Fluorometry of nanogram amounts of selenium in biological samples.

Abstract

For fluorometry of selenium in human blood, hair, and liver and in leaves, we wet-ashed the samples with conventional nitric and perchloric acids, and then extracted piazselenol (complex of Se and 2,3-diaminonaphthalene) in cyclohexane. Selenium was back-extracted from the cyclohexane into nitric acid to remove the fluorometric interferences of trace amounts of organic compounds. This fluorometric method is rapid and suitable for routine analysis. We applied the method to human hair samples and compared it with the data for non-destructive neutron activation analysis of the hair.

Fermentación in vitro y la correlación del contenido nutrimental de leucaena asociada con pasto estrella

“…Determinación del contenido mineral y nutrimentos: se tomaron submuestras molidas de 2 g de cada especie forrajera y cada DR por separado y se secaron totalmente a 105 °C por 12 h. Posteriormente, las muestras se incineraron en una mufla a 500 ºC durante 8 horas para cuantificar la proporción de cenizas y materia orgánica (MO) (AOAC, 1990). La cuantificación de Ca, Mg, Na, K, Cu, Zn, Fe y Mn se realizó mediante espectrofotometría de absorción atómica (Fick et al, 1979); el P se determinó utilizando el método colorimétrico (Clesceri et al, 1992); y mediante el método fluorométrico (Tamari et al, 1986). Extracto etéreo (EE) se determinó por el método de Goldsfich (AOAC, 2000), nitrógeno total por Kjeldahl (Harris, 1970), con el cual se obtuvo el porcentaje de proteína cruda (PC) multiplicando por 6.25, fibra detergente neutro (FDN), fibra detergente ácido (FDA) y lignina en H 2 SO 4 .…”

“…Determination of mineral content and nutrients: ground subsamples of 2 g of each forage species and each DR were made separately and completely dried at 105 °C for 12 h. The samples were incinerated in a muffle furnace at 500 °C for 8 h, to quantify the proportion of ash and organic matter (MO) (AOAC, 1990). Quantification of Ca, Mg, Na, K, Cu, Zn, Fe and Mn was performed by atomic absorption spectrophotometry (Fick et al, 1979); P was determined using the colorimetric method (Clesceri et al, 1992); and by fluorometric method (Tamari et al, 1986). Ether extract (EE) was determined by the method Goldsfich (AOAC, 2000), total nitrogen by Kjeldahl (Harris, 1970), with which the percentage of crude protein (CP) was obtained by multiplying by 6.25, neutral detergent fiber (NDF), acid detergent fiber (FDA) and lignin in H 2 SO 4 .…”

Application of Three Spectrometric Methods to Total Selenium Determination in Postmortem Material in a Case of Acute Selenium Compound Poisoning

“…Selenium(VI) in the digestion solution, 1-10 mL (method A) was reduced with 10 mL of 6 M hydrochloric acid at 100°C (1 h) to selenium(IV) and then quantified by the SF method using procedures modified by Tamari et al (13) and Petterson et al (14) procedures. Complexes of selenium with 5 mL DAN (piazselenols) were extracted into cyclohexane (2 · 10 mL) at pH 1.8 in the presence of 2 mL EDTA-NaF solution, shaken for 2 min, and after 5 min separated.…”

“…Care should also be taken to avoid sources of systematic error including loss of volatile selenium compounds in all the steps from sampling to the final measurement (2,12). Determination of selenium in body fluids and tissues is usually carried out by molecular fluorescence spectrometry, that is, spectrofluorimetry (SF; [13–15]), atomic absorption spectrometry using either hydride generation or direct electrothermal atomization (HG‐AAS or ET‐AAS [8,15–18]), atomic fluorescence spectrometry with hydride generation technique (HG‐AFS; [19–24]), gas chromatography‐mass spectrometry (GC‐MS [10]), neutron activation analysis (NAA; [25]), and other methods (18). The modern method of inductively coupled plasma‐mass spectrometry (ICP‐MS; [26–28]) has some advantages over rival techniques, including low detection limits and speed of analysis; however, not all determinations are straightforward, in particular, the determination of selenium in serum—the sensitivity with conventional ICP‐MS is generally poor because only 30% ionization is achieved with an argon plasma and that there are relatively high spectroscopic interferences caused by the formation of argon polyatomic species (26).…”

Risk Factors for Age-related Cortical, Nuclear, and Posterior Subcapsular Cataracts

“…Plasma selenium was measured spectrofluorometrically after complexing the tetravalent selenium with 2,3-diaminonaphthalene and successive extraction in cyclohexane (14,15).…”