The concentration of phthalates in toys and children's care items in Kosovo.

In this study, one hundred and twenty-eight toys and children's care items available in the Kosovo market were analyzed to determine the presence of phthalates and evaluate if the analyzed samples meet the national and EU standards. Toys and children's care items were imported from twelve countries, most of them from China. Phthalates were extracted and then analyzed using gas chromatography and mass spectrometry. Nine phthalates were analyzed in total, of them, benzyl butyl phthalate, di-isodecyl phthalate, diisobutyl phthalate and di-isononyl phthalate were the most frequently detected phthalates in the analyzed samples. Phthalates were not detected only in three toys and children's care items, others contained one or more phthalates, while none of them contained all (nine) analyzed phthalates. In total, 22 analyzed toys and children's care items did not fulfill at least one of the EU standards, of these 16 were toys and children's care items intended for children under age three and designed to be placed in the mouth. Overall, our work shows that toys and children's care items that exceed EU standards for phthalates are still present in the Kosovo market.

Flow Injection Amperometric Evaluation of Trolox Equivalent Antioxidant Capacity of Chocolates with Different Cocoa Content at a Boron-Doped Diamond Electrode.

RESEARCH BACKGROUND: The objective of this paper is to introduce an instrumentally simple analytical tool for determination of cocoa solid content in chocolates. This electroanalytical method is based on amperometric oxidation of all present antioxidants in chocolates at boron-doped diamond electrode (BDDE) that is integrated in a flow injection analysis (FIA) wall-jet electrode system. EXPERIMENTAL APPROACH: As part of optimisation, thirteen commonly occurring antioxidants were investigated using cyclic voltammetry at the BDDE in 0.1 mol/L phosphate buffer with different methanol (MeOH) content. Working parameters, such as MeOH volume fraction, flow rate and detection potential, were optimised. Principally, the height of the oxidation peak (current response) representing the oxidation of the sum of antioxidants (total antioxidant content; TAC) was expressed as Trolox equivalents. RESULTS AND CONCLUSIONS: For analytical purpose, a linear range from 5 to 100 mg/L described by regression equation and characterised by high correlation coefficient R2=0.9994 was achieved. Obtained high positive correlation between the determined values of Trolox equivalent antioxidant capacity (TEAC) and cocoa mass fractions characterised by correlation coefficient of 0.9187 for eight randomly selected samples (one white, two milk, and five dark chocolates) confirmed that cocoa solids represent the main source of antioxidants (reducing agents). NOVELTY AND SCIENTIFIC CONTRIBUTION: The research demonstrates that TEAC values could be considered as an additional marker of cocoa content in the chocolate analysis to the commonly used theobromine (authenticity of food products). The developed FIA could therefore serve as simple analytical tool in the food quality control.

A new voltammetric approach for the determination of ß-carotene in vegetables and pharmaceutical capsules using a gold electrode.

Significant improvements in the voltammetric determination of ß-carotene (BCA) have been achieved, mainly by the replacement of toxic dichloromethane with acetone and using non-mercury electrode. The respective procedure is based on anodic oxidation of BCA at a gold electrode in the disc configuration, when using square-wave voltammetry in pure acetone (99.8%) with 0.1 mol L-1 LiClO4 as the supporting electrolyte. The method comprises extraction of the analyte from the sample with acetone, thus avoiding the usually used highly toxic solvents. Analytically, it can be characterized by a linear range from 6.0 × 10-6 to 5.9 × 10-4 mol L-1 with regression equation Ipa = 0.0184c -0.1631 and correlation coefficient, R2 = 0.9998, limits of detection and quantification LOD = 1.6 × 10-6 mol L-1 and LOQ = 5.4 × 10-6 mol L-1, respectively; both being obtained at a potential step of 5 mV, with the pulse amplitude of 25 mV, and a frequency of 80 Hz. After optimization, the method was evaluated in series of analyses; namely, with two samples of vegetables and two pharmaceutical preparations (capsules), when the results could be compared to those of a reference spectrophotometric method. Due to a simple instrumentation, including sample preparation, the voltammetric method for the determination of BCA can be recommended as a quick screening assay in food and pharmaceutical analysis.

Flow injection tyrosinase biosensor for direct determination of acetaminophen in human urine.

An amperometric biosensor compatible with a flow injection analysis (FIA) for highly selective determination of acetaminophen (APAP) in a sample of human urine was developed. This biosensor is also suitable for use in the routine pharmaceutical practice. To prove this statement, two different commercially available pharmaceutical formulations were analyzed. This nano-(bio)electroanalytical device was made from a commercially available screen-printed carbon electrode covered by a thin layer of non-functionalized graphene (NFG) as amperometric transducer. A biorecognition layer was prepared from mushroom (Agaricus bisporus) tyrosinase (EC 1.14.18.1) cross-linked using glutaraldehyde, where resulting aggregates were covered by Nafion®, a known ion exchange membrane. Owing to the use of tyrosinase and presence of NFG, the developed analytical instrument is able to measure even at potentials of 0 V. Linear ranges differ according to choice of detection potential, namely up to 130 µmol L-1 at 0 V, up to 90 µmol L-1 at -0.1 V, and up to 70 µmol L-1 at -0.15 V. The first mentioned linear range is described by the equation Ip [µA] = 0.236 - 0.1984c [µmol L-1] and correlation coefficient r = 0.9987; this equation was used to quantify the content of APAP in each sample. The limit of detection of APAP was estimated to be 1.1 µmol L-1. A recovery of 96.8% (c = 25 µmol L-1, n = 5 measurements) was calculated. The obtained results show that FIA is a very selective method for APAP determination, being comparable to the chosen reference method of reversed-phase high-performance liquid chromatography.

