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Gold in Tuanjiegou natural waters: A method of determination by preconcentration with pretreated polyurethane foam in the field
Journal of Geochemical Exploration, 33 (1989) 255-259
255
Elsevier Science Publishers B,V., Amsterdam - - Printed in The Netherlands
Gold in Tuanjiegou natural waters: a method of determination by preconcentration with pretreated polyurethane foam in the field HOU ZHIHUI
Institute o/Geophysical and Geochemical Exploration, Langfang, Hebei 102849, The People's Republic of China (Received July 29, 1988; revised and accepted August 30, 1988)
ABSTRACT Hou, Z., 1989. Gold in Tuanjiegou natural waters: a method of determination by preconcentration with pretreated polyurethane foam in the field. In: Xie Xuejing and S.E. Jenness (Editors), Geochemical Exploration in China. J. Geochem. Explor., 33: 255-259. A rapid method has been developed for determining the concentration of Au in natural waters in Tuanjiegou, Heilongjiang Province, northeastern China. By preconcentration with pretreated polyurethane foam in the field, Au was analysed by graphite furnace atomic absorption spectrophotometry. INTRODUCTION
Gold content in rocks, soils, stream sediments, and vegetation has been successfully determined by preconcentration with polyurethane foam (Li, 1983; Hou, 1987), but little is known of the determination of Au in natural waters by preconcentration with polyurethane foam in the field. Present methods for determining trace amounts of Au in water involve anion-exchange procedures (Chao, 1969); spectrochemical analysis with preconcentration of Au on activated carbon (Chernyayev et al., 1969); neutron activation (Gosling et al., 1971 ); evaporation electrothermal atomization (Turner and Ikramuddin, 1982 ); electrothermal atomization after coprecipitation with tellurium (McHugh, 1983); and solvent extraction and electrothermal atomization (McHugh, 1984). A method for determining the concentration of Au in natural waters has been developed as part of the author's Masters thesis under the direction of Prof. Xie Xuejing at the Institute of Geophysical and Geochemical Exploration, Langfang. The following paper describes the new method and its application in detail. 0375-6742/89/$03.50
© 1989 Elsevier Science Publishers B.V.
256
H0U ZHIHUI
METHOD
Pretreatment of polyurethane foam Cut the polyurethane foam into ~ 0.3-g pieces, soak it in deionized water and boil it. After cooling, place it in ~ 5% aqua regia solution for 24 h. T h e n wash it with deionized water until it has no acidity, squeeze it dry, and wrap it up for use in the field. The polyurethane foam pretreated in this way is called PPF.
Processing condition in the field Before sampling, wash the polyethylene container and cover with the water to be taken 3-5 times. Collect a 2-1 water sample, acidify it with 1 : 1 HCI to pH < 3 on site in order to minimize the adsorption of trace amounts of Au by the container (Chao et al., 1968). Gold in natural water was preconcentrated by P P F in the field camp laboratory. The apparatus used in the field is shown in Figure 1. The sample was
Lip button Filter
Column PPF Down
I
/ Fig. 1. P P F apparatus used in the field.
button
DETERMINATION OF GOLD WITH POLYURETHANEFOAM
257
put through a filter (4.5 /~m pore size) to distinguish between residual and "solute gold ''1. The filtrate was processed with PPF. Before processing, the air in the P P F ' s pores must be expelled so as to enhance the adsorption. The flow rate of water was adjusted by up and down buttons. The flow rate selected in the study was 3 ml m i n - 1. Extensive precautions were taken throughout sampling and preconcentration procedures to eliminate the possibility of sample contamination. Gold in the P P F and residual was determined by graphite furnace atomic absorption spectrophotometry in the laboratory.
