Eluents silver nitrate

The recovered resin can be reconverted to the hydroxide form by eluting a column of the material with aqueous 10% sodium hydroxide until it is free of halide ion (silver nitrate-nitric acid test) and then with water until the eluent is no longer alkaline to pH paper. 

McIntyre et al. [58, 59] described a method for the analysis of polychlorobiphenyls and chlorinated insecticides in sewage sludges in which homogenized samples are extracted with hexane, concentrated and cleaned up on an alumina/alumina plus silver nitrate column and eluted with hexane. After concentration of the eluent, polychlorobiphenyl and organochlorine compounds were determined by a silica gel chromatographic procedure and gas chromatography. 

Fig. 8.19. Coordination ion spray mass spectrum of estradiol extracted from the reversed-phase CEC—CIS-MS separation of estrogenic compounds. Column, 250 x 0.1 mm i.d. packed with 3 pm GROM-SIL ODS-O AB eluent, 4 mmol/1 ammonium acetate, pH 9.0, 50% acetonitrile applied pressure, 8 MPa applied voltage, 15 kV detection, ESI-MS, 0.85 s/spectrum sheath liquid, 100 pg/ml aqueous silver nitrate, 3 pl/min mass spectrum extracted from a reconstructed ion chromatogram of the separation of estriol, estradiol, equiline, and estrone. (Reproduced from ref. [104] with permission of Wiley-VCh).

Long-chain alkylphenols present in natural cashew nut shell liquid have been chromatographed on argen-tated silica gel G [10% (w/w) silver nitrate] with di-ethylether-light petroleum-formic acid (30 70 1) as eluent for the separation of unsaturated constituents. 

Silver nitrate-impregnated silica gel has also been used successfully in the separation of some classes of compounds that contain double bonds in their structures. Thus it was used in the separation of glycerides and isomers of unsaturated fatty acid esters. The 2-D TLC on adjacent layers of silica gel G and sihca G impregnated with 5% of silver nitrate was used for development. The silica gel G layer covered a surface of 3 x 20 cm and the difference of the surface of 17 x 20 cm was covered with silica gel G impregnated with 5% AgNOs. The first direction was performed on silica gel G with petroleum ether-diethyl ether (9 1, v/v) as eluent. The second direction was carried out on the impregnated silica gel G and developed twice with the same eluent as in the first direction. After the first direction, the mixture was... 

In his pioneering paper, Small suggested silver nitrate as the eluent for alkaline-earth metals [3], which also exhibits a high affinity toward the stationary phase. However, this system required a suppressor column in the chloride form to precipitate the silver as insoluble silver nitrate. Application of this eluent quickly proved to be disadvantageous, since peak broadening and high backpressure from the suppressor column is associated with the precipitation. 

On silica gel plates impregnated with silver nitrate and eluted with petroleum ether-chloroform-acetone (50 10 17, by vol) vitamin A palmitate had the highest mobility (Revalue, 0.82). Retinol and retinal (Rf= 0.62) were not separated from each other, while vitamin E eluted before vitamin D2 (R/ values of 0.56 and 0.32, respectively) (18). Changing the eluent to hexane-ethyl acetate-diisopropyl ether (2 1 1, by vol) lowered the R/values of all these fat-soluble vitamins. With the latter solvent system retinyl palmitate still moved ahead (Revalue 0.77), but vitamin E eluted even faster than the pair retinol/retinal and vitamin D2 (R/values of 0.54,0.51, and 0.19). 

Stationary phase Precoated piates of siiica gei with fluorescent indicator (siiufoi UV2J4 Kavaiier, CSFR) and ceiiuiose (Merck, Germany). Mobiie phase M, = acetonitriie benzene (31 69) M2 = methanoi ether (I AY.My = methanol ether (1 1). Some other solvent systems used were, pentane, acetonitrile, and mixtures of dichioromethane and pentane in different proportions. Detection (a) UV illumination at A = 254 nm. (b) I x lO M aqueous solution of potassium permangnate. (c) I x 0 M aqueous silver nitrate solution. Conditions Layer thickness 0.1 mm, loading volume S p.1, development in a horizontal HPTLC chamber, plates were developed thrice with each eluent to 5 cm distance. Remarks Best separations were achieved on silica gel layra- with M,. Separations on cellulose were inferior than those obtained on silica gel. 

In the method proposed by van Staden for the determination of three halides, these are separated in a short colunm packed with a strongly basic ion-exchange resin (Dowex i-X8) that is placed in an FI manifold. A laboratory-made tubular silver/silver halide ion-selective electrode is used as a potentiometric sensor. Van Staden compared the response capabilities of the halide-selective electrodes to a wide concentration range (20-5000 pg/mL) of individual and mixed halide solutions in the presence and absence of the ion-exchange column. By careful selection of appropriate concentrations of the potassixun nitrate carrier/eluent stream to satisfy the requirements of both the ion-exchange column and the halide-selective electrode, he succeeded in separating and determining chloride, bromide and iodide in mixed halide solutions with a detection limit of 5 /xg/mL [130]. 

---