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Adsorption of aflatoxin B1 on montmorillonite
Research Note Adsorption of Aflatoxin B1 on Montmorillonite Q. Desheng,1 L. Fan, Y. Yanhu, and Z. Niya College of Animal Science, Huazhong Agricultural University, Wuhan 430070, China hydrogen bond, and AFB1 molecules did not penetrate into the interlayer area of Mont. The Mont, when added to the diet of broiler chicken at 0.5%, significantly diminished the adverse effects of feeding 200 µg of AFB1 /kg of feed. And the concentrations of Ca, P, Cu, Fe, Zn in the broiler bones were not affected by AFB1 and Mont, but the concentrations of Mn, Pb, and F were decreased by Mont.
(Key words: montmorillonite, aflatoxin, adsorption, broiler, mineral) 2005 Poultry Science 84:959–961
adsorptive law and adsorptive mechanism of AFB1 on aluminosilicate were uncertain, and aluminosilicates can have other effects on the deposit of minerals in animal bones when included in animal diets. Thus, the research reported herein was conducted to explore the adsorptive law and adsorptive mechanism and to evaluate the efficacy of Mont for protection against the toxicity of AFB1 and the deposit of minerals in male broiler chicks.
INTRODUCTION Aflatoxins (a structurally similar group of polysubstituted coumarins) have been recognized as important mycotoxins due to their toxicity and their occurrence as natural contaminants of feeds. Aflatoxin B1 (AFB1) and 3 structurally similar compounds (AFB2, AFG1, and AFG2) have been detected as contaminants of crops before harvesting and drying, in storage, and after processing and manufacturing. The frequent contamination of agricultural commodities with aflatoxin and the chronic exposure of poultry to these toxins can greatly affect the profitability of poultry production. Consequently, large-scale, practical, and cost-effective methods for detoxifying aflatoxin-containing feedstuffs currently are in great demand. A relatively new and more encouraging approach to control aflatoxin is the use of relatively nonnutritive adsorptive materials in the gastrointestinal tract of animals. Hydrated sodium calcium aluminosilicate at 0.5% of diet significantly diminishes many deleterious effects caused by AFB1 or other aflatoxins in chickens (Kubena et al., 1990; Kubena and Harvey, 1993; Scheideler, 1993; Phillips et al., 1988), turkeys (Kubena et al., 1991), growing swine (Harvey et al., 1989), growing lambs (Harvey et al., 1991), and goats (Nageswara Rao and Chopra, 2001). These reports show that aluminosilicates have good prospects when used in feed for alleviating aflatoxicosis, but the
MATERIALS AND METHODS Sorbents, calcium montmorillonite (Mont) was extracted from calcium bentonite according to Stoke’s law. AFB1 (purity >99%) was purchased.2 The purity of AFB1 was confirmed by thin-layer chromatography. All solvents were analytical grade. Water was distilled in glass and demineralized prior to use. Isothermal sorption of AFB1 was studied by methods previously described (Tao and Chu, 2000; Yao, 2000). Samples of each sorbent (50.0 mg) were individually weighed into clean glass tubes (4 replicates per sample). We added 0, 0.1, 0.5, 1.0, 3.0, 5.0, 10.0, or 20.0 µg of AFB1 and water (pH 2.0 or 8.0) to 10.0 mL. Each sample tube was incubated at 37°C for 1.5 h. All tubes were mixed at 5-min intervals throughout the incubation period. The interaction was terminated after 1.5 h by centrifugation for 10 min at 3,000 rpm, and the supernatant was decanted carefully into a clean tube. The concentration of AFB1 in each supernatant was measured by violet spectrophotometric analysis; the adsorptive amount of AFB1 was calcu-
2005 Poultry Science Association, Inc. Received for publication September 23, 2004. Accepted for publication January 31, 2005. 1 To whom correspondence should be addressed: qds@mail. hzau.edu.cn. 2 Sigma Chemical Co., St. Louis, MO.
Abbreviation Key: AFB1 = aflatoxin B1; Mont = calcium montmorillonite.