Analysis Put the P P F into a porcelain crucible, and ash in a muffle furnace for about 2 h. A white or yellow colour is preferable for the ash. After cooling, add 3-5 ml of aqua regia and heat at a temperature of 80-100°C until a mirror-like surface is formed. Now, quantitatively add 3 ml 5% aqua regia, stir, and allow it to become clear. The Au was analysed by GFAAS (Hou, 1987 ). Residual Au was determined by dissolving the sediment filtered in the field. The advantages of the method were its light apparatus, easy processing, and convenient shipment. A precision study showed that the relative standard deviation is 19%. A recovery study showed that the method recovers Au at an average of 90%. The detection limit with a 2-1 sample was I ppt. RESULT
The method was used to investigate Au in the natural waters in Tuanjiegou (a placer Au area), Heilongjiang Province, northeastern China. The results are shown in Table 1. In slope water, stream water, and ground water the solute Au always exceeds the residual Au, which suggests that Au is not an inert TABLE1 Gold concentration in natural waters in Tuanjiegou (in ppt) Water type
Stream water Slope water ~ Ground water
No. of samples
12 6 7
Range
Average
residual
solute
residual
solute
No-2.1 No-1.2 0.1
0.8-8.4 0.5-3.4 0.6-0.9
0.4 0.7 0.1
2.1 2.7 0.8
~Slope w a t e r - - w a t e r oozed from the slope-soil horizons. No -- Not detected. 'Solute Au represents the Au passing through a 4.5/zm filter whether in true solution, as an organic or inorganic complex, or as a colloid, according to Perel'man (1957).
258
HOU ZH IHUI
element, b u t a mobile e l e m e n t in the surficial biogeochemical e n v i r o n m e n t . In P e r e l ' m a n ' s ( 1957 ) classification, Au is c a t a l o g u e d with the m i g r a t o r y to easily mobile elements. T h e solute Au c o n t r i b u t e s to the f o r m a t i o n of placer Au particles in T u a n j i e g o u (Xie et al., 1987). CONCLUSIONS (1) A m e t h o d for the d e t e r m i n a t i o n of Au in n a t u r a l w a t e r s by p r e c o n c e n t r a t i o n with P P F in the field and analysis with graphite f u r n a c e atomic absorption s p e c t r o p h o t o m e t r y has been developed. Its light apparatus, simple operation, a n d good r e c o v e r y are suitable to the field conditions. (2) Solute Au in T u a n j i e g o u c o n t r i b u t e s to the f o r m a t i o n of placer Au particles. ACKNOWLEDGEMENTS T h e a u t h o r gratefully acknowledges the useful discussions with, a n d the critical review by, his director and thesis advisor Prof. Xie Xuejing. Mr. Liu S h u x i n a n d Mr. W a n g Zhigui are t h a n k e d for t h e i r help in the field. T h e a u t h o r especially t h a n k s Mr. L u Yinxiu for his considerable assistance in developing this p r e c o n c e n t r a t i o n system. F i n a n c i a l assistance in the field was a w a r d e d by the Heilongjiang Geology a n d M i n e r a l Resources Bureau.
REFERENCES Chao, T.T., 1969. Determination of gold in waters in the nanogram range by anion exchange and atomic absorption spectrophotometry. Econ. Geol., 64: 287-290. Chao, T.T., Jenne, E.A. and Heppting, L.L., 1968. Prevention of adsorption of trace amounts of gold by containers. U.S. Geol. Surv., Prof. Pap,, 600-D, pp. 16-19. Chernyayev, A.M., Chernyayer, L.E., Yeremeyeva, M.N. and Andreyev, M.I., 1969. Hydrogeochemistry of gold. Geochem. Int., 6: 348-358. Gosling, A.W., Jenne, E.A. and Chao, T.T., 1971. Gold content of natural waters in Colorado. Econ. Geol., 66: 309-313. Hou, Zh.H., 1987. Influence of the siliceous composition in determination of gold in plant material. J. Geochem. Explor., 27: 323-328. Li, Sh.L., 1983. Determination of gold in mineral materials by extraction with polyurethane foam and atomic absorption spectrophotometry. Phys. Chem. Anal., 20:56-58 (in Chinese). McHugh, J.B., 1983. Determination of gold in water in the nanogram range by electrothermal atomization after coprecipitation with tellurium. At. Spectrosc., 4: 66-68. McHugh, J.B., 1984. Gold in natural water: a method of determination by solvent extraction and electrothermal atomization. J. Geochem. Explor., 20: 303-310. Perel'man, A.E., 1957. Introduction to Landscape Geochemistry. Translated into Chinese by J.Sh. Chen et al., 1958, Geological Publishing House. Turner, L.D. and Ikramuddin, M., 1982. Electrothermal atomic absorption determination of gold, silver, and arsenic in stream waters and their relationship to gold-silver occurrences in the
I)ETERM1NATION OF GOLD WITH POLYURETHANE FOAM
259
Republic Graben, NE Washington. In: A.A. Levinson (Editor), Precious Metals in the Northern Cordillera. Assoc. Explor. Geochem., Rexdale, Ont., pp. 79-88. Xie, X.J., Hou, Zh.H. and Liu, Sh.X., 1987. The genesis of placer gold in Tuanjiegou, Northeastern China. Geol. Prospect., 23:46-55 {in Chinese).
