RESUMO
We developed a robust analytical method for quantification of malondialdehyde (MDA) in exhaled breath condensate (EBC) via derivatization with 2,4-dinitrophenylhydrazine (DNPH). The target MDA-DNPH hydrazone was separated by ultra-performance liquid chromatography using two reversed-phase analytical columns (C18 and phenyl-hexyl) inter-connected via a two-position, six-port switching valve to a single-quadrupole mass spectrometer. The target derivative was analyzed under positive electrospray ionization using single ion monitoring mode (m/zâ¯=â¯235 for the target derivative, and m/zâ¯=â¯237 for its labeled isotopic analog). This pseudo two-dimensional chromatographic separation provided optimum separation conditions for the target derivative resulting in the limit of detection of 0.58â¯nM in EBC sample (or 36.2â¯pmol on-column amount), which is comparable to those reported previously using different techniques, including tandem mass spectrometry. Based on the calibration solutions, the method had a linear quantification range of 1.0-200â¯nM (r2â¯=â¯0.998). The method showed good relative recoveries (92.2-102.0%) and acceptable precisions (3.6-12.2% for inter-day precision, and 4.3-12.4% for intra-day precision for two quality control levels, prepared from 5â¯nM and 25â¯nM solutions). The derivative was found to be stable at room temperature for 48â¯h or during analysis. The method was used to analyze 205 exhaled breath condensate samples collected from individuals from a healthy population of student athletes. MDA was detected in approximately 95% of these samples, with concentrations ranging from 1.16 to 149.63â¯nM. The median concentration was 6.82â¯nM, (IQR 4.08-9.88). These data demonstrate that our method can be successfully used to measure MDA in population studies.
Assuntos
Testes Respiratórios/métodos , Cromatografia Líquida de Alta Pressão/métodos , Malondialdeído/análise , Espectrometria de Massas/métodos , Adolescente , Adulto , Atletas , Feminino , Humanos , Limite de Detecção , Modelos Lineares , Masculino , Reprodutibilidade dos Testes , Adulto JovemRESUMO
In 2017, we surveyed 101 SHEA Research Network hospitals regarding Legionnaires' disease (LD). Of 29 respondents, 94% have or are developing a water management plan with varying characteristics and personnel engaged. Most LD diagnostic testing is limited to urine antigen testing. Many opportunities to improve LD prevention and diagnosis exist.