Pilone G J
J Assoc Off Anal Chem. 1985 Mar-Apr;68(2):188-90.
A dichromate-spectrophotometric method for the determination of ethanol in wine was compared in a collaborative, matched pair study with the AOAC dichromate-titrimetric method, 11.008-11.011. Both methods require distillation of the sample into dichromate. The titrimetric method measures ethanol by titrating the excess dichromate with ferrous ammonium sulfate after conversion of ethanol to acetic acid; the spectrophotometric method directly measures the reduced dichromate formed after oxidation. In addition to comparing the 2 methods, the collaborative study also compared the use of 2 types of assemblies for obtaining the ethanol distillate: the Scott-type, which is used in 11.008-11.011, and the electric Kirk-type. Results of the collaborative study indicated that the repeatability and reproducibility of the official titrimetric method were generally far superior to those of the spectrophotometric method; therefore, adoption of the spectrophotometric method is not recommended. Comparison of titrimetric method results obtained using the 2 types of stills indicated that repeatability and reproducibility were somewhat better when Scott apparatus was used, but measurements using Kirk-type compared well in the range of ethanol concentrations found in table and fortified wines. The Kirk-type distillation apparatus has been adopted official first action as an alternative to Scott apparatus in the dichromate oxidation method for ethanol in wine, 11.008-11.011.
在一项协同配对研究中，将一种用于测定葡萄酒中乙醇的重铬酸盐分光光度法与美国官方分析化学师协会（AOAC）的重铬酸盐滴定法（11.008 - 11.011）进行了比较。两种方法都需要将样品蒸馏到重铬酸盐中。滴定法是在乙醇转化为乙酸后，用硫酸亚铁铵滴定过量的重铬酸盐来测定乙醇；分光光度法则直接测量氧化后形成的还原重铬酸盐。除了比较这两种方法外，协同研究还比较了用于获得乙醇馏出物的两种装置组件的使用情况：11.008 - 11.011中使用的斯科特型装置和电动柯克型装置。协同研究结果表明，官方滴定法的重复性和再现性总体上远优于分光光度法；因此，不建议采用分光光度法。使用两种蒸馏器获得的滴定法结果比较表明，使用斯科特装置时重复性和再现性稍好一些，但在餐酒和加度葡萄酒中发现的乙醇浓度范围内，使用柯克型装置的测量结果也比较理想。柯克型蒸馏装置已被官方首次采用，作为11.008 - 11.011中葡萄酒中乙醇重铬酸盐氧化法中斯科特装置的替代方法。