255
Elsevier Science Publishers B,V., Amsterdam - - Printed in The Netherlands
Gold in Tuanjiegou natural waters: a method of determination by preconcentration with pretreated polyurethane foam in the field HOU ZHIHUI
Institute o/Geophysical and Geochemical Exploration, Langfang, Hebei 102849, The People's Republic of China (Received July 29, 1988; revised and accepted August 30, 1988)
ABSTRACT Hou, Z., 1989. Gold in Tuanjiegou natural waters: a method of determination by preconcentration with pretreated polyurethane foam in the field. In: Xie Xuejing and S.E. Jenness (Editors), Geochemical Exploration in China. J. Geochem. Explor., 33: 255-259. A rapid method has been developed for determining the concentration of Au in natural waters in Tuanjiegou, Heilongjiang Province, northeastern China. By preconcentration with pretreated polyurethane foam in the field, Au was analysed by graphite furnace atomic absorption spectrophotometry. INTRODUCTION
Gold content in rocks, soils, stream sediments, and vegetation has been successfully determined by preconcentration with polyurethane foam (Li, 1983; Hou, 1987), but little is known of the determination of Au in natural waters by preconcentration with polyurethane foam in the field. Present methods for determining trace amounts of Au in water involve anion-exchange procedures (Chao, 1969); spectrochemical analysis with preconcentration of Au on activated carbon (Chernyayev et al., 1969); neutron activation (Gosling et al., 1971 ); evaporation electrothermal atomization (Turner and Ikramuddin, 1982 ); electrothermal atomization after coprecipitation with tellurium (McHugh, 1983); and solvent extraction and electrothermal atomization (McHugh, 1984). A method for determining the concentration of Au in natural waters has been developed as part of the author's Masters thesis under the direction of Prof. Xie Xuejing at the Institute of Geophysical and Geochemical Exploration, Langfang. The following paper describes the new method and its application in detail. 0375-6742/89/$03.50
© 1989 Elsevier Science Publishers B.V.
256
H0U ZHIHUI
METHOD
Pretreatment of polyurethane foam Cut the polyurethane foam into ~ 0.3-g pieces, soak it in deionized water and boil it. After cooling, place it in ~ 5% aqua regia solution for 24 h. T h e n wash it with deionized water until it has no acidity, squeeze it dry, and wrap it up for use in the field. The polyurethane foam pretreated in this way is called PPF.
Processing condition in the field Before sampling, wash the polyethylene container and cover with the water to be taken 3-5 times. Collect a 2-1 water sample, acidify it with 1 : 1 HCI to pH < 3 on site in order to minimize the adsorption of trace amounts of Au by the container (Chao et al., 1968). Gold in natural water was preconcentrated by P P F in the field camp laboratory. The apparatus used in the field is shown in Figure 1. The sample was
Lip button Filter
Column PPF Down
I
/ Fig. 1. P P F apparatus used in the field.
button
DETERMINATION OF GOLD WITH POLYURETHANEFOAM
257
put through a filter (4.5 /~m pore size) to distinguish between residual and "solute gold ''1. The filtrate was processed with PPF. Before processing, the air in the P P F ' s pores must be expelled so as to enhance the adsorption. The flow rate of water was adjusted by up and down buttons. The flow rate selected in the study was 3 ml m i n - 1. Extensive precautions were taken throughout sampling and preconcentration procedures to eliminate the possibility of sample contamination. Gold in the P P F and residual was determined by graphite furnace atomic absorption spectrophotometry in the laboratory.
Analysis Put the P P F into a porcelain crucible, and ash in a muffle furnace for about 2 h. A white or yellow colour is preferable for the ash. After cooling, add 3-5 ml of aqua regia and heat at a temperature of 80-100°C until a mirror-like surface is formed. Now, quantitatively add 3 ml 5% aqua regia, stir, and allow it to become clear. The Au was analysed by GFAAS (Hou, 1987 ). Residual Au was determined by dissolving the sediment filtered in the field. The advantages of the method were its light apparatus, easy processing, and convenient shipment. A precision study showed that the relative standard deviation is 19%. A recovery study showed that the method recovers Au at an average of 90%. The detection limit with a 2-1 sample was I ppt. RESULT
The method was used to investigate Au in the natural waters in Tuanjiegou (a placer Au area), Heilongjiang Province, northeastern China. The results are shown in Table 1. In slope water, stream water, and ground water the solute Au always exceeds the residual Au, which suggests that Au is not an inert TABLE1 Gold concentration in natural waters in Tuanjiegou (in ppt) Water type
Stream water Slope water ~ Ground water
No. of samples
12 6 7
Range
Average
residual
solute
residual
solute
No-2.1 No-1.2 0.1
0.8-8.4 0.5-3.4 0.6-0.9
0.4 0.7 0.1
2.1 2.7 0.8
~Slope w a t e r - - w a t e r oozed from the slope-soil horizons. No -- Not detected. 'Solute Au represents the Au passing through a 4.5/zm filter whether in true solution, as an organic or inorganic complex, or as a colloid, according to Perel'man (1957).
