Ascorbic acid (AA) is a water-soluble vitamin which shows no fluorescence. However, in reaction with iron(III), AA is oxidised to dehydroascorbic acid and iron(III) is reduced to iron(II) which forms a complex with 2,4,6-tripyridyl-S-triazine (TPTZ) in buffered medium. The relative fluorescence intensity of the resulting Fe(TPTZ)22+ complex can be measured at excitation and emission wavelengths of 393 and 790 nm, respectively. Based on this data, a new indirect spectrofluorimetric method for the determination of AA in pharmaceutical samples was proposed. Influence of the reaction conditions, such as acidity of acetic buffer, concentration of TPTZ and iron(III), reaction time and instrumental parameters were investigated in detail. The linear range was from 5.4 × 10−4 to 5.4 × 10−6 mol·L−1 (R = 0.9971). The LOD was 7.7 × 10−7 mol·L−1 and LOQ was 2.3 × 10−4 mol·L−1. Fourteen pharmaceutical samples containing various amounts of AA were analysed. Influences of potential interfering substances were also examined. Analysis of commercial pharmaceutical formulations showed good correlation with the nominal values given by the manufacturers and with the results obtained by a titration method. The proposed method can be applied in routine quality control in the pharmaceutical industry due to its sensitivity, simplicity, selectivity and low cost.

Communication is a great value of the whole humankind. People who communicate well are able to convey their knowledge and ideas to other people. Good and quality communication is necessary for functioning in all spheres of the social life, and at the same time for the functioning of the pedagogical-educational process. The research has been conducted for determining which types, i.e. what sort of communication is dominant in the relation principal - students. The sample included 590 students of primary and secondary school and 14 principals from the region of Herzegovina (Bosnia and Herzegovina). Licker's scale was used for gathering data. Results of the research showed that communication between principal and students, there was democratic, direct and non-violent communication between principals and students. Communication between a principal and students is still the area, which is not given great significance. Most often, the accent is on communication between students and teachers, avoiding the analysis of communication between students and principals. Although in the pedagogical-educational work, communication between students and teachers is dominant; our opinion is that it is necessary to develop this communicational area as well. Quality communication at school should be a strategic point of principals, and it should be planned and applied consciously and continuously.