scholarly journals EFFECT OF STERIC ACCESSIBILITY OF EXCHANGE CENTER OF HIGHER QUATERNARY AMMONIUM SALTS AND PLASTICIZER NATURE ON CHARACTERISTICS OF ELECTRODES, REVERSIBLE TO DOUBLE-CHARGED ANIONS

2018 ◽  
Vol 59 (1) ◽  
pp. 9
Author(s):  
E.M. Rakhman’ko ◽  
Yu.V. Matveiychuk
Keyword(s):  
Detection Limit ◽  
Quaternary Ammonium ◽  
Limit Of Detection ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Ion Selective Electrodes ◽  
Selectivity Coefficients ◽  
Low Detection Limit ◽  
Order Of Magnitude ◽  
Steric Accessibility

The effect of the steric accessibility of the exchange center of higher quaternary ammonium salts and plasticizer nature on the selectivity and the limit of detection for film electrodes reversible to hydrophilic double-charged anions was studied. It was established the decrease in selectivity coefficients lgKi,jPot by 2.8−3.8 order of magnitude and low detection limit by 2−3 order of magnitude in the series of QAS: TOD≤TC<TL<TNODA<TB<TE<TM< DCPBTM. Also, the increase in low detection limit by 1−0.7 order of magnitude in the series of plasticizers: DBP>DDP>o-NPDE>1-BN was established. The composition of membranes of ion-selective electrodes was optimized.

scholarly journals NITRATE-SELECTIVE ELECTRODE AND ITS USE FOR ANALYSIS OF VEGETABLES AND MINERAL WATERS

2019 ◽  
Vol 62 (9) ◽  
pp. 20-26
Author(s):  
Yulya V. Matveichuk
Keyword(s):  
Detection Limit ◽  
Quaternary Ammonium ◽  
Maximum Permissible Concentration ◽  
Ion Association ◽  
Quaternary Ammonium Salts ◽  
Mineral Waters ◽  
Ammonium Salts ◽  
Selective Electrode ◽  
Iodide Ions ◽  
Silver Sulfate

The effect of the length of the radicals at the exchange center of the quaternary ammonium salts on the selectivity and the detection limit of the nitrate-selective electrode is investigated. The observed effects of improving the analytical characteristics while reducing the steric availability of the exchange center for quaternary ammonium salts are explained on the basis of the theory of ion association. The composition of the polyvinyl chloride (33 wt.%) electrode membrane for the quaternary ammonium salt (3,4,5-tris bromide (dodecyloxy)benzyltricethylammonium bromide, 5 wt.%) and the plasticizer (o-nitrophendecyl ether, 62 wt.%) was optimized. The developed electrode has a low detection limit (2.0∙10−7 mol/l) and a close to theoretical slope of the electrode function (56.8 mV/pNO3), and the potential of the nitrate-selective electrode is not affected by fluoride, nitrite, bicarbonate-, dihydrophosphate-, sulfate ions. The interfering action of chloride, bromide, and iodide ions can be eliminated by introducing 1·10–3 mol/l of a background solution of silver sulfate. Thiocyanate and perchlorate ions interfere with the operation of the electrode, but they are practically not found in real objects. The developed electrode was used to determine the nitrate ions in vegetables (white cabbage, cucumber, lettuce, tomato, onion, carrots, and potatoes), greens (dill, parsley) and mineral water. It was established that the maximum permissible concentration of nitrates is exceeded more than 4.5 times for cabbage (MAC = 500 mg/kg), almost 2 times for salad (maximum permissible concentration 1500 mg/kg), 1.5 times for potatoes (maximum permissible concentration 250 mg/kg) and 3 times for dill (maximum permissible concentration 1500 mg/kg).

scholarly journals Influence of plasticizer nature on the analytical characteristics of ion-selective electrodes based on higher quaternary ammonium salts reversible to doubly charged inorganic anions

2019 ◽  
Vol 54 (4) ◽  
pp. 428-433
Author(s):  
Yu. V. Matveichuk
Keyword(s):  
Quaternary Ammonium ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Ion Selective Electrodes ◽  
Qualitative Explanation ◽  
Hydrogen Phosphate ◽  
Lower Detection Limit ◽  
Born Model ◽  
Lower Detection ◽  
Doubly Charged

It has been established that membranes of carbonate and hydrogen phosphate selective electrodes based on higher quaternary ammonium salts are preferable to be plasticized with o-nitrophenyldecyl ether, membranes of sulfate, selenate, selenite-selective electrodes with 1-bromonaphthalene, sulfite, molybdate, tungstate-selective electrodes with dibutylphthalate. The use of an optimum plasticizer allows, in general, reducing both the lower detection limit of electrodes and the values of selectivity coefficients by about 1 order (depending on the interfering ion). A qualitative explanation is given to the results obtained from the Fouoss theory and the Born model.

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