This paper shows the use of membrane filters in adsorption of solution of tetracycline hydrochloride on graphene materials. The adsorption process was monitored at different wavelengths, different pH values at certain time intervals. The absorbances of the solutions were measured by UV-Vis spectrophotometry at two wavelengths (275 nm and 356 nm), and three pH values (pH 4, pH 7 and pH 10) every 90 minutes for 6 hours of monitoring, with constant stirring in an ultrasonic bath. The results showed decrease in absorbance at both wavelength and in all three pH values which proved the adsorption of tetracycline hydrochloride on GO and rGO. The largest decrease in absorbance was 98.1%. The most suitable pH value for adsorption was pH 4. This paper used a unique approach to filtration through membrane filters, which in the future could lead to the development of membrane filters based on graphene materials.

Introduction: Considering that the research has shown that homosalate act as endocrine-active substance, it is very important to develop quick and sensitive method for tracking its concentrations in sunscreen products. The aim of this paper is to develop and validate the method for determining homosalate in sunscreen preparations and controlling the content of the products found on the market of Bosnia and Herzegovina. Methods: A high pressure liquid chromatography (HPLC) method for determination homosalate in sunscreen products has been developed and validated. Samples of six different manufacturers have been analyzed. HPLC method is method of choice for this type of investigation. Results: According to the calibration curve it has been found that the proposed analytical method in a given range of concentration is linear and that the correlation coefficient is R2=0.9998. Accuracy of the method is in range 94.26% -121.53%.The results have shown that the homosalate concentration in the tested samples did not exceed the maximally permissible concentration (10%). In the sample AV50 homosalate was not declared as an active ingredient, but it was identified and quantified at a concentration of 0.143%. Conclusion: Results of investigation of cosmetic products that are widely present on the market show the need of developing a sufficiently sensitive, easily accessible, analytical method for controlling the content of organic UV filters since the exceeding of the maximally permissible concentration can have a harmful effect on people who use these kinds of products. The results show that developed method meets conditions and is suitable for wide application.

In this study the efficacy of short tandem repetitive sequences - STR was examined to prove kinship among the descendants of one parent pairs within the small local population by analyzing sharing of alleles per locus at siblings and non-siblings of the two villages: Vukotići and Orahovica and comparing these results with the results of a heterogeneous Bosnian-Herzegovinian population of our previous research. There was a significant difference in this division in the group of siblings and a group of non-siblings as well and the phenomenon of polarization when it comes to the representation of sharing zero and two alleles in the samples for both villages, with significantly overrepresented sharing of zero alleles at non-siblings and significantly overrepresented sharing of two alleles at siblings. By comparing sharing of alleles between sample from the small local population and the sample from mixed population from our earlier research, there is no statistically significant difference in the distribution of 2, 1 and 0 alleles between samples of these two population. This obtained ratio of dividing 2, 1 and 0 alleles in these two samples is about that both samples belongs to the same Bosnian-Herzegovinian population. and in the village of Vukotići. One of the possible reasons is the fact that Vukotići is less than the Orahovica. Using STR system in determining the kinship, or lack of the kinship in a small local populations within the Bosnian-Herzegovinian population, is proved to be a successful method based on the results of this research.

The increasing use of sun-creams containing organic UV-filters has led to increased concentration of these compounds in aquatic environment. Chlorinated water can convert these chemicals into chlorinated products whose toxic effects are of primary concern. The new compound may be more toxic than the starting primary compound. Many studies have shown that UV filters absorb UV light and decompose under solar irradiation, due to their unstable properties. This may lead to formation of certain by-products with harmful effects. Their decomposition products can cause allergic and toxic reactions to the human skin. This study follows the stability of most commonly used UV filters, homosalate, in conditions that include those existent in swimming pools. Stability of the homosalate in chlorinated water was studied in simulated swimming pool water samples. UV spectroscopy was used to follow the reaction of homosalate in presence of free chlorine. Water samples were filtered, acidified, and extracted by use of solid-phase extraction. Gas chromatography with mass spectrometry was used to identify the major transformation by-products. Under the experimental conditions, homosalate reacted with chlorine following zero order reaction. The chemical transformation of the homosalate in chlorinated water led to formation of chlorinated by-products that was identified as:

Lorazepam is an almost water insoluble substance. This study investigated the solubilization of lorazepam depending on media pH, cosolvents (ethanol, propylene glycol, polyethylene glycol 200 and 400), surfactants (Tween 80, Tween 20, Brij 35, sodium-cholate, sodium-deoxycholate, sodium-taurocholate) and cyclodextrins (α-cyclodextrin, -cyclodextrin and 2-hydroxypropyl-β-cyclodextrin). The main objective was to find the most suitable method for providing good solubility of this drug and thus its formulation in a liquid dosage form. Based on the results, the changes in the pH value of the media do not lead to a greater solubility of lorazepam. Of the cosolvents used, the greatest increase in solubility of lorazepam in water was achieved with ethanol. Of the bile salts used, sodium taurocholate showed the best solubilization ability, while Brij 35 was the best of the non-ionic surfactants. The solubility of lorazepam with the cyclodextrin derivative, 2-hydroxypropyl-β-cyclodextrin was better than natural cyclodextrin. Surfactants have the highest ability of solubilization of lorazepam in water.

