1、BRITISH STANDARD BS 5666-4: 1979 Incorporating Amendment No.1 Methods of analysis of Wood preservatives and treated timber Part 4: Quantitative analysis of preservatives and treated timber containing copper naphthenate NOTEIt is essential that this Part is read in conjunction with Part1 “General con
2、siderations and sampling and preparation of materials for analysis”. UDC 674.048:634.0.841BS5666-4:1979 This British Standard, having been prepared under the directionof the Wood PreservationStandards Committee, was published underthe authority of the Executive Board and comes intoeffect on 31August
3、1979 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference WPC/11 Draft for comment 77/54135 DC ISBN 0 580 10843 0 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for the
4、ir correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see co
5、pyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue Comments 3262 March 1980 Indicated by a sideline in the marginBS5666-4:1979 BSI 10-1999 i Contents Page 1 Scope
6、and field of application 1 2 References 1 3 Method 1. Atomic absorption spectrophotometric method 1 4 Method 2. Colorimetric method 2 5 Test report 4 Publications referred to Inside back coverii blankBS5666-4:1979 BSI 10-1999 1 1 Scope and field of application This Part of this British Standard deta
7、ils procedures for the determination of copper naphthenate, expressed as the amount of copper present, in preservatives and in treated timber containing this preservative. The methods have been found suitable for the determination of copper in the presence of tributyltin oxide, pentachlorophenol, o-
8、phenylphenol, monochloronaphthalene, polychloronaphthalene, -HCH, dieldrin, zinc naphthenate, potassium salts and sodium salts. The wood sample may be in the form of sawdust, wood flour, or thin sections. The procedure for the analysis of preservatives has been primarily designed for solutions compl
9、ying with the requirements of BS5056; for samples of other compositions it may be necessary to make adjustments. It is difficult to make recommendations as to the quantity of sample to be taken in the case of treated wood because the predominant factor is the quantity of preservative within the wood
10、 rather than the mass of the wood itself. It may thus be necessary to make some adjustment to the values quoted in the standard, either to the mass of the treated wood sample taken for analysis or to the level of dilution of the copper solution resulting from extraction. Two methods are described, t
11、he first involving atomic absorption spectrophotometry and the second colorimetry. 2 References The titles of the publications referred to in this Part of this standard are listed on the inside back cover. 3 Method 1. Atomic absorption spectrophotometric method 3.1 Principle. The copper is extracted
12、 quantitatively from wood samples or preservatives with a hydrochloric acid solution. The resulting copper solution is analysed using an atomic absorption spectrophotometer. 3.2 Reagents. All reagents shall be of recognized analytical reagent quality, and water complying with the requirements of BS3
13、978 shall be used throughout. 3.2.1 Hydrochloric acid solution, approximately 5M. Dilute500ml of hydrochloric acid solution ( 20 =1.18g/ml) to1 litre with water. 3.2.2 Hydrochloric acid solution, approximately 1M. Dilute100ml of hydrochloric acid solution ( 20 =1.18g/ml) to1 litre with water. 3.2.3
14、White spirit, complying with the requirements of BS245. 3.2.4 Standard copper solution. (1ml=2004g of copper). Weigh0.1000g of oxide-free copper foil or turnings into a100ml conical flask, add3ml of water and3ml of nitric acid solution ( 20 =1.42g/ml) and heat on a hot-plate until digestion is compl
15、ete. When the fuming subsides, evaporate the solution to dryness. Add a few drops of hydrochloric acid solution ( 20 =1.18g/ml) and again evaporate to dryness. Repeat the addition and evaporation of a few drops of the hydrochloric acid solution. Remove from the hot-plate and when cool, dissolve the
16、resulting residue in hydrochloric acid solution(3.2.2). Transfer to a500ml one-mark volumetric flask, make up to the mark with hydrochloric acid solution(3.2.2), and mix. 3.3 Apparatus 3.3.1 Volumetric glassware, complying with the requirements for class A quality in accordance with BS 700 (typeII),
17、 BS846, BS1583 or BS1792, as appropriate. 3.3.2 Atomic absorption spectrophotometer, together with a suitable source of resonance radiation for copper, e.g.a hollow cathode lamp. 3.4 Procedure 3.4.1 Instrument settings and operation. The instrument settings and operating conditions for the determina
18、tion of copper shall be as recommended in the Instrument Users Manual. Copper is determined in a fuel-lean air/acetylene flame at324.8nm. 3.4.2 Preparation of calibration solutions. Transfer aliquot portions of0.50ml,1.00ml,2.50ml,5.00ml,10.0ml, 20.0ml and30.0ml of the standard copper solution(3.2.4
