Boron isotope dilution in cellular fractions of coffee leaves Evaluated by Inductively Coupled Plasma Mass Spectrometry with direct injection nebulization (DIN-ICP-MS)

Abstract

A diluição isotópica do B enriquecido em 94,14 átomos % em 10 B fornecido durante o cultivo de mudas de cafeeiro foi avaliada na parede celular, núcleo e cloroplastos de células foliares. Para isto foi necessária a determinação de 11 B/ 10 B em pequenos volumes de amostras conseguidas pelo processo de fracionamento por centrifugação diferenciada. As determinações isotópicas foram efetuadas por espectrometria de massas com fonte de plasma acoplado indutivamente (ICP-MS) utilizando-se nebulizador de injeção direta (DIN). Razões isotópicas de B entre 1,002 e 1,326 foram determinadas em 50 µL das amostras enriquecidas com precisão caracterizada por RSD<1,5%. As concentrações de B encontradas nas frações celulares variaram entre 3,3 e 10,8 µg g -1 , e em média os átomos % de 10 B foram 46,7; 44,5 e 48,8 na parede celular, núcleo e cloroplasto, respectivamente. O limite de detecção foi estimado em 0,5 ng B mL -1 .Enriched 10 B (94.14 atom %) was supplied to coffee plantlets for three months. Then boron isotope ratios were determined in the leaf cell compartments, cell wall, nuclei and chloroplast, after a sub-cellular fractionation procedure. The isotopic measurements were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) provided with a direct injection nebulizer (DIN), introducing a sample volume of 50 µL. Isotopic ratios from 1.002 to 1.326 were determined with precision characterized by RSD lower than 1.5% for the enriched cell fractions with B concentrations ranging from 3.3 to 10.8 µg g -1 . The detection limit (3σ) was 0.5 ng B mL -1 . The average enrichments in 10 B atom % found in the cell walls, nuclei and chloroplasts were 46.7, 44.5 and 48.8, respectively. Keywords: isotope dilution, inductively coupled plasma mass spectrometry, biological cell fractionation, boron isotope ratios, plant analysis IntroductionThe interest in determining traces of boron has increased in recent years, since boron is an essential element for plants and may also be essential for animals and humans. 1 Besides, the application of 10 B in neutron capture therapy (BNCT) is increasing as well as its isotopic determination in biological tissues. 2 Thermal ionization mass spectrometry (TI-MS) may be used for boron isotope ratio measurements with precisions ranging from 0.2 and 0.3%. 3 The main disadvantage of this method is the time-consuming sample preparation. With inductively coupled plasma mass spectrometry (ICP-MS) boron concentrations and isotope ratios are determined with minimal requirements in sample preparation. 4 The principal concerns when using ICP-MS for B isotopic determinations concern memory effects and mass discrimination. Memory effects are mainly due to interactions of B with the heated quartz torch. Some authors use washout times of several minutes to reduce boron memory. [5][6] Others use a sodium fluoride solution, 7 Triton X-100 surfactant, 8 mannitol 9 or ammonia 10 as washing agents. These methods slowly remove the memory effect when solutions with more than 0.5 mg L -1 of boron are analyzed. ...

A Rapid Method for Determining Boron Concentration (ID‐ICP‐MS) and δ11B (MC‐ICP‐MS) in Vegetation Samples after Microwave Digestion and Cation Exchange Chemical Purification

“…), and B absorption pathways and translocation within plant tissues have been inferred using 10 B enriched solution (Bellato et al . , de Mello Prado et al . ).…”

“…) with a slight isotopic fractionation by comparison with the nutritional solution (Bellato et al . , Cividini et al . ).…”

A review on the determination of isotope ratios of boron with mass spectrometry

“…A mixture of 0.1 M HNO 3 and 0.3M HF was used with a Teflon spray chamber (Misra et al, 2014). A demountable directinjection high-efficiency nebulizer (d-DIHEN; Bellato, Menegario, & Gine, 2003) was also used to circumvent the memory effect. A comparison on the Meinhard pneumatic nebulizer with a Scott-type double-spray pass chamber and direct injection nebuliser (Smith et al, 1991) showed the advantages of DIN from the point of view of low sample consumption as well as quick wash with negligible memory.…”

From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)

“…Brown and Shelp, 1997;Blevins and Lukaszewki, 1998), very sparse d 11 B data in vegetation are available in literature and none is really conducted in a way suitable for determining the behavior of B isotopes during root absorption and translocation within plants (Vanderpool and Johnson, 1992;Wieser et al, 2001;Bellato et al, 2003;Suzuki et al, 2003). As mentioned above, showing that all the spring waters and the main stream plot within two end-members represented by th RH3 and SH springs.…”