Indirect UV Detection Research Articles

Development of capillary electrophoresis methods for the detection of microbial metabolites on potential future spaceflight missions.

The search for chemical indicators of life is a fundamental component of potential future spaceflight missions to ocean worlds. Capillary electrophoresis (CE) is a useful separation method for the determination of the small organic molecules, such as amino acids and nucleobases, that could be used to help determine whether or not life is present in a sample collected during such missions. CE is under development for spaceflight applications using multiple detection systems, such as laser induced fluorescence (LIF) and mass spectrometry (MS). Here we report CE-based methods for separation and detection of major polar metabolites in cells, such as amino acids, nucleobases/sides, and oxidized and reduced glutathione using detectors that are less expensive alternatives to LIF and MS. Direct UV detection, indirect UV detection, and capacitvely coupled contactless conductivity detection (C4D) were tested with CE, and a combination of direct UV and C4D allowed the detection of the widest variety of metabolites. The optimized method was used to profile metabolites found in samples of Escherichia coli and Pseudoalteromonas haloplanktis and showed distinct differences between the species.

Development of a capillary zone electrophoresis method to monitor magnesium ion consumption during in vitro transcription for mRNA production.

Messenger RNA (mRNA) vaccines represent a landmark in vaccinology, especially with their success in COVID-19 vaccines, which have shown great promise for future vaccine development and disease prevention. As a platform technology, synthetic mRNA can be produced with high fidelity using in vitro transcription (IVT). Magnesium plays a vital role in the IVT process, facilitating the phosphodiester bond formation between adjacent nucleotides and ensuring accurate transcription to produce high-quality mRNA. The development of the IVT process has prompted key inquiries about in-process characterization of magnesium ion (Mg++) consumption, relating to the RNA polymerase (RNAP) activation, fed-batch mode production yield, and mRNA quality. Hence, it becomes crucial to monitor the free Mg++ concentration throughout the IVT process. However, no free Mg++ analysis method has been reported for complex IVT reactions. Here we report a robust capillary zone electrophoresis (CZE) method with indirect UV detection. The assay allows accurate quantitation of free Mg++ for the complex IVT reaction where it is essential to preserve IVT samples in their native-like state during analysis to avoid dissociation of bound Mg complexes. By applying this CZE method, the relationships between free Mg++ concentration, the mRNA yield, and dsRNA impurity level were investigated. Such mechanistic understanding facilitates informed decisions regarding the quantity and timing of feeding starting materials to increase the yield. Furthermore, this approach can serve as a platform method for analyzing the free Mg++ in complex sample matrices where preserving the native-like state of Mg++ binding is key for accurate quantitation.

Versatile capillary electrophoresis method for the direct chiral separation of aliphatic and aromatic α-hydroxy acids, β-hydroxy acids and polyhydroxy acids using vancomycin as chiral selector

Hydroxy acids (HAs) are ubiquitous in nature and play significant roles in various industrial and biological processes. Most HAs harbor at least one chiral center, therefore the development of efficient chiral analysis techniques for HA stereoisomers is of crucial importance across a wide range of fields. A capillary electrophoresis (CE) method was developed for the chiral analysis and quantification of aliphatic and aromatic α-hydroxy acid (AHA) enantiomers, aliphatic β-hydroxy acid (BHA) enantiomers and aliphatic polyhydroxy acid (PHA) stereoisomers. Using a modified partial filling-counter current method with indirect UV detection, high resolution (Rs) was achieved with vancomycin as a chiral selector added to the background electrolyte composed of 10 mM of benzoic acid/L-histidine at pH 5 using a polyacrylamide-coated capillary. This method could be readily applied to the determination of the enantiomers of 12 aliphatic AHAs, 4 aromatic AHAs, 3 aliphatic BHAs, as well as to the determination of the stereoisomers of tartaric acid, 2,3-dihydroxybutanoic acid, 2,3,4,5-tetrahydroxypentanoic acid, and 2,3,4,5,6-pentahydroxyhexanoic acid without the need for sample derivatization. Finally, our study provides a robust and versatile strategy for the chiral and stereoselective analysis of a broad range of hydroxy acid compounds.

