volume with water and mix thoroughly.


29 (b). 3.4. 2 working solution of zinc (100 lg/ml). In a 200 ml volumetric flask, dilute 20 ml of the stock solution (29 (b). 3.4. 1) with 0,5 M hydrochloric acid solution (29 (b). 3.2). Make up to volume with hydrochloric acid solution 0.5 M. homogenize.


29 (b).4 procedure.


29 (b). 4.1-preparation of the test solution. Dissolution of the zinc. See 23 methods (e) and 23 (f) and, where applicable, 23 (g).


29 (b). 4.2 preparation of the test solution. See paragraph 23 (h). 4.1.2. The test solution must contain 10 per 100 (v/v) of a lanthanum salt solution.


29 (b). 4.3 preparation of the blank solution. See paragraph 23 (h). 4.2. The test solution must contain 10 per 100 (v/v) solution of lanthanum salt used in 29 (b). 4.2.


29 (b). 4.4-preparation solutions pattern. See paragraph 23 (h). 4.3. For an optimum determination range of 0 and 5 lg/ml of zinc (Zn), place, respectively, 0, 0.5, 1, 2, 3, 4 and 5 ml of the solution of work 29 (b). 3.4. 2 in 100 ml volumetric flasks. If necessary, adjust the concentration of hydrochloric acid for approaching as close as possible to the test solution. Add to each flask 10 ml of the lanthanum salt used in 29 (b). 4.2. Make up to volume with 0,5 M hydrochloric acid solution (29 (b). 3.2). Homogenize.


These solutions contain, respectively, 0, 0.5, 1, 2, 3, 4 and 5 lg/ml of zinc (Zn).


29 (b). 4.5 measurements. See paragraph 23 (h). 4.4. Prepare the spectrometer (29 (b). 2.1) for measurements at a wavelength of 213.8 nm.


29 (b).5 calculations.


See paragraph 23 (h). 5.


The percentage of zinc (Zn) in the fertiliser is equal: Zn (%) = (X - X) X V X D M X 10 if it has followed the 23 method (g): Zn (%) = (X - X) X V X M X 10 being 2D: Zn = the amount of zinc (Zn), expressed as a percentage of the fertiliser.


X = the concentration of the test solution (29 (b). 4.2) lg/ml.


X = the concentration of the blank solution (29 (b). 4.3) lg/ml.


V = the volume of the extract obtained according to method 23 (e) or 23 (f), in ml.


D = the factor corresponding to the dilution carried out in (29 (b). 4.2).


M = the mass of the sample taken in accordance with method 23 (e) or 23 (f), in grams.


D: dilution factor calculation if (a), (a), (a),... (a) and (a) are the aliquot and (v), (v), (v),... (v) and 100 volumes corresponding to the respective dilutions, the dilution D factor will be equal a: v / v / v / 100 D = / / X / / X... X / / X / to / a / a / a (/) / (/) / (/) / (/) 29 (b).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.11.


VII. METODO 30 (c) 30 (c) quantitative determination of copper in fertiliser extracts content exceeding 10 per 100 by volume.


30 (c).1 principle.


This document describes a method for the determination of copper in fertiliser extracts.


The cupric ions are reduced in an acidic medium with potassium iodide: 2 Cu ' +' 1 4I 2CuI + I iodine so liberated is titrated with a standard solution of sodium thiosulfate in the presence of starch as an indicator, according to the following reaction: I + 2NaSO 1 2NaI + NaSO this method applies to extracts from samples of fertilizers obtained by methods 23 (e) or 23 (f) for which the order of 14 June 1991 on fertilizers and related products, establishes the determination of copper content.


30 (c).2 reagents.


30 c. 2.1 nitric acid (HNO, p: 1,40 g/ml) 30 c. 2.1 Urea ((NH) C = 0) 30 c. 2.2 to 10 per 100 solution (w/v) ammonium bifluoride (NHHF) keep the solution in a plastic container.


30 c. 2.3 solution of ammonia (1 + 1).


Mix 1 volume of ammonia (NHOH, p: 0.9 g/ml) with 1 volume of water.


