Search

In this work, the use of complexing acids (HF and HCl) combined with HNO3 was carefully evaluated for the digestion of several types of lipsticks and further Cd and Pb determination by inductively coupled plasma mass spectrometry (ICP-MS). Creamy, opaque and shimmering lipsticks were digested using HNO3 (6 mL) or a mixture containing HNO3 (6 mL) plus HCl (0.5 or 2 mL) or HNO3 (6 mL) plus HF (2 mL). The results indicate that complexing acids are not required for the subsequent determination of Cd in all types of lipsticks evaluated. On the other hand, complexing acids were essential for ensuring quantitative results for Pb in shimmering lipstick. Thus, by using HNO3 combined with only 0.5 mL of HCl, it was possible to obtain quantitative results for Pb and Cd in lipsticks. Under these conditions, recoveries for Cd and Pb were between 95 and 103%. No statistical difference was observed between the results obtained using the proposed method (HNO3/HCl) and those obtained using HNO3/HF, where a complete dissolution of the lipsticks' inorganic fraction occurred. Moreover, by using HCl, HF was avoided and solutions more compatible with ICP-MS analysis were obtained. The limits of detection for Cd and Pb were 3 and 77 ng g−1, respectively. This method was applied for a variety of lipsticks, and the concentration of Cd and Pb ranged from ＜3 to 31 ng g−1 and 271 to 2250 ng g−1, respectively. [ABSTRACT FROM AUTHOR]

Abstract Microwave-assisted digestion using diluted acid under oxygen pressure is proposed for sample preparation of sports supplements and subsequent determination of Ca, Cu, Fe, K, Mg, Mn, Na, Zn, P and S by inductively coupled plasma-optical emission spectrometry (ICP-OES). In this sense, 1350 mg of sport supplement were digested in a microwave oven using only 6 mL of 5 mol L−1 HNO 3 under 5 bar of oxygen pressure during 15 min. Accuracy of proposed method was evaluated by recovery tests using a standard solution and using a certified reference material. Suitable recoveries (ranging from 86% to 108%) were obtained in both evaluations for all analytes. Results were compared with those obtained by conventional microwave-assisted digestion (without oxygen pressure) for further analytes determination by ICP-OES, and no statistical differences were observed (Student's t -test, confidence level of 95%, p > 0.05). The precision of proposed method was evaluated in terms of repeatability (RSDs ≤3%) and intermediate precision (RSDs ≤7%), and suitable results were obtained for all analytes. In addition, the limits of detection for all analytes using proposed method were lower than those obtained using conventional digestion in view of use a high sample mass and a diluted acid solution for sample digestion. The use of diluted acid reduces risks to analyst – since it eliminates the concentrated acid handling; reduces the consumption of reagents and, consequently, the waste generation, in accordance with the principles of green chemistry. Using the proposed method was possible to perform the determination of ten elements in a single analysis with suitable precision and accuracy. Six sport supplements were analyzed and the results are alarming because in most cases they were in disagreement with those informed on the label. Thus, a suitable quality control of sports supplements should be performed and the proposed method is a green, safe, accurate, precise and sensitive alternative for this purpose. Graphical abstract Unlabelled Image Highlights • The proposed method is a green, safe, accurate, precise and sensitive alternative to quality control of sports supplements. • The use of diluted acid nitric provided digests compatible with multitechnique determination, including IC and ICP-OES. • Proposed method was suitable for determination of ten elements in a single analysis with suitable precision and accuracy. • It was possible to determine metals and non-metals in sport supplements at low concentration. • Six sport supplements were analyzed and the results were in disagreement with those informed on the label. [ABSTRACT FROM AUTHOR]