In acidic media, Fe(Ш) could be reduced to Fe(Ⅱ) by isoniazid, reacts with 2,2'-bipyridine form an orange complex a maximum absorption wavelength of 522 nm. According this principle, the content isoniazid can measured indirectly measuring amount Fe(Ⅱ). A new method for determination Fe(Ⅱ)-2,2'-bipyridine spectrophotometry has been established. At optimum conditions, linear relationship is good ...