Raman spectroscopy coupled to high-resolution continuum source flame molecular absorption spectrometry for sequential determination of nitrogen species in fertilizers

Author(s)

Oliveira, Evilim M. ; Ferreira, Edilene C. ; Neto, Jose A. Gomes ; Donati, George L. ; Jones, Bradley T.

• Document type: Journal article
• Source: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 283, p. 6-pg., 2022-08-11.

Abstract

Raman spectroscopy (RS) was used to identify and quantify different nitrogen species in fertilizers. This is a fast and inexpensive method that requires no extensive sample preparation. Urea and nitrate were determined at 1000 and 1045 cm-1, respectively. Calibration plots obtained for these analytes showed adequate linearity, with regression coefficients (r) of 0.9989 and 0.9976, respectively. Ammonium was determined by difference after total N determination by high-resolution continuum source flame molecular absorption spectrometry (HR-CS FMAS), which provided a calibration plot with r = 0.9960. The inline coupling of RS and HR-CS FMAS allowed for a fast sequential determination of ammonium, nitrate, and urea, with limits of detection of 0.03 mg/L ammonium, 0.03 mg/L nitrate, and 0.01 mg/L urea. Relative standard deviations were <= 11 %, and the external standard calibration method provided accurate results for all analytes determined in certified reference mate-rials, raw materials, and commercial samples of fertilizers. For comparison purposes, all samples were also analyzed by traditional Kjeldahl method. The RS HR-CS FMAS method was further validated by addition and recovery experiments, which provided recoveries in the 93 - 113 % range. (AU)

• FAPESP's process: 19/07537-6 - STRATEGIC STUDIES OF SPECTROCHEMICAL ANALYSIS BY HR-CS AAS, LIBS AND RAMAN SPECTROSCOPY
• Grantee: José Anchieta Gomes Neto
• Support Opportunities: Regular Research Grants