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1.
Anal Bioanal Chem ; 415(5): 809-821, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36507958

RESUMO

The US National Institute of Standards and Technology (NIST) developed a Standard Reference Material® (SRM®) 3949 Folate Vitamers in Frozen Human Serum to replace SRM 1955 Homocysteine and Folate in Human Serum. The presence of increased endogenous levels of folic acid and 5-methyltetrahydrofolate (5mTHF) in SRM 3949, enhanced folate stability via addition of ascorbic acid, and inclusion of values for additional minor folates are improvements over SRM 1955 that should better serve the clinical folate measurement community. The new SRM contains folates at three levels. To produce SRM 3949, pilot sera were collected from 15 individual donors, 5 of whom were given a 400-µg folic acid supplement 1 h prior to blood draw to increase serum levels of 5mTHF and folic acid for the high-level material. To stabilize the folates, 0.5% (mass concentration) ascorbic acid was added as soon as possible after preparation of serum. These pilot sera were screened for five folates plus the pyrazino-s-triazine derivative of 4-α-hydroxy-5-methyltetrahydrofolate (MeFox) at the US Centers for Disease Control and Prevention (CDC) by isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). Based on these results, a blending protocol was specified to obtain the three desired folate concentrations for SRM 3949. ID-LC-MS/MS analysis at the CDC and NIST was utilized to assign values for folic acid and 5mTHF, as well as several minor folates.


Assuntos
Ácido Fólico , Espectrometria de Massas em Tandem , Humanos , Ácido Fólico/análise , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Padrões de Referência , Ácido Ascórbico
2.
Anal Chem ; 89(19): 10461-10467, 2017 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-28930436

RESUMO

A new tobacco filler Standard Reference Material (SRM) has been issued by the National Institute of Standards and Technology (NIST) in September 2016 with certified and reference mass fraction values for nicotine, N-nitrosonornicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and volatiles. The constituents have been determined by multiple analytical methods with measurements at NIST and at the Centers for Disease Control and Prevention, and with confirmatory measurements by commercial laboratories. This effort highlights the development of the first SRM for reduced nicotine and reduced tobacco-specific nitrosamines with certified values for composition.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas em Tandem/métodos , Produtos do Tabaco/análise , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida de Alta Pressão/normas , Congelamento , Cromatografia Gasosa-Espectrometria de Massas/normas , Nicotina/análise , Nicotina/normas , Nitrosaminas/análise , Nitrosaminas/normas , Transição de Fase , Padrões de Referência , Espectrometria de Massas em Tandem/normas , Produtos do Tabaco/normas , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/normas
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