solution are metered in 10 20 ppm and then 100 ml of the test solution b are added after sealing the beaker it is placed into the shaking bath for 24 h at 70 u00b0 c after cooling approximately 1 h the sample solutions are filtered off by suction through membrane filters 0 45 u03bcm 50 ml of the filtered solution are then taken for determining the residual amount of phosphate by adding 10 ml of the vanadate molybdate reagent after a reaction time of 10 minutes the phosphate content can then be determined using the photometer on the basis of calibration curves kh 6 42 mmol l p0 4 10 ppm polymer 10 20 ppm of active substance the basis is the test of inhibitory action of polymers for use in cooling circuits equipment dr lange photometer type lp 2 w 800 nm filter suction filter apparatus equipped with 0 45 u03bcm membrane filter shaking water bath gfl model 1083 300 ml lupolen beaker sealable dr lange test kit lck 350 sartorius balance type lc 4800 p 2 2 g l of hedp 1 strength ws dequest 2010 or 5 7 g l of pbtc 1 strength ws bayhibit am or 2 1 g l of atmp 1 strength ws dequest 2000 make up to 11 with distilled water test solution b 1 64 g l of caci 2 6 h 2 o 0 79 g l of mgso 4 7 h 2 o 1 08 g l of nahco 3 0 1 polymer solution based on active substance procedure 100 ml of test solution a are placed in the lupolen beaker 2 4 ml of 0 1 strength polymer solution are added 10.