The selective determination of sulfates, sulfonates and phosphates in urine by CE‐MS

Abstract

Metabolite identification and metabolite profiling are of major importance in the pharmaceutical and clinical context. However, highly polar and ionic substances are rarely included as analytical tools are missing. In this study, we present a new method for the determination of urinary sulfates, sulfonates, phosphates and other anions of strong acids. The method comprises a CE separation using an acidic BGE (pH<or=2) and anodic detection by MS via negative ESI. In this way, only sulfates and sulfonates are detected in the first part of the electropherogram, followed by phosphates and potentially highly acidic carboxylates. The selectivity for sulfur-containing species is proved using extracted ion electropherograms based on certain isotopic ratios. Ethyl sulfate can be determined by this method and, thus, CE-MS can be used for determination of this alcohol consumption marker. An SPE method was developed for the extraction of ethyl sulfate and other organic anions. Several additional compounds can be identified based on the accurate mass determined by the TOF MS in conjunction with databases. However, numerous detected compounds have not been reported in urinary metabolite databases so far. Thus, it is demonstrated that the presented method is complementary to the existing methods for metabolite characterization in urine.

Monitoring of alcohol markers by capillary electrophoresis

“…EtS was monitored at its m/z value of 124.99 ([M‐H] − ion). An LOD of 0.05 ppm (0.05 mg/L) was reached but no real samples were analyzed . CZE coupled to sheath liquid‐based ESI and multiple‐stage IT mass spectrometry (MS n ) was used for confirmation analysis of EtS and EtG in human serum and urine collected after intake of alcoholic beverages .…”

“…Alternatively, the use of CZE with optical and MS detection of EtS has been investigated. CZE with optical or conductivity detection is an attractive technology which is less expensive than instrumentation featuring an MS. As EtS is a nonabsorbing compound, indirect optical (absorbance or fluorescence), conductivity or MS detection have to be used.…”

“…Under the investigated conditions, the sensitivity achieved was found to be sufficient for confirmation of the presence of EtS in serum and urine down to about 200 ng/mL. This is somewhat less sensitive compared to established LC‐MS/MS approaches and to the recent CZE‐ESI‐TOF investigation for EtS in spiked .…”

Capillary Electrophoresis/Mass Spectrometry of APTS-Labeled Glycans for the Identification of Unknown Glycan Species in Capillary Electrophoresis/Laser-Induced Fluorescence Systems

“…Different acidic systems, based on formic acid and acetic acid were examined. APTS-labeled glycan samples were applied to formic acid based BGE systems as described by Albrecht et al 14 (3 % formic acid) or a previously presented system for sulfonic acids 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BGE. No satisfying separations were obtained (data not shown) especially when compared to the CE/LIF/MS method published by Gennaro et al 17 , that met all requirements with respect to separation (i. e. high separation efficiency, analog migration order by anodic detection).…”

CE-MS in Forensic Sciences with Focus on Forensic Toxicology

“…A selective CZE-ESI-QTOF MS method in negative mode ionization was developed for the analysis of sulfate, sulfonate, and phosphate metabolites in urine by Bunz et al, which also proved to be suitable for the detection of EtS [115]. Before injection, it was necessary to perform a cleanup procedure by SPE extraction of EtS and removal of phosphates and other salts and proteins, for which, as in the previous work, Strata X-AW cartridges were chosen.…”