Determination of Barium, Chromium, Cadmium, Copper, Lead, and Tin in Medical Nasal Oxygen Tubes

1. Preparation Work

1.1 Reagents

Concentrated hydrochloric acid (HCl): analytical grade.

1.2 Preparation of Reagents

Hydrochloric acid (1:1): mix concentrated hydrochloric acid with ultrapure water at a 1:1 volume ratio.

1.3 Standard Substances and Standard Solution Preparation

Standard stock solution of barium, chromium, cadmium, copper, lead, and tin (1.0 mg/mL): purchased from Gangyan Nake Testing Technology Co., Ltd. (National Iron and Steel Materials Testing Center)

1.3.1 Mixed standard solution of barium, chromium, cadmium, copper, lead, and tin (barium, chromium, copper, lead, tin at 2.0 mg/L, cadmium at 0.1 mg/L): Take 2.0 mL from the barium, chromium, copper, lead, tin stock solutions and 0.1 mL from the cadmium stock solution, put them into the same 1000 mL volumetric flask, add 2.0 mL of HCl (1:1), top up to the mark with ultrapure water, and mix well.

1.3.2 Preparation of mixed standard curve concentrations:

Take 0 mL, 0.5 mL, 1.0 mL, 2.0 mL, 3.0 mL, and 4.0 mL of the mixed standard solution (1.3.1) into six 100 mL volumetric flasks, dilute with ultrapure water, and mix well. Their concentrations correspond to 0 ng, 10.0 ng, 20.0 ng, 40.0 ng, 60.0 ng, 80.0 ng of barium, chromium, copper, lead, tin per mL, and 0 ng, 0.5 ng, 1.0 ng, 2.0 ng, 3.0 ng, 4.0 ng of cadmium per mL.

1.4 Instruments and Equipment

Note: All glass instruments used must be soaked in 1:4 nitric acid solution for more than 24 hours, rinsed repeatedly with water, and finally rinsed with deionized water.

Atomic absorption spectrophotometer (CAAM-2001E with graphite furnace and hollow cathode lamp for barium, chromium, cadmium, copper, lead, and tin).

Drying oven.

Electronic balance: sensitivity of 0.1 mg and 1 mg.

2. Sample Preparation

Prepare the test solution according to item 8 of Table 1 in GB/T 14233.1-2022.

The sample is a plastic hose, cut into small segments of about 2-5 mm with scissors. Weigh 5.00 g and 10.00 g into two 100 mL conical flasks, add 50 mL and 100 mL of pure water respectively according to the method's ratio, then place in a drying oven set to 70°C. After 24 hours, remove and cool, replenish any evaporated water, shake to mix well, and take part of the liquid for testing. ...