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Cannabinoids are typical chemical ingredients of a Cannabis sativa L. plant. The main psychoactive ingredient of this plant is Δ9-tetrahydrocannabinol, whose content mostly determines the strength or potential of a cannabis product. In addition to this ingredient, the forensic analysis also includes determination of the presence and content of cannabidiol and cannabinol. Over the last couple of decades, there have been changes in chemical composition of cannabis products in many countries, and they manifest through the increase of total psychoactive potential. Monitoring of basic cannabinoids content and their mutual ratios, processed in this paper, has shown that there is a growing number of samples with high tetrahydrocannabinol (THC) content, while the cannabidiol (CBD) content is very low or is not present in samples at all. The THC/CBD ratio also confirms changes in plant chemotype in terms of increasing total psychoactive potential of a cannabis plant.

The products of the Cannabis sativa L. plant are the most widely used type of illegal drugs. In addition to growing under natural conditions, illegal breeders tend to produce, under artificial conditions, a plant with a high psychoactive potential i.e. high content of the psychoactive ingredient tetrahydrocannabinol. This paper includes the analyses results of the content of tetrahydrocannabinol in cannabis plant samples seized in the Republic of Srpska from 1999 to 2008 and from 2011 to 2016, in order to monitor the psychoactive potential of the samples available on the illegal market and the assessment trends in the future. The analyses of tetrahydrocannabinol content conducted for 3.718 samples was performed by gas chromatography with flame ionization detector according to the method of external standard. The results showed that the illegal market has samples of cannabis plant material with a noticeable difference in psychoactive ingredient content, with an increase in the number of high-potent samples. Besides the high-potent samples, health risks are caused by a great variety and sudden changes in potential of illegal drug samples, as it is necessary to continue to monitor the psychoactive potential of cannabis plants samples on the illegal market.

In a semi-ideal gas, entropy changes cannot be determined through the medium specific heat capacity in a manner as determined by the change of internal energy and enthalpy, i.e. the amount of heat exchanged. Taking this into account, the authors conducted two models through which it is possible to determine the change in the specific entropy of a semi-ideal gas for arbitrary temperature interval using the spread sheet method, using the mean values of the appropriate functions. The idea is to replace integration, which occurs here in evitably, with mean values of the previous functions. The models are derived based on the functional dependence of the actual specific heat capacity on the temperature. The theorem used is that of the mean value of a function as well as the mathematical properties of the definite integral. The mean value of a fractional function is determined via its integrand while the logarithmic functions were performed by applying a suitable transformation of the differential calculus. The relations derived relation, using the computer program, have enabled the design of appropriate thermodynamic tables through which it is possible to determine the change in entropy of arbitrary state changes in an efficient and rational manner, without the use of calculus or finished forms. In this way, the change in the entropy of a semi-ideal gas is determined for an arbitrary temperature interval using the method which is analogous to that applied in determining the change of internal energy and enthalpy or the amount of heat exchanged, which was the goal of the work. Verification of the proposed method for both the above functions was performed for a a few characteristic semi-ideal gases where change c(T) is significant, for the three adopted temperature intervals, for the characteristic change of state. This was compared to the results of the classical integral and the proposed method through the prepared tables. In certain or special cases, it is possible to apply the presented method also in determining the change in entropy of the real gas. Apart from that, the paper shows that the change in entropy for the observed characteristic case can be represented or graphically determined using the planimetric method of diagrams with suitably selected coordinates.

Starting from the definition of the average specific heat capacity for chosen temperature range, the analytic dependence between the real and the mean specific heat capacities is obtained using differential and integral calculation. The obtained relation in differential form for the defined temperature range allows for the problem to be solved directly, without any special restrictions on its use. Using the obtained relation, a general model in the form of a polynomial of arbitrary degree in the function of temperature was derived, which has more suitable and faster practical application and is more general in character than the existing model. New graphical method for solving the problem is obtained based on differential geometry and using the derived equation. This may also have practical significance since many problems in thermodynamics are solved analytically and graphically. This result was used in order to obtain the amount of specific heat exchanged using an analytical model or a planimetric method. In addition, this graphical solution was used for the construction of the diagram showing the dependence between the specific heat exchanged and temperature. This diagram also gives a simple graphical procedure for the calculation of the real and the average specific heat capacity for arbitrary temperature or temperature interval. The confirmation for all graphic constructions is obtained using the differential properties between thermodynamic units. In order for the graphical solutions presented to be applicable in practice, suitable ratio coefficients have been determined for all cases. Verification of the model presented, as well as the possibilities of its application, were given using several characteristic examples of semi-ideal and real gas. Apart from linear and non-linear functions in the form of polynomials, the exponential function of the dependence between specific heat capacities and temperature was also analysed in this process.

The aim of this study was to determine the quality of the mineral water from Vitinički Kiseljak (Nos. 1 to 9, except No. 3) and Kozluk springs that are located near the town of Zvornik in the northwestern Republic of Srpska, BIH. The results were compared with those presented in previous reaserches in order to determine if the water quality has changed and if the water is still suitable for therapeutic purposes. The physicochemical (temperature, odor, pH value, total hardness, electro-conductivity, evaporated residue, suspended materials, chemical consumption of oxygen and KMnO4) and chemical (Fe2+, Mg2+, Mn2+,Zn2+, K+, Ca2+, Cu2+, Al3+, HCO3-, Cl-, CO32-, SiO2, SO42- and S2-) characteristics were analyzed. The obtained results showed that the waters could be classified as hydrocarbonate-sodium-chloride with the mineralization of 2450-5830 mg/dm3. It can also be concluded that the waters are rich in calcium, magnesium and iron, as well as that those are acidic waters due to the presence of free carbon dioxide. In the samples from Kozluk and Kiseljak No. 2 springs oxygen-sulphide is present as well. The ideal ratio of the minerals in these waters is suitable for therapeutical purposes.

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Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)