PDF《石墨炉原子吸收》

90 ?C was used for all three elements. Standard (non-endcapped) pyrolytically coated THGA tubes (Part No. B3000641) were used for all analyses. The autosampler cups were soaked in 20% nitric acid overnight to minimize sample contamination, and were thoroughly rinsed with deionized water before use. Prior to unknown sample analysis, a five-point calibration curve (four standards and one blank) using isopropyl alcohol (IPA) was constructed for each analyte. By employing the latest analytical concepts of the Stabilized Temperature Platform Furnace (STPF) technique and the instrumental advances of THGA tubes, chemical interfer- ences are overcome allowing for faster, simpler direct calibration. This method reports the development of a direct analysis method for edible oil samples using GFAAS without digestion. The advantages of using this method include small sample volume, direct introduction of samples, high sensitivity, and rapid analysis times. The application of GFAAS to arsenic, lead and cadmium analysis in edible oils was performed. The optimal pyrolysis and atomization temperatures, limit of detection, quality control (QC) checks and recoveries were studied in order to develop a rapid and accurate method. Experimental Conditions Instrumentation The measurements were performed using the PerkinElmer PinAAcle? 900T atomic absorption spectrophotometer (PerkinElmer, Inc., Shelton, CT, USA) (Figure 1) equipped with an AS

900 graphite furnace autosampler and WinLab32? for AA software running under Microsoft? Windows?

7 operating system. Figure 1. PerkinElmer PinAAcle 900T atomic absorption spectrophotometer equipped with AS

900 graphite furnace autosampler. Table 1. Analytical conditions for analyzing several toxic metals in edible oils on the PinAAcle 900T. Analyte As Pb Cd Wavelength (nm) 193.70 283.31 228.80 Slit Width (nm) 0.7 0.7 0.7 Lamp Type EDL EDL HCL Signal Processing Peak Area Peak Area Peak Area Read Time (sec)

3 3

2 Standard/Sample Volume (?L)

20 20

20 Diluent Volume (?L)

4 4

5 Matrix Modifier

5 ?g Pd + 0.5 ?g Mg

5 ?g Pd + 0.5 ?g Mg

5 ?g Pd + 0.5 ?g Mg Matrix Modifier Volume (?L)

5 5

5 Injection Temp (?C )

90 90

90 Pipet Speed (%)

40 40

40 Calibration Equation Linear Through Zero Linear Through Zero Linear Through Zero Standard Concentration (?g/L) 0, 20, 30, 40,

50 0, 20, 30, 40,

50 0, 0.5, 1.0, 1.5, 2.0 QC Concentration (?g/L)

10 10 0.4 Automatic Spike Conc. (?g/L)

10 10 0.5 PerkinElmer PinAAcle 900T具有高效的, 真正意义的 双光束光学系统和固态检测器, 从而提供卓越的性噪 比. 整个系统的特点为: 采用纵向塞曼扣背景效进行石 墨炉分析, 双倍的光能量通过系统, 同时使用偏振光 学系统消除多余的光. 横向加热石墨原子化器 (THGA) 技术可以在整个石墨管长度上提供均匀一致的温度. 采用最新的分析技术上的概念产品: 恒温平台石墨炉? (STPF) 技术和先进的横向加热石墨管, 可使化学干扰 得以克服, 更快速, 更简单的进行直接校准. 分析条件 (表1) 和石墨炉升温程序 (表2) 在下表中给出. 90?C 加热进样均可用于三种元素. 标准 (无-封口端) 的热解 涂层横向加热石墨管 (货号 b3000641) 用于所有的分 析. 自动进样杯用20%的硝酸浸泡过夜, 在使用前用 0.5%的硝酸彻底冲洗, 以减少样品的污染. 在未知样 品分析之前, 先做一条包含五个点的校准曲线 (四个标 准点和一个空白点) , 每一个样品都使用异丙醇(IPA)配制. 采用最新的分析技术上的概念产品: 恒温平台石墨 炉? (STPF) 技术和先进的横向加热石墨管, 可使化学 干扰得以克服, 更快速, 更简单的进行直接校准. 图1. PerkinElmer? PinAAcle? 900T原子吸收分光光度计 配以AS900石墨炉自动进样器