The Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1991

APPARATUS

4

4.1

Atomic absorption spectrophotometer with a copper lamp (324.8 nm).

PREPARATION OF SAMPLE

5

See Method 1.

PROCEDURE

6

Preparation of the solution for analysis

6.1

In the absence of organic matter 6.1.1 Weigh to the nearest 0.001 g, 5 g of the prepared sample, place it in a 400 ml beaker, add carefully 5 ml hydrochloric acid (3.1) (there may be a vigorous reaction due to carbon dioxide formation). Add more hydrochloric acid, if necessary. When effervescence has stopped, evaporate to dryness on a steam bath, stirring occasionally with a glass rod. Add 15 ml 6 N hydrochloric acid solution (3.2) and 120 ml water. Stir with the glass rod, which should be left in the beaker, and cover the beaker with a watch glass. Boil the solution gently until dissolution appears complete and then filter through a filter paper[^f00032] into a 250 ml graduated flask. Wash the beaker and filter with 5 ml hot 6 N hydrochloric acid solution (3.2) and twice with boiling water. Cool and make up to the mark with water (the hydrochloric acid concentration of this solution should be about 0.5 N).

• (6.1.2) In the presence of organic matter Weigh to the nearest 0.001 g, 5 g of the prepared sample into a silica or platinum crucible and place the crucible into a cold muffle furnace. Close the furnace and gradually raise the temperature to 450 – 475°C over about 90 minutes. Maintain this temperature for at least 16 hours and then open the furnace and allow the crucible to cool. Moisten the ash with water and transfer it into a 250 ml beaker. Wash the crucible with about 5 ml hydrochloric acid (3.1) and add the latter slowly and carefully to the beaker (there may be a vigorous reaction due to carbon dioxide formation). If necessary, add more hydrochloric acid (3.1) with stirring, until all effervescence has stopped. Evaporate the solution to dryness, occassionally stirring with a glass rod. Add 15 ml 6 N hydrochloric acid solution (3.2) and 120 ml water. Stir with the glass rod, which should be left in the beaker, and cover with a watch glass. Boil the solution gently until dissolution appears complete and filter through a filter paper[^f00032] into a 250 ml graduated flask. Wash the beaker and filter with 5 ml of hot 6 N hydrochloric acid solution (3.2) and twice with boiling water. Cool and make up to the mark with water. (The hydrochloric acid concentration of this solution should be about 0.5 N).

Blank Solution

6.2

Prepare a blank solution from which only the sample has been omitted and allow for this in the calculation of the final results.

Determination

6.3

Preparation of sample and blank test solutions 6.3.1 Dilute the sample solutions (6.1.1 or 6.1.2) and the blank test solution (6.2) with 0.5 N hydrochloric acid solution (3.3) to a concentration within the optimal measuring range of the spectrophotometer.

Preparation of the calibration solution 6.3.2 By diluting the standard solution (3.5.2) with 0.5 N hydrochloric acid solution (3.3) prepare at least 5 standard solutions corresponding to the optimal measuring range of the spectrophotometer.

Measurement

6.4

Set up the spectrophotometer (4.1) at a wavelength of 324.8 nm using an oxidising air-acetylene flame. Spray successively, in triplicate, the standard solution (6.3.2), the sample solution and the blank test solution (6.3.1), washing the instrument through with distilled water between each spraying. Plot the calibration curve using the mean absorbances as the ordinates and the corresponding concentrations of copper in μg/ml as the abscissae.

EXPRESSION OF THE RESULTS

7

Calculate the copper content of the sample taking into account the weight of the test sample and the dilutions carried out in the course of the analysis. Express the result either as a percentage or as mg/kg.

13. — DETERMINATION OF IRON

SCOPE AND FIELD OF APPLICATION

1

This method is applicable to all fertilisers.

PRINCIPLE

2

The sample is ashed and dissolved in dilute hydrochloric acid or, if it contains no organic substances, it is dissolved directly in dilute hydrochloric acid. The solution is diluted and the iron content of the extract is determined by atomic absorption spectrophotometry.

REAGENTS

3

3.1

Hydrochloric acid (d = 1.18 g/ml).

3.2

Hydrochloric acid, 6 N solution.

3.3

Hydrochloric acid, 0.5 N solution.

3.4

Hydrogen peroxide, approximately 100 volume, 30% by weight.

