Letters to Separation and Sensitive Determination of Metal Ions by Capillary Zone Electrophoresis with 2-(5.-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol the Editor

Keywords Capillary zone electrophoresis, metal ion, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N sulfopropylamino)phenol, cobalt determination, nickel salt Capillary zone electrophoresis (CZE) was first introduced as a powerful and important technique for the separation of charged substances by Mikkers et al. ' Since then, one of the most important breakthroughs was achieved by Terabe et al.; they made it possible to separate non-charged organic compounds by using micellar electrokinetic chromatography (MEKC).2 Saitoh (T) et al.3.4 as well as Saitoh (K) et al.5 separated non-charged metal chelates by MEKC. Besides, there have been several studies on the separation of metal ions as their complex ions.6-11 These studies have mainly been aimed at utilizing the high separation ability of CZE. However, CZE seems to be very useful for the simultaneous determination of metal ions, if the sensitivity and reproducibility could be sufficiently improved for the quantitative analysis of metals. Motomizu et al. have reported on methods for determining alkaline earth metal ions with EDTA12 and CyDTA (1,2-cyclohexanediamine-N, N, N',N'-tetraacetic acid)13 by CZE. In this work, the authors studied the separation and determination of metal ions based on the formation of chelate anions with Nitro- Apparatus, reagents and procedure The CZE system used was the same as that in a previous study.12 Separations were performed in an untreated fused-silica capillary (50 µm i.d., 375 µm o.d.) obtained from GL Science. The capillary, which was mounted in a temperature-controlled room (35° C), was 72 cm in total length and 50 cm in separation length from the anode to the detector. A chelating agent (Nitro-PAPS) was purchased from Dojin Laboratories. Pairs of either KH2PO4 and Na2HPO4 or CH3COOH and CH3000Na were used for preparing buffer solutions. All of the reagents used were of analytical reagent grade, and were dissolved in water purified with both a deionizing-distilling apparatus and a Milli Q Lab (Millipore Ltd.). Carrier solutions containing buffer components and Nitro-PAPS were used. Sample solutions (about 9X 10.9 dm3) containing metal ions and Nitro-PAPS were injected using a vacuum injection system. Results and Discussion Detection of metal chelates Most metal chelates of Nitro-PAPS exhibited absorption maxima at wavelengths from 520 to 600 nm, where the molar absorptivities were about 105 dm3 moL1 cm 1. In this work the detection was carried out at 560 nm, where most of the metal chelates showed a relatively large absorption. Effect of the pH of the carrier solution The velocity of electroosmotic flow ( U) and electrophoretic mobility (eueo; µe0= UJ E, where E is the potential field strength) are almost constant in the pH region above 7, and gradually become slow in the pH region below 7. This indicates that most of the silanol is deprotonated in the pH region above 7

Empagliflozin in Patients with Chronic Kidney Disease

Background The effects of empagliflozin in patients with chronic kidney disease who are at risk for disease progression are not well understood. The EMPA-KIDNEY trial was designed to assess the effects of treatment with empagliflozin in a broad range of such patients. Methods We enrolled patients with chronic kidney disease who had an estimated glomerular filtration rate (eGFR) of at least 20 but less than 45 ml per minute per 1.73 m(2) of body-surface area, or who had an eGFR of at least 45 but less than 90 ml per minute per 1.73 m(2) with a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of at least 200. Patients were randomly assigned to receive empagliflozin (10 mg once daily) or matching placebo. The primary outcome was a composite of progression of kidney disease (defined as end-stage kidney disease, a sustained decrease in eGFR to < 10 ml per minute per 1.73 m(2), a sustained decrease in eGFR of & GE;40% from baseline, or death from renal causes) or death from cardiovascular causes. Results A total of 6609 patients underwent randomization. During a median of 2.0 years of follow-up, progression of kidney disease or death from cardiovascular causes occurred in 432 of 3304 patients (13.1%) in the empagliflozin group and in 558 of 3305 patients (16.9%) in the placebo group (hazard ratio, 0.72; 95% confidence interval [CI], 0.64 to 0.82; P < 0.001). Results were consistent among patients with or without diabetes and across subgroups defined according to eGFR ranges. The rate of hospitalization from any cause was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.86; 95% CI, 0.78 to 0.95; P=0.003), but there were no significant between-group differences with respect to the composite outcome of hospitalization for heart failure or death from cardiovascular causes (which occurred in 4.0% in the empagliflozin group and 4.6% in the placebo group) or death from any cause (in 4.5% and 5.1%, respectively). The rates of serious adverse events were similar in the two groups. Conclusions Among a wide range of patients with chronic kidney disease who were at risk for disease progression, empagliflozin therapy led to a lower risk of progression of kidney disease or death from cardiovascular causes than placebo