Statistics for analytical chemistry

Sample pretreatment methods, such as separation and/or preconcentration prior to the determination of metal ions have developed rapidly due to the increasing need for accurate and precise measurements at extremely low levels of ions in diverse matrices. This review covers new sorbents including microorganisms and nanomaterials used for the solid-phase extraction of metal ions from various sample matrices. A literature survey of the last three years (2005-2007) offering a critical review of these new sorbents available for use in trace metal enrichment is provided. To keep the focus on new sorbents, some of the papers relating to well-known sorbents such as activated carbon are excluded.

New Sorbents for Solid-Phase Extraction for Metal Enrichment

Amberlite XAD-1180 was functionalized with salicylaldoxime by coupling it through an −N=N− spacer to obtain a chelating resin for separation and preconcentration of Pb(II), Ni(II), Cu(II) and Mn(II) in water samples prior to the determination by using flame atomic absorption spectrometry. The resulting chelating resin was characterized by infrared spectroscopy (IR) and used as solid sorbent. Different factors including pH of sample solution, amount of solid phase, volume and concentration of eluent, sample volume and matrix effects were optimized to obtain quantitative recovery of the analytes. The optimum pH value for quantitative sorption was 6.0 and all the metal ions could be eluted using 5 mL of 1 mol L−1 HNO3. A good relative standard deviation (≤2.1%), quantitative recovery (≥92%), high enrichment factor (100 for Pb and 150 for Ni(II), Cu(II) and Mn(II)) and low detection limits (from 0.2 to 1.6 µg L−1) were obtained. The accuracy of the developed procedure was confirmed by determining the analytes in a certified reference material (TMDA-62, lake water) and analysing spiked water samples. The method was applied to the determination of the analytes in well water samples with satisfactory results.

Synthesis and application of a new chelating resin functionalized with salicylaldoxime for the determination of Pb(II), Ni(II), Cu(II) and Mn(II) ions in water samples by flame atomic absorption spectrometry

The invention is the test paper, the preparation and the application of the fast testing heavy metallic cadmium The test paper adopts the quantitative filter paper and is marinated by 00015-00025% Victoria blue B color-showing agent for 50-70 minutes and airs naturally The application is that it processes the water and the vegetable samples and orderly adds the 010-020mol/L iodine iodide, 020-030 mol/L oil of vitriol in the 1mL alcoholic solution with 2% concentration and mixes them; puts the test paper into the PVC plastic slot and drops 30 muL test-waiting solution on the test paper to reflect for 90-180 seconds in the sun or 240-360 seconds in non-sunshine and compares it to the standard color phase The test paper can fast test the water sample and properly treat the polluted vegetables, which protects the environment and ensure the safety of consumers

Test paper for detecting heavy metal cadmium rapidly, preparation method and application

A new chelating resin, 2-hydroxybenzaldehyde thiosemicarbazone loaded XAD-4, was synthesized and characterized by FT-IR and elemental analyses. The synthesized resin was used for solid phase extraction (SPE) and preconcentration of Cu 2+ , Cd 2+ , and Pb 2+ from aqueous solution, where the metal ions were subsequently determined by graphite furnace atomic absorption spectrometry (GF-AAS). The optimum pH for preconcentration and separation of these metal ions was found to be 6.00. Optimum flow rate for quantitative sorption of the metal ions on functionalized resin was found to be 1 mL/min whereas 2 M nitric acid was selected as the eluent for quantitative release of the three metal ions from the resin column. The maximum adsorption capacity of the functionalized resin was found to be 3.5, 6.1, and 11.26 mg/g for Cu 2+ , Cd 2+ , and Pb 2+ , respectively. The detection limits for these metal ions are 0.87, 0.95, and 1.09 µg/L, respectively and limits of quantification are 1.12, 1.29, and 1.16 µg/L, respectively. The sorption half time (t1/2) was found to be 6 min for Cu 2+ and Cd 2+ and 8 min for Pb 2+ . Tolerance limits for various foreign electrolytes have also been investigated. A high preconcentration factor (~100) and low relative standard deviation ≤ 5% (n=3) values were obtained. Under optimum conditions, recovery of all metal ions was found to be nearly quantitative. The validation of the procedure was carried out by analysis of certified reference materials. The functionalized resin is highly stable and can be reused more than 100 times. The newly developed method was applied to the separation, preconcentration and determination of Cu 2+ , Cd 2+ , and Pb 2+ in tea leaves

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Solid Phase Extraction of Copper, Cadmium and Lead using Amberlite XAD-4 Resin Functionalized with 2-Hydroxybenzaldehyde Thiosemicarbazone and its Application on Green Tea Leaves

A solid phase extraction and preconcentration methodology utilizing a new chelating resin is described for the separation of Cd, Ni, Co, Cu, and Zn. The chelating resin matrix was prepared by covalently linking 2,2′‐dithiobisaniline synthesized from 2‐aminothiophenol with the benzene ring of polystyrene‐divinylbenzene resin Amberlite XAD‐2 through a –N˭N– group. Its adsorption and preconcentration behavior for Cd, Ni, Co, Cu, and Zn in aqueous solution was studied using batch and column procedures in detail. The newly designed resin quantitatively adsorbs Cd, Ni, Co, Cu, and Zn above pH 5.0. Subsequent elution with 2 M HCl readily strips the sorbed metal ions from the resin. The sorption capacity is 360, 230, 170, 200, and 150 mol g−1 for Cd, Ni, Co, Cu, and Zn, respectively. Their preconcentration factors are 80–200. The time for 80% sorption was less than 10 min for all five metal ions. The effects of electrolytes on the preconcentration were also investigated with the recoveries >95%. The proc...

Solid Phase Extraction and Preconcentration of Trace Heavy Metal Ions in Natural Water with 2,2′‐Dithiobisaniline Modified Amberlite XAD‐2

A process for preparing triazene as high-molecular chelating agent features that the functional group "-S-" is introduced to the adjacent position of amino in a compound. It has strong chelating action to heavy metal ions (such as Cd and Hg) and excellent regeneration performance.

Bingjun Ding

Papers

Solid Phase Extraction and Preconcentration of Trace Heavy Metal Ions in Natural Water with 2,2′‐Dithiobisaniline Modified Amberlite XAD‐2

Preparation method of triazene polymer chelant and its application