30 c. 2.4 solution sodium thiosulfate standard. In a 1 litre graduated flask, dissolve 7,812 g of Sodium Thiosulphate pentahydrate (NaSO, 5HO) in water. This solution must be prepared in such a way that 1 ml is equal to 2 mg Cu. Stabilize the solution by adding a few drops of chloroform. Solution should be stored in a glass container and protected from direct light.


30 c. 2.5 iodide of potassium (KI) 30 c. 2.6 (KSCN) potassium thiocyanate solution to 25 per 100 (w/v). Keep this solution in a plastic jar.


30 c. 2.7 starch solution to the 0.5 per 100, approximately. Put in a glass beaker 600 ml 2.5 g of starch ((CHO) n). Add approximately 500 ml of water. Bring to the boil stirring. Cool at room temperature. The solution is not retained long.


30 (c).3 procedure.


30 c. 3.1 dissolution of copper. See 23 methods (e) and 23 (f).


30 c. 3.2 preparation of the test solution. Introduce an aliquot portion of the solution containing not less than 20 or 40 mg Cu in a conical flask of 500 ml. eliminate the excess oxygen eventually present by a brief boiling. Make the volume up to 100 ml, approximately, with water. Add 5 ml of nitric acid (30 c. 2.1) and boil for half a minute, approximately.


Remove the Erlenmeyer flask from the heat source, add 3 g, approximately of urea (30 c. 2.1) and return to boil for another half minute, approximately.


Remove from the heat source and add 200 ml of cold water. If necessary, cool the contents of the Erlenmeyer flask to ambient temperature.


Gradually add ammonia (30 c. 2.3), until the solution turns blue. Then add 1 ml more.


Add 10 g of potassium iodide (30 c. 2.5) and dissolve.


30 c. 3.3 estimation of the solution. Place the Erlenmeyer flask on a magnetic stirrer. Insert the rod into the Erlenmeyer flask and adjust the stirrer to the desired speed.


Using a burette, add standard solution of sodium thiosulfate (30 c. 2.4) until it decreases the intensity of the brown colour of the iodine released from the solution.


Introduce 10 ml of the solution of starch (30 c. 2.7). Continue the titration with sodium thiosulfate (30 c. 2.4) solution to the virtual disappearance of the color purple.


Add 20 ml of solution of thiocyanate potassium (30 c. 2.6) and continue the titration until the total disappearance of violet-blue color.


Note the used volume of Thiosulphate solution.


30 (c).4 calculations.


1 ml of the standard solution of sodium thiosulfate (7,812 mg) corresponds to 2 mg Cu.


The percentage of copper in the fertilizer is: Cu (%) = X V a X M X 5 being: X = the volume used in ml of Sodium Thiosulphate solution,.


V = the volume of the extract, obtained according to the methods 23 solution (e) or 23 (f), in ml.


a = volume of the aliquot, in ml.


M = the mass of the treated sample methods 23 (e) or 23 (f), in grams.


30 (c).5 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.7.


VIII. 32 METODO (b) 32 (b) quantitative determination of iron in fertilizer extracts in content greater than 10 per 100 by atomic absorption spectrometry.


32 (b).1 principle.


This document describes a method for the determination of iron in fertiliser extracts.


Once treated and diluted extracts properly, the iron is determined by atomic absorption spectrometry.


This method applies to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f) and for which the order of 14 June 1991, on fertilizers and related products, establishes the definition of the content of total and/or water-soluble iron.


32 (b).2 Material and devices.


Atomic Absorption Spectrometer, see paragraph 2 of the method 23 (h). The appliance must be fitted with a source of radiation characteristic of iron (248.3 nm).


32 (b).3 reagents.


32 (b). 3.1 solution of hydrochloric acid, approximately 6 M. see paragraph 3.1 method 23 (h).


32 (b). 3.2 hydrochloric acid, approximately 0.5 M. solution see paragraph 3.2 method 23 (h).


32 (b). 3.3 hydrogen peroxide solution (HO to 30 per 100, p = 1,11 g/ml) free from trace elements.


32 (b). 3.4 lanthanum salt solutions (10 g of the per litre). See section 3.3 method 23 (h).


32 (b). 3.5 iron calibration solutions.