• (3.5.1) Iron solution[^f00033] (stock):

weigh to the nearest 0.001 g, 1 g pure iron, dissolve in 200 ml 6 N hydrochloric acid solution (3.2), add 16 ml hydrogen peroxide solution (3.4) and dilute to 1 litre with water.

1 ml of this solution = 1,000 μg of iron (Fe).

• (3.5.2) Iron solution (dilute):

dilute 10 ml of stock solution (3.5.1) to 100 ml with water.

1 ml of this solution =00 μg of iron (Fe).

3.6

Lanthanum chloride solution: dissolve 12 g lanthanum oxide in 150 ml water, add 100 ml 6 N hydrochloric acid solution (3.2) and dilute to 1 litre with water.

APPARATUS

4

4.1

Atomic absorption spectrophotometer with an iron lamp (248.3 nm).

PREPARATION OF SAMPLE

5

See Method 1.

PROCEDURE

6

Preparation of the solution for analysis

6.1

• (6.1.1) In the absence of organic matter

Weigh to the nearest 0.001 g, 5 g of the prepared sample, place it in a 400 ml beaker, add carefully 5 ml hydrochloric acid (3.1) (there may be a vigorous reaction due to carbon dioxide formation). Add more hydrochloric acid, if necessary. When effervescence has stopped, evaporate to dryness on a steam bath, stirring occasionally with a glass rod. Add 15 ml 6 N hydrochloric acid solution (3.2) and 120 ml water. Stir with the glass rod, which should be left in the beaker, and cover the beaker with a watch glass. Boil the solution gently until dissolution appears complete and then filter through a filter paper[^f00034] into a 250 ml graduated flask. Wash the beaker and filter with 5 ml of hot 6 N hydrochloric acid solution (3.2) and twice with boiling water. Cool and make up to the mark with water. (The hydrochloric acid concentration of this solution should be about 0.5 N).

In the presence of organic matter 6.1.2 Weigh to the nearest 0.001 g, 5 g of the prepared sample into a silica or platinum crucible and place the crucible in a cold muffle furnace. Close the furnace and gradually raise the temperature to 450 – 475°C over about 90 minutes. Maintain this temperature for at least 16 hours and then open the furnace and allow the crucible to cool. Moisten the ash with water and transfer it into a 250 ml beaker. Wash the crucible with about 5 ml hydrochloric acid (3.1) and add the latter slowly and carefully to the beaker (there may be a vigorous reaction due to carbon dioxide formation). If necessary, add more hydrochloric acid (3.1) with stirring, until all effervescence has stopped. Evaporate the solution to dryness, occasionally stirring with a glass rod. Add 15 ml 6 N hydrochloric acid solution (3.2) and 120 ml water. Stir with the glass rod, which should be left in the beaker, and cover with a watch glass. Boil the solution gently until dissolution appears complete and filter through a filter paper[^f00035] into a 250 ml graduated flask. Wash the beaker and filter with 5 ml of hot 6 N hydrochloric acid solution (3.2) and twice with boiling water. Cool and make up to the mark with water. (The hydrochloric acid concentration of this solution should be about 0.5N)

Blank solution

6.2

Prepare a blank solution from which only the sample has been omitted and allow for this in the calculation of the final results.

Determination

6.3

Preparation of sample and blank test solutions 6.3.1 Dilute the sample solutions (6.1.1 or 6.1.2) and the blank test solution (6.2) with 0.5 N hydrochloric acid solution (3.3) to a concentration within the optimal measuring range of the spectrophotometer. The final solution must contain 10% (V/V) of the lanthanum chloride solution (3.6).

Preparation of the calibration solutions 6.3.2 By diluting the standard solution (3.5.2) with 0.5 N hydrochloric acid solution (3.3) prepare at least 5 standard solutions of increasing concentration corresponding to the optimal measuring range of the spectrophotometer. The final solutions must contain 10% (V/V) of the lanthanum chloride solution (3.6).

Measurement

6.4

Set up the spectrophotometer (4.1), at a wave length of 248.3 nm using an oxidising air-acetylene flame. Spray successively, in triplicate, the standard solutions (6.3.2), the sample solution, and the blank test solution (6.3.1), washing the instrument through with distilled water between each spraying, Plot the calibration curve using the mean absorbances as the ordinates and the corresponding concentrations of iron in Fg/ml as the abscissae. Determine the concentration of iron in the final sample and blank solutions by reference to the calibration curve.

