[en] The sum peak method based on the perturbed angular correlation of two gamma rays in cascade decay from the radioactive nucleus has been considered for the purpose. A sum peak is observed as a result of simultaneous detection of two cascading gamma rays as one event. The intensity ratio of the sum peak to the singles peak has been used to observe changes caused by the different environments of decaying atoms of ⁷⁵Se. In all the samples the sum peak intensity I₄₀₀ (279 + 121 keV) relative to its singles peak intensity I₂₇₉ or I₁₂₁ was determined by gamma-gamma summing technique in a single HPGe detector. The electric field gradient was found to vary with chemical complex formation; the components of the electric field gradient (in esu/cm 2 ) were as follows (EFG/ample; Se; Se+EDTA; Se+Glycerol; Se+HCl; Se+HClO₄; Se+Blood(A+)): V_ZZ*10²⁵: 0.6290; 4.190; 7.764; 2.370; 1.469; 1.259; V_YY*10²⁵: 0.5031; 3.305; 6.302; 1.646; 1.101; 0.975; V_XX*10²⁵: 0.1258; 0.885; 1.462; 0.723; 0.735; 0.284. Large variation in the values indicates that various environments influence the magnitude of EFG at the Se site differently. It is clearly demonstrated that the sum peak method, alternative for time integral perturbed angular correlation formation provides information on various chemical environments surrounding the decaying atoms of ⁷⁵Se and thus ⁷⁵Se can be used as a useful probe to study biological specimens and proteins. It does not need a complicated system of coincidence circuits as required in ordinary Perturbed Angular Correlation (PAC) experiments. This technique is a simpler yet versatile alternative to the standard PAC method. (author)