959
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 2, 2015
ABSTRACT The isothermal adsorption and the adsorptive mechanism of aflatoxin B1 (AFB1) on calcium montmorillonite (Mont) were studied in vitro trials. The maximum amounts of AFB1 on Mont in aqueous solution at 2 and pH 8 were 613.5 and 628.9 µg of AFB1 /g of Mont, respectively. The structure of AFB1-Mont was measured by x-ray diffraction and infrared absorption spectrum. The results suggested that the mechanism of AFB1 on Mont was AFB1 sorbed onto the edge of Mont by a double
960
DESHENG ET AL. TABLE 1. Performance and bone mineral content of broiler fed montmorillonite (Mont) and aflatoxin B1 (AFB1)1 Diet Item ABW, 2 g ADG, g Feed/gain Ca, % P, % Cu, mg/kg Fe, mg/kg Zn, mg/kg Mn, mg/kg F, mg/kg Pb, mg/kg
Control 751 33.8 1.87 17.63 12.24 60.4 1,098.7 1,412.4 35.6 311.2 120.5
± ± ± ± ± ± ± ± ± ± ±
36 1.7 0.08a 0.67 0.43 4.6 97.3 132.5 4.7a 26.3a 8.7a
0.5% Mont 748 33.5 1.89 17.67 12.33 59.8 1,119.4 1,397.6 23.8 217.8 108.3
± ± ± ± ± ± ± ± ± ± ±
200 µg/kg AFB1
45 2.0 0.06a 0.72 0.65 4.9 101.5 116.8 5.2b 24.9b 5.9b
744 33.4 2.10 17.49 12.19 59.6 1,145.7 1,389.7 34.0 311.4 121.1
± ± ± ± ± ± ± ± ± ± ±
0 1.8 0.06b 0.69 0.56 5.4 131.4 124.4 6.0a 25.9a 6.5a
200 µg/kg AFB1 + 0.5% Mont 746 33.4 1.90 17.54 12.12 60.9 1,105.3 1,403.1 24.2 208.6 103.6
± ± ± ± ± ± ± ± ± ± ±
40 1.9 0.07a 0.71 0.49 4.5 110.9 129.5 5.4b 23.7b 7.3b
lated from the concentration of unbound AFB1 remaining in the supernatant after incubation.
Stability of Mont AFB1 Complex Test samples (50.0 mg) of calcium Mont, containing 19.8 µg of AFB1, were added to test tubes and mixed thoroughly with 10 mL of the following solvents: water, methanol, acetone, and chloroform. Water was tested at pH 2 and 8, and all solvents were tested at 37°C. The calcium Mont was pelleted by centrifugation at 3,000 rpm for 10 min, and the supernatant was removed for determining the concentration of AFB1. The washing procedure was repeated twice, and the total percentage of desorption of AFB1 was determined for each sample.
Structure of Calcium Mont AFB1 Complex The interlayer spacing of Mont was measured by xray diffraction,3 and the infrared absorption spectrum of Mont (infrared absorption spectrometer4was analyzed before and after AFB1 was adsorbed.
Studies In Vivo
chicks were recorded on a weekly basis. Feed consumption was determined for each group, and feed conversion ratios were computed weekly. At termination, all chicks were killed by cervical dislocation and used to determine the mineral concentrations in air-dried bones.
Statistical Analysis Variable means for treatments showing significant differences were indicated using Duncan’s new multiple range procedure (Duncan, 1955). All statements of significance were based on P < 0.05.
RESULTS AND DISCUSSION The isothermal adsorption of AFB1 on Mont (Figure 1) could be determined using the equation of Langmuir and Freundlich, which suggested a monolayer of molecular of AFB1 adsorbed on Mont, and the maximum amounts of AFB1 adsorbed on Mont in aqueous solution were 613.5 and 628.9 µg/g at pH 2 and 8, respectively. The interlayer spacing of Mont (d001) was not significantly changed before or after AFB1 being sorbed and remained approximately 1.41 nm, which suggested that the AFB1 molecules
Day-old Avian5 male chicks (6 replicate lots of 10 birds each per treatment group) were fed a practical maizesoybean meal diet. Treatments consisted of control, 0.5% calcium Mont, 200 µg of AFB1/kg, and 0.5% calcium Mont + 200 µg AFB1/kg. All treatment diets contained 21.0% crude protein and were calculated to contain 3,086 kcal/ kg ME. Other critical nutrients met or exceeded levels recommended by the National Research Council (1994). Feed and water were available ad libitum throughout the treatment period (3 wk). Individual body weights of
3
X-ray diffractometer JEOL, Ltd., Tokyo. Model 55, Equinox, Bruker, Germany. Wuhan Conti Poultry Breeding Company, China.
