资源描述
ATOMIC ABSORPTION SPECTROPHOTOMETRY COOKBOOK
Section 6
Foodstuffs Analysis Fertilizer and Feed Analysis
Atomic Absorption Analysis Cookbook
Section 6
Table of Contents
10. Foodstuffs Analysis 1
10.1 Vegetables, Fruits Analysis Method 1
10.1.1 Sample Pretreatment 1
10.1.2 Electrical Heating Atomic Absorption Method 2
10.1.3 Flame Atomic Absorption Method 4
10.1.4 Hydride Vapor Generation Atomic Absorption Method 13
10.1.5 Reduction Vaporization Atomic Absorption Method 15
10.2 Grains, Beans, Potatoes Analysis Method 18
10.3 Meat, Fish Analysis Method 18
10.4 Fats and Oils, Dairy Products Analysis Method 18
10.4.1 Sample Pretreatment 18
10.4.2 Electrical Heating Atomic Absorption Method 19
10.4.3 Flame Atomic Absorption Method 23
10.4.4 Hydride Vapor Generation Atomic Absorption Method 23
10.4.5 Reduction Vaporization Atomic Absorption Method 23
10.5 Spirits, Alcoholic Beverage Analysis 24
10.5.1 Sample Pretreatment 24
10.5.2 Electrical Heating Atomic Absorption Method 24
10.5.3 Flame Atomic Absorption Method 31
10.5.4 Hydride Vapor Generation Atomic Absorption Method 31
10.5.5 Reduction Vaporization Atomic Absorption Method 32
10.6 Processed Foods Analysis Method 33
10.6.1 Sample Pretreatment 33
10.6.2 Electrical Heating Atomic Absorption Method 33
10.6.3 Flame Atomic Absorption Method 33
10.6.4 Hydride Vapor Generation Atomic Absorption Method 33
10.6.5 Reduction Vaporization Atomic Absorption Method 33
11. Fertilizer and Feed Analysis 34
11.1 Fertilizer Analysis Method 34
11.1.1 Sample Pretreatment 34
11.1.2 Flame Atomic Absorption Method 36
11.1.3 Hydride Vapor Generation Atomic Absorption Method 41
11.1.4 Reduction Vaporization Atomic Absorption Method 43
11.2 Feed Analysis Method 45
11.2.1 Sample Pretreatment 45
11.2.2 Flame Atomic Absorption Method 45
G 10. foodstuffs analysis
10.1 Vegetables, Fruits Analysis Method
Reference materials:
Health Testing Methods Commentary, Japan Pharmaceutical Society Publication, Kanehara Publishing Co.,
Foodstuffs Analysis Methods, Japan Foodstuffs Manufacturing Society, Foodstuffs Analysis Methods Editorial Commission Publication (Korin Co.)
10.1.1 Sample Pretreatment
a) Nitric acid, perchloric acid decomposition
First, grind and air dry 2 ~ 5g of sample and place in a conical beaker. Wet with water, add 25 ml of nitric acid, and after mixing, set aside. Next, gently heat to start a sample reaction. After cooling, add 10 ml of perchloric acid and gently heat to concentrate. Midway, if the contained material becomes dark, add 2~3 ml portions of nitric acid and continue heating. When the contained material turns yellowish or colorless, decomposition is complete. After cooling, add 2 ml of hydrochloric acid, and use water to prepare fixed volumes of measurement solution.
Remarks:
1) If during the decomposition process the sample becomes carbonized and hardens, it will certainly explode, so be sure that nitric acid is always present in the sample while heating.
2) Measurement is suitable for As, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb, Sb, Sn, Zn, etc., but if halogens are coexistent with As, Sb, Se and Sn, or if the contained material becomes carbonized, volatilization and loss will occur.