258
HOU ZH IHUI
element, b u t a mobile e l e m e n t in the surficial biogeochemical e n v i r o n m e n t . In P e r e l ' m a n ' s ( 1957 ) classification, Au is c a t a l o g u e d with the m i g r a t o r y to easily mobile elements. T h e solute Au c o n t r i b u t e s to the f o r m a t i o n of placer Au particles in T u a n j i e g o u (Xie et al., 1987). CONCLUSIONS (1) A m e t h o d for the d e t e r m i n a t i o n of Au in n a t u r a l w a t e r s by p r e c o n c e n t r a t i o n with P P F in the field and analysis with graphite f u r n a c e atomic absorption s p e c t r o p h o t o m e t r y has been developed. Its light apparatus, simple operation, a n d good r e c o v e r y are suitable to the field conditions. (2) Solute Au in T u a n j i e g o u c o n t r i b u t e s to the f o r m a t i o n of placer Au particles. ACKNOWLEDGEMENTS T h e a u t h o r gratefully acknowledges the useful discussions with, a n d the critical review by, his director and thesis advisor Prof. Xie Xuejing. Mr. Liu S h u x i n a n d Mr. W a n g Zhigui are t h a n k e d for t h e i r help in the field. T h e a u t h o r especially t h a n k s Mr. L u Yinxiu for his considerable assistance in developing this p r e c o n c e n t r a t i o n system. F i n a n c i a l assistance in the field was a w a r d e d by the Heilongjiang Geology a n d M i n e r a l Resources Bureau.
REFERENCES Chao, T.T., 1969. Determination of gold in waters in the nanogram range by anion exchange and atomic absorption spectrophotometry. Econ. Geol., 64: 287-290. Chao, T.T., Jenne, E.A. and Heppting, L.L., 1968. Prevention of adsorption of trace amounts of gold by containers. U.S. Geol. Surv., Prof. Pap,, 600-D, pp. 16-19. Chernyayev, A.M., Chernyayer, L.E., Yeremeyeva, M.N. and Andreyev, M.I., 1969. Hydrogeochemistry of gold. Geochem. Int., 6: 348-358. Gosling, A.W., Jenne, E.A. and Chao, T.T., 1971. Gold content of natural waters in Colorado. Econ. Geol., 66: 309-313. Hou, Zh.H., 1987. Influence of the siliceous composition in determination of gold in plant material. J. Geochem. Explor., 27: 323-328. Li, Sh.L., 1983. Determination of gold in mineral materials by extraction with polyurethane foam and atomic absorption spectrophotometry. Phys. Chem. Anal., 20:56-58 (in Chinese). McHugh, J.B., 1983. Determination of gold in water in the nanogram range by electrothermal atomization after coprecipitation with tellurium. At. Spectrosc., 4: 66-68. McHugh, J.B., 1984. Gold in natural water: a method of determination by solvent extraction and electrothermal atomization. J. Geochem. Explor., 20: 303-310. Perel'man, A.E., 1957. Introduction to Landscape Geochemistry. Translated into Chinese by J.Sh. Chen et al., 1958, Geological Publishing House. Turner, L.D. and Ikramuddin, M., 1982. Electrothermal atomic absorption determination of gold, silver, and arsenic in stream waters and their relationship to gold-silver occurrences in the
I)ETERM1NATION OF GOLD WITH POLYURETHANE FOAM
259
Republic Graben, NE Washington. In: A.A. Levinson (Editor), Precious Metals in the Northern Cordillera. Assoc. Explor. Geochem., Rexdale, Ont., pp. 79-88. Xie, X.J., Hou, Zh.H. and Liu, Sh.X., 1987. The genesis of placer gold in Tuanjiegou, Northeastern China. Geol. Prospect., 23:46-55 {in Chinese).