Item

Index

90%

88%

85%

Food grade

Na₂ S₂ O₄

≥90%

≥88%

≥85%

≥85%

Fe)

≤ 20ppm

≤ 20ppm

≤ 20ppm

≤ 20ppm

Zn)

≤ 1ppm

≤ 1ppm

≤ 1ppm

≤ 1ppm

Clarity

Clear

Clear

Clear

Clear

EDTA

-

-

-

Qualified

As)

-

-

-

≤ 1ppm

Others heavy metals ( as Pb )

-

-

-

≤ 1ppm

Formate ( as HCHO )

-

-

-

≤ 0.05%

Water insoluble matter

≤ 0.05%

≤ 0.05%

≤ 0.05%

-

Valid period (month)

12

12

12

12