Preconcentration system automated

In some cases, ultrasonic nebulization or preconcentration is used to enhance detection limits. As, Se, and Sb were measured in cloud water detection limits were 20, 100, and 20 pg/mL, respectively, using pneumatic nebulization and four to five times lower using ultrasonic nebulization [311]. In another study [312], activated charcoal from a 1-L sample volume was used to preconcentrate Pd and Pt in fresh waters. Detection limits were 0.3-0.8 ng/L. An automated online preconcentration system based on a cationic resin (AG50W-X8) was used to measure Cd, Pb, Ni, Cu, and Zn. A preconcentration factor of 30 was obtained even with a sample throughput of 20 samples per hour [313]. 

Bosch, O.C., Sanchez, R.F., Cano, P.J., Garcia de Torres, A. Automated on-line separation-preconcentration system for platinum determination by electrothermal atomic absorption spectrometry. Anal. Chlm. Acta 494, 97-103 (2003)... 

Although the automated, trace-metal preconcentration system has undergone a number of design changes, the major characteristics are summa-... 

F.L. da Silva, E.M. GanzarolU, and E. Carasek. Use of Nb205-Si02 in an automated online preconcentration system for determination of copper and cadmium by FAAS. Talanta 62 727-733, 2004. 

Y. Sung, Z. Liu, and S. Huang. Automated on-line preconcentration system for electrothermal atomic absorption spectrometry for the determination of copper and molybdenum in seawater. Journal of Analytical Atomic Spectrometry 12 841-847,1997. 

D. G. da Silva and L. Dos Santos, Application of simplex optimisation in the development of an automated online preconcentration system for manganese determination, J. Brazil. Chem. Soc., 2010, 21(12), 2340-2346. 

Sample preconcentration was performed by means of an automated on-line SPE sample processor Prospekt-2 (Spark Holland, Emmen, The Netherlands). Oasis HLB cartridges (Waters, Barcelona, Spain) were used to preconcentrate cannabi-noids present in the water samples whereas isolation of the rest of the compounds was done in PLRPs cartridges (Spark Holland). Before extraction, influent samples were diluted with HPLC water (1 9, v/v) to reduce matrix interferences and to fit some analyte concentrations, e.g., cocaine (CO) and benzoylecgonine (BE), within the linear calibration range. A sample volume of 5 mL was spiked with the internal standard mixture (at 20 ng/L) in order to correct for potential losses during the analytical procedure, as well as for matrix effects. Elution of the analytes to the LC system was done with the chromatographic mobile phase. 

Automated online SPE LC systems are used extensively for environmental assays. Trays of SPE cartridges and autosampler can be used in the field. Water samples are preconcentrated trays of SPE cartridges loaded with analytes are brought to the laboratory and mounted onto an online SPE LC/ MS/MS system for analysis. Prospekt and Symbiosis systems were used for monitoring herbicides and transformation products (Hogenboom et al. 1998,1999a and b Lopez-Roldan et al. 2004 Kato et al. 2003 Lacorte and Barcelo 1995 Ferrer and Barcelo 1999,2001 Riediker et al. 2002), phenols... 

Preconcentration can enhance instrumental detection Hmits by two orders of magnitude. Interfering sample components (i.e. high salt contents) are readily removed. The commercially available TraceCon system provides a simple automated step for combining flame-AAS or ICP-OES analytical methods. Its robust design shows many good aspects of laboratory automation. 

Higher-specificity techniques such as immunoaffinity chromatography have been also found widespread acceptance for the determination of chloramphenicol residues in edible animal products. The first pertinent reports concerned the determination of chloramphenicol residues in swine muscle (60) and milk and eggs (21). Alternative immunoaffinity chromatography procedures were suggested later for exiraction/preconcentration of chloramphenicol residues from swine tissues (50), or for online immunoaffinity extraction for the determination of chloramphenicol in milk and swine muscle by an automated column-switching system (22). 

Liquid chromatography cleanup on a LiChrosorb Diol column has been further proposed for the offline purification of chloramphenicol residues from bovine muscle and eggs (32). An online approach based on reversed-phase principles has also been described for isolation of chloramphenicol residues from swine kidney by an automated column switching system (63). Use of a protein exclusion column (Hisep) has been also suggested in an online trace-enrichment method for the determination of chloramphenicol in animal tissues (52). By employing a column-switching system, all chloramphenicol that eluted from the protein exclusion column was trapped at the entry of a 5 m Supelcosil LC-18 preconcentration column, to be subsequently back-flashed into the analytical column. 

Figure 11. Diagram of system used to carry out automated preconcentration and analysis of water samples. Detection accomplished with UV absorption and photochemical dehalogenation with subsequent fluorescence detection of the photochemical reaction products. (Reproduced with permission from reference 50. Copyright 1982 Vieweg.)...

An automated system for offline SPE is ASPEC XL. The main advantage of using offline SPE is that the analytes can be stored in disposable preconcentration cartridges. Polymeric sorbent Lichrolut EN or ENV was used for groundwater preconcentration (42,43). 

In 1994, Dadfarnia and McLeod described the analysis of uranium in surface waters and sea water using a simple FI system with an alumina column for preconcentration.77 Species eluted from this column were delivered to an ICP-MS as the detector. Also in 1994, Hollenbach et al. described the automation of extraction chromatographic methods based on TRU-Resin and TEVA-Resin to separate and preconcentrate U, Th, and Tc from soil samples, using ICP-MS for detection.49125 In 1996, Aldstadt et al. described the use of FI and extraction chromatography using TRU-Resin to determine U in environmental samples by ICP-MS.78... 

The development of solvent-impregnated resins and extraction-chromatographic procedures has enabled the automation of radiochemical separations for analytical radionuclide determinations. These separations provide preconcentration from simple matrices like groundwater and separation from complex matrixes such as dissolved sediments, dissolved spent fuel, or nuclear-waste materials. Most of the published work has been carried out using fluidic systems to couple column-based separations to on-line detection, but robotic methods also appear to be very promising. Many approaches to fluidic automation have been used, from individual FI and SI systems to commercial FI sample-introduction systems for atomic spectroscopies. 

Katarina, R.K., N. Lenghor, and S. Motomizu. 2007. On-line preconcentration method for the determination of trace metals in water samples using a fully automated pretreatment system coupled with ICP-AES. Anal. Sci. 23 343-350. 

Off-line dicarbamate solvent extraction and ICP-MS analysis [317] provided part-per-trillion detection limits Cd (0.2 ppt), Co (0.3 ppt), Cu (3 ppt), Fe (21 ppt), Ni (2 ppt), Pb (0.5 ppt), and Zn (2 ppt). Off-line matrix removal and preconcentration using cellulose-immobilized ethylenediaminetetraacetic acid (EDTA) have also been reported [318]. Transition metals and rare earth elements were preconcentrated and separated from the matrix using on-line ion chromatography with a NTA chelating resin [319]. Isotope-dilution-based concentration measurement has also been used after matrix separation with a Chelex ion-exchange resin [320]. The pH, flow rate, resin volume, elution volume, and time required for isotope equilibration were optimized. A controlled-pore glass immobilized iminodiacetate based automated on-line matrix separation system has also been described [321]. Recoveries for most metals were between 62% and 113%. 

The Miniature automatic Continuous Agent Monitoring System (MiniCAMS ) utilizes an automated near-real-time gas chromatograph. An air sample is drawn through a preconcentrator loop filled with an... 

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