Development of a new method for the determination of 4-hydroxyproline as a measurement of collagen content in meat products and dietary supplements by cyclodextrin-assisted electrokinetic chromatography

The rise in consumption of ultra-processed meat and dietary collagen supplements challenges food quality control. 4-hydroxyproline stands out as collagen signature amino acid, and its determination is a well-known way to estimate collagen content, although for this measurement, the majority of the methods require a mandatory derivatization step. Therefore, this study aimed to develop an innovative method using cyclodextrin-assisted electrokinetic chromatography with indirect UV detection to determine 4-hydroxyproline for collagen monitoring in dietary supplements and meat products. Separations were performed in fused silica capillaries, at 12.5 °C, detection at 220 nm, 30 kV voltage, and hydrodynamic injection. Background electrolyte consisted of histidine 25 mmol L-1, butylamine 180 mmol L-1, and β-cyclodextrin 10 mmol L-1 at pH 11.4. Samples were hydrolyzed with sulfuric acid, and their removal was accomplished by simultaneous neutralization/precipitation reactions using strontium carbonate. Validation assured method detectability, accuracy (recoveries 88% - 102%), and precision (CV < 7%). Dietary supplements and meat products were successfully evaluated, indicating that this method is a feasible quality control alternative.

Determination of fluoride content in infant food samples by sample stacking capillary electrophoresis-indirect UV detection and the estimation of daily-fluoride-intake

Fluoride ion plays a major role in the decline of the prevalence and severity of dental caries. However, exposure to a high level of fluoride causes dental and skeletal fluorosis and reduced levels of intelligence quotient (IQ) in children. This study reports a rapid, selective, sensitive, and economic capillary electrophoresis-sample stacking technique for fluoride analysis in infant food samples. Indirect UV detection of fluoride was performed by 10 mmol/L chromate in the separation electrolyte and 0.1 mmol/L cetyltrimethylammonium bromide (CTAB) was added to the separation medium as an electroosmotic flow modifier. The buffer pH was adjusted to 9.37. The conductivity of the separation electrolyte was increased with 10 mmol/L Na2SO4 and sample stacking was performed. The injections were administered throughout 200 s duration. The limit of detection of the method was 0.0079 mg/L. The method was applied to 7 various commercially available infant food samples which are in puree and powdered form. The fluoride concentrations ranged from 2.28 – 3.85 µg fluoride/g infant food. The proposed method is suitable for the rapid and sensitive determination of fluoride content in infant formulas, and it is recommended that fluoride content be determined by reliable methods in all commercial infant food samples.

Detection techniques for carbohydrates in capillary electrophoresis – a comparative study

Capillary electrophoresis methods for the separation of carbohydrates with four different detection techniques, namely direct UV, indirect UV, capacitively coupled conductivity, and laser-induced fluorescence detection, were tested and their performance was evaluated and compared in terms of linearity, limits of detection and quantitation, repeatability, recovery, analysis time, and sample treatment. The test set of analytes comprised sucrose, glucose, and fructose. The effect of using lactose as an internal standard on the individual methods was investigated, too. The results showed that laser-induced fluorescence detection is a technique of choice for applications requiring the detection of very low amounts of reducing carbohydrates. Contactless conductivity detection is favorable when detection sensitivity is not a crucial parameter but fast and reliable analysis is required. When only a UV detector is available as a standard part of capillary electrophoresis instruments, direct UV detection can be used when analysis time is not a critical parameter. For fast analysis with UV detectors, indirect UV detection is the technique of choice. Finally, to verify the applicability of the tested methods, samples of cola beverage, honey, and orange juice were analyzed and the results obtained by all four methods were compared.Graphical abstract

Determination of carbohydrates in brewer's wort by capillary electrophoresis with indirect UV detection

Determination of carbohydrates in brewer's wort by capillary electrophoresis with indirect UV detection

Short-End Injection Capillary Electrophoresis and Multivariate Analysis for Simultaneous Determination of Heavy Metals in Passiflora incarnata Tea.

An ultra-fast method for the simultaneous determination of heavy metals in Passiflora incarnata tea by capillary electrophoresis (CE) using a short-end injection combined with multivariate analysis was proposed. Separation was conducted by hydrodynamic injection (5 s at 0.5 psi) using the short-end injection procedure in a fused uncoated silica capillary (50 cm total length, 10.2 cm effective length, 50 µm i.d.) with separation time less than 2 min. An indirect UV detection at 214 nm was employed by using imidazole as a chromophore. The buffer used was 6 mmol/L hydroxybutyric acid (HIBA). The optimum conditions by full factorial with a central point were achieved by 18-crown-6 concentration (23.3 mmol L−1), voltage (+11.4 kV), methanol concentration (3.8%), and temperature (20 °C). The method showed good linearity (R2 > 0.998) for both Cd and Pb, inter-day precision of less than 14.49%, and an adequate limit of quantification only for Cd (LOQ < 0.5 µg mL−1 for Cd) based on the US Pharmacopeial Convention limit requirements for elemental impurities. After method validation, the method was applied to Passiflora incarnata tea samples from a local market. Furthermore, the developed method showed great potential for the determination of metals in other samples with proper sample preparation procedures.

