为评价北豆腐凝固剂氯化镁引入的杂质中铜的残留情况，在梯度添加工业级氯化镁与食品级氯化镁制成豆腐后，分别用分光光度法与火焰原子吸收光谱法对豆腐中铜残留量进行测定，并进行了精密度、加标回收率和检出限试验。结果表明：添加量3.2%食品氯化镁的豆腐中，铜残留量为9.49 mg·kg－1；添加量2.4%工业级氯化镁的豆腐中，铜残留量10.79 mg·kg－1。精密度、回收率和最低检出限的试验结果评价了方法的可靠性。试验结果证实了豆腐中铜残留量超过食品中铜限量标准源于过量使用食品级氯化镁和违法使用工业级氯化镁。研究结果对于利用铜与氯化镁中的其他重金属的残留量评价氯化镁的使用情况具有指导意义。% To evaluate the amount of copper residue situation in Bei Tofu which contained magnesium chloride. Bei Tofu was produced by adding industrial grade-magnesium chloride and food-grade magnesium chloride.The spectrophotometry and flamless atomic absorption spectrophotometry(FAAS)methods were applied for detecting the amount of copper residue. And the experiment of precision,the recovery,the minimum detection limit was tested ,respectively .The results showed that the amount of copper residue was 9.49 mg·kg-1,when 3.2% food magnesium chloride was added into Tofu. When 2.4% industrial grade magnesium chloride was added into Tofu,the amount of copper residue was 10.79 mg·kg-1.The method evaluated by the experiment of precision,the recovery, the minimum detection limit was reliable. The test results confirmed that the amount of copper residue in tofu exceeded the limits of copper in food,from excessively used of the food-grade magnesium chloride,and unlawfully used of the industrial-grade magnesium chloride. The results provided guiding significance to evaluation the magnesium chloride usage by detecting the residues of the copper and the other heavy metals in magnesium chloride.
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