Fluorescent method for monitoring oil degradation

A method for determining the presence or amount of hydrogen ion activity in a substantially non-aqueous medium rendered substantially free of paramagnetic metal cation, the method comprising the steps of:

• mixing a non-azo substituted 4(.omega.-aminoalkyl)amino-N-alkyl-1,8-naphthalimide dye with the hydrogen ion, if any, in the non-aqueous medium to form a mixture;
• irradiating the mixture with a light sufficient to cause the mixture to emit a detectable fluorescent emission spectrum;
• detecting the fluorescent emission spectrum of the mixture;
• and
• comparing the detected fluorescent emission spectrum with standard fluorescent emission spectra generated by reacting the non-azo substituted 4(.omega.-aminoalkyl)amino-N-alkyl-1,8-naphthalimide dye with different known hydrogen ion activities, wherein differences between the fluorescent emission spectra compared are dependent upon the presence or level of the hydrogen ion activity present in the mixture.

A method for assaying the degradation of an oil rendered substantially free of paramagnetic metal cation, the method comprising the steps of:

• forming a mixture from the oil in a suitable solvent with a compound having the structure of ##STR1## wherein a=2to 8;
• R=(CH.sub.2).sub.b CH.sub.3, b=3 to 17;
• R'=H;
• or (CH.sub.2).sub.c CH.sub.3, c=0 to 5;
• R"=H;
• or (CH.sub.2).sub.d CH.sub.3, d=0 to 5;
• R.sub.a =H;
• F;
• Cl;
• Br, I;
• NO.sub.2 ;
• or (CH.sub.2).sub.e CH.sub.3, e=0 to 5;
• and
• R.sub.b =H;
• F;
• Cl;
• Br;
• I;
• NO.sub.2 ;
• or (CH.sub.2).sub.f CH.sub.3, f=0 to 5;
• wherein R.sub.a and R.sub.b are not both F, Cl, Br, I or NO.sub.2 ;
• irradiating the mixture with a light sufficient to cause the mixture to emit a detectable fluorescent emission spectrum;
• detecting the fluorescent emission spectrum of the mixture;
• and
• comparing the detected fluorescent emission spectrum with standard fluorescent emission spectra generated by reacting the compound with standard oil samples having different known hydrogen ion activities, wherein differences between the fluorescent emission spectra compared are dependent upon the presence or level of the hydrogen ion activity present in the mixture, and wherein the presence of hydrogen ion activity in the oil over a predetermined level of activity indicates a degradation of the oil.

A method for determining the presence or amount of hydrogen ion activity in a substantially non-aqueous medium rendered substantially free of paramagnetic metal cation, the method comprising the steps of:

• forming a mixture from the hydrogen ion, if any, in the non-aqueous medium with a compound having the structure of ##STR2## wherein a=2 to 8;
• R=(CH.sub.2).sub.b CH.sub.3, b=3 to 17;
• R'=H;
• or (CH.sub.2).sub.c CH.sub.3, c=0 to 5;
• R"=H;
• or (CH.sub.2).sub.d CH.sub.3, d=0 to 5;
• R.sub.a =H;
• F;
• Cl;
• Br;
• I;
• NO.sub.2 ;
• or (CH.sub.2).sub.e CH.sub.3, e=0 to 5;
• and
• R.sub.b =H;
• F;
• Cl;
• Br;
• I;
• NO.sub.2 ;
• or (CH.sub.2).sub.f CH.sub.3, f=0 to 5
• wherein R.sub.a and R.sub.b are not both F, Cl, Br, I or No.sub.2
• irradiating the mixture with a light sufficient to cause the mixture to emit a detectable fluorescent emission spectrum;
• detecting the fluorescent emission ratio of about 490 to about 520 nm of the mixture;
• and
• monitoring differences in the detected fluorescent emission ratio of about 490 to abut 520 nm of the mixture, as compared to standard fluorescent emission spectra ration of about 490 to about 520 nm generated by reacting the compound with different known hydrogen ion activities, the differences being dependent upon the presence or level of the hydrogen ion activity present in the mixture.