Study On Solid Phase Extraction- Determination Of Cadmium, Copper, Zinc, Arsenic, Lead, Nickel, Manganese And Chromium In Food Packaging Aluminum By Inductively Coupled Plasma Atomic Emission Spectroscopy

This paper reviewed the requirements and researches on toxic trace metal elements in food packaging materials, determination of impurities in high purity material, and the matrix interference in determination of impurities in high purity material. On this basis, the paper focused on separation and enrichment of cadmium, copper, zinc, arsenic, lead, nickel, manganese and chromium from food packaging aluminum by the ion exchange fibers and determination of these elements by ICP-AES.1. The conditions about extraction and separation of Cd, Cu and Zn from food packaging aluminum by strong base anion exchange fiber, and the determination of the separating Cd, Cu and Zn by ICP-AES were discussed. Strong base anion exchange fiber was used as a solid phase extraction solvent to extract Cd, Cu and Zn. Cd, Cu and Zn were adsorbed in the 1.00 mol·L-1 NH4SCN solution at 25℃, then eluted by 2.00 mol-L"1 (NH4)2SO4 solution (with ammonia adjusted to pH=8.0) with ultrasonic at 70℃ for 1 h. The results showed that after separation and enrichment, the concentration of residual Al was equal to about 33 times of Cd,3 times of Cu,16 times of Zn in the eluent, which had not interfered the determination of Cd, Cu and Zn by ICP-AES. The detection limit (3s) were Cd 0.0540 μg·mL-1, Cu 0.00900 μg·mL-1, Zn 0.00810 μg·mL-1, and the quantification limit (10s) were Cd 0.180 μg·mL-1, Cu 0.0300 μg·mL-1, Zn 0.0270 μg·mL-1. The proposed method was successfully applied for the separation and determination of Cd, Cu and Zn in the aluminum cans and the barbecue aluminum foil. Recovery was in the range of 95.7%-105% and RSD (n=3)% was in the range of 0.1-3.0.2. The conditions about separation trace As from Al with strong acid cation exchange fiber were discussed. On this basis, the analysis method of determination of arsenic in food packaging aluminum by ICP-AES was established. Strong acid cation exchange fiber was used to extract the aluminum from the sample solution of pH 2.0 at 55℃ with ultrasonic assisted, 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 the test solution contained 0.100μg·mL-1 arsenic and 2.00 mg·mL-1 aluminum, arsenic did not lose. The mass concentration of residual aluminum in the raffinate was about 2000 times of As, which had not interfered the determination of arsenic. The detection limit (3s) was 0.0270 μg·mL-1 and quantification limit (10s) was 0.0910 μg·mL-1. The proposed method was successfully applied for 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 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).3. The conditions about separation trace Cd and Pb from Al with strong base anion exchange fiber was discussed. On this basis, the analysis method of determination of Cd and Pb in food packaging aluminum by ICP-AES was established. Strong base anion exchange fiber was used as a solid-phase extraction agent, which was put in the sample solution contained 0.500 mol·L-1 KI at 25 ℃ and with oscillation. Cd2+and Pb2+ complex to I" respectively and form stable complex anions, which was adsorbed and enriched by strong base anion exchange fiber. Load fibers were drained, washed with demineralised water, and eluted by 0.0500 mol·L-1 EDTA (pH=8.0) solution with ultrasonic vibration at 75 ℃, then Cd and Pb in the eluate were measured. The results showed that Cd and Pb did not lose, after treating the test solution contained 0.100 μg·mL-1 Cd, Pb and 5.00 mg·mL-1 Al. The mass concentration of residual aluminum in the eluate was about 790 times of Cd and Pb, which had not interfered the determination of Cd and Pb. The detection limit (3s) were Cd 0.000300 μg·mL’1, Pb 0.00300 μg·mL-1 and quantification limit (10s) were Cd 0.00100 μg·mL-1, Pb 0.0100 μg·mL-1. The proposed method was successfully applied for the separation and determination of Cd and Pb in the aluminum cans, the barbecue aluminum foil and the standard substance. Recovery of food packaging aluminum samples were in the range of 90.1%-104% and RSD (n=3)% was below 4.0. The measured value to certified values relative error of standard substance is less than 5.0%.4. The conditions about separation Ni, Cu and Zn from Al matrix with strong acid cation exchange fiber were discussed. On this basis, the analysis method of determination of Ni, Cu and Zn in food packaging aluminum by ICP-AES was established. At room temperature, a small amount of EDTA was added in the test solution to a concentration of 0.0100 mol·L-1 and the solution was adjusted pH=5.0, than strong acid cation exchange fibers adsorbed Al3+ with ultrasonic assisted. Al3+ could not quickly form a complex anion with EDTA, which was adsorbed by strong acid cation exchange fiber. Cu2+, Ni2+ and Zn2+ could form complex anions with EDTA rapidly, which was not adsorbed by strong acid cation exchange fiber and left in the solution to be determined. The results showed that Cu, Ni, Zn did not lose, after treating the test solution contained 0.500 μg·mL-1 Cu, Ni, Zn and 1.00 mg·mL-1 Al. The mass concentration of residual aluminum in the raffinate was about 170 times of Cu, Ni and Zn, which had not interfered with the determination of Cu, Ni and Zn. The detection limit (3s) were Cu 0.00120 μg·mL-1, Ni 0.00270 μg-mL-1, Zn 0.00150 μg·mL-1 and quantification limit (10s) were Cu 0.00400 μg·mL-1, Ni 0.00900 μg·mL-1, Zn 0.00500 μg·mL-1. The proposed method was successfully applied for the separation and determination of Cu, Ni and Zn in the aluminum cans, the barbecue aluminum foil and the standard substance. Recovery of food packaging aluminum samples were in the range of 95.3%-104% and RSD (n=3)% was in the range of 0.4-2.5. The measured value to certified values relative error of standard substance is less than 5.0%.5. The conditions about separation Cr and Mn from Al matrix with strong acid cation exchange fiber were discussed. On this ba^is, the analysis method of determination of Cr and Mn in food packaging aluminum by ICP-AES was established. The strong acid cation exchange fibers were put to the 0.0200 mol L-1 EDTA test solution (pH=3.0), and the test solution was extracted with ultrasonic assisted 10 min at 100℃. Under these conditions, Al3+ could form a stable complex anion with EDTA, which was not adsorbed by strong acid cation exchange fibers. And thanks to acid effect, Cr3+ and Mn2+ could not form stable complex anions with EDTA, which was adsorbed by fibers. The Load fibers were drained, washed with demineralised water, and eluted by 10% HNO3 solution with ultrasonic vibration at room temperature then Cr and Mn in the eluate were measured. The results showed that Cr, Mn did not lose, after treating the 200 mL test solution contained 0.0500 μg·mL-1 Cr,0.0500 μg·mL-1 Mn and 200 μg·mL-1 Al. The mass concentration of residual aluminum in the eluate was about 370 times of Cr and 20 times of Mn, which had not interfered with the determination of Cr and Mn. The detection limit (3.s) were Cr 0.00120 μg·mL-1, Mn 0.000300 μg·mL-1 and quantification limit (10s) were Cr 0.00400 μg·mL-1, Mn 0.00100 μg·mL-1. The proposed method was successfully applied for the separation and determination of Cr and Mn in the aluminum cans, the barbecue aluminum foil and the standard substance. Recovery of food packaging aluminum samples were in the range of 95.5%-103% and RSD (n=3)% was in the range of 0.1-2.9. The measured value to certified values relative error of standard substance is less than 5.0%.