It has been reported that ion enrichment phenomena are observed in liquid chromatographic processes with an aqueous mobile phase on the columns packed with nonionic materials. However, the mechanism of the ion enrichment is not at all well understood. In this study, we investigated the retention and enrichment behaviors of simple inorganic anions on a C18-bonded silica column and a cross-linked hydroxylated methacrylic polymer gel column with pure aqueous mobile phases containing various electrolytes. We show that the stacking of ionic solutes can successfully be accounted for by the ion partition model, and it takes place due to the effect of the background coion in the eluent and/or sample solution on the distribution of the ions between the bulk water and the water incorporated in the packing material, which acts as the stationary phase. Using the ion exclusion effect of fixed anionic charges on a packing material as well as the ion stacking by partition, we developed a simple and versatile method for effective enrichment of anionic solutes in aqueous solutions. The enrichment factor and the elution time of the stacked ion zone can be predicted by the ion partition model.

A new analytical methodology for a simple and efficient on-line preconcentration of trace inorganic anions in water and salt samples prior to ion chromatographic determination is proposed. The preconcentration method is based on partition/ ion-exclusion chromatographic ion stacking (PIEC ion stacking) with a hydrophilic polymer gel column containing a small amount of fixed anionic charges. The developed on-line PIEC ion stacking-ion chromatography method was validated by recovery experiments for the determination of nitrate in tap water in terms of both accuracy and precision, and the results showed the reliability of the method. The method proposed was also successfully applied to the determination of trace impurity nitrite and nitrate in reagent-grade salts of sodium sulfate. A low background level can be achieved since pure water is used as the eluant for the PIEC ion stacking. It is possible to reach sensitive detection at sub-μg L -1 levels by on-line PIEC ion stacking-ion chromatography.

This descriptive type of cross-sectional study of 72 cases of uterine rupture was conducted over 1 year (from September 2006 to August 2007) in the department of Obstetrics and Gynaecology, Mymensingh Medical College Hospital, Bangladesh to evaluate the maternal outcome of different types of surgery, to assess the maternal mortality and maternal morbidity. All cases of ruptured uterus which were received & treated and did not die within 30 minutes of admission are included in the study. Data were collected by preformed data collection sheet. The results showed that the common age groups were between 20-30 years in 31(68.00%) cases. Among all ruptured cases, 6 cases (8.33%) were Primigravida, 52 cases (72.22%) were between gravida 2nd to 4th and 14 cases (19.44%) were gravida 5th or above. Among all cases, 66 cases (91.66%) required blood transfusion; Subtotal hysterectomy was done in 36 cases (50.00%), total hysterectomy in 4 cases (5.56%), and repair of the rent in 32 cases (44.44%). Associated operations were done along with repair or hysterectomy in 13 (18.05%) cases. Postoperative complications were found in 23 (31.94%) cases. The shortest stay was 8 days & the longest stay was 62 days. The hospital staying was about 2 weeks in 48(66.70%) cases. Among 10 death cases (13.90%) maximum patient died within first 5 hours. The causes of maternal death were due to septicemia, renal failure and shock in 20%, 30% and 50% respectfully. CBMJ 2016 January: Vol. 05 No. 01 P: 20-26

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J. Sep. Sci. 2017, 40, 3205–3213 DOI: https://doi.org/10.1002/jssc.201700081 The cover picture shows the enrichment behavior of an anionic solute (NO3−) at the trailing edge of the background electrolyte zone in an aqueous liquid chromatographic process on a column packed with a polymer gel containing anionic fixed charges. The stacking of ionic solutes takes place due to the effect of the background coexisting coion on the distribution of the target ion between the bulk mobile phase water and the water incorporated in the packing material, which acts as the stationary phase. Using ion exclusion effect of the fixed ionic charges on a packing material as well as the ion stacking by the ion partition, a simple and versatile method for effective enrichment of ionic solutes in aqueous solutions was developed.