GB/T 5009.47-2003 Analytical methods for hygienic standards of eggs and egg products

This standard specifies the analysis methods for various hygienic indicators in eggs and egg products. This standard is applicable to the analysis of various hygienic indicators in eggs and egg products. GB/T 5009.47-2003 Analysis methods for hygienic standards for eggs and egg products GB/T5009.47-2003 Standard download decompression password: www.bzxz.net

ICS67.040
National Standard of the People's Republic of China
GB/T5009.47--2003
Replaces GB/T5009.47-1996
Method for analysis of hygienic standard of egg and egg products
Promulgated on August 11, 2003
Ministry of Health of the People's Republic of China
Standardization Administration of the People's Republic of China
Implementation on January 1, 2004
GB/T5009.47-—2003
This standard replaces GB/T5009.47—1996 "Method for analysis of hygienic standard of egg and egg products". Compared with GB/T5009.47-1996, the main modifications of this standard are as follows: The structure of the original standard has been modified in accordance with GB/T20001.4-2001 "Standard Preparation Rules Part 4: Chemical Analysis Methods".
This standard is proposed and managed by the Ministry of Health of the People's Republic of China. This standard is drafted by the Food Hygiene Supervision and Inspection Institute of the Ministry of Health and the Henan Provincial Health and Epidemic Prevention Station. This standard was first issued in 1985 and revised for the first time in 1996. This is the second revision. 386
1 Scope
Analysis methods for hygienic standards for eggs and egg products This standard specifies the analysis methods for various hygienic indicators in eggs and egg products. This standard is applicable to the analysis of various hygienic indicators in eggs and egg products. 2 Normative references
GB/T5009.47-2003
The clauses in the following documents become the clauses of this standard through reference in this standard. For dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to agreements based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest versions are applicable to this standard. GB2748 Hygienic Standard for Fresh Eggs
GB2749 Hygienic Standard for Egg Products
GB/T5009.3—2003 Determination of Water in Foods GB/T5009.11 Determination of Total and Inorganic Arsenic in Foods GB/T5009.12 Determination of Lead in Foods
GB/T5009.14 Determination of Zinc in Foods
GB/T5009.17 Determination of Total and Organic Mercury in Foods GB/T5009.19 Determination of 666 and DDT Residues in Foods Fresh Eggs
Applicable to fresh eggs, refrigerated fresh eggs, and chemically stored fresh eggs. Sensory inspection
3.1 Fresh eggs
The eggshell is clean and complete. When the light is turned through, the whole egg is slightly red. The yolk is not visible or slightly shadowed. After opening, the yolk is raised and complete, and has toughness. The egg white is clear and transparent, and the consistency is clear. 3.2 Refrigerated fresh eggs
The quality of refrigerated eggs should meet the requirements of GB2748. 3.3 Chemically stored eggs
The quality of eggs stored by chemical methods (lime water, sodium carbonate, etc.) should meet the requirements of GB2748. 4 Physical and chemical tests
4.1 Inorganic arsenic
Take 10 fresh eggs, remove the shells, mix them all, and take samples. The analysis is carried out in accordance with GB/T5009.11.
Take 10 fresh eggs, remove the shells, mix them all, and take samples. The analysis is carried out in accordance with GB/T5009.17.
GB/T5009.47—2003
Take 10 fresh eggs, remove the shells, mix them all and take samples. Analysis shall be carried out in accordance with GB/T5009.14.
4.4 BHC and DDT
According to GB/T5009.19.
Frozen whole eggs
Applicable to egg products made from fresh eggs through beating, filtering and freezing. 5 Sensory inspection
Firm and uniform, yellow or light yellow, with the normal smell of frozen whole eggs, without peculiar smell and impurities. Use the following methods for identification when necessary.
