Analysis of Sports Supplements for Proteins by Polyacrylamide Gel Electrophoresis (PAGE) and Macronutrients by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES)

Abstract

This study reports the microwave-assisted preparation of sports supplements using dilute nitric acid followed by the determination of Ca, K, Mg, Na, P and S using inductively coupled plasma–optical emission spectrometry (ICP-OES). Microwave-assisted digestion was optimized using modified Doehlert experimental design based on the overall desirability of residual acidity, dissolved organic carbon and recoveries obtained for a diet-certified reference material using the nitric acid concentration and volume of hydrogen peroxide. The digestion was performed using 2 M HNO₃ and 1 mL 30% H₂O₂. The accuracy and precision were evaluated by recovery tests, and satisfactory recoveries ranging from 91% to 110% were obtained by ICP-OES. Nine sports supplements were analyzed with concentrations from 3351 to 7069 mg kg⁻¹ for Ca, 3870 to 13,639 mg kg⁻¹ for K, 626 to 2678 mg kg⁻¹ for Mg, 1293 to 5170 mg kg⁻¹ for Na, 2888 to 7845 mg kg⁻¹ for P and 3217 to 10,965 mg kg⁻¹ for S. Qualitative analysis by gel electrophoresis characterized the similarities and differences between the supplement protein profiles. In addition, a comparison of the correlations between the analytes and the supplement formulations was performed by a correlation graph and principal component analysis (PCA).

Keywords:

• Design of experiments
• inductively coupled plasma – optical emission spectrometry (ICP-OES)
• macronutrients
• polyacrylamide gel electrophoresis (PAGE)
• sport supplements

Acknowledgment

Instrumental support provided by Analítica and Thermo Scientific is gratefully acknowledged.

Additional information

Funding

The authors are grateful to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq - grants 141311/2017-7, 141634/2017-0, 302719/2020-2 and 142162/2018-3). The authors also would like to express their gratitude to the Instituto Nacional de Ciências e Tecnologias Analíticas Avançadas – CNPq, Grant No. 573894/2008-6 and FAPESP, Grants No. 2014/50951-4 and 2019/24223-5. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.