Isotope determination of sulfur by mass spectrometry in soil samples

Abstract

SUMMARYSulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes ( 32 S, 33 S, 34 S, and 36 S) with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS) in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO 4 2-), which was determined by dry combustion with alkaline oxidizing agents. The total S-SO 4 2-concentration was determined by turbidimetry and the results showed that the conversion process was adequate. To produce gaseous SO 2 gas, BaSO 4 was thermally decomposed in a vacuum system at 900 ºC in the presence of NaPO 3 . The isotope determination of S (atom % 34 S atoms) was carried out by isotope ratio mass spectrometry (IRMS). In this work, the labeled material (K 2 34 SO 4 ) was used to validate the method of isotopic determination of S; the results were precise and accurate, showing the viability of the proposed method.Index terms: sample preparation, soil samples, isotopic dilution, labeled material, stable isotope, 34 S. RESUMO: DETERMINAÇÃO ISOTÓPICA DE ENXOFRE POR ESPECTROMETRIA DE MASSAS (IRMS) EM AMOSTRAS DE SOLO

Determination of the Geographical and Botanical Origin of Hops (Humulus lupulus L.) Using Stable Isotopes of C, N, and S

“…Isotope Ratio Mass Spectrometry (IRMS). In hop samples 13 C/ 12 C, 15 N/ 14 N, and 34 S/ 32 S ratios were determined using IRMS. A…”

“…where E is the element (C, N, S), R is the isotope ratio between the heavier "i" and the lighter "j" isotope ( 13 C/ 12 C, 15 N/ 14 N, 34 S/ 32 S) in the sample and in the relevant internationally recognized reference standard. The δ-values are multiplied by 1000 and expressed in units "per mil" (‰).…”

“…The hop is a C3 plant and has a δ 13 C between −29 ‰ and −23 ‰ . Similarly, the stable isotopic composition of nitrogen (δ 15 N) and sulfur (δ 34 S), the two of the main soil nutrients, , are mainly influenced by the isotopic composition of nitrate as ammonia and sulfur in the soil, which in turn depend on climatic and geographic conditions. , Factors, such as soil depth, vegetation type, and climate can affect soil processes, such as mineralization, nitrification, volatilization, and nitrate reduction, which also results in a measurable isotopic fractionation . Usually, the analyses of single isotope ratios cannot provide satisfactory results for determining geographical origin, and two or more isotope ratios of elements are required. , …”

Optimisation of laser parameters for the analysis of sulphur isotopes in sulphide minerals by laser ablation ICP-MS

“…2 Measurement techniques require a high spatial resolution to investigate zonation and uid evolution during crystal growth. High precision sulphur isotopes are conventionally measured by gas source isotope ratio mass spectrometry via the production of SO 2 either from combustion of powdered samples 3,4 or via laserinduced combustion of solid samples at a resolution of 100-500 mm. [5][6][7][8][9] Secondary ion mass spectrometry (SIMS) can also give precise isotopic analyses with high spatial resolution; however this technique can be prone to matrix effects and is not widely available.…”

Optimization of a Microwave Assisted Extraction of Organic Sulphur from Domestic Sewage Sludge by UV-Vis Spectrophotometry Determination

“…Conventional methods for the oxidation of organic sulphur to sulfate use nitric acid and perchloric acid, which requires safety measures against fire and explosion, in addition to the possibility of material loss, which may render the method useless (ROSSETE et al, 2012).…”