Analytical characterization of choline chloride in oilfield process waters and commercial samples by capillary electrophoresis

In this study, a rapid and sensitive method using capillary electrophoresis with indirect UV detection and minimal sample pretreatment was developed and evaluated to analyze choline chloride in oilfield process water samples. To improve peak resolution and separation of choline chloride from other cations present in the samples, the addition of a cationic visualization agent in the background electrolyte, imidazole, and a complexing agent, 18-crown-6, were introduced. Other factors affecting separation and sensitivity were also investigated. Under optimized conditions, choline chloride was baseline separated (&lt;7 min) from common cationic adulterants in commercial choline chloride products with a peak resolution of &gt;1.5 between adjacent peaks. The limits of detection (signal-to-noise ratio = 3) and quantitation (signal-to-noise ratio = 10) were 14.7 and 48.9 mg L−1, respectively. The peak area and migration time’s intraday and interday precision (percent RSD) were all &lt;15%, and the recoveries ranged from 79.4% to 115.2% at different spiking levels. Finally, statistical (Student’s t-test) comparison of the choline chloride content data of oilfield process water samples from the proposed capillary electrophoresis (CE) method compare favourably with traditional methods such as liquid chromatography – mass spectrometry (LC–MS) and Reinecke salt gravimetry.

Ion-pair hollow fiber liquid-phase microextraction combined with capillary electrophoresis for the determination of biogenic amines in rat tissues

Herein, the development of an ion-pair hollow fiber liquid-phase microextraction (IP-HF-LPME) procedure followed by capillary electrophoresis (CE) with indirect UV detection for the simultaneous extraction and determination of aliphatic biogenic amines including spermidine, spermine, and cadaverine in tissue samples of rat is described. In this study, tissue samples were firstly homogenized with a cold trichloroacetic acid solution then the developed method was applied to the supernatant resulting from tissue homogenization. Different CE separation and indirect UV detection conditions, as well as IP-HF-LPME extraction conditions were studied in detail and optimized. A 11 mmol L−1 imidazole solution containing 13 % (v/v) ethanol adjusted at pH 3.3 (by acetic acid) was the best running buffer for indirect UV detection of non-UV-absorbing amines. 1-Octanol in combination with salicylic acid, respectively as the membrane solvent and ion-pair reagent provided the highest extraction recovery for the studied amines. Method performances were established and good results of linearity, recovery, sensitivity, and repeatability were achieved for all the studied amines. Limits of detection were found to be between 2.8 and 4.5 ng mL−1 and limits of quantification were 15 ng mL−1 and the dynamic range was 15–2000 ng mL−1 for all three analytes.

Rapid chloride and bicarbonate determination by capillary electrophoresis for confirmatory testing of cystic fibrosis infants with volume-limited sweat specimens

Objectives Cystic fibrosis (CF) is a debilitating genetic disorder that benefits from early detection. CF diagnosis relies on measuring elevated sweat chloride that is difficult in neonates with low sweat rates. We introduce a new method for sweat chloride determination from volume-limited specimens, and explore the potential utility of sweat bicarbonate in neonatal CF screening.Methods A rapid assay (< 5 min) was developed to analyze chloride and bicarbonate using capillary electrophoresis with indirect UV detection (CE-iUV). Pilocarpine-stimulated sweat samples from screen-positive CF infants were collected at two hospital sites, including confirmed CF (n = 12), CF screen-positive inconclusive diagnosis (n = 4), and unaffected non-CF cases (n = 37). All sweat chloride samples were analyzed by a coulometric titrator and CE-iUV, and the viability to measure acid-labile bicarbonate was also evaluated.Results Stability studies revealed that bicarbonate can be reliably assessed in sweat if acidification and heating were avoided. Method validation demonstrated that sweat chloride and bicarbonate were quantified with acceptable accuracy (recovery of 102%), precision (CV = 3.7%) and detection limits (∼ 0.1 mM). An inter-laboratory comparison confirmed a mean bias of 6.5% (n = 53) for sweat chloride determination by CE-iUV relative to a commercial chloridometer. However, sweat bicarbonate did not discriminate between CF and non-CF infants (AUC = 0.623, p = 0.215) unlike chloride (AUC = 1.00, p = 3.00 × 10−7).Conclusions CE-iUV offers a robust method for sweat chloride testing from presumptive CF infants that may reduce testing failure rates. However, sweat bicarbonate does not have clinical value in newborn CF diagnosis.

