JOURNAL ARTICLE

Shifting the Measuring Range of Chloride Selective Electrodes and Optodes Based on the Anticrown Ionophore [9]Mercuracarborand-3 by the Addition of 1-Decanethiol

Aleksandar Radu, Eric Bakker
Chemia Analityczna 2005, 50 (1): 71-83
16429590
Ion-selective electrodes and optodes based on the anticrown ionophore mercuracarborand-3 (MC-3) exhibit excellent selectivity to halide ions but suffer from a low upper detection limit because of very strong complexation in the sensing phase. In this work, we have successfully improved the upper detection limit and widened the working range of chloride selective electrode based on MC-3 by introducing 1-decanethiol into the membrane cocktail. With an assumed 1:2 stoichiometry between chloride and MC-3 the apparent complex formation constant was reduced from log beta = 13.4 as reported for the membrane without the addition of 1-decanethiol to log beta = 12.13, log beta = 10.84 and log beta = 5.67 with the addition of a 1:1, 1:2 and 1:4 molar ratio of 1-decanethiol to MC-3. Besides these values, obtained with the sandwich membrane method, similar shifts in the measuring range of thin optode film responses to lower chloride concentrations were observed as well. The selectivity of the modified membrane was found to be very good, with hydroxide and the other halides: bromide and iodide, as the main interferences. Based on these results, corresponding iodide selective electrodes were prepared that showed a near-Nernstian iodide slope, rather than a cationic slope as observed without thiol additive.Jonoselektywne elektrody i optody stosujace antykoronowy jonofor [9]merkuracarborand-3 (MC-3) charakteryzuja sie doskonała selektywnościa w stosunku do jonów halogenków lecz wskutek silnego kompleksowania w fazie receptora maja ograniczony zakres górnej granicy oznaczalności. W przedstawionej pracy poszerzono zakres stosowalności dzieki wprowadzeniu 1-dekanotiolu do membrany zawierajacej MC-3. Przy załozonej stechiometrii kompleksu chlorek-MC-3 równej 1:2 stała tworzenia kompleksu została obnizona, z wartości log beta = 13,4 (w przypadku membrany bez dodatku 1-dekanotiolu) do wartości log beta = 12,13; log beta = 10,84 i log beta = 5,67 (po dodaniu 1-dekanotiolu) dla stosunków molowych stezeń-1-dekanotiol:MC-3 wynoszacych odpowiednio 1:1, 1:2 i 1:4. Ponadto oprócz tych danych otrzymanych metoda warstwowej membrany, podobne przesuniecie zakresu pomiarowego obserwowano w przypadku małych stezeń chlorków dla cienkowarstwowej optody. Selektywnoś ć modyfikowanej membrany była dobra, przy czym głównymi interferentami były jony bromkowe, jodkowe i wodorotlenkowe. W oparciu o te wyniki skonstruowano elektrode czuła na jony jodkowe, charakteryzujaca sie nachyleniem anionowym charakterystyki bliskim Nernstowskiemu, a nie kationowym wykazywanym w nieobecności tiolu.

Full Text Links

Find Full Text Links for this Article

Discussion

You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read
16429590
×

Save your favorite articles in one place with a free QxMD account.

×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"