Medical brain notes 35

  Developing   a   Standard   Method The   goals   of   analytical   chemistry   are   to   improve   established   methods   of   analysis,   to   extend   existing   methods   of   analysis to   new   types   of   samples,   and   to   develop   new   analytical   methods.   Once a   method   has   been   developed   and   tested,   its   application   is   best described   as   chemical   analysis.   We   recognize   the   status   of   such methods   by   calling   them   standard   methods.   A   standard   method   may   be unique   to   a   particular   laboratory,   which   developed   the   method   for   their specific   pu...

  Optimizing the Experimental Procedure In   the   presence   of   H 2 O 2   and   H 2 SO 4 ,   solutions   of   vanadium   form   a   reddish   brown color   that   is   believed   to   be   a   compound   with   the   general   formula   (VO) 2 (SO 4 ) 3 . Since   the   intensity   of   the   color   depends   on   the   concentration   of   vanadium,   the   ab- sorbance   of   the   solution   at   a   wavelength   of   450   nm   can   be   used   for   the   quantitative analysis   of   vanadium.   The   intensity   of   the   color,   however,   also   depends   on   the  amount   of   H 2 O 2   and   H 2 SO 4   present. ...

  Response Surfaces One   of   the   most   effective   ways   to   think   about   optimization   is   to   visualize   how   a   sys- tem’s   response   changes   when   we   increase   or   decrease   the   levels   of   one   or   more   of   its factors.   A   plot   of   the   system’s   response   as   a   function   of   the   factor   levels   is   called   a  response   surface.   The   simplest   response   surface   is   for   a   system   with   only   one   fac- tor.   In   this   case   the   response   surface   is   a   straight   or   curved   line   in   two   dimensions. A   calibration ...

  Searching Algorithms for Response Surfaces Imagine   that   you   wish   to   climb   to   the   top   of   a   mountain.   Because   the   mountain   is covered   with   trees   that   obscure   its   shape,   the   shortest   path   to   the   summit   is   un- known.   Nevertheless,   you   can   reach   the   summit   by   always   walking   in   a   direction that   moves   you   to   a   higher   elevation.   The   route   followed   (Figure   14.3)   is   the   result of   a   systematic   search   for   the   summit.   Of   course,   many   routes   are   possible   leading from   the   initial   starting   point ...