19、) to a series of100ml one-mark volumetric flasks, dilute to the mark with hydrochloric acid solution(3.2.2) and mix each solution. This will provide solutions containing14g/ml,24g/ml,54g/ml, 104g/ml,204g/ml,404g/ml and604g/ml, respectively, of copper NOTECalibration solutions of different concentrat
20、ions may be necessary to suit the sensitivity of the spectrophotometer used.BS5666-4:1979 2 BSI 10-1999 3.4.3 Analysis of preservative. Weigh out accurately a suitable quantity 1)of the copper naphthenate preservative and dilute it in approximately50ml of white spirit(3.2.3). Transfer the solution q
21、uantitatively to a100ml one-mark volumetric flask, make up to the mark with white spirit(3.2.3) and mix thoroughly. Filter the solution through a filter paper 2) , discard the first runnings and collect approximately50ml of the filtrate. Transfer5ml of this solution to a50ml separating funnel and ma
22、ke up to approximately10ml with white spirit(3.2.3). Add20ml of hydrochloric acid solution(3.2.2) and extract the copper from the organic layer by shaking vigorously for at least90s. Allow the two phases to separate and run off the aqueous layer into a100ml one-mark volumetric flask. Repeat the extr
23、action procedure three more times, each time using a fresh20ml aliquot portion of hydrochloric acid solution(3.2.2). When all extracts have been combined in the 100ml one-mark volumetric flask, make up to the mark with hydrochloric acid solution(3.2.2) and mix to give the test solution. Using the op
24、erating conditions suitable for the instrument being used, aspirate successively, the hydrochloric acid solution(3.2.2) to obtain the blank absorbance, a suitable range of the calibration solutions and, then, the test solution(s). Check the calibration solutions after the last test solution has been
25、 run. NOTEIf a number of samples are to be analysed it may be advisable to check the instrument stability by bracketing each test solution with appropriate standard solutions. Plot a calibration curve of 4g/ml of copper against absorbance. Determine the copper content in the test solution by compari
26、ng the absorbance reading with the calibration curve and express the result as 4g/ml of copper in the test solution. 3.4.4 Analysis of treated wood. Accurately weigh approximately0.1g 3)of the wood sample into a50ml conical flask. Add10ml of hydrochloric acid solution(3.2.1) and stand the flask in a
27、 water bath at a temperature of55 C to60 C for30min with occasional swirling. Remove the flask from the water bath, cool to room temperature, and filter the flask contents through a filter paper 4)into a50ml one-mark volumetric flask. Wash the residue and the filter paper thoroughly with water and a
28、dd the washings to the filtrate in the one-mark volumetric flask. Make up to the mark with water and mix to give the test solution. Using the operating conditions suitable for the instrument being used, aspirate successively, the hydrochloric acid solution(3.2.2) to obtain the blank absorbance, a su
29、itable range of the calibration solutions and, then, the test solution(s). Check the calibration solutions after the last test solution has been run (seenote in3.4.3). Plot a calibration curve of 4g/ml of copper against absorbance. Determine the copper content in the test solution by comparing the a
30、bsorbance reading with the calibration curve and express the result as 4g/ml of copper in the test solution. 3.4.5 Calculations 3.4.5.1 The percentage of copper in a preservative. The percentage, by mass, of copper in the preservative is given by the formula: where C is the concentration in 4g/ml of
31、 copper in the test solution; m 1is the mass in grams of the copper naphthenate preservative solution taken. 3.4.5.2 The percentage of copper in treated wood. The percentage, by mass, of copper in the dry wood is given by the formula: where C is the concentration in 4g/ml of copper in the test solut
32、ion; m 2is the oven-dry equivalent mass in grams of the wood sample taken. To calculate the oven-dry equivalent mass, determine the moisture content (seePart1) of a similar sample of wood to that used for the analysis. 4 Method 2. Colorimetric method 4.1 Principle. The copper is extracted quantitati
33、vely from wood samples or preservatives with a hydrochloric acid solution. The resulting copper solution is allowed to react with a zinc dibenzyldithiocarbamate solution and the concentration of the resulting coloured complex is measured spectrophotometrically. 1) For solutions complying with the re
34、quirements of BS5056,0.800g is suitable. 2) A Whatman no. 42filter paper has been found to be suitable. 3) See clause1. 4) Whatman no.44 filter paper has been round to be suitable. C 5m 1 - C 200m 2 -BS5666-4:1979 BSI 10-1999 3 4.2 Reagents. All reagents shall be of recognized analytical reagent qua
