AS NZS 1605.4:2018 pdf free.Methods for sampling and analysing timber preservatives and preservative- treated timber Part 4: Analysis methods for determination of preservative solution concentration.
2.1 PRINCIPLE
Copper and arsenic are determined by atomic-absorption spectrophotornetry. Hexavalent chromium is determined by back-titration of excess iron added as ferrous ammoniurn sulphate.
This method is applicable to CCA mix tank or working tank solutions.
2.2 REAGENTS
All reagents shall be of analytical reagent quality. The water used for preparing the reagents shall be distilled.
The following reagents shall be used:
(a) BDS indicator Make a slurry of 0.2 g barium diphenylamine suiphonate in 1 mL to 2 mL water, gradually diluting to 100 mL, with stirring. Filter the solution into the reagent flask.
(b) Ferrous ainnioniuni sulphate (FAS) solution Dissolve 140 g ferrous ammonium sulphate in 500 mL water before adding 25 mL concentrated sulphuric acid and final dilution to 1000 mL.
Dilute this stock solution 10:1 volumetrically before usc.
(c) Mixed acid solution Gradually add, with stirring, 500 mL concentrated sulphuric acid to 500 mL water. When cool adjust the volume to 1000 rnL with water, and add 500 mL orthophosphoric acid to complete the mixture.
(d) Standard potassIum dichromate solution Dissolve exactly 10.000 g potassium dichromate in water and dilute volumetrically to 1000 mL.
Dilute this stock solution volumetrically 10:1 before use (1 mL contains exactly 0.00 10 g K2Cr2O7 after dilution and is equivalent to 0.3535 mg Cr).
(e) Standard copper solution, 1000 pg copper/mL Dissolve 7.8580 g copper sulphate pentahydrate in water and dilute to 2000 mL in a volumetric flask.
(0 Standard arsenic solution, 1000 pg As/inL Dissolve 2.64 15 g arsenous trioxide (As203) in 50 mL of 20% potassium hydroxide solution, and dilute to 2000 mL with 1% aqueous sulphuric acid.
2.3 PROCEDURE
2.3.1 Instrument settings and operation
The instrument settings and operating conditions for the determination of copper and arsenic shall be as recommended in the instrument user’s manual. Copper shall be determined in a fuel-lean air acetylene flame at 324.8 or 3.28 nrn, and arsenic in a nitrous oxide/acetylene flame at 193.7 nm, with background correction for non-atomic absorption.
2.3.2 Preparation of calibration solutions
The calibration solutions shall be prepared as follows:
(a) Transfer aliquot portions of 2, 4, 8 and 16 mL of the standard solutions [Clauses 2.2(e) and 2.2(f)] to a series of 200 mL one-marked volumetric flasks.AS NZS 1605.4 pdf download.