32 (b). 3.5. 1 solution iron (1,000 lg/ml) stock. In a glass of precipitated 500 ml weigh 1 g of pure iron, with a precision of 0.1 mg wire and add 200 ml of 6M hydrochloric acid (32 (b). 3.1) and 15 ml of solution of peroxide of (32 (b). 3.3). Heating plate heating until complete dissolution, leave to cool and into a flask of 1000 ml. make up to volume with water and mix thoroughly. 32 (b). 3.5. 2 working solution of iron (100 lg/ml). In a 200 ml volumetric flask, place 20 ml of stock solution (32 (b). 3.5. 1). Make up to volume with the 0,5 M hydrochloric acid solution (32 (b). 3.2). Homogenize.


32 (b).4 procedure.


32 (b). 4.1 dissolution of the iron. See methods 23 (e), 23 (f) and where applicable 23 (g).



32 (b). 4.2 preparation of the test solution. See the paragraph 4.1.2 method 23 (h). The test solution must contain 10 per 100 (v/v) of a lanthanum salt solution.


32 (b). 4.3 preparation of the blank solution. See paragraph 4.2 method 23 (h). The blank solution must contain 10 per 100 (v/v) solution of lanthanum salt used in 32 (b). 4.2.


32 (b). 4.4-preparation of the calibration solutions. See paragraph 4.3 method 23 (h). For an optimum interval of detection between zero and 10 lg/ml of iron (Fe) place respectively in 100 ml volumetric flasks: 0, 2, 4, 6, 8 and 10 ml of the working solution (32 (b). 3.5. 2). If necessary, adjust the concentration of hydrochloric acid for approaching as close as possible to the test solution. Add 10 ml of the lanthanum salt used in 32 (b). 4.2. Make up to volume with 0,5 M hydrochloric acid solution (32 (b). 3.2). Homogenize. These solutions contain, respectively, 0, 2, 4, 6, 8 and 10 lg/ml of iron (Fe).


32 (b). 4.5 measurements. See the section 4.4 method 23 (h). Prepare the spectrometer (32 (b).2) for measurements at a wavelength of 248.3 nm.


32 (b).5 calculations.


See paragraph 5 of the 23 (h) method.


The percentage of iron (Fe) in the fertiliser is equal: Fe (%) = X V X 2D ((X-X)) /(M X 10) being: faith = amount of iron (Fe), expressed as a percentage of the fertiliser.


X = the concentration of the test solution (32 (b). 4.2) lg/ml.


X = the concentration of the blank solution (32 (b). 4.3) lg/ml.


V = the volume of the extract obtained with the method 23 (e) or 23 (f) in ml.


D = the factor corresponding to the dilution carried out in (32 (b). 4.1).


M = the mass of the sample taken with arrangement method 23 (e) or 23 (f) in grams.


D: dilution factor calculation if (a), (a), (a)... (a) and (a) are the aliquot and (v), (v) (v)... (v) and (100) the volumes in ml corresponding to the respective dilutions, the dilution D factor will be the same: D = (v/a) X (v/a) X (v/a) x.x.x.x (v/a) X (100/a) 32 (b).6 reference.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.8.


IX. 33 METODO (b) 33 (b) quantitative determination of manganese content exceeding 10 per 100 in fertiliser extracts by titration as permanganate.


33 (b).1 principle.


Where there are chloride ions present in the extract, disposed of by boiling the extract, which has been added to sulfuric acid. Manganese is oxidized by nitric acid sodium bismuthate. The permanganate formed is reduced by an excess of ferrous sulfate. This excess is titrated with a solution of potassium permanganate.


This method applies to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f) for which the order of 14 June 1991, on fertilizers and related products, the Declaration of content of MN 33 (b).2 Material and devices.


33 (b). 2.1 Filter Crucible P16/ISO 4793, porosity 4, capacity 50 ml, mounted on a 500 ml filtration flask.


33 (b). 2.2 magnetic stirrer.


33 (b).3 reagents.


33 (b). 3.1 concentrated sulfuric acid (HSO, q: 1,84 g/ml).


33 (b). 3.2 sulphuric acid approximately 9 m carefully mix 1 volume of concentrated sulphuric acid (33 (b). 3.1) and one volume of water.


33 (b). 3.3 nitric acid, 6 m mix 3 volumes of nitric acid (HNO, q: 1,40 g/ml) with 4 volumes of water.


