Time-based and volume-based sampling for flow-injection on-line sorbent extraction graphite furnace atomic absorption spectrometry

✍ Scribed by Bernhard Welz; Xuefeng Yin; Michael Sperling

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 945 KB
• Volume: 261
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)80229-z

✦ Synopsis

Flow-mJectlon on-hne preconcentratlon systems for graphite furnace atomic absorptton spectrometry are comphcated by the low eluate volume of typtcally less than 50 ~1 which can be accommodated m a graphtte tube or on a graphite platform Even when a column wtth an extra small capactty of 15 ~1 was used, It was found tmposstble to elute the sorbed analyte completely with an eluate volume that was compatible with the capacity of the graphite furnace Two approaches for mtroducmg only the most concentrated fraction of the eluate mto the graphite tube while discarding the rest were mvesttgated and compared controlhng the bme interval for collectIon and mtroductton of the eluate fraction mto the furnace tube (time-based samphng), and colleetlon of the eluate fraction of interest m thm tubmg of fixed volume, followed by mtroductton of thts fraction mto the tube using a low flow of an (volume-based samphng) Cadmmm, copper, lead and mckel were the analyte elements mvesttgated A U-30% greater enhancement factor was obtamed for volume-based sampling because dlsperslon was interrupted durmg sample mJectton by atr segmentatton The short-and long-term reproduclbdlty were also better for volume-based samphng because vanatlons m the pump tubmg had no Influence on the eluate volume Introduced These combmed effects resulted m an tmprovement m detectlon hmlts of the four elements by factors of 1 3-2 0 Sample throughput (23 h-l), sample consumption (3 ml mm-') and reagent consumptton were the same for both approaches There were no significant differences m the accuracy and preclslon of the two techniques m the analysts of sea water, estuarme water and Ilver water standard reference materials