Application of Capillary Electrophoresis for Determination of Inorganic Analytes in Waters.

Aside from HPLC and GC, capillary electrophoresis (CE) is one of the most important techniques for high-performance separations in modern analytical chemistry. Its main advantages are the possibility of using different detection techniques, the possibility of in-capillary sample processing for preconcentration or derivatization, and ease of instrumental miniaturization down to the microfluidic scale. Those features are utilized in the separation of macromolecules in biochemistry and in genetic investigations, but they can be also used in determinations of inorganic ions in water analysis. This review, based on about 100 original research works, presents applications of CE methods in water analysis reported in recent decade, mostly regarding conductivity detection or indirect UV detection. The developed applications include analysis of high salinity sea waters, as well as analysis of other surface waters and drinking waters.

Separation of Sucralose in Food Samples using Amines as Background Electrolyte Supported with DFT Calculations

Background: Sucralose is a high intensity artificial sweetener and chemically known as 1,6-dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranoside. It is used as a sweetener and flavour enhancer in foods and beverages. Due to its high stability at wider temperatures and pH, it made its applicability in various food products throughout the world. As per Joint FAO/WHO Expert Group on Food Additives (JECFA) in 1990, the daily intake of sucralose is 0-15 mg/kg body weight. The literature reports suggest that sucralose has a possible health threat due to the presence of chlorine groups, thereby leading to several illnesses. The growing interest in the use of sucralose (SCL) in the foods makes it necessary in developing a fast, reliable, cost effective and reproducible analytical method to determine SCL in food samples. The detection of sucralose and other carbohydrates like fructose, glucose and sucrose is a challenging task owing to its: (i) unavailability of the charged functions and (ii) lack of absorption of strong chromophoric nature in the UV region. Therefore, separation of non-absorbing neutral molecules needs a careful procedure with suitable electrolyte systems. Methodology: An indirect UV detection capillary electrophoretic method is described for the separation of sucralose in different food samples. It was achieved by nucleophile substitution (SN2) in the presence of amine as background electrolytes. The morpholine buffer showed good buffering capacity in terms of migration time (&lt; 8.0 min) and baseline stability when compared to other amine buffers (ethylamine, piperidine, triethylamine). The analytical applications of proposed method showed by recovery percentages of sucralose in real and spiked samples on intra and inter-day basis at optimum experimental conditions of 0.2 M buffer concentration and pH 12.0 at 230 nm UV detection. Results: The selection of BGE, UV detection wavelength, buffer concentration, buffer pH, cassette temperature and applied voltage was optimized to enhance the sensitivity and selectivity of the separation method. Recoveries obtained were ranging from 96.87 to 98.82% for real samples and 94.45 to 98.06% for spiked samples, respectively. Linearity was studied in the range of 2-10 mM, and showed a correlation coefficient of 0.9942. LOD and LOQ were found to be 0.3804 mg L-1 and 1.5215 mg L-1 with % RSD (n = 5) ± 1.27 and 1.19% with respect to migration time and peak area. Furthermore, to better understand the separation of sucralose with amine buffers, were investigated computationally using HOMO-LUMO calculations. The obtained results showed that the band gap decreases in the presence of amine moiety irrespective of its nature. Conclusion: In the study, a novel background electrolytic system was successfully applied to separate sucralose using indirect UV detector with capillary electrophoresis. The FTIR results confirmed that the interaction of sucralose with different amine buffers to better understand the separation chemistry behind sucralose and amine complexes. Moreover, computational results indicate that the direction of charge transfer from the amine functionality to the glucofuranosyl ring in each amine derivative of sucralose confirms the strong interaction between sucralose and amines, which led to the baseline separation of sucralose in different food samples.

