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80. ADAPTATION OF BIOLOGICAL SAMPLES FOR DETERMINATION OF STEROIDS BY ECLIA Páez JB1, Arias AJ2, Terán ZP1, Zelarayán LI2. 1Facultad de Bioquímica, Química y Farmacia. UNT. Ayacucho 471. 2Instituto de Biología. INSIBIO-UNT. Chacabuco 461. Tucumán. E-mail: jbpaez@arnet.com.ar The determination of steroids dissolved in saline matrix with ECLIA validated for serum protein matrix and with a definite reporting range can lead to inexact and imprecise results. In this work we adapted a procedure for steroid extraction from biological samples to reach the reporting range for serum matrices using ECLIA. In order to analyze the influence of the matrix, a volume of high protein pattern was diluted 1/10 with Ringer and another portion with universal protein diluent DUP/ECLIA (1/10). Testosterone and progesterone were determined. The samples consisted of saline solution (Ringer) containing steroids from the incubation of Rhinella arenarum ovarian follicles. We investigated a consistent adaptation in: steroids extraction with dichloromethane (DCM), reversible emulsion, centrifugation, removal of the aqueous phase, dry DCM evaporation and final stripping of the steroids with DUP. In order to reach the reporting range, different ratios of sample volumes to DUP were tested. Assays of steroid recovery were performed to assess adaptation. Quintuplicate samples were used to evaluate systematic error. The results indicated the need for the protein matrix since recovery was 66% in saline solutions and 97% when using DUP. The 2:1 ratio of saline sample to DCM and the 4:1 ratio of saline sample to DUP were optimal. The recovery range achieved was 95-100% and CV between 5.0-5.4%. These results are consistent with the validation of the automated homogeneous analysis system ECLIA. We conclude that the adaptation of the steroid samples in Ringer solution allows their correct measurement by ECLIA.