PubMed · 9553485
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1998-04-01. Quantifying HIV-1 RNA without amplification.. https://doi.org/10.1021/ac981798w
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Next-generation sequencing (NGS) provides increased discriminatory power in forensic DNA analysis due to the detection of isoalleles. Differences in sequences between alleles allow for a second layer of differentiation between DNA contributors beyond the number of short tandem repeat (STR) repeat units. However, because NGS is a more time and resource-intensive analysis than conventional capillary electrophoresis (CE), laboratories may benefit from indicators that suggest NGS is likely to provide added value. This study examined whether CE migration offsets, measured as residuals in the OSIRIS analysis software, can differ significantly among STR isoalleles. Residuals represent the time offset between a sample allele peak and its corresponding allelic ladder peak. Paired CE and NGS data from 95 single source samples were analyzed for CE-based residual differences, as the NGS data provided the sequence information of the corresponding isoalleles. Residual values differed significantly among isoalleles at several STR loci. Statistically significant differences were identified at D16S539 and D3S1358, as well as at specific allele lengths within D12S391, D13S317, and D8S1179. These findings demonstrate that CE residual variation can reflect underlying STR sequence differences between contributors. In practice, residual-based metrics could help laboratories to identify casework reference samples where NGS is likely to provide additional discrimination, without the need for processing outside of a routine CE workflow. Due to the potentially large number of isoalleles, community wide efforts to aggregate CE residual differences versus isoallele sequences may be useful in the validation and implementation of this approach to add value to forensic DNA analyses.
Through correct pH, pKa and activity coefficients values, a model describing the effect of pH on electrophoretic mobility of substances has been applied to a series of peptides in water and in acetonitrile-water mixtures. The derived equations permit prediction of the optimum pH for the electrophoretic separation from only a few experimental values and they also permit determination of pKa values of analytes in the aqueous-organic media employed. Furthermore, the electrophoretic resolution between pairs of substances can be predicted, in order to evaluate electrophoretic separations of the studied peptides.
Eosin has been used to generate the background signal for indirect fluorimetric detection of inorganic and organic ions, simultaneously separated by capillary zone electrophoresis (CZE). This reagent provides constant fluorescence over the pH range of 5-10 and is compatible with the excitation by an argon ion laser at 488 nm with emission at 520 nm. The use of esosine as fluorophore, H3BO3, and Na2B4O7 as electrolyte and diethylentriamine as modifier of the electroosmotic flow in CZE were optimised. The analytical potential of the studied buffer was tested on a group of 12 anions, used as model compounds. Both, hydrodynamic and electrokinetic injection mode were optimised. The detection limits determined by the last injection mode, were in the range 0.008-0.037 mg l(-1). By using this method, the quantitation of the common anions in tap and mineral water has been carried out successfully.