交联壳聚糖分离富集——火焰原子吸收光谱法测定奶制品中的痕量Pb

Determination of lead in dairy products after preconcentration and separation with crosslinked chitosan by flame atomic absorption spectrometry

以环氧氯丙烷作为交联剂,合成了聚乙二醇交联壳聚糖.用红外光谱(FI-IR)对交联壳聚糖进行了结构表征.研究了不同条件下交联壳聚糖对铅离子吸附性能.结果表明,当溶液pH为6、吸附时间为60 min、吸附温度为40℃、吸附剂用量为30 mg时,交联壳聚糖对溶液中Pb2+的吸附效率较高,吸附在交联壳聚糖上的铅离子可用1 mol/L的稀HCl洗脱.用火焰原子吸收光谱测定,该法对Pb2+的检出限为0.72μg/mL(3σ,n=8),相对标准偏差为2.1%(n=5,ρ=5μg/mL),线性范围为0-20.00μg/mL,加标回收率在97.8%-102.6%之间.该方法用于奶制品中铅的测定结果令人满意.

In this paper,epoxy chloropropane is used as crosslinking agent reacting with poly（ethylene glycol） and purification of chitosan gel to make water-insoluble cross-linking chitosan firstly.To research adsorption effect of crosslinking chitosan on lead ions,factors such as pH,temperature,time,the dosage of crosslinking which affect adsorption efficiency of crosslinking chitosan are studied.The results showed that,when the pH is 6,adsorption time is 60min,adsorption temperature is 40 ℃,adsorption dose is 30 mg,adsorption efficiency of Pb2＋ is higher.Pb2＋ could be adsorpted by crosslinking chitosan at pH=6 and eluted from crosslinking chitosan with 10 mL of 1 mol/L HCl,and then determined by flame atomic absorption spectrometry（FAAS）.A method for concentrationand separation of Pb2＋ was proposed under the optimum experimental conditions.The relative standard deviation of themethod was found to be 2.1%.And the limit of detection（3σ,n=8） of the method was found to be 0.72 μg/L.The linear range was 0-20.00 μg/mL.The recoveries were in the range of 97.8%-102.6%.The method has been applied to the determination of lead in dairy products samples with satisfactory results.