Parabens are esters of p-hydroxybenzoic acid and belong to group of effective preservatives commonly used in cosmetic products, drugs and food. Their antimicrobial activity increases with increasing carbon number of the ester group. A number of cosmetic products and skincare products are preserved with parabens, as well in Europe as in the United States. Methyl, ethyl and propyl paraben are preservatives commonly used in cosmetic products. Usage of parabens should be under great attention, because some studies mentioned that the increased concentration can cause skin irritation and contact dermatitis.. This paper shows optimization of HPLC method for determination of methyl, ethyl and propyl paraben in sunscreen products. The advantage of this analytic method is that the same stationary phase with different mobile phases is used for determination UV filters and parabens as well in sunscreen products. Determination was performed using reversed stationary phase C8 with wavelength 254 nm. Separation was performed using mobile phase methanol: water (60:40 w/w). Analytic method was validated through specificity, linearity, limit of detection (LOD) and limit of quantification (LOQ). Determined limit of detection and limit of quantification for methyl, ethyl and propyl paraben are respectively: LOD-0.035 μg/ml LOQ-0.116 μg/ml; LOD-0.061 μg/ml LOQ-0.203 μg/ml and LOD0.009 μg/ml LOQ-0.031 μg/ml. Coefficient of quantification for methyl, ethyl and propyl paraben are respectively: R-0.9996; R-0.9988 and R-1. A content of parabens was examined on commercial samples available on market in Bosnia and Herzegovina. Concentration of ethyl, methyl and propyl paraben does not exceed maximal allowed concentrations (0.4% for single ester and 0.8% for mixture of esters) in tested samples.

Purpose – The purpose of this paper is to test absorption characteristics of some newly synthesised 4‐hidroxycoumarins, containing phenyl‐prop‐2‐enoyl group at the 3‐position. Change in spectral characteristics in solvents of different polarity (chloroform and acetonitrile) was followed in regard to the influence of the substitution at the phenyl ring and influence of concentration H+ ions. Effectiveness of tested substances was compared with well‐known UV absorbers such as benzophenone‐3 and butyl methoxydibenzoylmethane (BMDM).Design/methodology/approach – All the tested substances were dissolved in chloroform and acetonitrile, with 10‐3 mmol concentration range. The pH was adjusted using 0.1 mol/l HCl, glacial acetic acid, 0.1 mol/l NaOH (aqueous solution) and 0.1 mol/l NaOH (methanolic solution). Spectrophotometric measurement was recorded in the range of 200‐800 nm, using 1‐cm quartz cells.Findings – The tested 4‐hydroxycoumarin derivatives showed good UV absorption properties in the range 280‐380 nm...

The protection of sun radiation is a problem on global level for all living organisms on Earth. The need of people for the overexposure to the UV radiation led human population towards finding novel ways of protection of this kind of radiation, in form of cosmetic preparations applied on the skin. So far, the high values of protection factors of preparations and total block preparations with sun protection factor of 50+ were achieved. Physical and chemical filters which absorb radiation are constituents of these preparations. European Union has set regulations as which substances and in what amounts could be used as UV absorbers. American FDA (Food and Drug Administration) also gave its list of the most frequently used UV absorbers in the sunscreen products, as well as their declared concentrations. The most frequently used concentrations of UV filters in cosmetics is between 0.1% and 10%. Concentrations of UV filters in sunscreen products have to be monitored in order to ensure that they are not less from the declared levels, on which depends the efficacy and safety of the product.

Derivatives of chlorophenoxy carboxylic acids have been the first class of herbicides in continuous use since 1947. The main interest for these substances is due to their evident chronic toxicity and carcinogenic effect. On the other hand, they can cause acute toxicity and have significant role in suicidal attempts. In this paper we have investigated analytical approaches that could be used for rapid identification and determination of chlorophenoxy herbicides in modestly equipped laboratories for the clinical toxicology. Thin layer chromatography on cellulose layer using neutral red as ion pairing reagent gave the best results in separation of different herbicides, making possible visualisation at the daylight without further reagents or equipment. High performance liquid chromatography (HPLC) methods for separation on C8 and C18 phases with and without ion-pairing reagent were compared. It was found that HPLC on C18 phase utilising ion-suppression mode has the best reproducibility, linearity and mass limit of detection suitable for quantification of chlorophenoxy herbicides after acute poisoning.