A process for determining the pH value in the interior of a cell is described. This is accomplished by measurement of the emission of a fluorescent substance which is absorbed by the cell through incubation in a solution. The solution contains a compound of the said fluorescent substance; the fluorescent substance is separated from this compound in the cell by an enzyme present in the cell. The fluorescent substance selected is one such that the frequency of the emission maximum is dependent on the pH value. The compound of this fluorescent substance which is selected is one which is membrane penetrating. Measurement of the fluorescence is based on the principle of measurement of the frequency at which the emission maximum occurs. A fluorescent substance suitable for this purpose is 2,3-dicyano-1,4-hydroquinone. A suitable membrane penetrating compound is 1,4-diacetoxy-2,3-dicyanobenzene or 1,4-dibutyryloxy-2,3-dicyanobenzene or 1,4-di(-tert-butyloxycarbonyl-1-alanyloxy)-2,3-dicyanobenzene.
                            本文描述了一种确定细胞内pH值的过程。这是通过测量荧光物质的发射来实现的,该荧光物质通过在溶液中孵育后被细胞吸收。溶液中含有所述荧光物质的化合物;该荧光物质在细胞内通过存在于细胞中的酶与该化合物分离。所选的荧光物质是一种发射最大值频率取决于pH值的荧光物质。所选的该荧光物质的化合物是一种穿膜化合物。荧光测量基于测量发射最大值发生的频率的原理。适用于此目的的荧光物质是2,3-二
氰基-1,4-
对苯二酚。适用的穿膜化合物是1,4-
二乙酰氧基-2,3-二
氰基苯或1,4-二丁酰氧基-2,3-二
氰基苯或1,4-二(叔丁氧羰基-1-丙氧基)-2,3-二
氰基苯。