(来学网)为测定水样中氰化物,水样采集后应加入下列哪种试剂,并在4℃保存
  • A.
    (来学网)NaOH,使pH>10
  • B.
    (来学网)NaOH,使pH>12
  • C.
    (来学网)HNO3,使pH<2
  • D.
    (来学网)H2SO4,使pH<2
  • E.
    (来学网)醋酸锌