A Low-Cost, Simple Method for Isotopic Analysis of Enriched Boron Pharmaceutical Substances by Capillary Zone Electrophoresis with Indirect UV Detection

A novel, cheap and simple method for the determination of 10B and 11B mole fractions in 10B enriched boron compounds by capillary zone electrophoresis with indirect UV detection was developed. The background electrolyte contained 35 mM phenylalanine adjusted to pH of 8.8 with putrescine. The running conditions were + 25 kV at 34° C. Indirect photometric detection was performed at 210 nm. The analysis time was less than 17 min. The interday RSD of migration times and peak areas were less than 0.9% and 2.3%, respectively (n = 18). Linearity was demonstrated in the range 0.3–15 mM for both isotopes. Analysis of boron compounds with mole fraction of 10B ranging from 19.8 (natural abundance) up to 90.0% was successfully demonstrated.

Lyophilized fecal short-chain fatty acid and electrolyte determination by capillary electrophoresis with indirect UV detection for assessment of pediatric inflammatory bowel disease

Short-chain fatty acids (SCFAs) and electrolytes are major constituents of human feces involved in maintaining gastrointestinal homeostasis that underlie complex diet, host and microbiome interactions. Reliable quantification of SCFAs and electrolytes is challenging given the heterogeneity of stool specimens from pediatric patients with diarrhea-predominate inflammatory bowel disease (IBD). Herein, we introduce two validated methods for determination of 3 SCFAs and 5 electrolytes consistently quantified from fecal extracts when using capillary electrophoresis with indirect UV detection (CE-iUV), where concentrations are normalized to total dried weight (mmol/kg d.w.). Lyophilization facilitates sample handling and extraction of heterogeneous stool specimens (∼ 15 mg) from a cohort of children with Crohn’s disease (CD, n = 12) and ulcerative colitis (UC, n = 10) treated with exclusive enteral nutrition (EEN) or corticosteroid (CS) therapy to induce remission, respectively. Good technical precision (mean CV = 13 %, n = 14) and accuracy (recovery from 84 to 116%) is demonstrated for SCFAs and electrolytes from freeze dried stool extracts using a modified Bligh-Dyer protocol with low micromolar detection limits (∼ 2–15 μM). Fecal butyrate is 2.6-fold higher in CD as compared to UC patients (effect size = 1.51; p = 0.00291), and there is a strong co-linearity between fecal butyrate and acetate (r = 0.835) unlike propionate, which is correlated with fecal calprotectin (r = 0.517), a protein biomarker of intestinal inflammation. Also, a longitudinal study of matching stool samples collected from a sub-set of IBD patients revealed about a 7-fold enrichment in magnesium and calcium following 4 weeks of EEN as compared to baseline (F > 4.1 ; p < 0.05) unlike the CS treatment arm with no changes in other fecal SCFAs and electrolytes, including sodium, potassium, and ammonium. CE-iUV enables rapid fecal SCFA and electrolyte determination as required for new insights into the role of gut dysbiosis in IBD, as well as treatment monitoring of nutritional interventions that stabilize the disease course in affected children.

Lactate determination in human vitreous humour by capillary electrophoresis and time of death investigation.

Forensic inquests, particularly, in assessing time since death currently recognize the importance of the analysis of vitreous humour (VH) biomarkers. Present research, studies, and validates the determination of lactate (La) in VH by CZE with indirect UV detection. The BGE (pH 8.9) consisted of Tris buffer (37mM) containing 4-methoxybenzoic acid (4mM) and alkyl-trimethyl-ammonium bromide (1.2mM). Each VH specimen was diluted with a butyric acid solution (internal standard 0.057mM) and La and butyrate were separated within 3-5min (30kV). The La LOQ and LOD were 4 and 2mM, respectively. The calibration curve linearity ranged from 4 to 80mM; intra- and interruns precisions were less than 10% for standard as well as for VH specimen, respectively. To investigate postmortem interval (PMI) and VH lactate level correlation, human VH specimens were collected during autopsy (n = 40) and stored at -20°C until assay. La levels ranged from 16 to 42mM; PMI values ranged from 10 to 141 h. La (mM) and PMI (h) correlation was statistically significant (r2 = 0.527; p < 0.05). In conclusion, the present CZE analysis is efficacious to determine VH La as a biomarker for PMI investigation.

Analysis of honey using capillary electrophoresis with electrokinetic injection – Direct analysis of viscous samples without sample pretreatment

Although the electrokinetic injection mode is applicable for direct introduction of ionic components from highly viscous samples, this is the first work which studies this special feature of capillary electrophoresis for this purpose. 9 metal cations were determined in honey utilizing direct injection, zone electrophoretic separation and indirect UV detection of the sample components. Reproducibility better than 4 RSD% was found for peak areas and the LOD values ranged between 0.045 and 0.44 mg/kg when injection parameters were set to 7.5 kV × 5 s. In order to remedy the quantitation problems arising from mobility and matrix bias, the applicability of the internal universal calibration was examined. It was found that in cases where the mobilities of cations do not differ from the mobilities of the monitoring ion and the internal universal standard (IUS) by more than 10%, the obtained results agreed well with the data measured with ICP-OES.

