Is Capillary Electrophoresis a New Tool to Monitor Acute Lithium Poisoning in Human?†

A 38-year-old man was admitted in the intensive care unit (ICU) after supposed ingestion of 504 sustained-release tablets of Theralithe™ corresponding ~200 g of lithium carbonate. At the admission, ~19.5 h after ingestion, the patient was conscious with trembling limbs, intense thirst, profuse sweats and vomiting and lithium serum concentration was 14.2 mmol/L. Toxicological screenings performed in urine and serum, were negative. Patient was treated with continuous extrarenal epuration by continue veno-venous hemodiafiltration starting (CCVHDF) 24 h post-admission and was carried on until 64 h. After 11 days in ICU, the patient was dismissed to the service without sequelae, and transferred to a psychiatric unit. To follow lithium concentrations in serum, urines and dialysates, we developed a simple, rapid and reliable method by capillary zone electrophoresis (CZE). Separation was achieved in 7 min. The method was linear between 0.14 and 1.44 mmol/L for serum samples, and between 0.07 and to 1.44 mmol/L for urines and dialysates. Limits of quantification were 0.15 mmol/L and 0.07 mmol/L for serum and others fluids, respectively. Intra- and inter-day precisions expressed as CV were systematically inferior to 12.1% for serum and 8.2% for other fluids. Results obtained regarding precision, accuracy, recovery and stability were satisfying, with recoveries ranging from 91.0 to 102.0%. Serum, urine and dialysate samples were measured using CZE and flame photometry. We observed a strong correlation between both methods as assessed by linear regression and Bland-Altman analysis. For the intoxicated patient, the assay was successfully applied to serum, urine and dialysates to determine the amount of lithium present in circulation and excreted. Lithium amounts in dialysates were estimated to correspond to 89% of total lithium excreted during CCVHF session while urine excretion account only for 11%.

Postoperative Compensatory Ammonium Excretion Subsequent to Systemic Acidosis in Cardiac Patients

Background

Postoperative acid-base imbalances, usually acidosis, frequently occur after cardiac surgery. In most cases, the human body, not suffering from any severe preexisting illnesses regarding lung, liver, and kidney, is capable of transient compensation and final correction. The aim of this study was to correlate the appearance of postoperatively occurring acidosis with renal ammonium excretion.

Materials and Methods

Between 07/2014 and 10/2014, a total of 25 consecutive patients scheduled for elective isolated coronary artery bypass grafting with cardiopulmonary bypass were enrolled in this prospective observational study. During the operative procedure and the first two postoperative days, blood gas analyses were carried out and urine samples collected. Urine samples were analyzed for the absolute amount of ammonium.

Results

Of all patients, thirteen patients developed acidosis as an initial disturbance in the postoperative period: five of respiratory and eight of metabolic origin. Four patients with respiratory acidosis but none of those with metabolic acidosis subsequently developed a base excess > +2 mEq/L.

Conclusion

Ammonium excretion correlated with the increase in base excess. The acidosis origin seems to have a large influence on renal compensation in terms of ammonium excretion and the possibility of an overcorrection.

Sample pretreatment for the capillary electrophoretic determination of organic acids in chromium(III) plating baths

This work deals with the development and optimization of the sample pretreatment and consequent electrophoretic analysis of two modern plating baths containing chromium(III) and either citric acid or oxalic acid. Some model mixtures containing known amounts of components of industrial baths have been prepared to simulate simplified bath matrices. Prior to analysis, a sample pretreatment consisting of the addition of some agents that could release acid from the stable chromium complex was tested. Determination of organic anions was accomplished by indirect UV detection. The best results were achieved by precipitation of chromium(III) hydroxide. The content of oxalate and citrate in real samples was calculated as 96.5% (SD 2.3%) and 97.3% (SD 0.8%), respectively, of the declared amount. Very good robustness of the method and satisfactory repeatability of migration time and peak area were obtained. This simple inexpensive method is suitable for routine determination of citric and oxalic acid in chromium(III)-based plating baths.

Modeling the electrophoresis of oligolysines

CE is used to measure the electrophoretic mobility of low molecular mass oligo-L-lysines (n=1-8) in aqueous LiH₂PO₄ buffer, BGE, at pH 2.5 over a range of temperatures (25-50 °C) and ionic strengths (10-100 mM). Mobilities are corrected for Joule heating and under the conditions of the experiment, interaction of the peptides with the capillary walls can be ignored. A "coarse grained" bead modeling methodology (BMM) (H. Pei et al., J. Chromatogr. A 2009, 1216, 1908-1916) is used to model the mobilities. This model partially accounts for peptide conformation as well as the assumed form of its secondary structure. For highly charged oligolysines, it is necessary to properly account for the relaxation effect. In the present study, the BMM approach tends to overestimate oligolysine mobility and that effect tends to increase with increasing ionic strength and peptide length. It is proposed that association between the oligolysines and buffer components (H₂PO₄⁻ in this case) that go beyond classical electrostatic interactions are responsible for this discrepancy. A simple binding model is introduced that illustrates how this association can reconcile model and experiment.