Ultraviolet-absorbing organic anions in uremic serum separated by capillary zone electrophoresis, and quantification of hippuric acid

Abstract

Organic anions accumulated in blood serum of patients with chronic renal failure were separated by a novel technique: closed-system capillary zone electrophoresis (CZE) in a pH6 carrier-electrolyte system. Hippuric acid (HA), p-hydroxyhippuric acid, and uric acid were identified by their co-elution with standards prepared in ultrafiltered normal serum and by comparison with the corresponding ultraviolet-detected peaks positively identified in the HPLC analyses. Analysis time for the entire profile is 8 min. Repeatabilities (CVs) of CZE migration times and peak areas of the three acids in serum samples were about 0.7% and 6%, respectively. We quantified HA in 10 ultrafiltered uremic serum samples and compared results with those by a previously described HPLC procedure. The very good agreement further supports the identification of hippuric acid. Accuracy and precision of the CZE method were similar to those for the HPLC gradient-elution method, but analysis time for HA (8 min) is much less than by HPLC (90 min). Our technique is very suitable for selective, rapid analysis for (ultraviolet-absorbing) anionic constituents in ultrafiltered uremic serum, without any sample pretreatment.

Poly(tetrafluoroethylene) separation capillaries for capillary electrophoresisProperties and applications

“…Although polymer materials have captured a significant percentage of the CE-on-a-chip microfluidic devices [11,12], somewhat surprisingly the use of polymeric separation capillaries in CE has remained limited to a dozen or so reports over the last 20 years. Poly(tetrafluoroethylene) (PTFE) has been the polymer used most frequently [13][14][15][16][17][18][19][20][21][22] and it seems that its use as large diameter capillaries (∼200 m) in the early papers may have originated from the previous use of about 200 m i.d. PTFE capillaries in capillary isotachophoresis (cITP) [23].…”

On‐line preconcentration and quantitative analysis of peptide hormone of brain and intestine using on‐column transient isotachophoresis coupled with capillary electrophoresis/electrospray ionization mass spectrometry

“…23 In practice, a more than 100-fold larger injection volume than that of normal CZE can be used for analysis without losing resolution after ITP focusing. 24 There are two different configurations for performing isotachophoresis -capillary zone electrophoresis (ITP-CZE): the single capillary (one column) or dualcapillary (two columns coupled together) mode. 25,26 Compared with the latter approach, the main advantage of the single capillary mode lies in easy automation and simple instrumentation.…”