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Determination of 10 Metals in Sediments by ICP-AES after Microwave Digestion only using HCl and HNO3

时间: 2012-7-25 发布人:

Determination of 10 Metals in Sediments by ICP-AES after Microwave Digestion only using HCl and HNO3

 

Qing Tan,1* Tian Tian,2 Hui Yin,1 Jin He,1 Yuan Tian,1

1Chengdu Environment Monitoring Centre, 610072,China; 2Qingyang Environment Monitoring Station, 610072, China

E-mail: xxtanqing@163.com

 

Usually, a wet digestion step using HF/HClO4 is preferred for decomposing sediments for trace metals detection. However, HF is highly corrosive and the boiling point of HClO4 is rather high, and this makes the final heating step time-consuming. In order to save sample preparation time, microwave digestion [1, 2] only using HCl and HNO3 associated with an ultrasonic-assisted leaching step [3, 4] was proposed in this study.

Sample preparation procedure: 0.2 g samples were accurately weighed into Teflon vessels. 3 mL HNO3 and 10 mL HCl were added and heated to 200℃ in the microwave oven for 20 min. The vessels were then heated on the electric heater at 180℃ to nearly dryness. The residues were dissolved with 10 mL 1% HNO3. Slurries were prepared by ultrasonicating for 20 minutes and then quantitatively transferred to Polyethylene volumetric flasks. Thereafter, slurries were transferred into the centrifuge tubes and centrifuged for 10 min at 3000 rpm, and finally 10 trace metals in the supernatants were determined by ICP-AES.

The analytical results listed in Table 1 refer to two geochemical standard materials treated by the proposed method. It can be seen that the analytical results are in good agreement with the certified values while the precision is better than 5% in terms of RSD. Finally, the proposed method was also applied to the determination of the 10 metals in an unknown sediment sample. The recoveries were typically in the range of 94.2%~106%.

Table 1. The analytical results of 10 metals in sediments (mg g-1)

 

Metal

GBW08301

GSD-9

Unknown Sample

Measured value*

Certified value*

Measured value*

Certified value*

Measured value*

Recovery(%)

Cu

Pb

Zn

Co

Mn

Ni

Ba

Ti

Fe (%)

Al (%)

49.5±2.1

77.2±2.2

264±15

16.0±1.0

964±22

30.5±1.3

363±11

5574±124

3.80±0.12

7.59±0.33

53±6

79±12

251

16.5±1.5

975±34

32

375±22

5635

3.94±0.13

7.32

32.8±1.8

21.1±0.7

76.5±3.8

15.4±0.9

599±11

32.6±1.0

421±15

5424±102

7.39±0.09

10.47±0.42

32.1

23

78

14.4

620

32.3

430

5500

7.46

10.58

22.3±0.6

38.5±2.6

95.9±1.8

13.9±0.7

717±20

24.4±0.4

295±18

4425±87

3.26±0.09

5.87±0.4

99.5

96.1

106

97.9

98.5

102

98.9

101

95.4

94.2

 

* Average of three measurements ±3 SD.

 

References

[1] Abu-sarma A, Morris JS Koirtyohann SR. Anal Chem, 1975, 47(8): 1475-1477.

[2] Ellyn S, Bear Y, Paul J, et al. Anal Chem, 1997, 69: 758-766.

[3] Priego-Capote F, de Castro M D L. Trends Anal Chem, 2004, 23(9): 644-653.

[4] Tan Q, Wu P, Wu L, Hou XD. Microchim. Acta, 2006, 155: 441-445.