GB/T 36406-2018Test method of tin penetrated on float glass surface (English PDF)

4.2 Reagent

The density of commercially available solution reagents listed in this Standard refers to the density (rho) at 20°C ambient conditions. The unindicated concentration of the used acid refers to the concentration of commercially available acid.

Use the volume ratio to express the dilution degree of the reagent, for instance, hydrochloric acid (1+3) means that the 1 part by volume of concentrated hydrochloric acid is mixed with 3 parts by volume of water.

4.3 Parallel test

Perform two sets of tests in parallel under repetitive conditions.

5.1 Phenylfluorone-cetyltrimethylammonium bromide spectrophotometry

5.1.1 Principle

The surface of the glass sample was etched with a mixed acid solution of hydrofluoric acid-nitric acid; transfer all the penetrated tin into the mixed acid solution. Use potassium permanganate to oxide all the divalent tin into tetravalent tin. Tin(Iv)- phenylfluorone-cetyltrimethylammonium bromide forms a red ternary complex in a sulfuric acid medium. Measure its absorbance at a wavelength of 510nm. In a certain centration range, the absorbance is proportional to the concentration of tin. From this, the amount of penetrated tin per unit surface area (µg/cm2) of the glass sample can be calculated.

5.1.2 Reagent

5.1.2.1 Nitric acid

The density is about 1.42g/mL; the mass fraction is 65%~68%.

5.1.2.2 Hydrofluoric acid

Warning. Hydrofluoric acid is toxic and corrosive. Wear rubber gloves during operation to prevent skin contact!

The density is about 1.14g/mL; the mass fraction is 40% above.

5.1.2.15 Phenylfluorone (0.3g/L)

Take 0.15g of phenylfluorone; dissolve into 5mL of sulfuric acid solution (5.1.2.7); dilute with anhydrous ethanol to 500mL.

5.1.2.16 Tin standard stock solution (100µg/mL)

Accurately take 0.1000g of high-purity tin metal (more than 99.9% tin content; wash the surface oxide with dilute hydrochloric acid before weighing; then wash thoroughly with water and anhydrous ethanol; dry it); place into 10mL of sulfuric acid (5.1.2.3); evaporate till there is sulfur dioxide white smoke; take off to cool off. Use sulfuric acid solution (5.1.2.8) to dissolve; then transfer into 1000mL volumetric flask; dilute with sulfuric acid solution (5.1.2.8) to the scale; shake up; or use the nationally recognized standard solution to prepare.

5.1.2.17 Tin standard use solution (10.0µg/mL)

Accurately pipette 10.00mL of tin standard stock solution (5.1.2.16) into 100mL volumetric flask; dilute with sulfuric acid solution (5.1.2.9) to the scale; shake up.

5.1.3 Drawing of standard curve

Accurately pipette 0.00mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, 5.00mL of tin standard use solution (5.1.2.17) into a group of 100mL volumetric flasks; separately add 10mL of sulfuric acid solution (5.1.2.8); titrate potassium manganate solution (5.1.2.11) till red color appears; add water to about 30mL. Titrate ascorbic acid solution (5.1.2.12) till the solution is colorless; titrate another excessive 2 drops. Successively add 6mL of oxalic acid aqueous solution (5.1.2.13), 10mL of ascorbic acid solution (5.1.2.12), 10mL of CTMAB solution (5.1.2.14), 8mL of penylfluorone solution (5.1.2.15). Shake well after each addition of a solution. Finally, dilute with water to the scale; shake up; prepare the standard solution series with tin contents of 0.00µg, 10.0µg, 20.0µg, 30.0µg, 40.0µg, 50.0µg. After 20min, take blank reagent as a reference on the spectrophotometer at the wavelength of 510nm; use 0.5cm cuvette to measure the absorbance of the solution; draw the standard curve of tin content in tin standard solution corresponding to the absorbance.

5.1.4 Analysis steps

5.1.4.1 Preparation of sample solution

Cut the glass piece into a rectangular piece with size of 5cm×5cm; use the tin surface tester to distinguish the to-be-tested surface. Use the Vernier caliper (3.4) to accurately measure the length and width of the to-be-tested surface of the glass sample; calculate its surface area (S1). Clean it, and place into plastic erosion plate (3.3.1); and maintain […]

5.2.2.7 Sulfuric acid solution (1+1)

Warning. Improper dilution is dangerous!

Slowly inject 1 part by volume of sulfuric acid into 1 part by volume of water, mix evenly.

5.2.2.9 Zirconium oxychloride solution (Zr10mg/mL)

Take 0.36g of zirconium oxychloride (ZrOCl2·8H2O); dissolve into 10mL of water.

5.2.2.10 Tartaric acid-zirconium matrix improver (Zr 1mg/mL; tartaric acid 100mg/mL)

Pipette 1mL of zirconium oxychloride solution (5.2.2.9) into a small beaker containing 1mL of nitric acid solution (5.2.2.6); successively add 8mL of water, 1g of tartaric acid (5.2.2.8); dissolve completely.

5.2.2.11 Tin standard stock solution (100µg/mL)

Accurately take 0.1000g of high-purity tin metal (more than 99.9% tin content; wash the surface oxide with dilute hydrochloric acid before weighing; then wash thoroughly with water and anhydrous ethanol; dry it); place into 100mL beaker; add 10mL of nitric acid (5.2.2.1); after dissolving, transfer into 1000mL volumetric flask; dilute with nitric acid solution (5.2.2.6) to the scale; shake up; use the nationally recognized standard solution to prepare.

5.2.2.12 Tin standard intermediate solution (10µg/mL)

Accurately pipette 10.00mL of tin standard stock solution (5.2.2.11) into 100mL volumetric flask; dilute with the nitric acid solution (5.2.2.6) to the scale; shake up.

5.2.2.13 Tin standard use solution (1µg/mL)

Accurately pipette 10.00mL of tin standard intermediate solution (5.2.2.12) into 100mL volumetric flask; dilute with nitric acid solution (5.2.2.6) to the scale; shake up.

5.2.3 Drawing of standard curve

5.2.3.1 Use a micropipette to transfer about 150µL of zirconium oxychloride solution (5.2.2.9) into the pyrolytic graphite tube; select the instrument operating parameters and conditions as per the instrument operating instructions; perform a full process atomization in the graphite furnace; prepare the zirconium-coated graphite tube.

5.2.3.2 Separately and accurately pipette 0.00mL, 1.00mL, 2.00mL, 4.00mL, 6.00mL, 8.00mL, 10.00mL of tin standard use solution (5.2.2.13) into a group of 100mL […]