5.1 State
Use a table knife to press hard on the surface of the product. A well-frozen frozen egg product cannot be cut into the interior by a knife, which means it is frozen hard. After the sample is thawed, observe the frozen whole egg with the naked eye. The ice protein is all evenly liquid, and the ice yolk is a dense and even paste. 5.2 Odor
In the frozen state and after thawing, test by smell. It should have the smell of the product and no other peculiar smell. If necessary, the following test can be combined. Take 20g of the sample in a 100mL beaker, add 50mL boiling water, and smell it immediately while it is hot. 5.3 Color
Observe the color of the frozen state before thawing. After thawing, pour the egg liquid into a 50mL colorless beaker and observe it on white paper. 5.4 Impurities
Take 100mL of thawed egg liquid, place it in a white porcelain plate, slowly add 100mL~200mL of clean water to make a diluent, and then observe whether it has impurities. If there are suspected impurities and unmelted egg pieces, remove them with tweezers, and then move the remaining clear liquid into a sieve with a mesh of 1mm and filter. If there are impurities left on the sieve, rinse them with water once and check them together with the above detected ones with a magnifying glass. 6 Physical and Chemical Tests
6.1 Moisture
6.1.1 Method A: Operate in accordance with the direct drying method of GB/T50093--2003. 6.1.2 Method B: Weigh about 1.50g of the sample into a weighing bottle with constant weight, place it in a constant temperature drying oven at 120℃±2℃ and dry it for 2h, take it out, move it into a dryer, place it for 30min, weigh it again after cooling, and calculate it in the same way as Method A. 6.2 Fat (Trichloromethane Cold Immersion Method)
6.2.1 Principle
Trichloromethane extract is calculated as fat.
6.2.2 Reagents
Neutral chloroform: Contains anhydrous ethanol (1%). Take trichloromethane, wash it once with an equal amount of water, and at the same time add sodium hydroxide solution (100g/L) in a ratio of 20:1 to the volume of trichloromethane, wash it twice, and let it stand to separate. Pour out the washing liquid, and then wash with an equal amount of water for 2-3 times until it is neutral. Dehydrate chloroform with anhydrous calcium chloride, and distill it in a water bath at 80℃. Take the intermediate distillate and check whether it is neutral. Add 1mL of anhydrous ethanol to every 100mL of chloroform and store in a brown bottle. 6.2.3 Apparatus
6.2.3.1 Fat immersion tube: glass, tube length 150mm, inner diameter 18mm, fill the neck with absorbent cotton, see Figure 1. 6.2.3.2 Fat bottle: standard ground mouth, capacity about 150mL. 388
6.2.4 Analysis steps
6.2.4.1 Method A
Figure 1 Fat leaching tube
GB/T5009.47—2003
Weigh 2.00g~2.50g of homogenized sample into a 100mL beaker, add about 15g of anhydrous sodium sulfate powder, stir with a glass rod, grind thoroughly, carefully transfer to the fat leaching tube, wipe the sample attached to the beaker and the glass rod with a little absorbent cotton, and transfer the absorbent cotton into the fat leaching tube. Use 100mL of neutral chloroform to extract the sample in the tube 10 times until the fat is completely extracted, filter the chloroform into a fat bottle of known mass, transfer the fat bottle to a water bath and connect a condenser to recover the chloroform. Place the fat bottle in a constant temperature vacuum drying oven at 70℃75℃ and dry for 4h (evacuate to a vacuum degree of 53.3kPa within the first 30min, and then evacuate at least three times, each time to a vacuum degree below 93.3kPa), take it out, move it into a desiccator and place it for 30min, weigh it, and weigh it once every 1h of drying (evacuate twice) until the difference between the two weighings does not exceed 2.0mg.
6.2.4.2 Calculation of results
The fat content in the sample is calculated according to formula (1). X
Where:
X is the fat content in the sample,
mass of the sample, in grams (g)
(m2-m3)
mass of fat bottle plus fat, in grams (g);
mass of fat bottle, in grams (g). The calculation result should retain two significant figures.
6.2.4.3 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 3% of the arithmetic mean. 6.2.4.4 Method B
Same as 6.2.4.1 Sampling, leaching, and recovery of chloroform. Then dry the fat bottle at 78℃~80℃ for 2h, take it out and put it in a dryer for 30min, weigh it, and weigh it every 1h of drying thereafter until the difference between two weighings does not exceed 2.0mg. 6.2.4.5 Calculation of results
Same as 6.2.4.2.
6.2.4.6 Precision
Same as 6.2.4.3.
