Determination of Cr in Hollow Capsules by Atomic Absorption Graphite Furnace Method

Comparison of High Pressure Digestion, Microwave Digestion, and Wet Sample Processing Methods

1.Preparation of reagents and standard solutions required for the experiment

1.1 Reagents

Nitric acid (HNO3): ultra pure

Perchloric acid (HClO4): High grade purity

Chromium single element standard solution (National Center for Reference Material Research)

1.2 Standard solution preparation

1.2.1 Preparation of chromium standard intermediate solution: Take 100uL of chromium single element standard solution with a concentration of 1000ug/mL and place it in a 100mL volumetric flask. Add 2mL of nitric acid and dilute to the mark with deionized water to obtain a chromium standard intermediate solution with a concentration of 1 μ g/mL.

1.2.2 Preparation of Chromium Standard Curve: Take 0, 0.25, 0.50, 0.75, 1.00, 1.50, and 2.50mL of the chromium standard intermediate solution prepared above into a 50mL volumetric flask, add 1mL of nitric acid, dilute with deionized water, and prepare the 0, 5, 10, 15, 20, 30, and 50ng/mL series.

Summary of Method 2

Chromium is an essential trace element for the human body, and its deficiency or excess can cause serious harm to both humans and animals. Moderate chromium can increase the breakdown and excretion of cholesterol in the human body, and is an effective component of the glucose energy factor in the body. Lack of chromium can affect the metabolism of sugars and lipids, but excessive chromium can also pose a risk of cancer.

The determination of chromium is usually carried out by colorimetric method and atomic absorption spectroscopy. There are many interference factors in colorimetric method, and the operation is complicated; Atomic absorption spectroscopy has the advantages of easy operation, speed, and accuracy. This article refers to the 2010 edition of the Chinese Pharmacopoeia and the food testing method GB-T5009.123-2003 "Determination of Chromium in Food". Multiple user hollow capsule samples were processed using high-pressure digestion, microwave digestion, and wet methods. After being tested in a graphite furnace, the results of the three methods were compared and found to be very close, proving that all three methods are suitable for detecting chromium in capsules.

3. Instruments and working conditions required for the experiment

3.1 Main instruments

AA7003 atomic absorption spectrophotometer

constant temperature drying oven

High pressure digestion tank

Microwave digestion instrument

electric hot plate

Adjustable electric furnace

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