A simple voltammetric method using a glassy carbon working electrode was developed for the determination of two members from the neonicotinoid group of insecticides: imidacloprid and thiamethoxam. The experiments showed that the voltammetric response depends on the mode of electrode surface pretreatment and the polarization mode. The response appeared to be linear in the range from 0.028 to 0.50 mg/cm3 for both analyses. The limit of detection was 0.0077 mg/cm3 for imidacloprid and 0.0085 mg/cm3 for thiamethoxam, the limit of quantitation was 0.026 mg/cm3 and 0.028 mg/cm3, respectively. The developed method was applied for the determination of these insecticides in potato samples sprayed with Confidor 200-SL or Actara 25-WG as well as commercial formulations of imidacloprid and thiamethoxam. A recovery trial was performed to assess the accuracy of the results, the recovery values being between 95?102 % for both of neonicotinoids.

A comparative study was carried out of the potentiometric application of boronand phosphorus-doped and undoped glassy carbon samples prepared at the same heat treatment temperature (HTT 1000 ?C). The electrochemical activities of the obtained electrode materials were investigated on the example of argentometric titrations. It was found that the electrochemical behaviour of the doped glassy carbon samples are very similar to a Sigri (undoped) glassy carbon sample (HTT 2400 ?C). The experiments showed that the potentiometric response depends on the polarization mode, the nature of the sample, the pretreatment of the electrode surface, and the nature of the supporting electrolyte. The amounts of iodide, bromide, and of chloridewere determined to be 1.27 mg, 0.80 mg and 0.54 mg, respectively, with a maximum relative standard deviation of less than 1.1%. The obtained results are in good agreement with the results of comparative potentiometric titrations using a silver indicator electrode. The titrationmethod was applied to the indirect determination of pyridoxine hydrochloride, i.e., vitamin B6.

A simple first-order derivative spectrophotometric method was developed for the simultaneous determination of acetamiprid and 6-chloronicotinic acid (6-CNA) at pH 7.0. By using the zero-crossing approach, acetamiprid was determined at 269.0 nm and 6-CNA at 216.0 nm with the detection limits of 7.19x10-7 and 8.25x10-7 mol dm-3, respectively and relative standard deviations not exceeding 1.2% in the case of model systems

It is known that certain bile acids have a promotive effect on the action of some drugs. Special attention is paid to bile acids having oxo groups instead of OH groups in the steroid skeleton of their molecule, since these derivatives have a lower hemolytic potential (membrane toxicity). This study examined the effects of sodium salts of 3α,12α-dihydroxy-7-oxo-5β-cholanoic acid (7-oC) and 3,7,12-trioxo-5β-cholanoic acid (3,7,12-toC) on the adsorption of verapamil hydrochloride on activated carbon (model of the cell membrane). The interaction was followed by measuring the effect of verapamil on the functional dependence between the spin-lattice relaxation time T 1 (protons of the C18 angular group of the bile acid molecule) and the bile acid concentration in deuterated chloroform (model of the cell membrane lipid phase). Whether a depot effect of verapamil exists when 7-oC and 3,7,12-toC (in the form of methyl esters) are present in chloroform was also investigated. It was found that 7-oC exhibited a significant effect in the experiments with verapamil, whereas 3,7,12-toC showed no difference of the measured parameters with respect to the control. This indicates that bile acid molecules should have OH groups bound to the steroid nucleus, in order to exhibit an effect on the monitored physico-chemical parameters of verapamil.