4 5
FIGURE 1. Adsorption isotherms of aflatoxin B1 (AFB1) on montmorillonite.
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 2, 2015
a,b Values represent the mean ± SEM of 6 replicates of 10 birds each per treatment. The different markers on shoulder in line indicate that there was a significant difference (P < 0.05) in the 2 treatments. 2 Average body weight (ABW), average daily weight gain (ADG), and feed/gain were based on entire period.
961
RESEARCH NOTE
Mn in bones was decreased with Mont (Table 1). Thus, it was necessary to supply Mn in the diet when Mont was used. The Pb and F are toxic elements for animals and humans, and the content of Pb and F in bones could be reduced by Mont (Table 1) so additional potential profit could be gained as Mont is used in diet.
REFERENCES
maybe adsorbed on the edge of Mont but not into the interlayer. Mont sorbed more than 80% of the available AFB1 from aqueous solution at pH 2 and 90% at pH 8. The stability of Mont-AFB1 sorption complex was evaluated by extraction and an eluotropic series of solvents. Less than 16% of the AFB1 sorbed by Mont was extracted, and the complex was also stable in water at pH 2 and 8 and 37°C, suggesting chemisorption. The infrared absorption bands at 1,403 and 1,355 cm–1 of Mont (Figure 2) that were assigned to the bending vibration of OH in plane were weakened or disappeared after AFB1 was sorbed, which indicated that the main mechanism of the chemisorption was the formation of double hydrogen bonds between AFB1 and Mont.
Effect of Mont in the Broiler Dietary Mont (0.5%) fed to broiler significantly decreased the adverse effects of feeding 200 µg of AFB1/kg on broiler performance (Table 1). Deposits of Ca, P, Cu, Fe, and Zn in bones were not affected, but the content of
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 2, 2015
FIGURE 2. Infrared absorption spectrum of montmorillonite (Mont) before and after aflatoxin B1 (AFB1) was adsorped.
Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11:1–42. Harvey, R. B., L. F. Kubena, T. D. Phillips, D. E. Corrier, M. H. Elissalde, and W. E. Huff. 1991. Diminution of aflatoxin toxicity to growing lambs by dietary supplementation with hydrated sodium calcium aluminosilicate. Am. J. Vet. Res. 52:152–156. Harvey, R. B., L. F. Kubena, T. D. Phillips, W. E. Huff, and D. E. Corrier. 1989. Prevention of aflatoxicosis by addition of hydrated sodium calcium aluminosilicate to the diets of growing barrows. Am. J. Vet. Res. 50:416–420. Kubena, L. F., R. B. Harvey, T. D. Phillips, D. E. Corrier, and W. E. Huff. 1990. Diminution of aflatoxicosis in growing chickens by dietary addition of a hydrated sodium calcium aluminosilicate. Poult. Sci. 69:727–735. Kubena, L. F., W. E. Huff, R. B. Harvey, A. G. Yersin, M. H. Elissalde, D. A. Witzel, L. E. Giroir, T. D. Phillips, and H. D. Petersen. 1991. Effects of a hydrated sodium calcium aluminosilicate on growing turkey poults during aflatoxicosis. Poult. Sci. 70:1823–1830. Kubena, L. F., and R. B. Harvey. 1993. Effect of hydrated sodium calcium aluminosilicates on aflatoxicosis in broiler chicks. Poult. Sci. 72:651–657. Nageswara Rao, S. B., and R. C. Chopra. 2001. Influence of sodium bentonite and activated charcoal on aflatoxin M1 excretion in milk of goats. Small Rumin. Res. 41:203–213 National Research Council. 1994. Nutrient requirements of chickens. Pages 19–34 in Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. Phillips, T. D., L. F. Kubena, R. B. Harvey, D. R. Taylor, and N. D. Heidelbaugh, 1988. Hydrated sodium calcium aluminosilicate: A high affinity sorbent for aflatoxin. Poult. Sci. 67:243–247. Scheideler, S. E., 1993. Effects of Various types of aluminosilicates and aflatoxin B1 or aflatoxin toxicity, chick performance and mineral status. Poult. Sci. 72:282–288 Tao, Z., and C. Taiwei. 2000. On applicability of the Langmuir equation to estimation of adsorption equilibrium constants on powered solid from aqueous solution. J. Colloid Interface Sci. 231:8–12. Yao, C. 2000. Extended and improved Langmuir equation for correlating adsorption equilibrium data. Sep. Purif. Technol. 19:237–242.
