José Antonio Muñoz

Development and validation of a simple determination of urine metabolites (oxalate, citrate, uric acid and creatinine) by capillary zone electrophoresis.

Oxalate, citrate, uric acid and creatinine are important urine markers for the evaluation and treatment of urolithiasic patients. They have been traditionally analysed by enzymatic and chromatographic techniques which present practical drawbacks, mainly in the sample pre-treatment step. The purpose of this study was to evaluate those markers in urine samples, by an easy multi-analyte assay using capillary zone electrophoresis. The four urine metabolites were determined, at 25 degrees C, by using a 50 cm x 75 microm capillary in 50 mmol l(-1) phosphate buffer (pH 6.5), at constant voltage of -30 kV and UV detection at 195 nm (for oxalate and citrate) or 30 kV and 234 nm (for creatinine and uric acid). The sample pre-treatment was minimum, 5- and 20-fold dilution of the urine sample and acidification to pH 3-4. Validation parameters (linear range, sensitivity, accuracy, precision and detection limits) were statistically comparable to those obtained with the official methods normally used in the clinical practice. The effect of freezing as a conservation method of urine samples is also discussed in terms of recoveries of the analytes. The analytical method developed is highly useful as a diagnostic tool for detecting metabolic renal disorders due to its simplicity, time consuming, easy automation, cost efficiency and analytical effectiveness, accomplishing with the clinical requirements.

Application of a new phosphadithiamacrocycle to ClO−4-selective CHEMFET and ion-selective electrode devices

Abstract A new dithiamacrocycle incorporating a phosphine donor group (I) has been synthesized and tested as neutral carrier in PVC membranes. ClO−4-selective CHEMFET and ISE devices based on these plasticized membranes have been developed. Both devices have shown Nernstian response and a wide working pH range. Most common anions, except BF−4, do not cause interferences. The response properties and selectivity found for perchlorate ions compare favourably with the commercial and conventional ClO−4 electrodes based on quaternary ammonium ion-exchange sites. This is probably the first example of perchlorate selective CHEMFETs.

Perchlorate-selective MEMFETs and ISEs based on a new phosphadithiamacrocycle

Abstract A new phosphadithiamacrocycle has been synthesized and used as neutral carrier in ion-selective PVC membranes. These membranes have been applied to the development of perchlorate-selective MEMFETs and ISEs. Both devices have shown Nernstian response and a wide working pH range. The response and selectivity found for perchlorate ions is better than those of conventional Cl O 4 − electrodes based on hydrophobic cations as electroactive species.

Minimum handling method for the analysis of phosphorous inhibitors of urolithiasis (pyrophosphate and phytic acid) in urine by SPE-ICP techniques.

Pyrophosphate (PPi) and phytic acid (IP6) are natural phosphorous compounds with growing interest in the biomedical field due to their ability as potential inhibitors of urolithiasis among others. Existing methodologies for their evaluation show inconveniences mainly associated with sample treatment, matrix interferences and lack of resolution. The objective of the present work is the validation of a new method to determine both inhibitors in urine samples selectively and its application to the diagnosis of lithiasic patients. After urine purification by an off-line anion exchange solid phase extraction (SPE), based in an appropriate acidic elution gradient, the phosphorous compounds were analyzed by (31)P measurements by inductively coupled plasma mass spectrometry (ICP-MS) in the purified urine extracts. Linear range and limit of detection obtained were adequate for the analysis of the physiological amounts of the compounds in urine. The method was successfully applied to human urine samples, resulting in adequate accuracy and precision and allowing for the analysis of phosphorus inhibitors of urolithiasis in urine. The method simplicity and high sample throughput leads to a clear alternative to current determinations of the mentioned species in urine. Moreover, PPi and IP6 concentrations found in patients suffering from oxalocalcic urolithiasic were significantly lower than those for healthy controls, supporting the fact that the risk for oxalocalcic urolithiasis increases when urinary phosphorus inhibitors decrease. Thus, speciation of phosphorus inhibitors of urolithiasis in urine of stone formers can be performed, which is of unquestionable value in diagnostic, treatment and monitoring of urolithiasis.

