Search

A single method was developed for the determination of As and Hg in dietary supplements by chemical vapor generation coupled with microwave-induced plasma optical emission spectrometry (CVG-MIP OES) using a commercial multimode sample introduction system (MSIS). The MSIS setup, general CVG conditions, and pre-reduction methods for the conversion of As(V) to As(III) were evaluated. It was possible to reach a magnification factor of 7 and 2 times for As and Hg, respectively, using the optimized MSIS setup compared to the standard setup. The proposed method provided a limit of quantification (LOQ) in the range from 5 to 15 and 29 to 93 ng g−1 for As and Hg, respectively, which complies with the maximum concentration of 1.5 μg g−1 for these elements in dietary supplements set by United States Pharmacopeia (USP) General Chapter 2232. This method was applied for the simultaneous determination of As and Hg in four classes of dietary supplements (vitamins and minerals, minerals, amino acids, and botanicals), which were previously digested by microwave-assisted wet digestion. The concentrations of both elements were found to be below the maximum limit established by USP General Chapter 2232 in all the samples. The accuracy of the proposed method was evaluated using certified reference materials (CRMs) and no statistical difference was observed between the reference and obtained values (t-test, confidence level of 95%). Also, no difference was observed in the results obtained using the proposed method with those using comparative methods (CVG-ICP-MS for Hg after wet digestion and ICP-MS for As after microwave-induced combustion (MIC)). After optimizing the MSIS setup and CVG conditions, the proposed method can be considered an alternative for the quality control of As and Hg in dietary supplements, given that it is suitable for the determination of these elements according to the limit established by USP. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Food & Nutrition / Alimentos e Nutrição is the property of Faculdade de Ciencias Farmaceuticas, UNESP 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.)

A procedure for the determination of arsenic by batch hydride generation atomic absorption spectrometry (HG AAS) in commercial samples of injectable drugs, containing high concentrations of Sb(V), is described. The procedure is based on the complexing effect for Sb of citric, oxalic and acetic acids as reaction media. Aqua regia was used for sample digestion prior to As determination by HG AAS. The following experimental conditions for the determination of total As, as As(V), were evaluated: the acid medium and its concentration, sodium tetrahydroborate concentration, purge time, and influence of the different oxidation states of As. The effect of the delay time after mixing of sample and acid solution was also studied. Optimized conditions were: 10% (m/v) citric acid, 1.5% (m/v) sodium tetrahydroborate solution and 30 s for purge time. A delay time of 1 h was required after the digested sample had been mixed with citric acid, before As determination could be carried out. No interference on As(III) and As(V) signals was observed in the presence of up to 1 mg Sb(V). The tolerance limits for Ni(II), Cu(II) and Pb(II) were 1 mg, 100 μg and 100 μg, respectively. Recovery tests for As(III) and As(V) resulted in values between 97 and 101%. Characteristic mass and detection limit (3σ), using the recommended conditions, were 0.52 and 0.8 ng, respectively, for total As. [Copyright &y& Elsevier]

Microcapsules containing B. lactis were produced by complex coacervation in gelatin and gum Arabic followed by freeze drying and characterized by optical microscopy and scanning electron microscopy, as well as the resistance of probiotics to the in-vitro release in the simulated gastrointestinal tract and storage under different temperature conditions. Therefore, it formed microcapsules with high encapsulation efficiency (86.04% and 99.52%) and size between 100.12 and 203.32 μm. In addition, microencapsulated probiotics, both in wet and dry forms, maintained viability against the simulated gastrointestinal conditions. Finally, complex coacervation method was also efficient in maintaining the viability of probiotics during storage at temperatures of −18 °C for 120 days, 7 °C for 120 days and 25 °C for 90 days. Thus, our results demonstrated that complex coacervation method is an appropriate alternative to increase the viability of probiotics. [ABSTRACT FROM AUTHOR]

Microparticles containing inulin, hi-maize, and trehalose were produced through spray drying to encapsulate Lactobacillus acidophilus La-5. Afterwards, the encapsulation efficiency, thermal resistance, gastrointestinal simulation, storage stability, and the microparticles’ size and morphology were analyzed to evaluate the protective effect against the thermal conditions of the spray dryer of the different encapsulating matrices. Inulin and hi-maize encapsulating matrices showed the greatest encapsulation efficiency of 93.12% and 94.26%, respectively. Concerning thermal resistance, the trehalose encapsulating matrix provided the greatest protection for this microorganism. The microparticles produced with hi-maize showed the greatest viability in simulated gastrointestinal conditions thus providing higher protection for Lactobacillus acidophilus La-5. Regarding storage stability, microparticles containing trehalose showed the fewest viability losses during 120 days of storage. However, notably, at the end of 120 days of storage at room temperature (25 °C), microparticles containing inulin, hi-maize, and trehalose all kept their counts above the recommended level (>6 log CFU/g −1 ). Concerning the physical characteristics of the microparticles, particle sizes were as expected for products obtained by spray drying. Scanning electron microscopy showed no ruptures or cracks on the surfaces of the microparticles, a desirable characteristic for high protection. [ABSTRACT FROM AUTHOR]

Abstract: A procedure for chromium (Cr) determination in pharmaceutical grade barium sulfate by direct solid sampling electrothermal atomic absorption spectrometry (DSS-ET AAS) with Zeeman-effect background correction was developed. Operational conditions for the proposed procedure and the use of citric acid, ammonium phosphate, palladium and magnesium nitrate as chemical modifiers were evaluated. Pyrolysis and atomization temperatures were set at 1500 and 2400°C, respectively and the use of matrix modifiers did not improve these conditions. Graphite platform presented high degradation rate, but minima changes were observed in the sensitivity or signal profile. Samples (0.3–1mg) were weighted and introduced into the furnace using a manual solid sampling system. The linear concentration range of the calibration curve was from 100 to 1800pg (R 2 >0.995). The characteristic mass was 7.7pg and the limit of detection was 2.4pg. Chromium concentration in commercial samples ranged from 0.45 to 1.06μgg−1 and these results were confirmed by standard addition method. The mean reproducibility was 12% (n =20 in a 3-day period) and repeatability was less than 9%. Results obtained using inductively coupled plasma optical emission spectrometry and conventional electrothermal atomic absorption spectrometry after extraction with HNO3 were around 20% lower than those obtained by the proposed procedure. It was assumed that the low results were due to incomplete extraction even using hard conditions related to temperature and pressure. The proposed procedure by DSS-ET AAS provided some advantages related to recommended pharmacopoeias methodology, as lower risks of contamination and analyte losses, higher specificity, accuracy and sensitivity, no toxic or unstable reagents are required, and calibration with aqueous standards was feasible. [Copyright &y& Elsevier]