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Two different types of conductivity probes, that is, a torroidal probe and a resistance probe, were used as online sensors to monitor conductivity during the course of emulsion polymerizations of n‐butyl methacrylate (BMA). These measurements were first applied to a nonreactive system, but the results showed that this method cannot be used to monitor latex stability in this system. Batch emulsion polymerizations of BMA were then carried out using different concentrations (0.6, 1.2, 2.4, and 7.8 mM) of sodium lauryl sulfate (SLS) as surfactant. The profiles of the two conductivity curves changed with the variation of the SLS concentration. Because deposition of polymers on the surfaces of the electrodes of the resistance probe can reduce the measured conductivity values obtained from this probe (R) such that they are lower than the true values, as measured by the torroidal probe (T), the final conductivity ratio (R/T) between the two conductivity curves was chosen as a parameter to correlate the conductivity measurements to latex stability, which was estimated using blender tests and turbidity measurements. A linear relationship between them was found, indicating that the online conductivity measurements could be used to predict latex stability in the BMA emulsion polymerization system. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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A method is developed to determine salbutamol in human plasma and urine using high-performance liquid chromatography (HPLC) with a coulometric electrode array system, based on the electrochemical behavior of salbutamol at graphite electrode. The mobile phase component A is 30 mM sodium dihydroxy phosphate-30 mM triethylamine and is adjusted to pH 6.0 with 20% phosphate acid. The mobile phase component B is methanol. The optimized mobile phase composition was A and B in the proportion of 90:10 (v/v). Paracetamol is selected as the external standard. The human plasma and urine samples are pretreated using solid-phase extraction cartridges (Sep-Pak Silica), and the eluting solution is monitored by the coulometric electrode array system. The electrode potentials are set at 300, 400, 550, and 650 mV, respectively. Calibration curves show good linearity, and the recovery of salbutamol proves to be constant and unaffected by the concentration of the drug. This method, developed using HPLC-electrochemical detection, is reproducible and sensitive enough for the determination of salbutamol in human plasma and urine.