(Key words: montmorillonite, aflatoxin, adsorption, broiler, mineral) 2005 Poultry Science 84:959–961
adsorptive law and adsorptive mechanism of AFB1 on aluminosilicate were uncertain, and aluminosilicates can have other effects on the deposit of minerals in animal bones when included in animal diets. Thus, the research reported herein was conducted to explore the adsorptive law and adsorptive mechanism and to evaluate the efficacy of Mont for protection against the toxicity of AFB1 and the deposit of minerals in male broiler chicks.
INTRODUCTION Aflatoxins (a structurally similar group of polysubstituted coumarins) have been recognized as important mycotoxins due to their toxicity and their occurrence as natural contaminants of feeds. Aflatoxin B1 (AFB1) and 3 structurally similar compounds (AFB2, AFG1, and AFG2) have been detected as contaminants of crops before harvesting and drying, in storage, and after processing and manufacturing. The frequent contamination of agricultural commodities with aflatoxin and the chronic exposure of poultry to these toxins can greatly affect the profitability of poultry production. Consequently, large-scale, practical, and cost-effective methods for detoxifying aflatoxin-containing feedstuffs currently are in great demand. A relatively new and more encouraging approach to control aflatoxin is the use of relatively nonnutritive adsorptive materials in the gastrointestinal tract of animals. Hydrated sodium calcium aluminosilicate at 0.5% of diet significantly diminishes many deleterious effects caused by AFB1 or other aflatoxins in chickens (Kubena et al., 1990; Kubena and Harvey, 1993; Scheideler, 1993; Phillips et al., 1988), turkeys (Kubena et al., 1991), growing swine (Harvey et al., 1989), growing lambs (Harvey et al., 1991), and goats (Nageswara Rao and Chopra, 2001). These reports show that aluminosilicates have good prospects when used in feed for alleviating aflatoxicosis, but the
MATERIALS AND METHODS Sorbents, calcium montmorillonite (Mont) was extracted from calcium bentonite according to Stoke’s law. AFB1 (purity >99%) was purchased.2 The purity of AFB1 was confirmed by thin-layer chromatography. All solvents were analytical grade. Water was distilled in glass and demineralized prior to use. Isothermal sorption of AFB1 was studied by methods previously described (Tao and Chu, 2000; Yao, 2000). Samples of each sorbent (50.0 mg) were individually weighed into clean glass tubes (4 replicates per sample). We added 0, 0.1, 0.5, 1.0, 3.0, 5.0, 10.0, or 20.0 µg of AFB1 and water (pH 2.0 or 8.0) to 10.0 mL. Each sample tube was incubated at 37°C for 1.5 h. All tubes were mixed at 5-min intervals throughout the incubation period. The interaction was terminated after 1.5 h by centrifugation for 10 min at 3,000 rpm, and the supernatant was decanted carefully into a clean tube. The concentration of AFB1 in each supernatant was measured by violet spectrophotometric analysis; the adsorptive amount of AFB1 was calcu-
2005 Poultry Science Association, Inc. Received for publication September 23, 2004. Accepted for publication January 31, 2005. 1 To whom correspondence should be addressed: qds@mail. hzau.edu.cn. 2 Sigma Chemical Co., St. Louis, MO.
Abbreviation Key: AFB1 = aflatoxin B1; Mont = calcium montmorillonite.
