Determination by direct potentiometry

Membrane electrodes based on the TPB salts of barium-nonionic complexes have been used successfully to determine fatty alcohol-7EO condensates in detergent powders by direct potentiometry [7]. The electrodes were similar in construction to the first of the three types described in section 3.6.2. Two types of membrane were used, incorporating nonionics with EO chains ranging from four to 30 units. The most successful was prepared as follows. 

Mix 100 ml of a 0.01 M aqueous suspension of a nonylphenoMEO adduct (Antarox CO-430) with 10 ml 0.1 M barium chloride. 

Whilst still stirring, slowly add 95% ethanol (up to 200 ml, or 75% by volume) until a flocculent white precipitate is formed. 

Filter the precipitate, wash with 50% ethanol and dry under vacuum at 35°C. 

Dissolve 0.1 g of the dried precipitate, 0.3 g o-nitrophenyl phenyl ether and 0.17 g PVC powder in 6 ml tetrahydrofuran (caution flammable toxic vapour). 

---

The counterion activity of DADMAC polymers has been determined by direct potentiometry using chloride ion selective electrodes. If the polyelectrolyte con-... 

---