5-(and-6)-FAM (full name: 5-(and-6)-Carboxyfluorescein mixed isomer) has a pKa of 6.5 and can be used as a pH indicator. Its excitation spectrum and fluorescence response to pH are similar to those of BCECF. Carboxyfluorescein can also be used as a tracer dye. The dye is membrane-impermeant and can be loaded into cells by microinjection or scrape loading.
<ul>
<li>&lamba;_Ex/&lamba;_Em (pH 9) = 492/514 nm</li>
<li>&epsilon; (pH 9) = 82,000</li>
<li>Yellow orange solid soluble in pH&gt;6 water</li>
<li>Store at 4°C and protect from light, especially in solution</li>
<li>C₂₁H₁₂O₇</li>
<li>MW: 376</li>
<li>[72088-94-9]</li>
</ul>