What episode was the last appearance of the character, rikki sandoval?
CREATE TABLE "table1_11240028_3" (
  "character" text,
  "portrayed_by" text,
  "relationship" text,
  "first_appearance" text,
  "last_appearance" text
);
SELECT "last_appearance" FROM "table1_11240028_3" WHERE "character"='Rikki Sandoval';