33 (b). 3.4 nitric acid 0.3 M. mix one volume of 6 M nitric acid with 19 volumes of water.


33 (b). 3.5 to 85 per 100 (NaBiO) sodium bismuthate.


33 (b). 3.6 diatomaceous earth.


33 (b). 3.7 15 M orthophosphoric acid (H4 q: 1,71 g/ml).


33 (b). 3.8 0.15 M. ferrous sulphate solution In a 1 litre graduated flask, dissolve 41,6 g of ferrous sulphate heptahydrate (FeSO.7HO). Add 25 ml of concentrated sulphuric acid (33 (b). 3.1) and 25 ml of phosphoric acid (33 (b). 3.7). Make up to volume and mix thoroughly.


33 (b). 3.9 solution of potassium permanganate 0.020 M. weigh, with a precision of 0.1 mg, 3,160 g of potassium permanganate (KMnO), dissolve and make up to 1000 ml of water.


33 (b). 3.10 solution of silver nitrate. Dissolve 1,7 g of silver (AgNO) nitrate and lead to 100 ml with water 33 (b).4 procedure.


33 (b). 4.1-preparation of the test solution.


33 (b). 4.1. 1 dissolution of the manganese. See 23 methods (e) and 23 (f).


If there are doubts about the presence of chloride ions, put to test the solution with one drop of the silver nitrate solution (33 (b). 3.10).


33 (b). 4.1. 2 where there are no ions chloride, place in a 400 ml beaker an aliquot of the extract containing 10 to 20 mg of manganese. Carry a volume of 25 ml, either by evaporation or by adding water. Add 2 ml of concentrated sulfuric acid (33 (b). 3.1).


33 (b). 4.1. 3 if there are chloride ions, it is necessary to remove them in the following way: in a tall glass beaker with suitable capacity, introduce an aliquot containing between 10 and 20 mg of manganese. Add 5 ml of 9 M sulphuric acid (33 (b). 3.2). Under a hood, bring to boiling on a hotplate and keep boiling until there is an abundant release of white fumes. Continue until the volume is reduced to 2 ml, approximately (thin layer of fluid, syrupy in the bottom of the glass). Bring back the beaker at room temperature. Carefully add 25 ml of water and once again check the absence of chlorides with one drop of the silver nitrate solution (33 (b). 3.10). If chlorides still remain, start again the operation after adding 5 ml of 9 M sulphuric acid (33 (b). 3.2).


33 (b). 4.2 in a glass beaker 400 ml containing the solution problem, add 25 ml of 6 M nitric acid (33 (b). 3.3) and 2,5 g of sodium bismuthate (33 (b). 3.5). With magnetic stirrer (33 (b). 2.2), shake vigorously for three minutes. Add 50 ml of 0,3 M nitric acid (33 (b). 3.4) and shake again.


Filter vacuum with a crucible (33 (b). 2.1), the bottom is covered of diatomaceous earth (33 (b). 3.6). Wash the crucible with 0,3 M nitric acid several times (33 (b). 3.4) until a colourless filtrate is obtained.


Transfer the filtrate and the washing solution into a beaker of 500 ml. mix and add 25 ml of the solution of ferrous sulfate 0.15 M (33 (b). 3.8). If the filtrate turns yellow after the addition of ferrous sulphate, add 3 ml of orthophosphoric acid, 15 M (33 (b). 3.7).


Titrate the excess of ferrous sulphate with 0,02 M potassium permanganate solution by means of a burette (33 (b). 3.9) until you obtain a stable pink color for a minute.


Carry out a determination on white in the same conditions, omitting only the sample.


Note: The oxidized solution must not come into contact with rubber.


33 (b).5 calculations.


1 ml of potassium permanganate solution 0.02 M corresponds to 1,099 mg of manganese (Mn).


MN (%) of the fertilizer = (X - X) 0,1099 X X V X M be: X = volume of permanganate used in the blank, in ml.


X = the volume of permanganate used in the test with the sample in ml.


V = the volume of the extract obtained according to the methods 23 (e) and 23 (f), in ml.


a = volume of the aliquot taken from the extract in ml.


M = mass of sample, in grams.


33 (b).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.9.