EXPRESSION OF THE RESULTS

7

Calculate the iron content of the sample taking into account the weight of the test sample and the dilutions carried out in the course of the analysis. Express the result either as a percentage or as mg/kg.

14. — DETERMINATION OF MANGANESE

SCOPE AND FIELD OF APPLICATION

1

This method is applicable to all fertilisers.

PRINCIPLE

2

The sample is ashed and dissolved in dilute hydrochloric acid or, if it contains no organic substances, it is dissolved directly in dilute hydrochloric acid. The solution is diluted and the manganese content of the extract is determined by atomic absorption spectrophotometry.

REAGENTS

3

3.1

Hydrochloric acid (d = 1.18 g/ml).

3.2

Hydrochloric acid, 6 N solution.

3.3

Hydrochloric acid, 0.5 N solution.

Manganese solution[^f00036] (stock): 3.4.1 weigh to the nearest 0.001 g, 1 g pure manganese, dissolve in 25 ml 6 N hydrochloric acid solution (3.2) and dilute to 1 litre with water. 1 ml of this solution = 1,000 μg of manganese (Mn).

Manganese solution (dilute): 3.4.2 dilute 10 ml of stock solution (3.4.1) to 1 litre with water. 1 ml of this solution = 10 μg of manganese.

3.5

Lanthanum chloride solution: dissolve 12 g lanthanum oxide in 150 ml water, add 100 ml 6 N hydrochloric acid solution (3.2) and dilute to 1 litre with water.

APPARATUS

4

4.1

Atomic absorption spectrophotometer with a manganese lamp (279.5 nm).

PREPARATION OF SAMPLE

5

See Method 1.

PROCEDURE

6

Preparation of the solution for analysis

6.1

In the absence of organic matter 6.1.1 Weigh to the nearest 0.001 g, 5 g of the prepared sample, place it in a 400 ml beaker, add carefully 5 ml hydrochloric acid (3.1) (there may be a vigorous reaction due to carbon dioxide formation). Add more hydrochloric acid, if necessary. When effervescence has stopped, evaporate to dryness on a steam bath, stirring occasionally with a glass rod. Add 15 ml 6 N hydrochloric acid solution (3.2) and 120 ml water. Stir with the glass rod, which should be left in the beaker, and cover the beaker with a watch glass. Boil the solution gently until dissolution appears complete and then filter through a filter paper[^f00037] into a 250 ml graduated flask. Wash the beaker and filter with 5 ml of hot 6 N hydrochloric acid solution (3.2) and twice with boiling water. Cool and make up to the mark with water. (The hydrochloric acid concentration of this solution should be about 0.5 N).

In the presence of organic matter 6.1.2 Weigh to the nearest 0.001 g, 5 g of the prepared sample into a silica or platinum crucible and place the crucible into a cold muffle furnace. Close the furnace and gradually raise the temperature to 450 – 475°C over about 90 minutes. Maintain this temperature for at least 16 hours and then open the furnace and allow the crucible to cool. Moisten the ash with water and transfer it into a 250 ml beaker. Wash the crucible with about 5 ml hydrochloric acid (3.1) and add the latter slowly and carefully to the beaker (there may be a vigorous reaction due to carbon dioxide formation). If necessary, add more hydrochloric acid (3.1) with stirring, until all effervescence has stopped. Evaporate the solution to dryness, occasionally stirring with a glass rod. Add 15 ml 6 N hydrochloric acid solution (3.2) and 120 ml water. Stir with the glass rod, which should be left in the beaker, and cover with a watch glass. Boil the solution gently until dissolution appears complete and filter through a filter paper[^f00038] into a 250 ml graduated flask. Wash the beaker and filter with 5 ml of hot 6 N hydrochloric acid solution (3.2) and twice with boiling water. Cool and make up to the mark with water. (The hydrochloric acid concentration of this solution should be about 0.5 N).

Blank solution

6.2

Prepare a blank solution from which only the sample has been omitted and allow for this in the calculation of the final results.

