title: Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents.
abstract: In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium and gold ions in the digested samples were pre-column derivatized with HNATR to form colored chelates. The Pd-HNATR, Pt-HNATR, Rh-HNATR and Au-HNATR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] with a buffer solution of 0.05 mol L(-1) phosphoric acid as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and travelling towards the analytical column. These chelates separation on the analytical column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] was satisfactory with 72% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of Triton X-100) as mobile phase. The palladium, platinum, rhodium and gold chelates were separated completely within 2.5 min. Compared to the routine chromatographic method, more then 80% of separation time was shortened. By on-line solid phase extraction system, a large volume of sample (10 mL) can be injected, and the sensitivity of the method was greatly improved. The detection limits (S/N=3, the sample injection volume is 10 mL) of palladium, platinum, rhodium and gold in the original samples reaches 1.4, 1.8, 2.0 and 1.2 ng L(-1), respectively. The relative standard deviations for five replicate samples were 2.4-3.6%. The standard recoveries were 88-95%. This method was applied to the determination of palladium, platinum, rhodium and gold in human urine, water and geological samples with good results.
authors.affiliation: Department of Chemistry, Yunnan University, Kunming 650091, China.
authors.forename: Qiufen
authors.initials: Q
authors.lastname: Hu
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Yang
authors.forename: Zhangjie
authors.initials: Z
authors.lastname: Huang
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Guangyu
authors.initials: G
authors.lastname: Yang
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006046:Gold / Q000032:analysis* / Q000652:urine; D006801:Humans; D007202:Indicators and Reagents / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry*; D010165:Palladium / Q000032:analysis* / Q000652:urine; D010984:Platinum / Q000032:analysis* / Q000652:urine; D012236:Rhodanine / Q000031:analogs & derivatives* / Q000737:chemistry; D012238:Rhodium / Q000032:analysis* / Q000652:urine
chemical_list: C507678:5-(2-hydroxy-5-nitrophenylazo)thiorhodanine; D007202:Indicators and Reagents; D009574:Nitro Compounds; D010984:Platinum; D010165:Palladium; D006046:Gold; D012236:Rhodanine; D012238:Rhodium