Which of the following methods could be used to transform a qualitative emulsion test into a semi-quantitative test for lipids?

Using the control of sample mass and scaling emulsion height is crucial for transforming a qualitative emulsion test into a semi-quantitative assessment for lipids. By standardizing the sample mass, it ensures that each test has a consistent amount of lipid present, which allows for a more accurate comparison between different samples. Scaling emulsion height provides a visual measurement that can correlate to the amount of lipid in the sample—the higher the emulsion, the more lipid present. This method effectively converts subjective observations into measurable data, which is essential for semi-quantitative analysis.

The other options, while they might influence the outcome of the test, do not provide the same level of quantification. For instance, standardizing the volume of reagents used can create consistency in the reaction but does not directly measure lipid concentration. Conducting the test at room temperature could affect reaction rates but is not a method to quantify lipids. Similarly, reducing sample preparation time may streamline the process but does not contribute to the semi-quantitative transformation of the test.