959
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 2, 2015
ABSTRACT The isothermal adsorption and the adsorptive mechanism of aflatoxin B1 (AFB1) on calcium montmorillonite (Mont) were studied in vitro trials. The maximum amounts of AFB1 on Mont in aqueous solution at 2 and pH 8 were 613.5 and 628.9 µg of AFB1 /g of Mont, respectively. The structure of AFB1-Mont was measured by x-ray diffraction and infrared absorption spectrum. The results suggested that the mechanism of AFB1 on Mont was AFB1 sorbed onto the edge of Mont by a double
960
DESHENG ET AL. TABLE 1. Performance and bone mineral content of broiler fed montmorillonite (Mont) and aflatoxin B1 (AFB1)1 Diet Item ABW, 2 g ADG, g Feed/gain Ca, % P, % Cu, mg/kg Fe, mg/kg Zn, mg/kg Mn, mg/kg F, mg/kg Pb, mg/kg
Control 751 33.8 1.87 17.63 12.24 60.4 1,098.7 1,412.4 35.6 311.2 120.5
± ± ± ± ± ± ± ± ± ± ±
36 1.7 0.08a 0.67 0.43 4.6 97.3 132.5 4.7a 26.3a 8.7a
0.5% Mont 748 33.5 1.89 17.67 12.33 59.8 1,119.4 1,397.6 23.8 217.8 108.3
± ± ± ± ± ± ± ± ± ± ±
200 µg/kg AFB1
45 2.0 0.06a 0.72 0.65 4.9 101.5 116.8 5.2b 24.9b 5.9b
744 33.4 2.10 17.49 12.19 59.6 1,145.7 1,389.7 34.0 311.4 121.1
± ± ± ± ± ± ± ± ± ± ±
0 1.8 0.06b 0.69 0.56 5.4 131.4 124.4 6.0a 25.9a 6.5a
200 µg/kg AFB1 + 0.5% Mont 746 33.4 1.90 17.54 12.12 60.9 1,105.3 1,403.1 24.2 208.6 103.6
± ± ± ± ± ± ± ± ± ± ±
40 1.9 0.07a 0.71 0.49 4.5 110.9 129.5 5.4b 23.7b 7.3b
lated from the concentration of unbound AFB1 remaining in the supernatant after incubation.
Stability of Mont AFB1 Complex Test samples (50.0 mg) of calcium Mont, containing 19.8 µg of AFB1, were added to test tubes and mixed thoroughly with 10 mL of the following solvents: water, methanol, acetone, and chloroform. Water was tested at pH 2 and 8, and all solvents were tested at 37°C. The calcium Mont was pelleted by centrifugation at 3,000 rpm for 10 min, and the supernatant was removed for determining the concentration of AFB1. The washing procedure was repeated twice, and the total percentage of desorption of AFB1 was determined for each sample.
Structure of Calcium Mont AFB1 Complex The interlayer spacing of Mont was measured by xray diffraction,3 and the infrared absorption spectrum of Mont (infrared absorption spectrometer4was analyzed before and after AFB1 was adsorbed.
Studies In Vivo
chicks were recorded on a weekly basis. Feed consumption was determined for each group, and feed conversion ratios were computed weekly. At termination, all chicks were killed by cervical dislocation and used to determine the mineral concentrations in air-dried bones.
Statistical Analysis Variable means for treatments showing significant differences were indicated using Duncan’s new multiple range procedure (Duncan, 1955). All statements of significance were based on P < 0.05.
RESULTS AND DISCUSSION The isothermal adsorption of AFB1 on Mont (Figure 1) could be determined using the equation of Langmuir and Freundlich, which suggested a monolayer of molecular of AFB1 adsorbed on Mont, and the maximum amounts of AFB1 adsorbed on Mont in aqueous solution were 613.5 and 628.9 µg/g at pH 2 and 8, respectively. The interlayer spacing of Mont (d001) was not significantly changed before or after AFB1 being sorbed and remained approximately 1.41 nm, which suggested that the AFB1 molecules
Day-old Avian5 male chicks (6 replicate lots of 10 birds each per treatment group) were fed a practical maizesoybean meal diet. Treatments consisted of control, 0.5% calcium Mont, 200 µg of AFB1/kg, and 0.5% calcium Mont + 200 µg AFB1/kg. All treatment diets contained 21.0% crude protein and were calculated to contain 3,086 kcal/ kg ME. Other critical nutrients met or exceeded levels recommended by the National Research Council (1994). Feed and water were available ad libitum throughout the treatment period (3 wk). Individual body weights of
3
X-ray diffractometer JEOL, Ltd., Tokyo. Model 55, Equinox, Bruker, Germany. Wuhan Conti Poultry Breeding Company, China.
4 5
FIGURE 1. Adsorption isotherms of aflatoxin B1 (AFB1) on montmorillonite.
