Determination of Ca, Mg, Al and Ba Content in Cored Wire
1 Sample solution preparation：
2 Experimental equipment and reagents：
3 Instrument conditions
4 Standard solution preparation
5 Standard curve
When measuring Ca and Mg sample solutions, their lanthanum chloride concentration need to be the same as that in respective standard solution.
0.1000g sample (precision to 0.0001g) was weighed and placed in a PTFE beaker, 5mL nitric acid was added, and HF was slowly added drop by drop, until the violent reaction stops. 5mL perchloric acid was added, heated to smoke until nearly dry, cooled slightly, then 3mL perchloric acid was added and smoke until nearly dry. 10mL hydrochloric acid was added, heated to dissolve the salt, cooled to room temperature, transferred to a 50mL volumetric flask, diluted to make up to the volume with water, shaken well, spared for later use.
2 Experimental equipment and reagents：
AA7000 series atomic absorption spectrophotometer (with Ca, Mg, Al, Ba hollow cathode lamp, EWAI Inc.)
Temperature-controlled hot plate
PTFE beaker
PTFE volumetric flask
Hydrochloric acid (HCl): excellent grade purity
Nitric acid (HNO3): excellent grade purity
Hydrofluoric acid (HF): excellent grade purity
Perchloric acid (HClO4): excellent grade purity
100g / L lanthanum chloride solution: 11.73g lanthanum oxide was weighed and placed in a 100mL volumetric flask, first wet with small amount of water and then 37.5mL hydrochloric acid was added. Deionized water was added to dilute and make up to the volume.
Calcium standard solution (National Reference Materials Research Center)
Magnesium standard solution (National Reference Materials Research Center)
Aluminium standard solution (National Reference Materials Research Center)
Temperature-controlled hot plate
PTFE beaker
PTFE volumetric flask
Hydrochloric acid (HCl): excellent grade purity
Nitric acid (HNO3): excellent grade purity
Hydrofluoric acid (HF): excellent grade purity
Perchloric acid (HClO4): excellent grade purity
100g / L lanthanum chloride solution: 11.73g lanthanum oxide was weighed and placed in a 100mL volumetric flask, first wet with small amount of water and then 37.5mL hydrochloric acid was added. Deionized water was added to dilute and make up to the volume.
Calcium standard solution (National Reference Materials Research Center)
Magnesium standard solution (National Reference Materials Research Center)
Barium standard solution (National Reference Materials Research Center)
3 Instrument conditions
| Parameter | Wavelength （nm） |
Slit width（nm） | Burner height（mm） | Fuel gas flow rate（L/min） | Lamp current（mA） | Flame type |
| Ca | 422.7 | 0.2 | 10 | 1.5 | 2.0 | Air – acetylene |
| Mg | 285.2 | 0.2 | 10 | 1.5 | 3.0 | Air – acetylene |
| Al | 309.3 | 0.2 | 8 | 3.0 | 3.0 | Air – acetylene |
| Ba | 553.6 | 0.4 | 8 | 4.0 | 4.0 | Air - acetylene |
4 Standard solution preparation
For each 100 mL Ca and Mg standard solutions, 1.5 mL 100 g/L lanthanum chloride solution should be added respectively.
| Element | Concentration（μg/mL） | ||||
| Ca | 0 | 0.5 | 1.0 | 2.0 | 3.0 |
| Mg | 0 | 0.01 | 0.05 | 0.1 | 0.2 |
| Al | 0 | 5.0 | 10.0 | 15.0 | 20.0 |
| Ba | 0 | 1.0 | 5.0 | 10.0 | 20.0 |
When measuring Ca and Mg sample solutions, their lanthanum chloride concentration need to be the same as that in respective standard solution.
 Ca Curve equation：Y=0.06997*X-0.00136 Linearity coefficient：0.99990 |
 Mg Curve equation：Y=-1.40520*X^2+1.75320*X+0.00604 Linearity coefficient：1.00000 |
 Al Curve equation：Y=0.00909*X+0.00025 Linearity coefficient：1.00000 |
 Ba Curve equation：Y=0.00351*X-0.00076 Linearity coefficient：0.99930 |