6.3 Free fatty acids
6.3.1 Method A
6.3.1.1 Principle
Extract the fat in the egg with trichloromethane and then titrate it with sodium ethoxide standard titration solution to determine the content of free fatty acids (in terms of oleic acid). 389
GB/T5009.47—2003
6.3.1.2 Reagents
6.3.1.2.1 Neutral chloroform: Same as 6.2.2. 6.3.1.2.2 Phenol indicator solution: Ethanol solution (10 g/L). 6.3.1.2.3 Sodium ethoxide standard titration solution [c(CH.CH,ONa)=0.05mol/L] Take 800mL of anhydrous ethanol and place it in a conical flask. Cut 1g of metallic sodium into pieces and add them to the anhydrous ethanol in batches. After the reaction is complete, shake well, seal tightly, and let it stand overnight. Pour the clarified solution into a brown bottle (when preparing sodium ethoxide solution, sodium reacts with ethanol to release hydrogen, so it should be kept away from fire. The metallic sodium and the cut surface pieces should be returned to the original kerosene liquid for storage. Do not contact water to avoid fire. Wear glasses and gloves for protection during preparation). And calibrate according to the following method. Accurately weigh about 0.2g of reference potassium hydrogen phthalate dried to a constant amount at 105℃～110℃, add 50mL of freshly boiled cold water, shake to dissolve, add 3 drops of phenolic indicator solution, and titrate with the above-prepared sodium ethoxide solution until the initial pink color appears and does not fade for 30 seconds. At the same time, perform a reagent blank test.
The actual concentration of the sodium ethoxide standard solution is calculated according to formula (2). Where:
c=(V,-V)×0.2040
-the actual concentration of the sodium ethoxide standard solution, in moles per liter (mol/L); m the mass of potassium hydrogen phthalate, in grams (g); V-the volume of sodium ethoxide solution consumed by potassium hydrogen phthalate, in milliliters (mL); V, the volume of sodium ethoxide solution consumed by the reagent blank, in milliliters (mL): (2)
0.2040-the mass of potassium hydrogen phthalate equivalent to 1.00mL of sodium ethoxide standard titration solution [c(CH.CHzONa)=1.000mol/L], in grams (g).
6.3.1.3 Analysis steps
Dissolve the dry extract obtained after fat determination in 30 mL of neutral chloroform, add 3 drops of phenolic acid indicator solution, and titrate with sodium ethoxide standard titration solution (0.050 mol/L) until the solution turns pink and does not fade for 30 seconds. 6.4 Result calculation
The content of free fatty acids in the sample is calculated according to formula (3). x (in terms of oleic acid) = ×cX0.2820×100m
Wherein:
X is the content of free fatty acids in the sample, in grams per 100 grams (g/100g); V
is the volume of sodium ethoxide standard titration solution consumed by the sample, in milliliters (mL) - the actual concentration of sodium ethoxide standard titration solution, in moles per liter (mol/L); the mass of the dry extract obtained when determining fat, in grams (g); (3)
0.2820 is the mass of oleic acid equivalent to 1.00mL sodium ethoxide standard titration solution Lc(CH,CH,ONa)=1.000mol/L], in grams (g).
The calculated result shall be rounded to two significant figures.
6.5 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 5% of the arithmetic mean. 6.6 Method B
Free fatty acids (in terms of oleic acid) are calculated according to formula (4). Free fatty acids (in terms of oleic acid) = acid value × 0.503 Where:
Acid value—the number of milligrams of potassium hydroxide per gram of free fatty acids contained in egg oil; 0.503—
empirical value.
6.7Inorganic
According to GB/T5009.11.
According to GB/T5009.17.
According to GB/T5009.14.
6.10BHC and DDT
According to GB/T5009.19.
Pasteurized frozen whole eggs
Applicable to egg products made from fresh eggs through beating, filtering, pasteurization and freezing. Sensory inspection
GB/T5009.47—2003
Firm and uniform, yellow or light yellow. It has the normal smell of frozen whole eggs, without odor or impurities, and should meet the requirements of GB2749. Physical and chemical inspection
8.1 Moisture
Same as 6.1.
Same as 6.2.
8.3 Free fatty acids
8.4 Inorganic arsenic
Operate according to GB/T5009.11.
Operate according to GB/T5009.17.
Operate according to GB/T5009.14.
8.7 666, DDD
According to GB/T5009.19.