Aflatoxin M1 contamination of raw cow's milk in five regions of Kosovo during 2016.

During February and August 2016 (winter and summer season), 192 samples of raw bulk tank milk have been collected from small dairy farms in five different regions of Kosova (Prishtina, Prizren, Peja, Mitrovica, and Gjilan). These samples were analyzed for aflatoxin M1 (AFM1) contamination level by ultra-high performance liquid chromatography coupled with electrospray ionization triple quadrupole tandem mass spectrometry (UHPLC-ESI-MS/MS). The limit of quantification for AFM1 was 0.02 µg/L and recovery at 0.1-0.5 µg/L was 90-95% (coefficient of variation 15-25%). A total of 74 milk samples (38%) were found to be contaminated with AFM1 and 11 samples (5.7%) slightly exceeded the European Union maximum level of 0.05 µg/L. The maximum AFM1 level was at 0.082 µg/L. There was no relevant difference between summer and winter with regard to AFM1 frequency and levels. Although the frequency of AFM1-positive samples varied between regions, from 7% (Prishtina) to 53% (Prizren), only minor regional differences were observed with regard to average and maximum toxin levels. The high percentage of milk samples which were non-compliant with AFM1 maximum levels indicates that efforts to reduce the contamination levels of aflatoxin B1 in cows feed in Kosovo are necessary.

A surface enhanced Raman scattering probe for highly selective and ultra sensitive detection of iodide in water and salt samples.

Iodine is a biophilic and essential trace element for all life and especially for vertebrates, which require it to produce indispensable thyroid hormones in their thyroid glands. As a result, the adequate measurement of iodine in water and food samples is crucial to lead a healthy life. Motivated by its importance, this is the first time in the literature that the highly selective and ultra sensitive (30 ppt limit) surface enhanced Raman scattering (SERS)-based detection of iodide ions (I(-)) from environmental and food samples has been reported. The desired sensitivity and selectivity has been achieved by measuring the change in the SERS intensity originating from Rh6G-adsorbed 30 nm gold nanoparticles (GNPs) upon the addition of I(-). The strong chemical affinity offered by I(-) towards the gold surface results in extra negative charge being deposited on it. As a result, the GNP surface attracts a greater number of positively charged Rh6G molecules and induces a marked increase in the number of hot spots through aggregation, providing a significant enhancement of the Raman signal intensity. The oxidation of I(-) to molecular iodine (I(2)) by hydrogen peroxide (H(2)O(2)) is employed for the successful screening of the bromide ion (Br(-)) which shows substantial interference at higher concentrations.

Multifunctional oval-shaped gold-nanoparticle-based selective detection of breast cancer cells using simple colorimetric and highly sensitive two-photon scattering assay.

Breast cancer is the most common cancer among women, and it is the second leading cause of cancer deaths in women today. The key to the effective and ultimately successful treatment of diseases such as cancer is early and accurate diagnosis. Driven by the need, in this article, we report for the first time a simple colorimetric and highly sensitive two-photon scattering assay for highly selective and sensitive detection of breast cancer SK-BR-3 cell lines at a 100 cells/mL level using a multifunctional (monoclonal anti-HER2/c-erb-2 antibody and S6 RNA aptamer-conjugated) oval-shaped gold-nanoparticle-based nanoconjugate. When multifunctional oval-shaped gold nanoparticles are mixed with the breast cancer SK-BR-3 cell line, a distinct color change occurs and two-photon scattering intensity increases by about 13 times. Experimental data with the HaCaT noncancerous cell line, as well as with MDA-MB-231 breast cancer cell line, clearly demonstrated that our assay was highly sensitive to SK-BR-3 and it was able to distinguish from other breast cancer cell lines that express low levels of HER2. The mechanism of selectivity and the assay's response change have been discussed. Our experimental results reported here open up a new possibility of rapid, easy, and reliable diagnosis of cancer cell lines by monitoring the colorimetric change and measuring TPS intensity from multifunctional gold nanosystems.

Ultrasensitive and highly selective detection of Alzheimer's disease biomarker using two-photon Rayleigh scattering properties of gold nanoparticle.

Alzheimer's disease (AD) is a progressive mental disorder disease, which affects 26.6 million people worldwide and estimated increments can be 100 millions by 2050. Since there is no cure at present, early diagnosis of AD is crucial for the current drug treatments. Driven by the need, here we demonstrate for the first time that monoclonal anti-tau antibody-coated gold nanoparticle based two-photon scattering assay can be used for the detection of Alzheimer's tau protein in the 1 pg/mL level which is about 2 orders of magnitude lower than cutoff values (195 pg/mL) for tau protein in CSF (cerebrospinal fluid). We have shown that when anti-tau antibody-coated gold nanoparticles were mixed with 20 ng/mL of tau protein, two-photon Rayleigh scattering intensity (TPRS) increases by about 16 times. The mechanism of TPRS intensity change has been discussed. Our data demonstrated that our TPRS assay is highly sensitive to tau protein and it can distinguish from BSA, which is one of the most abundant protein components in CSF. Our results demonstrate the potential for a broad application of this type of nanobionanotechnology in practical biomedical applications.