3) Since there is a possibility of contamination with impurities to reagents and utensils, prepare processed blank test solutions in the same way as the samples.
b) Ashing by drying
First, grind and air dry 5~10g of sample and place in a quartz beaker. Then gently heat on a hot plate. Continue heating until enough water is driven off for partial carbonization to occur. Then place the beaker in an electrical furnace, and increase the heat at a rate of 100℃ per 1 hour. Then heat at 500℃ for several hours to conduct ashing. If ashing is incomplete, wet with 2~5 ml of a 50% magnesium nitrate solution or nitric acid (1+1). After drying, continue ashing. Add 2~4 ml of water to the ash, and after drying, add 5 ml of hydrochloric acid to dissolve the salts. Use water to prepare fixed volumes of measurement solution.
Remarks:
There is a possibility of volitilizing almost all of the elements, with Cd being volitilized during ashing above 500℃. If halogens are coexistent, As, Sb, Sn Zn, etc. will be volitilized. Heating above 550℃ will greatly reduce the element collection rate.
10.1.2 Electrical Heating Atomic Absorption Method
a) Target elements
Cd, Pb
b) Measurement procedure
Measurement is conducted using the following procedure. The lamp current value, and the slit width used are in accordance with Cookbook Section 4, item 7.5 Element Specific Measurement Conditions.
• Cd
Reagents:
1) Cd standard solution (0.01 mg Cd/ml) : Refer to Cookbook Section 2, item 3 Preparing Standards
2) Palladium nitrate (II) solution (10 mg Pd/ml) : Dissolve 0.108 g of palladium nitrate in 10 ml of nitric acid (1+1), and after bringing up to 500 ml using water, add water to 20 ml of this solution to bring up to 200 ml.
Procedure:
1) Place 15 ml each of pretreated sample (see note) into four 20 ml volumetric flasks, and add standard solution (0.01 mg Cd/ml) to three of them in increments in the range of 0.1~2 ml so that one flask contains no standard solution and the other three have increasing concentrations of standard solution added to the sample. After adding nitric acid (1+1) to each of the solutions so they all have the same concentration of acid, bring up to volume using water. (Note: If the pretreated sample contains more than 0.01 mg of Cd, decrease the sampling volume so that this becomes less than 0.01 mg.)
2) Place equal volumes of at least 100 ml of each sample prepared in step 1) into small volumetric flasks, and add equal volumes of the palladium nitrate (II) solution (10 mg Pd/ml) to each, and mix well for measurement.
Measurement:
Measurement wavelength: 228.8 nm
Calibration curve concentration range: 0.2~2 ng/ml
Tube: High density graphite tube
Sample injection volume: 10 ml
Heating conditions:
TEMP (℃) TIME (sec) HEAT GAS (l/min)
Stage 1 120 15 R 0.1
2 250 15 R 0.1
3 600 10 R 1.0
4 600 15 S 1.0
5 600 3 S 0.0H
6 2000 3 S 0.0H
7 2500 2 S 1.0
• Pb
Reagents:
1) Pb standard solution (0.2 mg Pb/ml) : Refer to Cookbook Section 2, item 3 Preparing Standards
2) Palladium nitrate (II) solution (10 mg Pd/ml) : Preparation is as described for Cd reagent, item 2).
Procedure:
1) Place 15 ml each of pretreated sample (see note) into four 20 ml volumetric flasks, and add standard solution (0.2 mg Pb/ml) to three of them in increments in the range of 0.1~2 ml so that one flask contains no standard solution and the other three have increasing concentrations of standard solution added to the sample. After adding nitric acid (1+1) to each of the solutions so they all have the same concentration of acid, bring up to volume using water. (Note: If the pretreated sample contains more than 0.1 mg of Pb, decrease the sampling volume so that this becomes less than 0.1 mg.)
2) Place equal volumes of at least 100 ml of each sample prepared in step 1) into small volumetric flasks, and add equal volumes of the palladium nitrate (II) solution (10 mg Pd/ml) to each, and mix well for measurement..
