INVESTIGATION ON CHEMICAL CONTAMINANTS IN SELECTED FOOD STUFFS

Abstract

This study describes determination of pesticide residues and heavy metals in fruits and vegetables, heavy metals in turmeric powder, aflatoxins in wheat and maize, benzoic acid and sorbic acid in fruit drinks and tomato ketchup, sudan red in chili powder and antibiotic residues in pasteurized milk. Quick, easy, cheap, effective, and rugged method was used for pesticide and antibiotic residues. Gas chromatograph equipped with electron capture detector (GC-ECD), gas chromatograph-mass spectrometer (GC-MS) and liquid chromatograph-mass spectrometer (LC-MS/MS) were the major equipment for analysis of pesticide residues in fruit and vegetable samples. Microwave digester was used for sample preparation of fruits, vegetables and turmeric powder for analysis of heavy metals by atomic absorption spectrophotometer (AAS). Aflatoxins B1, B2, G1and G2 were determined in maize and wheat by high performance liquid chromatograph (HPLC) equipped with fluorescence detector and coring cell as post column derivatization system. Phosphate buffered saline was used for extraction of sample and clean-up by immunoafinity column for analysis of aflatoxins. Benzoic acid and sorbic acid in fruit drinks and tomato ketchup was determined by HPLC. Extraction of benzoic acid and sorbic acid from sample was performed using a mixture of ammonium acetate buffer solution and methanol, under pH 4.5. Sudan dyes I, II, III, IV have been determined in chili powder by HPLC. Sudan dyes I, II, III, IV were extracted by ethanol. Antibiotic residues were extracted by methanol water mixture and were clean-up by MgSO4, PSA and C18. Antibiotic residues in pasteurized milk were analyzed by LC-MS/MS. Tomato and cabbage were used as representative matrix for method validation of pesticide residues. The LOD for pesticide residue was in the range of 0.02-0.81 μg/kg and LOQ was in the range of 0.08-2.71 μg/kg. Linear correlation coefficient (R2) value ranged from 0.996 to 0.999. Recoveries were in the range of 81-97%. Potato was used as representative matrix for method validation of heavy metals. For arsenic, lead and cadmium LOD were 2.49, 2.39, 0.09 μg/kg and LOQ were 8.30, 7.96, and 0.29 μg/kg, respectively. Linear correlation coefficient (R2) value for As, Pb and Cd were 0.998, 0.996 and 0.998, respectively. Recoveries for As, Pb and Cd were 98%, 95%, 96%, respectively. Turmeric powder was used as a representative matrix for determination of lead and chromium. For Pb and Cr LOD were 1.71, 2.17 μg/kg and LOQ were 5.69, 7.22 μg/kg, respectively. Linear correlation coefficient (R2) value for Pb and Cr were 0.996 and 0.995. Recoveries for Pb and C were 98% and 96%, respectively. Wheat was used as representative matrix for method validation of aflatoxin. LOD of aflatoxin G2, G1, B2 and B1 were 0.006, 0.021, 0.020, 0.046 μg/kg and LOQ were 0.020, 0.069, 0.066, 0.153 μg/kg, respectively. Linear correlation coefficient (R2) value were in the range of 0.998-0.999. Recoveries (%) were in the range of 85-96%. Apple fruit drink was used as representative matrix for method validation of benzoic acid and sorbic acid. LOD of benzoic acid and sorbic acid were 0.15 and 0.09 mg/kg and LOQ were 0.49 and 0.30 mg/kg, respectively. Linear correlation coefficient (R2) value for benzoic acid and sorbic acid was 1. Recovery (%) of benzoic acid and sorbic acid with apple fruit drink was 99%. Chili powder was used as representative matrix for method validation of sudan red. LOD of sudan red-I, II, III and IV were 0.22, 0.50, 0.38 and 1.49 mg/kg and LOQ were 0.72, 1.66, 1.25 and 4.96 mg/kg, respectively. Linear correlation coefficient (R2) value for sudan red-I, II, III and IV was 0.999. Recoveries (%) of sudan red-I, II, III and IV with chili powder were in the range 93- 99%. Pasteurized milk was used as representative matrix for method validation of antibiotic residues. LOD of six antibiotics in pasteurized milk were in the range of 1.53-4.87 μg/kg and LOQ was in the range of 5.09-16.25 μg/kg. Linear correlation coefficient (R2) value ranged from 0.995 to 0.999. Recoveries (%) of antibiotic were in the range of 84-101%. Fruits (n= 280) and vegetables (n= 455) samples were analyzed for pesticide residues. Chlorpyrifos was detected in 2 samples of cabbage which were within maximum residue limit (MRL) of 1.0 mg/kg set by Bangladesh Food Safety Authority (BFSA). Dimethoate was detected in 4 samples of green chili which were within MRL of 0.5 mg/kg set by BFSA. Carbofuran was detected in 2 sample of tomato and in 2 sample of eggplant. All these four samples were within MRL of 0.01 mg/kg set by European Commission (EC). Arsenic, lead and cadmium were analyzed for fruits (n= 280) and vegetables (n= 455) samples. Arsenic was detected in 13 potato samples, in 01 tomato samples, in 11 eggplant samples and in 1 carrot samples. Cadmium was detected in 6 potato samples. All these samples were within maximum limit of 0.1 mg/kg set by BFSA. Lead and chromium were analyzed in 17 turmeric powder samples. High amount of Pb and Cr were found in 8 turmeric powder samples. Eight samples exceeded maximum limit of Pb of 2.5 mg/kg set by Bangladesh Standards and Testing Institution (BSTI). Aflatoxin B1, B2, G1 and G2 were analyzed in 25 wheat and 25 maize samples. No targeted aflatoxin was detected in any sample of wheat and maize. Benzoic acid and sorbic acid were analyzed in 25 fruit drink and 27 tomato ketchup samples. Benzoic acid was detected in 17 fruit drink samples and in 21 tomato ketchup samples. Eleven fruit drink sample exceeded maximum limit of 120 mg/kg set by BSTI and 1 tomato ketchup sample exceeded maximum limit of 750 mg/kg set by BSTI. Sudan I, II, III and IV were analyzed in 20 chili powder samples. Sudan III was detected in 1 sample out of 20 samples. Six antibiotic residues were analyzed in 42 samples of pasteurized milk. No targeted antibiotic was detected in any sample. In this study analysis result showed that pesticide residues detected in 1.36 % sample of fruits and vegetables. Arsenic was detected in 3.54 % sample and cadmium was detected in 0.82% sample of fruits and vegetables. Lead and chromium was detected in 47.06% of the turmeric powder sample. Aflatoxin B1, B2, G1 and G2 was not detected in any wheat and maize sample. Benzoic acid was detected in 68% fruit drink sample and in 77.78% tomato ketchup sample. 64.71% of benzoic acid detected fruit drink sample exceeded maximum limit and 6.76% of benzoic acid detected tomato ketchup sample exceeded maximum limit. Sudan III was is detected in 5% chili powder sample. No targeted ciprofloxacin, levofloxacin, enrofloxacin, tetracycline, oxytetracycline and chlortetracycline were detected in any sample of pasteurized milk.