§ 172.820 Polyethylene glycol （mean molecular weight 200–9,500）.
Polyethylene glycol identified in this section may be safely used in food in accordance with the following prescribed conditions:
（a） Identity. （1） The additive is an addition polymer of ethylene oxide and water with a mean molecular weight of 200 to 9,500.
（2） It contains no more than 0.2 percent total by weight of ethylene and diethylene glycols when tested by the analytical methods prescribed in paragraph （b） of this section.
（b） Analytical method. （1） The analytical method prescribed in the National Formulary XV （1980）, page 1244, for polyethylene glycol 400 shall be used to determine the total ethylene and diethylene glycol content of polyethylene glycols having mean molecular weights of 450 or higher.
（2） The following analytical method shall be used to determine the total ethylene and diethylene glycol content of polyethylene glycols having mean molecular weights below 450.
Analytical Method
ethylene glycol and diethylene glycol content of polyethylene glycols
The analytical method for determining ethylene glycol and diethylene glycol is as follows:
apparatus
Gas chromatograph with hydrogen flame ionization detector （Varian Aerograph 600 D or equivalent）. The following conditions shall be employed with the Varian Aerograph 600 D gas chromatograph:
Column temperature: 165 °C.
Inlet temperature: 260 °C.
Carrier gas （nitrogen） flow rate: 70 milliliters per minute.
Hydrogen and air flow to burner: Optimize to give maximum sensitivity.
Sample size: 2 microliters.
Elution time: Ethylene glycol: 2.0 minutes. Diethylene glycol: 6.5 minutes.
Recorder: ?0.5 to +1.05 millivolt, full span, 1 second full response time.
Syringe: 10-microliter （Hamilton 710 N or equivalent）.
Chromatograph column: 5 feet ×1/8inch. I.D. stainless steel tube packed with sorbitol （Mathieson-Coleman-Bell 2768 Sorbitol SX850, or equivalent） 12 percent in H2O by weight on 60–80 mesh nonacid washed diatomaceous earth （Chromosorb W. Johns-Manville, or equivalent）.
reagents and materials
Carrier gas, nitrogen: Commercial grade in cylinder equipped with reducing regulator to provide 50 p.s.i.g. to the gas chromatograph.
Ethylene glycol: Commercial grade. Purify if necessary, by distillation.
Diethylene glycol: Commercial grade. Purify, if necessary, by distillation.
Glycol standards: Prepare chromatographic standards by dissolving known amounts of ethylene glycol and diethylene glycol in water. Suitable concentrations for standardization range from 1 to 6 milligrams of each component per milliliter （for example 10 milligrams diluted to volume in a 10-milliliter volumetric flask is equivalent to 1 milligram per milliliter）.
standardization
Inject a 2-microliter aliquot of the glycol standard into the gas chromatograph employing the conditions described above. Measure the net peak heights for the ethylene glycol and for the diethylene glycol. Record the values as follows:
A =Peak height in millimeters of the ethylene glycol peak.
B =milligrams of ethylene glycol per milliliter of standard solution.
C =Peak height in millimeters of the diethylene glycol peak.
D =Milligrams of diethylene glycol per milliliter of standard solution.
procedure
Weigh approximately 4 grams of polyethylene glycol sample accurately into a 10-milliliter volumetric flask. Dilute to volume with water. Mix the solution thoroughly and inject a 2-microliter aliquot into the gas chromatograph. Measure the heights, in millimeters, of the ethylene glycol peak and of the diethylene glycol peak and record as E and F, respectively.
Percent ethylene glycol=（ E × B ）/（ A ×sample weight in grams）
Percent diethylene glycol=（ F × D ）/（ C ×sample weight in grams）
（c） Uses. It may be used, except in milk or preparations intended for addition to milk, as follows:
（1） As a coating, binder, plasticizing agent, and/or lubricant in tablets used for food.
（2） As an adjuvant to improve flavor and as a bodying agent in nonnutritive sweeteners identified in §180.37 of this chapter.
（3） As an adjuvant in dispersing vitamin and/or mineral preparations.
（4） As a coating on sodium nitrite to inhibit hygroscopic properties.
（d） Limitations. （1） It is used in an amount not greater than that required to produce the intended physical or technical effect.
（2） A tolerance of zero is established for residues of polyethylene glycol in milk.
[42 FR 14491, Mar. 15, 1977, as amended at 49 FR 10105, Mar. 19, 1984]
更多关于美国 FDA 已批准的直接用于人类食品的添加剂种类法规，请点击美国FDA 21 CFR 第172部分已批准的直接用于人类食品的添加剂种类汇总