Measurement:
Measurement wavelength: 283.3 nm
Calibration curve concentration range: 2~20 ng/ml
Tube: High density graphite tube
Sample injection volume: 20 ml
Heating conditions:
TEMP (℃) TIME (sec) HEAT GAS (l/min)
Stage 1 120 20 R 0.1
2 250 10 R 0.1
3 600 10 R 1.0
4 600 15 S 1.0
5 600 3 S 0.0H
6 2000 3 S 0.0H
7 2500 2 S 1.0
10.1.3 Flame Atomic Absorption Method
a) Target elements
Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Pb, Zn
b) Measurement procedure
Measurement is conducted using the following procedure. The lamp current value, slit width and flame conditions used are in accordance with Cookbook Section 3, item 6.4 Element Specific Measurement Conditions. For preparation of the standard solutions for generating the calibration curve, refer to Cookbook Section 2, item 3 Preparing Standards.
• Ca
Reagents:
1) Ca standard solution (10 mg Ca/ml) :Refer to Cookbook Section 2, item 3 Preparing standards
2) La solution (50 g/l) : Dissolve 67 g of lanthanum chloride by adding small quantities of hydrochloric acid (1+1) little by little, and then add water up to a volume of 500 ml.
Procedure:
1) Place a suitable volume of pretreated sample (containing 5~150 mg of Ca) in a 50 ml volumetric flask. After adding 3 ml of La solution (50 g/l), bring up to volume with water for measurement. At this time, for a blank test, perform the same pretreatment as that performed for the sample, and place the same volume of this solution in a 50 ml volumetric flask. Then, after adding 3 ml of La solution (50 g/l), bring up to volume with water. The measurement value obtained with this solution is used for correction of the value obtained with the actual sample.
2) For the calibration curve, place stepwise increments of 1~30 ml of the Ca standard into 50 ml volumetric flasks, add 3 ml of lanthanum solution (50 g/l) to each flask, and add water to bring all the solutions up to volume.
Measurement:
Measurement wavelength: 422.7 nm
Calibration curve concentration range: 0.3~6 mg/ml
Measurement conditions: Refer to Cookbook Section 3, item 6.4, 9).
Remarks:
When Na is present in amounts greater that 200 times that of the Ca, and even the addition of La does not completely control the interference, conduct measurement using the N2O-C2H2 flame (refer to Cookbook Section 3, item 6.4, 10).
• Cd
Reagents:
1) Cd standard solution (10 mg of Cd/ml) : refer to Cookbook Section 2, item 3 Preparing Standards.
2) Ammonium dihydrogen citrate (10 g/l): Dissolve 10 g of ammonium dihydrogen citrate in approximately 80 ml of water. Add 2~3 drops of m-Cresol Purple solution (1 g/l), and after adding enough drops of aqueous ammonia (1+1) to adjust the pH to about 9, add water to a volume of 100 ml. Transfer this to a separating funnel, add 2 ml of diethyl sodium dithiocarbamate solution (10 g/l) and 10 ml of butyl acetate. After vigorously vibrating the solution, set it aside. Separate off the ammonium dihydrogen citrate layer and pass it through dry filter paper to eliminate the minute butyl acetate bubbles.
3) m-Cresol Purple solution (1 g/l) : Dissolve 0.1 g of m-cresol purple in 50 ml of ethanol, and add water to volume of 100 ml.
4) diethyl sodium dithiocarbamate solution (10 g/l) : Dissolve 1.3 g of sodium dithiocarbamate in water, and bring volume to 100 ml.
5) Butyl acetate
Procedure:
1) Place a suitable amount of pretreated sample (containing 0.5~10 mg of Cd) in a separating funnel, and add 10 ml of ammonium dihydrogen citrate solution (10 g/l) and 2~3 drops of indicator m-Cresol Purple solution (1 g/l). Then add aqueous ammonia (1+1) until the solution becomes slightly purple.