Ice yolk
Applicable to egg products made from fresh egg yolks, processed and frozen. Sensory inspection
Firm, uniform, yellow, with the normal smell of ice egg yolk, no peculiar smell and impurities, should meet the requirements of GB2749. 10 Physical and chemical examination
10.1 Moisture
Same as 6.1.
Same as 6.2, the sample weight should not exceed 2g.
GB/T5009.47—2003
10.3 Free fatty acids
Same as 6.3.
10.4 Inorganic arsenic
According to GB/T5009.11.
Operate according to GB/T5009.17.
Operate according to GB/T5009.14.
10.7 BHC and DDT
Operate according to GB/T5009.19.
Ice egg white
Applicable to egg products made from fresh egg whites, processed and frozen. 11 Sensory inspection
Firm and uniform, white or milky white, with the normal smell of normal ice egg white, without peculiar smell and impurities, should meet the requirements of GB2749. 12 Physical and chemical inspection
12.1 Moisture
Same as 6.1.
12.2 Inorganic arsenic
Operate according to GB/T5009.11.
Operate according to GB/T5009.17.
Operate according to GB/T5009.14.
12.5 BHC and DDT
Operate according to GB/T5009.19.
Pasteurized whole egg powder
Applicable to egg products made from fresh eggs through egg beating, filtering, pasteurization and spray drying. 13 Sensory inspection
Powder or very loose block, uniform light yellow, with the normal smell of whole egg powder, no peculiar smell and impurities, should meet the requirements of GB2749 14 Physical and chemical inspection
14.1 Solubility index
14.1.1 Principle
Calculate the solubility index based on the refractive index of the sample dissolved in sodium chloride solution (50g/L). 14.1.2 Reagents
Sodium fluoride solution (50g/L): Weigh 5g of sodium chloride and dissolve it in water and dilute it to 100mL. 14.1.3 Apparatus
14.1.3.1 Abbe refractometer.
14.1.3.2 Oscillator: left-right type.
14.1.4 Analysis steps
GB/T5009.47—2003
Weigh 1.00 g of the mixed sample (based on dry sample), place it in a 50 mL conical flask, accurately add 5 mL of sodium chloride solution (50 g/L), add 5 small glass beads, and seal the flask with a rubber stopper. Gently shake the conical flask to wet all the egg powder, and then oscillate for 0.5 h. Remove the conical flask, pour the sample solution into a test tube with an inner diameter of 15 mm (if there are still egg powder particles in the sample solution, repeat the test), and let it stand for 1.5 h. Take a pipette with a tip of about 2mm inner diameter, with the tip facing downwards, press the top of the pipette with your fingers, carefully insert the pipette into the test tube to the bottom of the sample solution, open the top of the pipette, let the sample solution at the bottom of the tube rise a little into the tip of the pipette, tightly seal the top of the pipette and take out the pipette, wipe the egg liquid on the outer wall of the pipette with absorbent cotton, carefully drop the sample solution on the prism of the refractometer, adjust the water temperature of the water pipe attached to the refractometer to 20℃, and read the refractive index of the sample solution. At the same time, determine the refractive index of the sodium chloride solution (50 g/L).
14.1.5 Calculation of results
The solubility index is calculated according to formula (5).
X=(RR)X100
Where:
X-solubility index;
R--refractive index of the sample solution;
R,--refractive index of the sodium chloride solution (50g/L). 14.2 Moisture
Accurately weigh 2.00g of the mixed sample and operate according to 6.1. 14.3 Fat
14.3.1 Reagents
Same as 6.2.2.
14.3.2 Instruments
Same as 6.2.3.
14.3.3 Analysis steps
Accurately weigh about 1.00 g of the mixed sample and place it in a fat immersion tube. Cover the sample with a little absorbent cotton. The following procedures are carried out according to 6.2.4.1 starting from "Use 100 mL of neutral chloroform to extract the sample in the tube 10 times..." 14.4 Free fatty acids
Same as 6.3.
14.5 Inorganic arsenic
Operate according to GB/T5009.11.
Operate according to GB/T5009.17. 2.8 g pasteurized whole egg powder is equivalent to 10 g fresh egg. 14.7 Zinc
According to GB/T5009.14. 2.8g pasteurized whole egg powder is equivalent to 10g fresh egg. 14.8 BHC, DDB
According to GB/T5009.19.
