Keywords
magnesium
erythrocytes
plasma
urine
validation
How to Cite
Abstract
This study aimed at validating the methodology for analyzing magnesium contents in urine, plasma, and erythrocytes samples by atomic absorption spectrophotometry. Pools of human urine, plasma, and erythrocytes samples were analyzed. The standard curve linearity, linear response range, detection limit (DL), quantitation limit (QL), precision, and accuracy of measurement were determined. DL and QL values were, respectively, 0.006 and 0.021 μg/mL of Mg for urine and plasma, and 0.003 and 0.010 μg/mL of Mg for erythrocytes. The linear response ranged from 0.05 to 0.5 μg/mL of Mg, and the standards curves showed the correlation coefficients higher than 0.99, which demonstrated the linearity of the methodology. Intra- and inter-assay precisions above 90% were considered adequate. The accuracy obtained with certified reference materials for urine and plasma was 101% and 97%, respectively. The average recoveries found by adding the standard were 87% for urine and erythrocytes, and 91% for plasma. Therefore, the evaluated methodology showed to be linear, sensitive, specific, precise and accurate, and the obtained results were reliable.References
1. Nielsen FH. Magnesium, inflammation, and obesity in chronic disease. Nutr Rev. 2010;68(6):333-40.
2. Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated? Nutr Rev. 2012;70(3):153-64.
3. Sales CH, Pedrosa LFC, Lima JG, Lemos TMAM, Colli C. Influence of magnesium status and magnesium intake on the blood glucose control in patients with type 2 diabetes. Clin Nutr. 2011;30:359-64.
4. Izquierdo AS, Boudet GA, Otero MS, Fernández GMD, González RJ, García de Janlón CA, et al. Estimation of precision and inaccuracy for serum magnesium determination on the basis of interlaboratory comparison data Accreditation ISO 15189. Magnes Res. 2008;21(1):51-7.
5. Noronha JL, Matuschak GM. Magnesium in critical illness: metabolism, assessment, and treatment. Intens Care Med. 2002;28:667-79.
6. Whitehouse RC, Prasad AS, Rabbanu PI, Cossack ZT. Zinc in plasma, neutrophils, lymphocytes, and erythrocytes as determined by flameless atomic spectrophotometry. Clin Chem. 1982;28(3):475-80.
7. Keith LH, Crummett W, Deegan JJ, Libby RA, Taylor JK, Wentler G. Principles of environmental analysis. Anal Chem. 1983;55(14):2210-8.
8. Brasil. Ministério da Saúde. Secretaria de Vigilância Sanitária. Resolução nº 899, de 29 de maio de 2003. Determina a publicação do guia de validação de métodos analíticos e bioanalíticos. Diário Oficial da República Federativa do Brasil, Brasília (DF); 2 jun 2003. [acesso em: 2007 jan 19]. Disponível em: [http://www.anvisa.gov.br/legis/resol/2003/re/899_03re.htm].
9. Sardinha FAA. Avaliação do estado nutricional em magnésio, ferro, zinco e cobre de atletas de polo aquático feminino em períodos de treinamento pré-competitivo, de destreinamento e de treinamento de manutenção [tese de doutorado]. São Paulo (SP): Universidade de São Paulo; 2002.
10. Mendes Netto RS. Estado nutricional em magnésio como determinante da eficiência da suplementação de creatina em praticantes de musculação [tese de doutorado]. São Paulo (SP): Universidade de São Paulo; 2004.
11. Nicoll GW, Struthers AD, Fraser CG. Biological variation of urinary magnesium. Clin Chem. 1991;37(10):1794-5.
12. Perkin-Elmer. Atomic absorption spectroscopy. Analytical methods. Norwalk: The Perkin-Elmer Corporation; 1996.
13. Austin JH, Drabkin DL. Spectrophotometric studies. III. Methemoglobin. J Biol Chem. 1935;112:67-88.
14. International conference on harmonization (ICH) of technical requirements for the registration of pharmaceuticals for human use. Validation of analytical procedures: text and methodology. Q2(R1). 2005. Disponível em: [http://www.ich.org/LOB/media/MEDIA417.pdf ].
15. Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (Brasil). DOQ-CGCRE-008. Orientação sobre validação de métodos analíticos. Revisão 03; fev 2010 [acesso em: 2012 maio 21]. Disponível em: [http://www.inmetro.gov.br/Sidoq/Arquivos/CGCRE/DOQ/DOQ-CGCRE-8_03.pdf].
16. Ribani M, Bottoli CBG, Collins CH, Jardim ICSF, Melo LFC. Validação em métodos cromatográficos e eletroforéticos. Quim Nova. 2004;27:771-80.
17. Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (Brasil). Vocabulário Internacional de Metrologia. Conceitos fundamentais e gerais e termos associados (VIM 2008). INMETRO: Rio de Janeiro; 2009. 78p.
18. Hulanicki A, Godlewska B, Brzóska M. Determination of total magnesium in biological samples using electrothermal atomic absorption spectrometry. Spectrochim Acta Part B. 1995;50:1717-24.
19. Stone MJ, Chowdrey PE, Miall P, Price CP. Validation of an enzymatic total magnesium determination based on activation of modified isocitrate dehydrogenase. Clin Chem. 1996;42(9):1474-7.
20. Gilroy CV, Burton SA, Horney BS, Mackenzie AL. Validation of the Nova CRT8 for the measurement of ionized magnesium in feline serum. Vet Clin Pathol. 2005;34:124-31.
21. Dos Santos HG, Sardinha FAA, Colli C. Zinco eritrocitário (validação de um método de análise) e zinco dietético na avaliação do estado nutricional de mulheres adultas. Braz J Pharm Sci. 2005;41(2):205-13.
22. Gimblet EG, Marney AF, Bonsnes RW. Determination of calcium and magnesium in serum, urine, diet, and stool by atomic absorption spectrophotometry. Clin Chem. 1967;13(3):204-14.
23. Willis JB. Determination of calcium and magnesium in urine by atomic absorptions spectroscopy. Anal Chem. 1961;33(4):556-9.
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