Solvent memory effect

There are problems in use of the frit nebulizer. Memory effects tend to be severe, and each sample needs to be followed by several wash-outs with clean solvent before the pores of the frit become free of residual sample. Biological samples frequently contain detergent-like materials, and... 

This is clearly a complex system, for it is pointed out that the calixarene-limiting area depends on the spreading solvent and is subject to a memory effect. In another study, mixed monolayers and the resulting LB films of C60 with two derivatized calix[4]resorci-nolarenes and with p-tert-butylcalix[6]arene and p-tcrt-butylcalix[8]arene were examined... 

Alkylimidazolinm tetraflnoroborates are, for example, ionic liquids at room-temperature that can provide an anion to stabilize an intermediate cation-radical with no possibility of nucleophilic attack on it. Ionic liquids have a huge memory effect, and their total friction is greater than that of conventional polar solvents. Thus, the total friction of l-ethyl-3-methylimidazolium hexafluoro-phosphate is about 50 times greater than that of AN (Shim et al. 2007). The solvent effects of ionic liquids on ion-radical ring closures deserve a special investigation. The ring closure reactions can be, in principal, controlled by solvent effects. 

TTie technique developed allows rapid and routine determination, both at trace and higher concentration levels, in either aqueous or non-aqueous solvents, of approximately 70 elements in the periodic table. It is fuUy automatic with aU the operations, including sampling and clean-out of the plasma jet, controlled by a microcomputer. Being able to control the time allowed for clean-out of the plasma jet is especially useful in the determination of elements which tend to cause memory effects in later samples. 

TPH analyses are particularly prone to false positive results. False positive GRO results are often reported for samples with a single peak, typically a solvent, present in the chromatogram in the absence of a gasoline pattern. Memory effects (carryover in the chromatographic column) often produce false positive results in TPH analysis. 

A solvent blank is used to eliminate the possibility of contamination arising from outside the sample, for example, from the syringe or from the instrument. It is recommended to use the sample solvent as solvent blank and run this test at the beginning and at the end of each sample series and whenever contamination is suspected. The memory effect is possible, for example, in the analysis of alkyl phosphonic acids. If the derivatization of these chemicals has not been complete, the nonderivatized acids are adsorbed on the injector liner. A silylation reagent may in such case react in situ with the adsorbed acids in the liner yielding false positive results. 

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