The experimental design approach to the optimization of a simple quick easy cheap effective rugged and safe method for the analysis of phytoestrogens in complex soy-based food

Experimental Design Step by Step: A Practical Guide for Beginners

Inside the world of chemometrics, a fundamental role is played by the experimental design. Although introduced almost a century ago (1935), it is still not widely employed by chemists and its usefulness continues to be underestimated. When asking why, the answers are often the following: it is too difficult to apply and too much experimental effort is required. Actually, a deeper knowledge on the topic could offer a different point of view. The aim of the present tutorial is to introduce the experimental design to beginners, by providing the theoretical basic principles as well as a practical guide to use the most common designs, from the experimental plan to the final optimization. Response surface methodology will be discussed, and the main terms related to model computation and statistical evaluations usually performed by software will be explained, in order to give suitable tools to properly use them.

Homoisoflavonoids profiling of Ophiopogon japonicus by off-line coupling high-speed countercurrent chromatography with high-performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry

Roots of Ophiopogon japonicus have been used as a functional food ingredient and traditional Chinese medicine for a long time in China. Homoisoflavonoids are one of the major kinds of bioactive compounds in O. japonicus; however, literature data about its homoisoflavonoids profile are scarce because of the complex ingredients with low abundance. Here, homoisoflavonoid fraction was prepared by petroleum ether extraction. Then, a high-speed countercurrent chromatography off-line coupling with high-performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry was developed for systematic identification of homoisoflavonoids. After that, 39 homoisoflavonoids, including 29 homoisoflavanone and 10 homoisoflavone, were unambiguously or tentatively identified, while 12 of them were reported in O. japonicus for the first time. Finally, eight available homoisoflavonoids were sensitively, precisely, and accurately determined by standard calibration curves, with limit of detection and limit of quantification in the range of 0.05-0.30 μg/mL and 0.12-0.66 μg/mL, relative standard deviation less than 7.3% for intra- and interday variations, and recovery at 94.5-105.2%. Collectively, our developed method is efficient, reliable, and valuable to profile chemical components of complex natural products.