Determination

6.3

Preparation of sample and blank test solutions 6.3.1 Dilute the sample solutions (6.1.1 or 6.1.2) and the blank test solution (6.2), with 0.5 N hydrochloric acid solution (3.3) to a concentration within the optimal measuring range of the spectrophotometer. The final solution must contain 10% (V/V) of the lanthanum chloride solution (3.5).

Preparation of the calibration solutions 6.3.2 By diluting the standard solution (3.4.2) with 0.5 N hydrochloric acid solution (3.3) prepare at least 5 standard solutions of increasing concentration corresponding to the optimal measuring range of the spectrophotometer. The final solutions must contain 10% (V/V) of the lanthanum chloride solution (3.5).

Measurement

6.4

Set up the spectrophotometer (4.1), at a wave length of 279.5 nm using an oxidising air-acetylene flame. Spray successively, in triplicate, the standard solutions (6.3.2), the sample solution and the blank test solution (6.3.1), washing the instrument through with distilled water between each spraying. Plot the calibration curve using the mean absorbances as the ordinates and the corresponding concentrations of manganese in μg/ml as the abscissae. Determine the concentration of manganese in the final sample and blank solutions by reference to the calibration curve.

EXPRESSION OF THE RESULTS

7

Calculate the manganese content of the sample taking into account the weight of the test sample and the dilutions carried out in the course of the analysis. Express the result either as a percentage or as mg/kg.

15. — DETERMINATION OF THE NEUTRALISING VALUE IN LIMING MATERIALS

SCOPE AND FIELD OF APPLICATION

1

This method is applicable to products in Groups 5(a) and 5(b) of Section A of the Table in Schedule 1 of the Fertilisers Regulations (Northern Ireland) 1990[^f00039].

PRINCIPLE

2

The sample is dissolved in a measured quantity of standard hydrochloric acid, the excess of which is titrated with a standard solution of sodium hydroxide.

REAGENTS

3

3.1

Hydrochloric acid, 0.5 N solution.

3.2

Sodium hydroxide, 0.5 N solution of carbonate free).

3.3

Phenolphthalein indicator solution: dissolve 0.25 g phenolphthalein in 150 ml 95% ethanol and dilute with water to 250 ml.

PREPARATION OF SAMPLE

4

Rapidly grind 50 g of the representative lime sample to pass through a 1 mm sieve.

PROCEDURE

5

Determination

5.1

Weigh to the nearest 0.001 g, 0.5 g of the prepared sample and transfer to a 300 ml conical flask. Add 50 ml of 0.5 N hydrochloric acid (3.1), cover the flask with a watch glass and boil the contents gently for five minutes. Cool the mixture to room temperature, add two or three drops of the phenolphthalein indicator (3.3) and titrate with 0.5 N sodium hydroxide solution (3.2) to the end point of the indicator.

EXPRESSION OF THE RESULTS

6

Determine the amount of hydrochloric acid consumed by the sample. 1 ml 0.5 N hydrochloric acid = 0.01402 g calcium oxide (CaO).

16. — DETERMINATION OF FINENESS OF PRODUCTS OTHER THAN POTASSIC BASIC SLAG

SCOPE AND FIELD OF APPLICATION

1

This method is applicable to “Rock phosphate” in Group 2(b) and to products in Groups 4(c), 5(a) and 5(b) of Section A of the Table in Schedule 1 of the Fertilisers Regulations (Northern Ireland) 1990.

PRINCIPLE

2

By hand sieve shaking, the proportion of material passing through the prescribed sieve is determined.

APPARATUS

3

Sieves having square apertures of 45 mm, 6.7 mm, 6.3 mm, 5 mm, 3.35 mm, 1.0 mm and 150 microns: lower receiver to fit sieve. Test sieve conforming to British Standard 410 : 1986 are suitable.

PROCEDURE

4

For sieving through 3.55 mm, 1.0 mm and 150 micron sieves

4.1

Thoroughly mix the sample and quarter down until a portion of about 100 g is obtained. Heat this portion at 100°C until dry and thoroughly mix. Weigh to the nearest 0.01 g, 20 g and transfer to the sieve with the lower receiver attached. Proceed as described in 4.4.

For sieving through 6.7 mm, 6.3 mm and 5 mm sieves

4.2

Oven dry the sample at 100°C for 24 hours and thoroughly mix. Weigh to the nearest 0.1 g, 200 g and transfer to the sieve with the lower receiver attached. Proceed as described in 4.4.