X. 35 METODO (b) 35 (b) quantitative determination of molybdenum content exceeding 10 per 100 in fertilizer extracts by the gravimetric method with 8-hydroxyquinoline.


35 (b).1 principle.


The quantitative determination of molybdenum is done by precipitation as molybdenyl oxinate under specific conditions.


This method applies to extracts from samples of fertilizers obtained by methods 23 (e) and 23 (f) for which the order of 14 June 1991, on fertilizers and related products, the Declaration of the molybdenum.


35 (b).2 Material and devices.


35 (b). 2.1 Filter Crucible P16/ISO 4793, porosity 4, capacity 30 ml.


35 (b). 2.2 pH meter with glass electrode.


35 (b). 2.3 drying oven regulated at 130-135 ° C.


35 (b).3 reagents.


35 (b). 3.1 solution of sulphuric acid, approximately 1 M. A graduated 1 litre flask containing 800 ml of water, add carefully 55 ml of sulphuric acid (HSO, q = 1,84 g/ml). Homogenize. Leave to cool and make up to 1 litre. Homogenize.


35 (b). 3.2 diluted ammonia solution (1:3). Mix 1 volume of concentrated ammonia (NHOH, q = 0,9 g/ml) with 3 volumes of water.


35 (b). 3.3 solution of dilute acetic acid (1:3). Mix 1 volume of concentrated acetic acid (99,7 CHCOOH 100, q = 1,049 g/ml) with 3 volumes of water.


35 (b). 3.4 solution of disodium salt of ethylene diamine tetraacetic acid (EDTA). In a 100 ml graduated flask, dissolve 5 g of NaEDTA in water. Make up to volume and mix thoroughly.


35 (b). 3.5 solution buffer. In a 100 ml graduated flask, dissolve in water 15 ml of concentrated acetic acid and 30 g of ammonium acetate. Make up the volume.


35 (b). 3.6-8-hydroxyquinoline (oxine) solution. In a 100 ml volumetric flask, dissolve 3 g of hydroxyquinoline in 5 ml of concentrated acetic acid. Add 80 ml of water. Add ammonia solution drop by drop (35 (b). 3.2) until the solution is cloudy, and then acetic acid (35 (b). 3.3) until the solution becomes clear. Make up to volume with water.


35 (b).4 procedure.


35 (b). 4.1-preparation of the test solution. Dissolution of molybdenum. See 23 methods (e) and 23 (f).



35 (b). 4.2 preparation of the test solution. Enter in a beaker of 250 ml, an aliquot containing between 25 to 100 mg mo. Make the volume up to 50 ml with water.


Take this solution at a pH of 5 added drop by drop of sulfuric acid solution (35 (b). 3.1).


Add 15 ml of the EDTA solution (35 (b). 3.4) and then, 5 ml of buffer solution (35 (b). 3.5). Make up to 80 ml, approximately, with water.


35 (b). 4.3-obtaining and washing the precipitate. Obtaining the precipitate. Heat the solution slightly. While I stirred constantly, add the oxine solution (35 (b). 3.6). Continue the precipitation until now is not observed formation of sediment. Add an excess of reagent until the supernatant solution take a light yellow color. Normally, it should be enough a quantity of 20 ml. continue heating slightly the precipitate for 2 or 3 minutes.


Filtration and washing. Filter through a filter Crucible (35 (b). 2.1). Rinse several times with 20 ml of hot water volumes. The rinse water should be progressively colorless, which indicates that oxine there is no.


35 (b). 4.4-weighing of the precipitate. Dry the precipitate at 130-135 ° C until constant weight (one hour at least). Leave to cool in a desiccator and weigh.


35 (b).5 calculations.


1 mg of molybdenyl oxinate, MoO (CHON) corresponds to 0,2305 mg Mo Mo (%) of the fertilizer = X X 0,02305 X V X D X M be: X = the mass of the precipitate of molybdenyl oxinate, mg.


V = the volume of the solution of the extract obtained according to method 23 (e) or 23 (f), in ml.


a = volume of the aliquot taken from the last dilution, in ml.


D = the dilution factor of this aliquot.


M = mass of sample, in grams.


35 (b).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.10.


