Buffer solution

About: Buffer solution is a research topic. Over the lifetime, 6948 publications have been published within this topic receiving 112440 citations. The topic is also known as: pH buffer & buffer.

Rapid determination of residual chlorine by flow injection analysis

Abstract: Flow injection determination of residual chlorine in solution has been carried out spectrophotometrically by methyl orange decolorisation and by formation of a yellow complex with o-tolidine. The carrier streams are 0.180 mM methyl orange in pH 2 buffer solution or 0.01 M hydrochloric acid, and 3.0 mMo-tolidinium dichloride (in 2 M hydrochloric acid), respectively. A sampling rate of 288 samples per hour has been obtained with the latter reagent and the detection limit is 0.08 p.p.m. of chlorine. Influence of flow parameters such as flow-rate, tube length and diameter and the effect of interferents on the determination have been investigated. A study of the hyprochlorite-ammonium-o-tolidine reaction system has been performed and a method for the simultaneous determination of NH4+ and OCl– is described.

Electrodeposition of zinc–nickel alloys from ammonia-containing baths

Abstract: This paper describes the use of ammonia-containing baths for Zn–Ni alloy electrodeposition. Buffering properties of the ammonia/ammonium couple limit the local change in pH in the vicinity of the electrode surface caused by simultaneous hydrogen evolution. In addition, it is shown that the divalent zinc and nickel species exist in the form of Zn(NH3)42+ and Ni(NH3)62+ complexes over a large pH range. The electrochemistry of the deposition at pH 10 was investigated by galvanostatic experiments and cyclic voltammetry, and compared with deposition from ammonium chloride baths at pH 5. The Ni content in the alloys were found to be 40–60% higher from the ammonia-containing bath than from the acidic baths. Reduction of divalent ions and hydrogen evolution were shown to occur at potentials 250 mV more cathodic than with baths at pH 5; the deposition mechanism may be affected by complexation of the metal cations by ammonia.

Determination of morphine at gold nanoparticles/Nafion® carbon paste modified sensor electrode

Abstract: A novel and effective electrochemical sensor for the determination of morphine (MO) in 0.04 mol L−1 universal buffer solution (pH 7.4) is introduced using gold nanoparticles electrodeposited on a Nafion modified carbon paste electrode. The effect of various experimental parameters including pH, scan rate and accumulation time on the voltammetric response of MO was investigated. At the optimum conditions, the concentration of MO was determined using differential pulse voltammetry (DPV) in a linear range of 2.0 × 10−7 to 2.6 × 10−4 mol L−1 with a correlation coefficient of 0.999, and a detection limit of 13.3 × 10−10 mol L−1, respectively. The effect of common interferences on the current response of morphine namely ascorbic acid (AA) and uric acid (UA) is studied. The modified electrode can be used for the determination of MO spiked into urine samples, and excellent recovery results were obtained.

A Fiber-Optic Carbon Dioxide Sensor for Fermentation Monitoring

Abstract: We have developed a fiber-optic chemical sensor for determining dissolved carbon dioxide and assessed its performance for the on-line monitoring of fermentation. The sensor operates on the Severinghaus pCO2 electrode principle; it consists of a pH sensitive dye (hydroxypyrenetrisulfonic acid, HPTS) in an HCO3− buffer solution entrapped in an expanded PTFE support held at the distal end of an optical fiber by a gas permeable membrane. CO2 crossing the membrane produces a pH change in the indicator solution. This change is related to the external CO2 concentration by the Henderson-Hasselbach equation. The sensor has a reversible working dissolved CO2 dynamic range of 0–0.25 atm. The sensor can be auto-claved without affecting its calibration. Results are presented for the on-line determination of CO2 production in beer fermentation.