Determination of oxalate and citrate in urine by capillary electrophoresis using solid‐phase extraction and capacitively coupled contactless conductivity based on an improved mini‐cell

Abstract

A new method for the rapid determination of the metabolites oxalate and citrate in urine samples was based on capillary electrophoresis and capacitively coupled contactless conductivity detection coupled with solid-phase extraction. The detection cell for capacitively coupled contactless conductivity detection was improved with a smaller inner volume (1.5 nL), reduced noise (0.2∼0.5 mV) and better reproducibility and durability. Under optimal conditions, oxalate and citrate can achieve baseline separation within 4 min and the detection limits (S/N = 3) for oxalate and citrate are about 44 and 244 ng/mL, respectively. The overall recovery is between 80.0 and 89.2%. This method offers a better choice for quantitative analysis of strong anions such as oxalate and citrate in diagnostic testing associated with human diseases.

Capillary electrophoresis with capacitively coupled contactless conductivity detection for the determination of urinary ethylmalonic acid for the diagnosis of ethylmalonic aciduria

“…As EOF in an uncoated capillary is toward the cathode, EMA migrates in the opposite direction of the EOF, resulting in extended analysis times. To increase the rate of the analysis, the EOF was reversed by adding the alkylammonium salt, CTAB, to the running buffer as a flow modifier .…”

“…Unlike UV detection, which can only detect conjugated compounds, C 4 D can detect both UV‐absorbing and nonabsorbing species and thus provides a simple, low‐cost, highly sensitive method for detecting anions with inadequate UV absorption, such as organic acids. CE coupled to C 4 D (CE–C 4 D) has been successfully used for the detection of a variety of small organic acids in biological medium, including formate in blood serum and human plasma ; valproic acid in biological fluids ; oxalate, citrate, and other organic acids in urine ; γ‐hydroxybutyric acid in serum and urine ; and uric acid in human urine and plasma . However, there have been no reports on the use of CE–C 4 D for the detection of EMA.…”

Application of capillary electrophoresis with capacitively contactless conductivity detection for biomedical analysis

“…Therefore, the determination formate in blood and urinary oxalate and citrate is very important for diagnosis and management of diseases. CE-C 4 D has been demonstrated as a satisfactory method for the determination of various types of small organic ions, such as oxalate, citrate, [77], lactate [78][79][80], lactate and pyruvate [81,82], formate [83][84][85], oxalate, formate, and glycolate [86], and fluoroacetate [87]. The analyses of organic acids such as γ-hydroxybutyric acid in urine and serum [88], valproic acid (VPA) [89], organic acids in urine [90], uric acid in plasma and human urine [91], Ghydroxybutyric acid, ibotenic acid, and psilocybin in saliva [92], and urinary ethylmalonic acid [93] employing CE-C 4 D were also reported.…”

Simultaneous determination of three sulfanilamide artificial sweeteners in foodstuffs by capillary electrophoresis coupled with contactless conductivity detection based on porous aromatic frameworks enhanced solid phase extraction

“…All experiments were performed on the HP 3D CE system equipped with ChemStation software (Agilent Technologies, Waldbronn, Germany) and a laboratory-made C 4 D detector 35 . The C 4 D parameters were the same as the previous report 35 .…”

“…All experiments were performed on the HP 3D CE system equipped with ChemStation software (Agilent Technologies, Waldbronn, Germany) and a laboratory-made C 4 D detector 35 . The C 4 D parameters were the same as the previous report 35 . The bare fused-silica capillaries were obtained from Yongnian Optical Fiber Corporation (Hebei, China) with an inner diameter of 50 μm and a length of 50 cm (41.5 cm to the detection window).…”