Separation, enrichment and detection method of trace lead and cadmium ions in table salt

Abstract

The invention discloses a separation and enrichment as well as detection method for trace lead and cadmium ions in edible salt. The method comprises the steps: based on the adsorption characteristic of EDTA type chelate resin, selectively separating lead ions and cadmium ions from a sodium chloride solution in a near neutral medium, washing off the lead and cadmium ions from resin by using a dilute nitric acid solution, separating targets from a high-salt base body, then enriching the targets, and performing atomic absorption spectrum detection. According to the method, the substances to be detected are separated from the base body and then are enriched, so that separation of the targets from the high-salt base body is realized; the spectral interference caused by a large amount of sodium chloride is eliminated, so that the subsequent detection is simpler; the method is accurate, reliable, high in sensitivity and high in selectivity; the base body interference is completely eliminated; the recycling rate and the precision are higher.

Description

technical field [0001] The invention relates to a method for measuring the content of lead and cadmium ions in table salt, in particular to a method for separating and enriching lead and cadmium ions from table salt and then detecting them by atomic absorption spectrum. Background technique [0002] There is a large amount of sodium chloride in high-salt samples such as pickled food, soy sauce, table salt, and brine. In the presence of a large amount of sodium salt, the determination of trace heavy metals is a recognized problem in analytical chemistry. For example, when using AAS to detect trace heavy metal elements At the same time, sodium chloride will affect the arc temperature and produce a large background interference, resulting in the inaccurate determination of some trace heavy metal elements. When ICP or ICP-MS is used for detection, a large amount of sodium chloride will also block the nebulizer or deposit on the torch and sampling cone, thereby affecting the norm...

AI Technical Summary

Problems solved by technology

[0002] There is a large amount of sodium chloride in high-salt samples such as pickled food, soy sauce, table salt, and brine. In the presence of a large amount of sodium salt, the determination of trace heavy metals is a recognized problem in analytical chemistry. For example, when using AAS to detect trace heavy metal elements At the same time, sodium chloride will affect the arc temperature and produce a large background interference, resulting in the inaccurate determination of some trace heavy metal elements

When ICP or ICP-MS is used for detection, a large amount of sodium chloride will also block the nebulizer or deposit on the torch and sampling cone, thus affecting the normal use of the instrument

[0003] At present, the methods for detecting heavy metal pollution residues in high-salt samples at home and abroad either use organic solvents, or require self-made complexing agents, or use special equipment, which are not easy to promote in ordinary laboratories. The complexing agent has a short lifespan and cannot be reused for a long time

The matrix improver method is often used, such as: ammonium dihydrogen phosphate, magnesium nitrate, palladium nitrate, etc., but experiments have proved that the improvement ability of the matrix improver is very limited, and the sodium chloride content of the system is best controlled at 1 / 1000 Within five, when encountering samples with high salt content (such as saturated saline), the background interference cannot be overcome at all. At the same time, there are trace amounts of heavy metals in food, it is not advisable to use dilution methods to reduce the content of sodium chloride, so the current The method of adding matrix improver is only a palliative solution that cannot fundamentally solve the problem

The matrix matching method actually still depends on the matrix modifier. The limitation of using the matrix modifier to eliminate the interference of sodium chloride still exists, and it is still unable to accurately detect high-salt samples.

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