Standard No.:	GB/T 223.49-1994
Chinese Name:	钢铁及合金化学分析方法 萃取分离-偶氮氯膦mA分光光度法测定稀土总量
English Name:	Methods for chemical analysis of iron, steel and alloy Extraction separation-chlorophosphonazo mA spectrophotometric method for the determination of the total rare earth content
Professional Classification:	H11 Steel and iron alloy analysis method
Professional Classification:	GB National Standard
ICS Classification:	77.080
Issued by:
Issued on:	1994-09-26
Implemented on:	1995-06-01
Status:	VALID
Language:	English
File Format:	PDF
Word Count:
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1 Subject Content and Application Scope

This Standard specifies the PMBP - extraction separation - chlorophosphonazo mA spectrophotometric method for the determination of the total rare earth content.
This standard is applicable to determination of total rare earth content in carbon steel, alloy steel, high temperature alloy and precision alloy. Determination range: 0.0010%~0.20%.

2 Principle

Where pH is about 2, extraction separation of iron shall be conducted with acetylacetone - trichloromethane. Where pH is 5.5, with the existence of ammonium thiocyanate and sulfosalicylic acid, PMBP-benzene is applied to extract rare earth to be separated from other coexisting elements. Back extraction is applied with diluted hydrochloric acid. Chlorophosphonago mA and rare earth generate blue coordination compound, and measure the absorbance at the wavelength of 670 nm at spectrophotometer.
Take the color development curve of gadolinium with a given amount of oxalic acid and Zn-EDTA as the working curve to determine the total rare earth content.