A novel approach for high precision rapid potentiometric titrations: Application to hydrazine assay

Abstract

We propose a high precision rapid personal computer (PC) based potentiometric titration technique using a specially designed mini-cell to carry out redox titrations for assay of chemicals in quality control laboratories attached to industrial, R&D, and nuclear establishments. Using this technique a few microlitre of sample (50-100 μl) in a total volume of ~2 ml solution can be titrated and the waste generated after titration is extremely low comparing to that obtained from the conventional titration technique. The entire titration including online data acquisition followed by immediate offline analysis of data to get information about concentration of unknown sample is completed within a couple of minutes (about 2 min). This facility has been created using a new class of sensors, viz., pulsating sensors developed in-house. The basic concept in designing such instrument and the salient features of the titration device are presented in this paper. The performance of the titration facility was examined by conducting some of the high resolution redox titrations using dilute solutions--hydrazine against KIO(3) in HCl medium, Fe(II) against Ce(IV) and uranium using Davies-Gray method. The precision of titrations using this innovative approach lies between 0.048% and 1.0% relative standard deviation in different redox titrations. With the evolution of this rapid PC based titrator it was possible to develop a simple but high precision potentiometric titration technique for quick determination of hydrazine in nuclear fuel dissolver solution in the context of reprocessing of spent nuclear fuel in fast breeder reactors.

Uranium Concentration Measurement Technique Viability Analysis

“…More recent work has focused on application of the ISO GUM (Guide to Uncertainty Measurements) method to quantifying uniformly the uncertainty associated with measurements made by modified Davies-Gray titrations, [24] as well as extending the analysis usefulness to sample sizes down to the tens of gs from the more typically used 10-30 mgs of uranium. [25][26] This list of references is not exhaustive, and is meant as examples of what can be found in the literature. For someone not familiar with the method it would best to start with the ASTM method.…”

Studies on oscillating chemical reaction in Cu(II)‐catalyzed thiocyanate–hydrogen peroxide–NaOH system using pulsating sensor

“…To design a high‐performance digital potentiometric measurement system, we considered the following major aspects: (a) direct conversion of emf generated from the electrochemical system to digital pulse frequency, which can be directly communicated to PC through its parallel port; (b) high precision and high resolution measurement in the entire range of application; (c) input voltage from −1.0 to +1.0 V, which covers the entire application range; (d) high input impendence; and (e) stable output frequency in a wide temperature range (between 22 and 30°C). The design of the electronic circuit is described elsewhere 34. The performance of the digital potentiometric measurement device is presented in the Results and Discussion.…”

“…In the present work, we introduced a new measurement approach to monitor real‐time shift in digital pulse frequency, a linear function of chemical emf (electromotive force), during the oscillating reaction using a new class of an in‐house–built pulsating sensor. The pulsating sensors of four different categories indigenously developed in this laboratory (IIS) have been successfully used in many physico‐chemical applications in a much simpler way 22–34. Hence in this work, we reported the use of one category of such sensor for high‐precision and high‐resolution online measurement of emf to study a well‐known halogen‐free OCR (Cu(II)‐catalyzed H 2 O 2 –KSCN–NaOH reaction).…”

Desenvolvimento de um titulador automático para caracterização de substâncias húmicas por supressão de fluorescência

“…Os conta-gotas podem ser criados de duas maneiras, sendo a mais comum um sistema que detecta o caimento de uma gota pela interrupção momentânea de um feixe de radiação infravermelha, mecanismos amplamente disponíveis comercialmente [42][43][44]. Outra forma de se contar gotas precisamente consiste na detecção da corrente elétrica que passa em um circuito que é fechado quando a gota é formada e entra em contato com um fio de aço [45].…”

“…As medidas potenciométricas, de íons H3O + e outras espécies para as quais existem eletrodos seletivos, e as amperométricas podem ser realizadas por meio da adaptação de eletrodos e microeletrodos aos próprios frascos de reação de diversas formas em tituladores automáticos [45,46,56,57].…”