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 2, 2015
a,b Values represent the mean ± SEM of 6 replicates of 10 birds each per treatment. The different markers on shoulder in line indicate that there was a significant difference (P < 0.05) in the 2 treatments. 2 Average body weight (ABW), average daily weight gain (ADG), and feed/gain were based on entire period.
961
RESEARCH NOTE
Mn in bones was decreased with Mont (Table 1). Thus, it was necessary to supply Mn in the diet when Mont was used. The Pb and F are toxic elements for animals and humans, and the content of Pb and F in bones could be reduced by Mont (Table 1) so additional potential profit could be gained as Mont is used in diet.
REFERENCES
maybe adsorbed on the edge of Mont but not into the interlayer. Mont sorbed more than 80% of the available AFB1 from aqueous solution at pH 2 and 90% at pH 8. The stability of Mont-AFB1 sorption complex was evaluated by extraction and an eluotropic series of solvents. Less than 16% of the AFB1 sorbed by Mont was extracted, and the complex was also stable in water at pH 2 and 8 and 37°C, suggesting chemisorption. The infrared absorption bands at 1,403 and 1,355 cm–1 of Mont (Figure 2) that were assigned to the bending vibration of OH in plane were weakened or disappeared after AFB1 was sorbed, which indicated that the main mechanism of the chemisorption was the formation of double hydrogen bonds between AFB1 and Mont.
Effect of Mont in the Broiler Dietary Mont (0.5%) fed to broiler significantly decreased the adverse effects of feeding 200 µg of AFB1/kg on broiler performance (Table 1). Deposits of Ca, P, Cu, Fe, and Zn in bones were not affected, but the content of
Downloaded from http://ps.oxfordjournals.org/ at D H Hill Library - Acquis S on May 2, 2015
FIGURE 2. Infrared absorption spectrum of montmorillonite (Mont) before and after aflatoxin B1 (AFB1) was adsorped.
Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11:1–42. Harvey, R. B., L. F. Kubena, T. D. Phillips, D. E. Corrier, M. H. Elissalde, and W. E. Huff. 1991. Diminution of aflatoxin toxicity to growing lambs by dietary supplementation with hydrated sodium calcium aluminosilicate. Am. J. Vet. Res. 52:152–156. Harvey, R. B., L. F. Kubena, T. D. Phillips, W. E. Huff, and D. E. Corrier. 1989. Prevention of aflatoxicosis by addition of hydrated sodium calcium aluminosilicate to the diets of growing barrows. Am. J. Vet. Res. 50:416–420. Kubena, L. F., R. B. Harvey, T. D. Phillips, D. E. Corrier, and W. E. Huff. 1990. Diminution of aflatoxicosis in growing chickens by dietary addition of a hydrated sodium calcium aluminosilicate. Poult. Sci. 69:727–735. Kubena, L. F., W. E. Huff, R. B. Harvey, A. G. Yersin, M. H. Elissalde, D. A. Witzel, L. E. Giroir, T. D. Phillips, and H. D. Petersen. 1991. Effects of a hydrated sodium calcium aluminosilicate on growing turkey poults during aflatoxicosis. Poult. Sci. 70:1823–1830. Kubena, L. F., and R. B. Harvey. 1993. Effect of hydrated sodium calcium aluminosilicates on aflatoxicosis in broiler chicks. Poult. Sci. 72:651–657. Nageswara Rao, S. B., and R. C. Chopra. 2001. Influence of sodium bentonite and activated charcoal on aflatoxin M1 excretion in milk of goats. Small Rumin. Res. 41:203–213 National Research Council. 1994. Nutrient requirements of chickens. Pages 19–34 in Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. Phillips, T. D., L. F. Kubena, R. B. Harvey, D. R. Taylor, and N. D. Heidelbaugh, 1988. Hydrated sodium calcium aluminosilicate: A high affinity sorbent for aflatoxin. Poult. Sci. 67:243–247. Scheideler, S. E., 1993. Effects of Various types of aluminosilicates and aflatoxin B1 or aflatoxin toxicity, chick performance and mineral status. Poult. Sci. 72:282–288 Tao, Z., and C. Taiwei. 2000. On applicability of the Langmuir equation to estimation of adsorption equilibrium constants on powered solid from aqueous solution. J. Colloid Interface Sci. 231:8–12. Yao, C. 2000. Extended and improved Langmuir equation for correlating adsorption equilibrium data. Sep. Purif. Technol. 19:237–242.