Chicken whole egg powder, egg yolk powder
Applicable to egg products made from fresh eggs through egg beating, filtering and spray drying. Applicable to egg products made from fresh egg yolk through processing and spray drying. 15 Sensory inspection
Powder or very loose block, uniformly light yellow (egg yolk powder is uniformly yellow), with the normal smell of egg powder or egg yolk powder, no 393
GB/T5009.47-2003
odor and impurities, should meet the requirements of GB2749. 16 Physical and chemical tests
16.1 Solubility index
Same as 14.1.
16.2 Water
Same as 14.2.
Same as 14.3.
16.4 Free fatty acids
Same as 6.3.
16.5 Inorganic minerals
According to GB/T5009.11. 2.8g whole egg powder is equivalent to 10g fresh egg, 4.8g egg yolk powder is equivalent to 10g fresh egg yolk. 16.6 Mercury
According to GB/T5009.17. 2.8g whole egg powder is equivalent to 10g fresh egg, 4.8g egg yolk powder is equivalent to 10g fresh egg yolk. 16.7 Zinc
According to GB/T5009.14. 2.8g whole egg powder is equivalent to 10g fresh egg, 4.8g egg yolk powder is equivalent to 10g fresh egg yolk. 16.8 BHC, DDD
According to GB/T5009.19. 2.8 Whole egg powder is equivalent to 10g fresh egg, 4.8g egg yolk powder is equivalent to 10g fresh egg yolk. Egg white flakes
Applicable to egg products made from fresh egg white as raw material, processed, fermented and dried. 17 Sensory inspection
Flake and crumb-shaped, uniform light yellow, with the normal smell of egg white flakes, no peculiar smell and impurities, should comply with the provisions of GB2749, and be identified by the following methods when necessary.
17.1 Impurities
Inspect with a double magnifying glass.
17.2 Debris
Weigh all the samples, place them on a copper sieve with a diameter of 300mm and a mesh size of 1.5mm, and sieve them evenly for 30 turns. Weigh the mass of the debris under the sieve and calculate it according to formula (6).
X-m2x1000
Where:
X——debris in the sample, in grams per hundred grams (g/100g);
——mass of the sample, in grams (g);
——mass of the debris under the sieve, in grams (g). 18 Physical and chemical tests
18.1 Moisture
Operate the same as 6.1.
18.2 Water-soluble matter
18.2.1 Principle
Calculate the water-soluble matter based on the amount of solid matter remaining after evaporating the water in the sample aqueous solution. 18.2.2 Analysis steps
18.2.2.1 Method A
GB/T5009.47--2003
Weigh 10.00g of the ground sample and place it in a 250mL beaker. First add about 20mL of water and stir gently with a glass rod. Then add about 150mL of water. After it is completely dissolved, move it to a 500mL volumetric flask. Wash the residue in the beaker with water, add the washing liquid to the volumetric flask, add water to the scale, and mix. After standing for 2h, continue to mix, take out about 80mL of the solution and place it in a 100mL centrifuge tube, and centrifuge it at a speed of 3000r/min for 30min. When the solution is transparent and clear, take 50mL and move it to a 100℃ drying constant volume evaporating dish. After evaporating to dryness on a water bath, dry it at 100℃ for 2h, place it in a desiccator for 30min, and weigh it. After that, weigh once every 1 hour after drying until the difference between the two masses does not exceed 10 mg.
18.2.2.2 Method
Weigh the sample according to 18.2.2.1, dissolve, make up to volume, let stand for 2 hours, then continue to shake, filter with quantitative filter paper into a 500mL conical flask, and discard about 30mL of the initial filtrate. Take 50 mL of the clarified liquid and proceed as per 18.2.2.1 starting from “transfer to a 100°C dry constant volume evaporating dish…\”.
18.2.2.3 Calculation of results
Calculate the water-soluble matter in the sample according to formula (7). Where:
m×50/500×100
water-soluble matter in the sample, in grams per 100 grams (g/100g); mass of the sample, in grams (g);
mz—mass of water-soluble matter in the sample for determination, in grams (g). The calculation result shall be rounded to two significant figures.
