## 3 Results and Discussion
### The Minimum Droplet Size that Can be Detected as a Spike  
Next, we used the present system to calculate the minimum diameter of an oil droplet in an O/W emulsion, \(D_{\rm min}\), which could be detected as a spike. Previously, the following equation was proposed for calculating the value [32]:  
\[D_{\rm min}\,=\,D_{\rm max}\,\sqrt{\frac{s_{\rm min}}{s_{\rm max}}} \tag{1}\]  
Figure 3: Time profile for toluene in an O/W emulsion with white turbidity. The time profile was obtained by extracting the peak areas at \(m/z\) 92 and 91 (see text). It is noted that the bottom time profile is a continuation of the top time profile. The bright-field image of a sample flowing through an inner capillary column is also shown. The most intense spike is specified by \(\alpha\), and was used for obtaining \(S_{\rm max}\) (see text). A peak with an \(S/B\) of 3 is marked with an asterisk (*). Figure 2: Time profile for toluene in an oil-in-water (O/W) emulsion after creaming that appeared transparent. The time profile was obtained by extracting the peak areas at \(m/z\) 92 and 91 (see text). The bright-field image of a sample flowing through an inner capillary column is also shown. [PERSON]; [PERSON]; [PERSON] Determination of the electrostatic potential of oil-in-water emulsion droplets by combined use of two membrane potential-sensitive dyes. _Anal. Sci._**2017**, _33_, 813-819. [CrossRef] [PubMed]
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