title: Determination of As, Cr, Mo, Sb, Se and V in agricultural soil samples by inductively coupled plasma optical emission spectrometry after simple and rapid solvent extraction using choline chloride-oxalic acid deep eutectic solvent.
abstract: A rapid, simple and green ultrasound-assisted extraction method using deep eutectic solvents (DES) for extraction of As, Cr, Mo, Sb, Se and V in soil samples, has been developed. Choline chloride-oxalic acid based DES was used as a solvent. The target analytes were subsequently quantified using inductively coupled plasma optical emission spectrometer (ICP OES). The parameters that affect the extraction of the target analytes was optimized using standard reference material of San Joaquin soil (SRM 2709a). In the optimization step, a two-level full factorial experimental design was used. The factors under investigation include extraction time, sample mass and acid concentration. Under optimized conditions, limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.009 to 0.1 and 0.03-0.3µgg-1, respectively. The repeatability (n=20) estimated in terms of relative standard deviation (%RSD) ranged from 0.9% to 3.7%. The accuracy of the proposed method was carried out using SRM 2709a. The obtained and certified/ indicative values were statistically in good agreement at 95% confidence level. The proposed method applied for quantification of As, Cr, Mo, Sb, Se and V in real soil samples. For comparison, the analytes of interest were also determined using a conventional acid digestion method. According to the paired t-test, the analytical results were not significant differences at 95% confidence level. The method was found to be accurate, precise and environmentally friendly.
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Johannesburg 2028, South Africa.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Matong
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Johannesburg 2028, South Africa.
authors.forename: Luthando
authors.initials: L
authors.lastname: Nyaba
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Johannesburg 2028, South Africa. Electronic address: pnnomngongo@uj.ac.za.
authors.forename: Philiswa N
authors.initials: PN
authors.lastname: Nomngongo
mesh_terms: D000383:Agriculture; D001151:Arsenic / Q000032:analysis* / Q000737:chemistry; D002794:Choline / Q000737:chemistry; D004784:Environmental Monitoring; D057230:Limit of Detection; D019216:Metals, Heavy / Q000032:analysis* / Q000737:chemistry; D019815:Oxalic Acid / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013054:Spectrophotometry, Atomic
chemical_list: D019216:Metals, Heavy; D012989:Soil Pollutants; D012997:Solvents; D019815:Oxalic Acid; D001151:Arsenic; D002794:Choline
keywords: Agricultural soils; Deep eutectic solvents; Green sample preparation; ICP-OES; Trace elements; Ultrasound assisted solvent extraction