AS NZS 1605.3:2018 pdf download.Methods for sampling and analysing timber preservatives and preservative-treated timber Part 3: Analysis methods for determination of preservative retention.
SECTION 6 DETERMINATION OF CREOSOTE OR PIGMENT-EMULSIFIED CREOSOTE IN PRESERVATIVE-TREATED TIMBER
6.1 PRINCIPLE
The retention of creosote, pigment-emulsified creosote, mineral oil and pentachlorophenol, or combinations of these, is measured by extracting these from a weighed timber sample using toluene as a solvent and expressing the mass loss as a percentage of the oven-dried extracted timber mass. The moisture content of the timber shall lie between 8% to 18% of the oven-dried extracted timber mass, or an appropriate volume correction shall be made.
6.2 REAGENT—TOLUENE
NOTE: Laboratory reagent-grade toluene may be used if it has been distilled to remove water.
6.3 PROCEDURE
6.3.1 Determination of moisture content
The moisture content of the test piece is the mass of water recovered during the extraction of preservative and is expressed as a percentage of the mass of extracted timber after oven-drying in a well-ventilated oven at 105 ±2°C to constant mass.
6.3.2 Apparatus
The following apparatus shall be used for the extraction of creosote or mineral oil, or both (see Figure 6.3.2):
(a) Extraction flask, Soxhiet extractor The apparatus shall be of glass with standard ground-glass joints open to the atmosphere at the top.
(b) Water trap, condenser The apparatus shall be a Dean and Stark side-arm attachment made of glass with standard ground-glass joints, fitted with a water-cooled condenser at the top and open to the atmosphere. The size of the apparatus shall be appropriate to collect within the graduation range of the water trap. The trap shall be chemically clean so that the shape of the meniscus at the end of the extraction is the same as at the beginning. Coating the trap from time to time with silicone resin gives a uniform meniscus.
NOTE: A thin rod of some material to which water does not adhere, such as polytetrafluoroethylene, may be used to transfer water condensed elsewhere to the water layer of the trap.
(c) Heating apparatus An electric heating mantle shall be used.
6.3.3 Extraction of timber
The procedure for the extraction of timber shall be as follows:
(a) Take a test piece of 5 g to 20 g treated timber. If the test piece to be analysed has been broken into fragments, use the larger of these fragments to make a composite sample of aggregate mass in excess of 10 g. Weigh the test piece in air to an accuracy of 0.02 g.
(b) Place in the extraction flask sufficient toluene to fill the water trap and Soxhlet extractor and to maintain a reservoir in the extraction flask. Add approximately 0.5 mL distilled water to the toluene. Assemble the apparatus, apply heat and reflux for 30 min. Allow the contents of the water trap to cool to room temperature then, using the polytetrafluoroethylene rod, transfer any water adhering to the walls of the condenser and water trap to the water layer in the trap. Note the volume of water in the trap to the nearest 0.01 mL.
(c) Transfer the test piece to the Soxhlet extractor in the assembled apparatus.
(d) Apply sufficient heat to the extraction flask to reflux the toluene at the base of the condenser and to operate the Soxhlet siphon at least once every 12 min. Continue the refluxing for 16 h or until no more colour is extracted from the sample, whichever is greater. Allow the contents of the trap to cool to room temperature before transferring any water adhering to the walls of the condenser or water trap, or both, to the water layer in the trap. Read and record the volume of water in the trap to the nearest 0.01 mL.
The difference between this reading and the first reading represents the mass of water in the test piece.AS NZS 1605.3 pdf download.
AS NZS 1605.3:2018 Part 3: Analysis methods for determination of preservative retention
PS:Thank you for your support!
