| Lead and cadmium are highly toxic heavy metals and can enter the human body through the food chain. Unlike organic pollutants, they are nondegradable and able to accumulate in living organisms, causing extremely high toxicity. Lead and cadmium have been included in the list of priority pollutants by the China national standard with a severe limit in food. Accurately determining their contents in food is therefore very important. Currently, some methods regarding the determination of lead and cadmium in food have been created and can be found in the China national standard. However, it is still difficult to determine the content of these two elements in matrix with high salt concentration by using these methods due to the matrix interference. On the other hand, the high salt concentration can also cause pipe blockage, reduced sensitivity and other else problems. By contrast, the method of anodic stripping voltammetry can be used to determine micro-trace amounts of heavy metals in matrix with a high salt concentration and the aforementioned problems may be avoided to some extent. In this paper, the determination of lead and cadmium in the condiments and food additives, which contain high concentration of sodium salt and phosphate salt, respectively, was studied by using the method of anodic stripping voltammetry. The main contents are as follows:(1) The effect of instrument conditions, electrolyte species and its dosage, and sodium salt with high concentration on the determination of lead and cadmium was investigated, and related experiments were conducted to understand the problem relating to the interference of acid species, acidity and coexisting ions. It was found that the linear ranges of the working curves for Pb and Cd were 2.00～50.0 μg·L-1 and 1.00～10.0 μg·L-1, respectively, with a correlation coefficient of 0.9999 and 1.0000, respectively. The detection limits of this method were found to be Pb 0.0022 mg·kg-1 and Cd 0.0014 mg·kg-1. The determination precisions of lead and cadmium in actual samples involving spicy dip, soy sauce, fish sauce were 1.11～4.66% and 0.69～5.34%, respectively. And corresponding recoveries were 93.9～109.9% and 94.7～107.5%, respectively.(2) Determination of Lead and Cadmium in chicken and monosodium glutamate by anodic stripping voltammetry and investigated GF-AAS background interference. For the anodic stripping voltammetry, the linear ranges of the working curves for Pb and Cd were 2.00～50.0 μg·L-1 and 1.00～10.0 μg·L-1,respectively, with a correlation coefficient of 0.99997 and 0.99996 respectively. The detection limits of this method were Pb 0.0032 mg·kg-1 and Cd 0.0022 mg·kg-1. The determination precisions of lead and cadmium were 1.23～1.56% and 0.66～2.86%, respectively, and the corresponding recoveries were 94.6～106.8% and 95.2～104.0%, respectively.(3) The method of anodic stripping voltammetry was also used to determine the content of lead and cadmium in food additives such as sodium dihydrogen phosphate, potassium dihydrogen phosphate, and calcium dihydrogen phosphate. We carried out some experiments aiming at finding the optimal instrument conditions, the influence of phosphate salt on the lead and cadmium peaks, the interference of elements, the linear range, the detection limit, the precision and the recovery rate. The linear ranges of the working curves for Pb and Cd were found to be 5.00～200 μg·L-1 and 1.00～10.0 μg·L-1 respectively, with a correlation coefficient of 0.99992 and 0.99994, respectively. The detection limits of this method were Pb 0.0045 mg·kg-1 and Cd 0.0016 mg·kg-1. The determination precisions of lead and cadmium in phosphate samples were 0.61～1.58% and 2.55～5.3%, respectively. And the corresponding recovery rates were 95.5～105.8% and 96.7～109.5%, respectively.The experimental results showed that the anodic stripping voltammetry had some advantages in the determination of lead and cadmium in sodium salts and phosphate salts with a high concentration. This method exhibited high sensitivity, wide linear range and good reproducibility as well as strong anti-interference characteristics. It had a significant advantage over the method of graphite furnace atomic absorption spectrometry in terms of anti-interference of matrix containing a high concentration of sodium salt or phosphate, thus showing excellent selectivity and good reliability.
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