For sieving through a 45 mm sieve

4.3

If the sample appears moist or damp, oven dry at 100°C for 24 hours, but if the sample appears dry, heating is not necessary. Thoroughly mix the sample and weigh to the nearest 0.1 g, 500 g and transfer to the sieve with the lower receiver attached. Proceed as in 4.4.

Sieving

4.4

Shake the sieve for 5 minutes, frequently tapping the side. Disintegrate soft lumps such as can be caused to crumble by the application of the fibres of a soft brush, taking care that the hard part of the brush does not make contact with the sieve, and that the brush is not used to brush particles through the sieve. Brush out the powder in the lower receiver and weigh. Replace the receiver and repeat the shaking and tapping procedure for 2 minutes. Add the powder in the receiver to the first portion and weigh. Repeat the process until not more than 0.04 g passes through the sieve during 2 minutes.

EXPRESSION OF THE RESULTS

5

Calculate the fineness by expressing the weight of the material passing through the sieve as a percentage of the weight of the portion of the dried (or as the case may be undried) sample taken for sieving.

17. — DETERMINATION OF FINENESS OF POTASSIC BASIC SLAG

SCOPE AND FIELD OF APPLICATION

1

Exclusively to “Potassic basic slag” in Group 3(b) of Section A of the Table in Schedule 1 of the Fertilisers Regulations (Northern Ireland) 1990.

PRINCIPLE

2

By hand sieve shaking and dissolution of the soluble salts, the proportion of slag passing through the prescribed sieve is determined.

APPARATUS

3

Sieve having square apertures of 0.5 mm (500 microns); lower receiver to fit sieve. Test sieves conforming to British Standard 410 : 1986 are suitable.

PROCEDURE

4

Preparation of the sample

4.1

Thoroughly mix the sample and quarter down until a portion of about 100 g is obtained. Heat this portion at 100°C until dry, and throughly mix.

Sieving

4.2

Weigh to the nearest 0.1 g, 20 g of the dry sample and transfer to the sieve with the lower receiver attached. Shake the sieve for five minutes, frequently tapping the sides. Disintegrate soft lumps that can be caused to crumble by the application of a soft brush, taking care that the hard part of the brush does not make contact with the sieve and that the brush is not used to brush particles through the sieve.

EXPRESSION OF THE RESULTS

5

Express the fineness of the slag as

$AB×100.$

APPENDIX TO SCHEDULE 2

KEY TO FIGURE 1

The equipment is made of borosilicate glass.

KEY TO FIGURE 2

KEY TO FIGURE 3

KEY TO FIGURE 4

KEY TO FIGURE 5

KEY TO FIGURE 6

KEY TO FIGURE 7

KEY TO FIGURE 8

SCHEDULE 3

Form of Certificate of Analysis Certificate of Analysis of Fertiliser⁽¹⁾

Regulation 6

Signed

Sealed with the Official Seal of the Department of Agriculture for Northern Ireland on

I. C. Henderson — Assistant Secretary — 19th December 1991.

Explanatory note

(This note is not part of the Regulations.)

1 These Regulations consolidate and supersede the Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1978 and the Fertilisers (Sampling and Analysis) (Amendment) Regulations (Northern Ireland) 1981. They implement the provisions of the Directives listed in paragraph 2 below.

2 The Directives implemented are— Commission Directive 77/535/EEC (O.J. No. L213, 22.8.77) on the approximation of laws of Member States relating to methods of sampling and analysis for fertilisers; Commission Directive 79/138/EEC (O.J. No. L39, 14.2.79, p. 3) amending Directive 77/535/EEC in respect of methods of analysis for magnesium; Commission Directive 87/94/EEC (O.J. No. L38, 7.2.87) on the approximation of the laws of Member States relating to the procedures for the control of characteristics of, limits for and resistance to detonation of straight ammonium nitrate fertilisers of high nitrogen content; Commission Directive 87/566/EEC (O.J. No. L342, 4.12.87, p. 32) amending Directive 77/535/EEC in respect of methods of sampling for fluid fertilisers; Commission Directive 88/126/EEC (O.J. No. L63, 9.3.88, p. 12) amending Directive 87/94/EEC, in respect only of its date for implementation by the Member States.