XI. 37 METODO (b) 37 (b) quantitative determination of cobalt in fertiliser extracts, for contents greater than 10 per 100, by the gravimetric method with 1-nitroso-2-naphthol.


37 (b).1 principle.


This document describes a method for the determination of cobalt in fertiliser extracts.


This procedure applies to extracts of fertilizers obtained by methods 23 (e) or 23 (f), for which the order of 14 June 1991, on fertilizers and related products, the Declaration of cobalt content.


The cobalt III forms with 1-nitroso-2-naphthol to give a red precipitate Co (CHONO). 2HO.


After the Cobalt present in the extract to the cobalt III State, cobalt is precipitated in the Middle acetic acid with a solution of 1-nitroso-2-naphthol. After filtration, the precipitate is washed and dried to constant weight and then weighed as Co (CHONO). 2HO.


37 (b).2 Material and devices.


37 (b). 2.1 Filter Crucible P 16/ISO 4793, porosity 4, capacity 30 or 50 ml.


37 (b). 2.2 stove drying set at 130 ± 2 ° C.


37 (b).3 reagents.


37 (b). 3.1 solution of hydrogen peroxide to 30 per 100 (HO, q = 1,11 g/ml).


37 (b). 3.2 solution of sodium hydroxide, approximately 2 M.


Dissolve 8 g of sodium hydroxide pellets in 100 ml of water.


37 (b). 3.3 diluted hydrochloric acid solution, about 6 m mix 1 volume of hydrochloric acid (q = 1,18 g/ml) with 1 volume of water.


37 (b). 3.4 acetic acid (99.7 per 100 of CHCOH, q = 1,05 g/ml).


37 (b). 3.5-1:2 (about 6 M) acetic acid solution. Mix one volume of acetic acid (37 (b). 3.4) with 2 volumes of water.


37 (b). 3.6 solution of 1-nitroso-2-naphthol in acetic acid. Dissolve 4 g of 1-nitroso-2-naphthol in 100 ml of acetic acid (37 (b). 3.4). Add 100 ml of warm water. Homogenize. Filter immediately. The solution obtained should be used at the time.


37 (b).4 procedure.


37 (b). 4.1 dissolution of cobalt. See 23 methods (e) and 23 (f).


37 (b). 4.2 preparation of the test solution. Introduce an aliquot of the extract containing not more than 20 mg of Co in a 400 ml beaker beaker.


If the extract is obtained following the method 23 (f), acidified with five drops of hydrochloric acid (37 (b). 3.3).


Add about 10 ml of hydrogen peroxide solution (37 (b). 3.1).


Allow the oxidant to act cold for fifteen minutes and then add water to about 100 ml. cover the beaker with a watch glass.


Heat and keep at boiling point for 10 minutes approximately. Cool. Alkalize by adding sodium hydroxide solution Dropwise (37 (b). 3.2) until black cobalt hydroxide begins to precipitate.


Add 10 ml of acetic acid (37 (b). 3.4) and fill with water up to 200 ml approximately. Heat until it begins to boil. Add Dropwise with burette 20 ml of the solution of 1-nitroso-2-naphthol (37 (b). 3.6) shaking constantly. Finish with a brisk agitation that the precipitate coagulate.


Filter through a filter Crucible (37 (b). 2.1) Tared, preventing the silting up of the crucible. To do this, verify that there is liquid above the precipitate throughout all the filtration.


Wash the beaker with dilute acetic acid (37 (b). 3.5) to drag the precipitate, wash the precipitate on the filter with dilute acetic acid (37 (b). 3.5) and then three times with hot water.


Drying stove (37 (b). 2.2) at 130 ± 2 ° C until constant weight.


37 (b).5 calculations.


1 mg of Co (CHONO). 2HO corresponds to 0,096381 mg Co.


The percentage of cobalt (Co) in the fertilizer is: Co (%) = X X 0,0096381 X V X D X M be: X = the mass of the precipitate, in mg.


V = the volume of the solution of the extract obtained according to method 23 (e) or 23 (f), in ml.


a = volume of the aliquot taken from the last dilution, in ml.


D = the dilution factor of this aliquot.


M = mass of sample, in grams.


37 (b).6 references.


Commission Directive 95/8/EC. «Official Journal of the European Communities' number L86, of 20 April 1995. Method 10.6.

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