Determination of hydrazines by chip electrophoresis with contactless conductivity detection

Abstract

In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.

Contactless conductivity detection for analytical techniques: Developments from 2010 to 2012

“…The determination of two proteins, human serum albumin and human transferrin, was demonstrated in urine samples of healthy individuals and patients with nephritic syndrome . Two analytical methods using headspace single‐drop microextraction for pretreatment of volatile organic compounds and subsequent MCE‐C 4 D of the preconcentrated analytes were demonstrated by Matysik et al . Up to five aliphatic amines were determined using MCE‐C 4 D and a possible application in food quality control was shown, which was based on the quantitative determination of selected amines in fresh and rotten shrimp samples .…”

“…Up to five aliphatic amines were determined using MCE‐C 4 D and a possible application in food quality control was shown, which was based on the quantitative determination of selected amines in fresh and rotten shrimp samples . Optimization of MCE‐C 4 D conditions and determination of three hydrazines after headspace single‐drop microextraction of river water and soil samples was demonstrated by Kumar et al . A list of applications of C 4 D in MCE reported in the last two years is given in Table .…”

Recent advances in applications of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE‐C4D): an update

“…Kumar et al . () developed new protocols for the rapid determination of hydrazine compounds, namely hydrozine (Hy), methylhydrazine (MH) and 1,1‐dimethylhydrazine (UDMH) in soil samples and river water. The approach is based on poly(methylmethacrylate) (PMMA) microchip separation with contactless conductivity detection.…”

Thermostatted dual‐channel portable capillary electrophoresis instrument

“…Portable CE instruments have therefore gained in interest in the last few years. Successful examples include many diverse applications such as the determination of residues of improvised explosive devices , chemical warfare agent detection , the detection of amphetamines in street drugs and urine of suspected users , the analysis of food samples , the detection of hydrazines in environmental samples , the determination of beta‐agonists in pig feed , the analysis of volatiles in air samples (after absorption) with a mobile robotic system , organic acids including herbicides in environmental samples , DNA fragments , inorganic ions in urine, blood serum samples, or exhaled breath condensate , as well as in environmental samples . Portable CE has also been combined with portable PCR for the detection of viral infections , the identification of cattle breeds , and forensic purposes .…”