35、lity, and water complying with the requirements of BS3978 shall be used throughout. 4.2.1 Hydrochloric acid, approximately 5M. Dilute500ml of hydrochloric acid solution ( 20 =1.18g/ml) to1litre with water. 4.2.2 Hydrochloric acid, approximately 1M. Dilute100ml of hydrochloric acid solution ( 20 =1.1
36、8g/ml) to1litre with water. 4.2.3 White spirit, complying with the requirements of BS245. 4.2.4 Standard copper solution. (1mlN 24g of copper). Weigh0.1000g of oxide-free copper foil or turnings into a100ml conical flask, add3ml of water and3ml of nitric acid ( 20 =1.42g/ml) and heat on a hot-plate
37、until digestion is complete. When the fuming subsides, evaporate the solution to dryness. Add a few drops of hydrochloric acid solution ( 20 =1.18g/ml) and again evaporate to dryness. Repeat the addition and evaporation of a few drops of the hydrochloric acid solution. Remove from the hot-plate and
38、when cool dissolve the resulting residue in hydrochloric acid solution(4.2.2). Transfer to a100ml one-mark volumetric flask, make up to the mark with hydrochloric acid solution(4.2.2), and mix. Transfer10ml of this solution to a100ml one-mark volumetric flask, make up to the mark with hydrochloric a
39、cid solution(4.2.2), and mix. Transfer2ml of this second solution to a100ml one-mark volumetric flask, make up to the mark with hydrochloric acid solution(4.2.2), and mix to give the standard copper solution. 4.2.5 Zinc dibenzyldithiocarbamate solution. Dissolve0.5g of zinc dibenzyldithiocarbamate i
40、n500ml of carbon tetrachloride. WARNING NOTE. Carbon tetrachloride is toxic and the necessary precautions should be taken to avoid contact with it or inhalation of the vapour. 4.3 Apparatus 4.3.1 Volumetric glassware, complying with the requirements for class A quality in accordance with BS700 (type
41、II), BS846, BS1583 or BS1792, as appropriate. 4.3.2 Spectrophotometer or photoelectric absorptiometer, suitable for the measurement of absorbance at435nm, with appropriate cells. 4.4 Procedure 4.4.1 Preparation of the calibration curve. Transfer aliquot portions of2ml,5ml,10ml,15ml and20ml of the st
42、andard copper solution(4.2.4) to a series of150ml separating funnels. The aliquot portions contain the equivalent of44g,104g,204g,304g and404g, respectively, of copper. Treat each aliquot portion as follows. Dilute to100ml with the hydrochloric acid solution(4.2.2) and swirl to mix. Add10ml of the z
43、inc dibenzyldithiocarbamate solution(4.2.5) and vigorously shake the separating funnel for90s. Allow the two phases to separate. Run off the carbon tetrachloride layer through a dry70mm filter paper 5) , discarding the first runnings, into one of the spectrophotometer cells. Measure the absorbance o
44、f the yellow complex against a reagent blank, prepared in a similar way, at a wavelength of435nm. Prepare the calibration curve by plotting the absorbance values against micrograms of copper. 4.4.2 Analysis of preservatives. Weigh out accurately a suitable quantity 6)of the copper naphthenate preser
45、vative, and add approximately50ml of white spirit(4.2.3). Transfer the mixture quantitatively to a100ml one-mark volumetric flask, make up to the mark with white spirit(4.2.3) and mix thoroughly. Filter the solution through a filter paper 7) , discard the first runnings and collect about50ml of the
46、filtrate. Transfer5ml of this solution to a50ml separating funnel and make up to approximately10ml with white spirit(4.2.3). Add20ml of hydrochloric acid solution(4.2.2) and extract the copper from the organic layer by shaking vigorously for at least90s. Allow the two phases to separate and run off
47、the aqueous layer into a100ml one-mark volumetric flask. Repeat the extraction procedure three more times, each time using a fresh20ml aliquot portion of hydrochloric acid solution(4.2.2). Add further hydrochloric acid solution(4.2.2) to the combined extracts to make up to the mark, and mix. Transfe
48、r2ml of this solution to a250ml separating funnel and make up to approximately100ml with hydrochloric acid solution(4.2.2). Add10ml of the zinc dibenzyldithiocarbamate solution(4.2.5) and vigorously shake the separating funnel for90s. Allow the two phases to separate. Run off the carbon tetrachlorid
49、e layer through a dry70mm filter paper 8) , after discarding the first runnings, into one of the spectrophotometer cells. Measure the absorbance of the yellow complex against a reagent blank, prepared in a similar way, at a wavelength of435nm. Determine the copper content, by comparing the absorbance value with the calibration curve (see4.4.1). 5) A Whatman no.1filter paper has been found to be suitable. 6) For solutions complying with the requirements of BS5056,0.800g is suitable. 7) A Whatman no.42 filter paper has been found to be suitable