Then add 5 ml of diethyl sodium dithiocarbamate solution (10 g/l), and after shaking the solution, add 10 ml of butyl acetate and vigorously shake for about 1 minute before setting the solution down. Separate off the butyl acetate layer and place it in a 20 ml volumetric flask. Add 5 ml of butyl acetate to the remaining aqueous layer, and repeat the extraction procedure. Add this extracted butyl acetate layer to the previous volumetric flask. Keep adding butyl acetate until it is brought up to the 20 ml volume. This will be used in measurement.
2) For the calibration curve, prepare stepwise standard solutions over the calibration curve concentration range using the Cd standard solution (10 mg of Cd/ml), and use the same procedure as that for the sample.
Measurement:
Measurement wavelength: 228.8 nm
Calibration curve concentration range: 0.02~0.5 mg/ml (concentration after extraction)
Measurement conditions:
Lamp current value : 8 mA
Slit width : 0.5 nm
Lamp mode : BGC-D2
Burner height : 7 mm
Support gas : Air
Fuel gas flow rate :
C2H2 0.8 l/min (If the flame turns reddish when the sample is sprayed, decrease the amount of sample drawn up.)
• Cu I (When concentration is within the quantitation range of 0.2 ~ 4 mg/ml, and there are no interfering components)
Reagents:
Cu standard solution (10 mg of Cu/ml) : Refer to Cookbook Section 2, item 3 Preparing Standards
Procedure:
1) The pretreated sample may be directly used for measurement, or it may be diluted with water so that its concentration is within the quantitation range. At this time, take an appropriate amount of water and perform the same pretreatment as that used for the sample, and then measure this solution. The obtained value may be used for correction of the value obtained in sample measurement.
2) For the calibration curve, place 2~40 ml of Cu standard solution (10 mg of Cu/ml) in stepwise volumes in 100 ml volumetric flasks. After adding acid epeat the extraction procedure. Add this extracted butyl ac. Add this extracted butyl acetate layer to the previous volumetric flask. Keep adding butyl acetate until it is brought up to the 20 ml volume. This will be used in measurement.
Measurement:
Measurement wavelength: 324.7 nm
Calibration curve concentration range: 0.2~4 mg/ml (concentration in solution after extraction)
Measurement conditions: Refer to Cookbook Section 3, Item 6.4, 15).
• Cu II (When Cu concentration is below the quantitation range)
Reagents:
1) Cu standard solution (10 mg of Cu/ml) : Same as for Cu I
2) Ammonium dihydrogen citrate (10 g/l)
3) m-Cresol Purple solution (1 g/l)
4) diethyl sodium dithiocarbamate solution (10 g/l) :
5) Butyl acetate
Items 2), 3), 4) and 5) are prepared as in 2) ~ 5), respectively, for the Cd reagents.
Procedure:
1) Place a suitable amount of pretreated sample (containing 2 ~ 40 mg of Cu) in a separating funnel, and proceed as described in step 1) of the Cd procedure.
2) For the calibration curve, prepare stepwise standard solutions over the calibration curve concentration range using the Cu standard solution (10 mg of Cd/ml). se the same procedure as that for the sample.
Measurement
Measurement wavelength: 324.7 nm
Calibration curve concentration range: 0.1~2 mg/ml (concentration in solution after extraction)
Measurement conditions:
Lamp current value : 6 mA
Slit width : 0.5 nm
Lamp mode : BGC-D2
Burner height : 7 mm
Support gas : Air
Fuel gas flow rate :
C2H2 0.8 l/min (If the flame turns reddish when the sample is sprayed, decrease the amount of sample drawn up.)
• Fe
Reagents:
Fe standard solution (10 mg of Fe/ml) : Refer to Cookbook Section 2, item 3 Preparing Standards
Procedure:
1) The pretreated sample may be directly used for measurement, or it may be diluted with hydrochloric acid (1+50) so that its concentration is within the quantitation r
展开阅读全文
浙ICP备2021020529号-1 | 浙B2-20240490 