A new pyridine-based phosphorus-containing macrocycle. Crystal structure of [Co(Lox)2][CoCl3(Lox)]2 (Lox=6-phenyl-6-oxo-15-aza-6-phospha-3,9-dithiabicyclo [9,3,1]pentadeca-1 (15), 11, 13-triene)

Abstract A new pyridine-based macrocycle 6-phenyl-15-6-phospa-3,9-dithiabicyclol[9,3,1]pentadeca-1(15),11,13-triene (L), containing the NS2P donor set, was prepared and characterised. The reaction of L with CoCl2 in acetonitrile yielded the double complex salt [Co(Lox)2][CoCl3(Lox)]2 where the phosphine groups of the ligands L are in the phosphine-oxide form (Lox). The single crystal structue of the complex was determined by X-ray diffraction methods. Crystal data: triclinic, space group P-1 (No.2), a = 11.634(1), b = 19.251(2), c = 9.497(1) A , α = 93.65(1), β = 109.711(9), γ = 95.12(1)°, U = 1984.4(4) A 3 , Z = 1 . In each [CoCl3(Lox)]− anion the Co(II) atoms is in a slightly distorted tetrahedral environment define by three chlorine atoms and the phosphine-oxide oyxygen atom of one Lox ligand, whereas in the [Co(Lox)2]2+ cation the Co(II) atom lies in a distroted octahedral environment of two pyridine nitrogen atoms, two thioethersulfur complex was investigated. atoms and two phosphinc-oxide oxygen atoms provided by two facially coordinating Lox ligands. The magnetic behaviour of the

Synthesis, Characterisation and Reactivity towards PdII and PtII of ortho‐, meta‐ and para‐Xylyl‐Based Phosphorus‐Containing Macrocycles

The new meta- and para-xylyl-based phosphadithiamacrocycles 6-phenyl-6-phospha-3,9-dithiabicyclo[9,3,1]pentadeca-1(15),12,14-triene (L2) and 6-phenyl-6-phospha-3,9-dithiabicyclo[9,2,2]pentadeca-1(13),12,14-triene (L3) have been synthesised and characterised. The reactivity of these ligands and the previously described ortho-xylyl macrocycle 6-phenyl-6-phospha-3,9-dithiabicyclo[9,4,0]pentadeca-1(11), 12,14-triene (L1) with [PdCl2(cod)] and K2[PtCl4] has been studied. [MCl2(L)] complexes have been obtained and characterised by NMR spectroscopy. X-ray structural analyses have been carried out in the case of [PdCl2L2]·CH3CN (2·CH3CN) and [PdCl2L3] (3). In both compounds the PdII ion adopts a slightly distorted square-planar coordination defined by one S-thioether, the P-phosphane atoms of the ligand and two chlorine atoms, which are oriented in a mutual cis position, whereas the second S-thioether atom of the ligand remains uncoordinated. According to the spectroscopic data, the same coordination mode is found for the PtII complexes. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Inhibitors of Oxalocalcic Lithiasis: Effects of Their Interactions on Calcium Oxalate Crystallization

OBJECTIVEnTo study the possible effects caused by the interaction of some urinary components on the inhibition of calcium oxalate crystallization. Such interactions are susceptible to importantly change the inhibitory behavior of some urinary components by producing either positive (synergistic) or negative effects on preventing crystallization.nnnMETHODSnA urinary lithogenic risk (ULR) test was used to follow the crystallization of calcium oxalate from artificial urine in the presence of binary mixtures of known inhibitors of its crystallization (phytate, pyrophosphate, citrate, and chondroitin sulfate), which were assayed in physiological concentrations.nnnRESULTSnOnly the mixtures phytate + pyrophosphate and phytate + citrate manifested interaction effects on the calcium oxalate crystallization. Although the former exhibited synergistic effects, the latter showed negative effects on the inhibition. These effects are explained in terms of the affinity of the inhibitors for the calcium oxalate crystals surface and their concentrations in urine.nnnCONCLUSIONnThe crystallization inhibitory capacity of target urine is explained by the combined effect of the compounds present in the complex urine matrix rather than the individual action of each compound. This kind of interactions is of key value in designing prophylactic treatments of urolithiasis based on inhibitors intake.