18.2.2.4 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 5% of the arithmetic mean. . 18.3 Total acidity
18.3.1 Principle
Calculate the total acidity based on the volume of sodium hydroxide standard titration solution consumed to neutralize the sample aqueous solution. 18.3.2 Reagents
18.3.2.1 Standard sodium hydroxide titration solution [c(NaOH)=0.05mol/L]. 18.3.2.2 Phenol-ethanol indicator solution (10g/L): Take 0.5g of phenolic acid, dissolve it in ethanol and dilute to 50mL. 18.3.3 Analysis steps
Take 50.0mL of the solution prepared in 18.2.2.1, place it in a 250mL conical flask, add 50mL of water and shake well, add 5 drops of phenol indicator solution, and use sodium hydroxide standard titration solution (0.05mol/L ) Titrate until a pink color appears and does not fade within 0.5 min. At the same time, draw 100 mL of water to perform a reagent blank test.
18.3.4 Calculation of results
The total acidity in the sample is calculated according to formula (8). XV-V)X0.09××100
m×50/500
Wherein:
X is the total acidity in the sample (calculated as lactic acid), in grams per hundred grams (g/100g); V, — the volume of the standard sodium hydroxide titration solution consumed by the sample solution, in grams per milliliter (mL); — the volume of the standard sodium hydroxide titration solution consumed by the blank test, in milliliters (mL); VbzxZ.net
GB/T5009.47—2003
c is sodium hydroxide The actual concentration of the standard titration solution is in moles per liter (mol/L); m
The mass of the sample is in grams (g);
0.09——The mass of lactic acid equivalent to 1.00mL of sodium hydroxide standard titration solution [c(NaOH)=1.000mol/LI] is in grams (g). The calculation result shall retain two significant figures.
18.3.5 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 5% of the arithmetic mean. 18.4 Inorganic arsenic
Operate in accordance with GB/T5009.11. 1.2g protein tablets are equivalent to 10g fresh protein. 18.5 Mercury
Operate in accordance with GB/T5009.17. 1.2g protein tablets are equivalent to 10g fresh protein. 18.6 Zinc
Operate in accordance with GB/T5009.14. 1.2g of egg white flakes is equivalent to 10g of fresh egg white. 18.7 666, Didi
Operate according to GB/T5009.19. 1.2g of egg white flakes is equivalent to 10g of fresh egg white. Preserved Eggs (Songhua Eggs)
19 Sensory Inspection
First carefully observe the appearance of the preserved eggs (mud coating, shape) for any signs of swelling. Pay attention to vibration and water sounds when shaking the preserved eggs for inspection. After scraping the mud off the preserved eggs, observe the integrity of the eggshell (note cracks), then peel off the eggshell. Pay attention to the integrity of the egg body and check for lead spots, mold spots, foreign matter (small blocks), and pine flower patterns. After opening, check the transparency, color, elasticity, smell, and taste of the egg white, and the shape, color, smell, and taste of the yolk. 20 Physical and Chemical Inspection
20.1 pH Value
20.1.1 Principle
The hydrogen ions (H+) in the solution to be tested have a certain functional relationship with the membrane potential of the glass electrode, and the pH value of the solution to be tested can be directly read from the acidometer.
20.1.2 Reagents
Buffers of various pH values ​​(provided with the acidometer). 20.1.3 Instruments
20.1.3.1 Acidometer.
20.1.3.2 Calomel electrode, glass electrode (lithium glass electrode is best). 20.1.3.3 Magnetic stirrer.
20.1.3.4 Tissue grinder.
20.1.4 Analysis steps
20.1.4.1 Sample preparation
Wash and peel 5 preserved eggs. Add water in a ratio of 2:1 preserved eggs: water, and pound into a homogenous slurry in a tissue grinder. 20.1.4.2 Determination
Weigh 15.00g of homogenate (equivalent to 10.00g of sample), add water and stir, dilute to 150mL, filter with double-layer gauze, measure 50mL to measure pH value.
20.2 Free alkalinity
20.2.1 Principle
The free water-soluble alkaline substances in the sample are calculated according to the amount of hydrochloric acid (1.0mol/L) consumed by 100g of preserved egg (the alkaline substances are calculated as 396% sodium hydroxide).
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