Determination of Nitrate in Feeds

1965 ◽  
Vol 48 (3) ◽  
pp. 648-653
Author(s):  
D W Hatcher ◽  
E D Schall
Keyword(s):  
Organic Matter ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Soluble Organic Matter ◽  
Nitrate Level ◽  
Low Level ◽  
Low Levels ◽  
Layer Chromatography

Abstract Attempts to measure nitrate at the low levels found in feeds by existing methods failed due to interferences from the soluble organic matter extracted from the samples along with the nitrate. The difficulties increased as the nitrate level decreased. A method for low-level materials was developed in which nitrate was isolated from interfering substances by thin-layer chromatography, eluted quantitatively from the absorbent, and measured colorimetrically by a modification of the 3,4-xylenol method. The procedure will determine nitrate accurately down to 10 ppm or less.

Comparison of Postcolumn Derivatization-Liquid Chromatography with Thin-Layer Chromatography for Determination of Aflatoxins in Naturally Contaminated Corn

1990 ◽  
Vol 73 (4) ◽  
pp. 579-581 ◽  
Author(s):  
Rodney W Beaver ◽  
David M Wilson ◽  
Mary W Trucksess
Keyword(s):  
Liquid Chromatography ◽  
Detection Limit ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Correlation Coefficient ◽  
Low Levels ◽  
Aflatoxin B2 ◽  
Layer Chromatography ◽  
Postcolumn Derivatization

Abstract Quantitation of aflatoxins by liquid chromatography with postcolumn iodine derlvatization (LC-PCD) and fluorescence detection was compared with quantitation by the AOAC CB method, 968.22. Thirty-seven naturally contaminated corn samples were ground and then divided. One portion was extracted, and the extract was cleaned up and analyzed by thin-layer chromatography according to the CB method. The second portion was extracted and cleaned up In a similar fashion, but quantitation was by the LC-PCD method. For aflatoxin B1, concentrations ranging from 0 to 150 ng/g, results obtained by the 2 methods were fitted to a linear equation with the LC-PCD results as the dependent variable. The correlation coefficient was 0.99, the Intercept was near 0, and the slope was near 1. For aflatoxin B2, the correlation coefficient was 0.97, and the Intercept was near 0. However, the slope of the equation relating LC-PCD concentration to TLC concentration was only 0.5. We believe that this lack of equivalence between the methods for determination of aflatoxin B2 is due to overestlmatlon by the TLC method because the low levels present are near the TLC detection limit for B2.

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