A Simple Approach to Analyze Sugar Nectar Composition in Flowers Using Capillary Electrophoresis and Enzymatic Assays

Despite the obvious importance of nectar, the composition of this solution remains surprisingly understudied to most of the flowers. Here we describe a simple, low-cost, and reliable methodology to analyze the three main sugars present in 210 nectar samples of Christmas Bellflowers using capillary electrophoresis (CE) and enzymatic assays. CE separation (-16 kV) was made using an electrolyte containing 36 mM NaOH pH 12, 15 mM sorbic acid, 0.5 mM hexadecyl trimethylammonium bromide (CTAB), and indirect UV detection. 72.9% of analyzed nectar samples were sucrose dominant; 13.3% sucrose rich only and 13.8% were fructose rich. The concentrations of fructose and glucose present in most of the samples were very similar, while the amount of sucrose varied considerably. The average amounts of fructose, glucose, sucrose and total sugar were 0.22, 0.21, 0.34 and 0.8 M, respectively. The nectar sample shows a pH average of 5. α-Glucosidase activity was observed in 65% of the samples with an average activity of 0.013 µU µL-1 providing a possible explanation for the similar concentrations of fructose and glucose in the samples. Under our knowledge, this is the first article that shows the analysis of sugars in nectar flowers using CE.

Rapid forensic chemical classification of confiscated flash banger fireworks using capillary electrophoresis

In the Netherlands, the illegal use of powerful flash bangers is popular and as a result these items are frequently encountered in forensic casework. In collaboration with the Dutch police a representative sample set of the most frequently confiscated flash bangers, the Cobra 6 and Cobra 6 2G, has previously been collected also including imitation items. Classification of the different flash bangers was performed by analysing the pyrotechnic charge using capillary electrophoresis (CE) with indirect UV-detection. Two rapid CE methods were used to determine the anions and cations present in the pyrotechnic mixtures. Black and flash powders were easily distinguishable based on their main inorganic compositions, i.e., KNO3 and KClO4, respectively. Differentiation of flash powders from the commercial and imitation pyrotechnic items was achieved by the identification of Ca2+ and Mg2+ cation traces in the imitation flash banger powders. Quantitative CE results were used to explore the possibilities to differentiate seized sets of flash bangers but this proved to be difficult for commercial items due to lack of impurities and uniform production processes. In addition, inherent inhomogeneity of the powders and incomplete sample extraction yielded a relative high measurement uncertainty within a set. For the imitation items potential for set-based differentiation was observed. Although the number of seized imitation sets was limited, a first step has been taken to classify pyrotechnic mixtures to provide additional information and intelligence in forensic casework of flash bangers.

Detection of 2,2′-Azobis(2-amidinopropane) Dihydrochloride in Polyvinylpyrrolidone by Capillary Electrophoresis with Field-Amplified Sample Injection

A sensitive method was developed for detecting 2,2′-azobis(2-amidinopropane) dihydrochloride in polyvinylpyrrolidone by capillary electrophoresis with indirect UV detection. The detection sensitivity was improved significantly using the field-amplified sample injection technique. The background electrolyte was composed of 25 mM imidazole-HCl solution (pH 4.0), in which imidazole acted as the cation probe for the indirect detection at UV 214 nm. Effects of the experimental parameters including pH, the concentration of imidazole as well as the sample injection time on sample preconcentration were investigated and optimized. Under the optimized conditions, baseline separation of 2,2′-azobis(2-amidinopropane) ion with other ions in the polyvinylpyrrolidone samples was achieved within 8 min. The RSD% for the repeatability of the migration time and the peak area were determined as 0.95% and 3.47%, respectively. The limit of detection (LOD, S/N = 3) and the limit of quantitation (LOQ, S/N = 10) were determined as 1.11 × 10−5 M and 2.77 × 10−5 M, respectively. The measured recovery at three concentration levels was in the range of 101–104%. This method was successfully applied to detect 2,2′-azobis(2-amidinopropane) in the commercial polyvinylpyrrolidone samples.