3 The Regulations provide for a number of matters concerning the sampling and analysis of fertilisers including; a the amounts of fertilisers from which samples are to be taken (regulation 2); b the manner of taking, marking, sealing and fastening up of samples (regulation 3 and Schedule 1); c the methods of sending part of a sample (regulation 4); d the methods by which analyses are to be carried out (regulation 5 and Schedule 2), and the form of certificate of analysis (regulation 6 and Schedule 3).

4 The principal changes from the superseded Regulations are the introduction of sampling procedures for fluid fertilisers (in Schedule 1) and of methods of analysis for straight ammonium nitrate fertiliser (in Schedule 2).

Footnotes

[^f00001]: 1970 c. 40; section 74A was inserted by s. 4(1) of, and paragraph 6 of Schedule 4 to the European Communities Act 1971 (c. 68) and there are other amendments not relevant to these Regulations.

[^f00002]: 1954 c. 33 (N.I.)

[^f00003]: S.R. 1990 No. 286

[^f00004]: S.R. 1978 No. 240

[^f00005]: S.R. 1981 No. 58

[^f00006]: Biuret can be purified beforehand by washing with an ammoniacal solution (10%), then with acetone and drying in a vacuum

[^f00007]: S.R. 1990 No. 286

[^f00008]: S.R. 1990 No. 286.

[^f00009]: S.R. 1990 No. 286

[^f00010]: S.R. 1990 No. 286

[^f00011]: Where the fertiliser is normal superphosphate or concentrated superphosphate in Group 2(a) of Section A, or NPK fertiliser in Group I, NP fertiliser in Group 2, or PK fertiliser in Group 4 of Section B or NPK fertiliser suspension, NP fertiliser suspension or PK fertiliser suspension in Section C of the Table in Schedule 1 of the Fertilisers Regulations (Northern Ireland) 1990.

[^f00012]: Where the fertiliser is triple superphosphate in Group 2(a) of Section A, or NPK fertiliser containing soft ground rock phosphate or partially solubilised rock phosphate in Group 1, or NP fertiliser containing soft ground rock phosphate or partially solubilised rock phosphate in Group 2, or PK fertiliser containing soft ground rock phosphate or partially solubilised rock phosphate in Group 4 of Section B of the Table in Schedule 1 of the Fertiliser Regulations (Northern Ireland) 1990.

[^f00013]: If no mechanical shaker is available, the flask may be shaken by hand every 5 minutes.

[^f00014]: Phosphorus soluble in mineral acids, water soluble phosphorus, phosphorus soluble in solutions of ammonium citrate, phosphorus soluble in 2% citric acid and phosphorus soluble in 2% formic acid.

[^f00015]: 21 ml when the solution to he precipitated contains more than 15 ml of citrate solution (neutral citrate, Petermann or Joulie alkaline citrate).

[^f00016]: To precipitate phosphate solutions containing more than 15 ml citrate solution (neutral, Petermann or Joulie) which have been acidified with 21 ml concentrated nitric acid (see footnote to paragraph 6.1) use 80 ml of the precipitating reagent.

[^f00017]: S.R. 1990 No. 286

[^f00018]: S.R. 1990 No. 286

[^f00019]: S.R. 1990 No. 286

[^f00020]: A reaction time of one-and-a-half-hours, is sufficient in the case of most of the organic substance in the presence of silver nitrate catalyst.

[^f00021]: Commercially available standard copper solution may be used

[^f00022]: Whatman 541 or equivalent.

[^f00023]: S.R. 1990 No. 286

[^f00024]: S.R. 1990 No. 286

[^f00025]: S.R. 1990 No. 286

[^f00026]: S.R. 1990 No. 286

[^f00027]: Whatman 42 or equivalent.

[^f00028]: Whatman 42 or equivalent.

[^f00029]: Whatman 541 or equivalent.

[^f00030]: Whatman 541 or equivalent.

[^f00031]: Commercially available standard copper solution may be used.

[^f00032]: Whatman 541 or equivalent.

[^f00033]: Commercially available standard iron solution may be used.

[^f00034]: Whatman 541 or equivalent.

[^f00035]: Whatman 541 or equivalent

[^f00036]: Commercially available standard manganese solution may be used.

[^f00037]: Whatman 541 or equivalent

[^f00038]: Whatman 541 or equivalent

[^f00039]: S.R. 1990 No. 286