Quantitative Determination of Ga, Zn, Cu, Hi, Mn, and Cr by X-Ray Fluorescence in Laterites and Bauxites Using Two Evaluation Methods

1981 ◽  
Vol 25 ◽  
pp. 127-131
Author(s):  
Hasso Schorin
Keyword(s):  
Quantitative Determination ◽  
Chemical Weathering ◽  
Limit Of Detection ◽  
Standard Addition ◽  
Standard Addition Method ◽  
Addition Method ◽  
X Ray ◽  
Minor Elements ◽  
Trace And Minor Elements

Laterites and bauxites are residual products derived from a wide variety of rocks by intensive chemical weathering under strongly oxidizing and leaching conditions. Generally the main constituents of these residues are Fe, Al and Ti present in form of hydroxides and/or oxides. The content of silica depends on the thoroughness of the leaching process. The behaviour of trace and minor elements as Ga, Zn, Cu, Ni, Mn and Cr during the laterite/bauxite formation is not yet well established. Precise and accurate analyses of these elements are a prerequisite for such investigations. In this paper the standard addition method is presented and the results are compared with those obtained by calibration standardization. The accuracy and the precision of the methods as well as the distinction limit and the limit of detection for each element are given.

scholarly journals Simultaneous spectrophotometric determination of phenolic antioxidant (BHA and BHT) concentrations in pharmaceutical preparations and chewing gums using the H-point standard addition method

2017 ◽  
Vol 36 (2) ◽  
pp. 211
Author(s):  
Mahmure Özgür ◽  
Zeynep Kalaycioğlu ◽  
Öznur Dülger
Keyword(s):  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Standard Addition ◽  
Butylated Hydroxytoluene ◽  
Standard Addition Method ◽  
Addition Method ◽  
Chewing Gums ◽  
Relative Standard

A simple, rapid, and sensitive spectrophotometric method was developed for the simultaneous determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) concentration in pharmaceutical preparations and chewing gums, without prior separation steps, using the H-point standard addition method (HPSAM).The concentration of one antioxidant was calculated by overlapping spectra at two appropriately selected wavelengths at which the interferent, other antioxidant, should has the same absorbance value. Absorbances at two pairs of wavelengths, 265 and 288 nm (with BHA as analyte) or 288 and 293 nm (with BHT as analyte) were monitored, while adding standard solutions of BHA or BHT, respectively. Calibration graphs were determined at 4–20 μgml–1(r = 0.9981) for BHA and 20–100 μgml–1(r = 0.9940) for BHT in binary mixtures. The proposed method was tested and validated using various parameters according to ICH guidelines. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.48 and 1.51 μgml–1for BHA and 0.72 and 2.41 μgml–1for BHT, respectively. The percentage recovery ranges were 100.44–102.50 % for BHA and 96.45–100.04 % for BHT, with relative standard deviations (RSD) less than 1.48 % indicating reasonable repeatability of the method. The intra-day and inter-day precision tests showed reliable RSD values (< 2 %). The results obtained using HPSAM were statistically compared with results obtained using the derivative spectrophotometric method that was previously reported by us, showing high similarity between results.

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