While platelet concentrates are stored at room temperature, lactic and other acids are produced and the pH decreases as the buffering capacity of the plasma is exhausted. Platelet viability will be compromised if the pH decreases to pH 6.0 and below. Similarly, a pH decrease can be produced also by bacterial contamination if the organisms produce acid as an end product. Thus the determination o...

We report on the determination of creatinine in human serum using a point-of-care device suitable for the use by untrained operators, the Medimate Multireader®. This device is based on electrophoretic separation and conductivity detection and its prefilled microfluidic chip has a single opening for sample introduction. The device was originally developed for the determination of lithium in bloo...

A spectrofluorometric method is described for the determination of germanium(IV) based on its complexation reaction with quercetin in presence of Brij-35. The fluorescence is monitored at 552 nm with excitation at 432 nm. The pH, quercetin and Brij-35 concentrations were optimized simultaneously using the response surface methodology from sequential experimental three-variable Doehlert designs....

A simple, sensitive and highly selective electrochemical method was developed for the simultaneous determination of nitazoxanide and ofloxacin in aqueous media (Britton-Robinson buffer, pH-8.36) on a hanging mercury drop electrode (HMDE) using differential pulse polarography (DPP). Using DPP a separation of about 936 mV between the peak oxidation potentials of nitazoxanide and ofloxacin present...

Plasticized poly(vinyl chloride) membranes that incorporate a highly lipophilic sodium-selective neutral ionophore (ETH 4120) and novel H(+)-selective chromo-ionophores, lipophilic isologs of Nile Blue, are used in the competitive binding of Na+ and H+ for a reversible, optical determination of sodium activities in buffered solutions at different selected pH values. These optode membranes are u...

Techniques for determining large transbilayer pH gradients (delta pH) and membrane potentials (delta psi) induced in response to delta pH in large unilamellar vesicle liposomal systems by measuring the transbilayer redistribution of radiolabeled compounds have been examined. For liposomes with acidic interiors, it is shown that protocols using radiolabeled methylamine in conjunction with gel fi...

We show that a pH-sensitive derivative of the green fluorescent protein, designated ratiometric GFP, can be used to measure intracellular pH (pHi) in both gram-positive and gram-negative bacterial cells. In cells expressing ratiometric GFP, the excitation ratio (fluorescence intensity at 410 and 430 nm) is correlated to the pHi, allowing fast and noninvasive determination of pHi that is ideally...