Determination of total chromium in soil. Flame atomic absorption spectrophotometry (1)

(1) Scope of application

It is suitable for the determination of total chromium in soil

(2) Method principle

The method of hydrochloric acid- nitric acid - hydrofluoric acid -perchloric acid is used to destroy the mineral crystal lattice of the soil, so that all the elements to be tested in the sample enter the test solution.

(3) Reagents and materials

The experimental water is newly prepared deionized water or distilled monk water.

(1) Hydrochloric acid, nitric acid, hydrofluoric acid , and perchloric acid are class pure

(2) Hydrochloric acid (1+1) solution

(3) Ammonium chloride aqueous solution (10%): Weigh accurately 10g of ammonium chloride (NH ₄ Cl), dissolve it with a small amount of water and transfer the entire amount into a 100mL volumetric flask, dilute to the mark with water, and shake it well

(4) Chromium standard stock solution, p=1.

(5) Standard filling solution, p=50mg/L: Pipette 5.

(4) Instruments and equipment

Atomic absorption spectrophotometer, chromium hollow cathode lamp, microwave digestion, agate mill or the like

Different models of atomic absorption spectrophotometer have different optimal measurement conditions, which can be selected according to the manual of the instrument

Table 5-14 Instrument measurement conditions

Table 5-15 Heating program of microwave digestion instrument

(5) Interference and elimination

(1) Chromium is easy to form high-temperature resistant oxides, and its atomization efficiency is greatly affected by the flame state and the height of the burner.

(2) Adding ammonium chloride can inhibit the interference of coexisting ions such as iron, cobalt, nickel, vanadium, aluminum, magnesium, and lead

Related Links: Determination of Lead, Zinc and Cadmium in Solid Waste Flame Atomic Absorption Spectrophotometry (3)