[Determination of Arsenic in Food Package Aluminum by Ultrasound Assisted Solid Phase Extraction/ICP-AES].

Determination of arsenic in pure aluminum by inductively coupled plasma atomic emission spectrometry was interfered by aluminum matrix. The experiment showed that when the mass concentration of Al was greater than or equal to 5 000 times the As in the test solution, the measurement error was greater than 5%. In order to eliminate the interference, strong acid cation exchange fiber (SACEF) was used as solid phase extraction agent to adsorb Al(3+). The extraction conditions included amount of SACEF, extraction time, temperature and pH were investigated. The optimal extraction conditions were that 0.9000 g SACEF was used to extract the aluminum from the sample solution of pH 2.0 at 55 °C for 5 min with the ultrasonic assist, and in this case, the arsenic in the form of arsenic acid was not extracted and left in the solution for the determination. The results showed that after treating 10. 00 mL test solution containing 1.00 µg arsenic and 20.0 mg aluminum, arsenic did not lose. The mass concentration of residual aluminum in the raffinate was about 2,000 times the As, which had not interfered the determination of arsenic. The detection limit (3 s) was 0.027 µg · mL(-1) and quantification limit (10 s) was 0.0091 µg · mL(-1). The proposed method was successfully applied to the separation and determination of arsenic in the synthetic samples, the aluminum cans and the barbecue aluminum foil. Recovery was in the range of 98.3%-105% and RSD (n = 3) was in the range of 0.1%-4.3%. The results showed that the content of arsenic in the aluminum cans and the aluminum barbecue foil was below the limited value of national standard (GB/T 3190-2008).

[Determination of trace arsenic in sulfur by graphite furnace atomic absorption spectrometry with La(NO3)3-Ni(NO3)2 matrix modifier].

In this paper, the decomposition method of sulfur and the determination of trace arsenic in sulfur by GFAAS with La(NO3)3-Ni(NO3)2 matrix modifier were studied in detail. The decomposition of sulfur with mixed acid HNO3-HClO4 by controlled temperature electrothermal method or pressure crucible method was efficient and safe. The sensitivity of the determination of arsenic with La(NO3)3-Ni(NO3)2 matrix modifier was higher than with Ni(NO3)2 or Mg(NO3)2 matrix modifiers. The detection limit was 0.034 microgram.mL-1 (k = 3). The analytical results of the sulfur samples were coincident with the results of determination by HG-ICP-AES. The adding recoveries were 97.5%-110% and the relative standard deviation was less than or equal to 2.1% (n = 4).