Effective separation of inorganic mercury (Hg2+), methylmercury (MeHg), ethylmercury (EtHg)
and phenylmercury (PhHg) within 2–2.5 min was achieved on two consecutive 12.5-mm strong cation
exchange guard columns with 2.0 mM l-cysteine or thiourea (pH 2.0) as the mobile phase