衍生液提取-高效液相色谱法快速测定香菇中的游离甲醛

以2,4-二硝基苯肼乙腈溶液-pH 5磷酸盐缓冲液(体积比为1:1)为提取溶液,提取香菇中游离的甲醛,采用高效液相色谱法测定。结果表明,乙腈-pH 5磷酸盐缓冲液(体积比为1:1)能够有效地抑制香菇中酶反应释放甲醛,达到提取香菇中游离甲醛的目的。在提取液中加入衍生化试剂2,4-二硝基苯肼,将甲醛的提取和衍生化反应相结合,此衍生液提取方法有效地提高了检测效率。鲜香菇样品中分别添加5.0、10.0、20.0 mg/kg的甲醛,平均回收率分别为89.2%、91.7%和90.4%,相对标准偏差(n=6)＜5.0%。方法的定量限（S/N＞10）为5.0 mg/kg。该方法适用于香菇中游离甲醛的检测,且快速简便、重现性好,是确定香菇中甲醛天然本底值的有效方法。

Determination of free formaldehyde in mushrooms by derivative solution extraction and high performance liquid chromatography

A derivative solution extraction was applied to determine free formaldehyde in mushrooms by high performance liquid chromatography. The formaldehyde in mushrooms directly reacted with 2,4-dinitrophenylhydrazine in acetonitrile-phosphate buffer (pH 5) (1:1, v/v) solution, and then determined by high performance liquid chromatography. The formaldehyde formation by enzyme reaction in mushrooms was inhibited in acetonitrile-phosphate buffer (pH 5) (1:1, v/v) solution, and therefore only free formaldehyde was extracted. To improve the detecting efficiency, 2,4-dinitrophenylhydrazine was dissolved in the solution and free formaldehyde was directly derived during extracting process. The recoveries were 89.2%, 91.7% and 90.4% at the spiking levels of 5.0, 10.0 and 20.0 mg/kg of formaldehyde in mushrooms, respectively, and the relative standard deviations (n=6) were less than 5.0%. The limit of quantification of the formaldehyde in mushrooms was 5.0 mg/kg. The method has been applied to the determination of formaldehyde in real samples and the results showed that the content of formaldehyde was significantly lower than that obtained by the traditional methods. The method has the advantages of simple operation, good accuracy, and meets the requirement of the determination of naturally-occurring formaldehyde in mushrooms.