Electrochemical detector in high-performance liquid chromatography

Bollet, C., Oliva, P., and Caude, M., Partial electrolysis electrochemical detector in high-performance liquid chromatography, /. Chromatogr., 149,625,1977. 

AN Masoud, Y N Cha. Simultaneous use of fluorescence, ultraviolet, and electrochemical detectors in high performance liquid chromatography-separation and identification of phenolic antioxidants and related compounds. J High Resolut Chromatogr Comm 5 299-305, 1982. 

Chromatopolarography appeared to be an important method, because on a well-chosen chromatographic column, substances which had almost identical voltam-metric characteristics (half-wave potentials) could be separated, if their affinities to the column-filling material (stationary phase) were sufficiently different. After separation, they could be polarographically detected and their content determined. This method may be considered a precursor of many combined voltammetric techniques developed in forthcoming years and specifically electrochemical detectors in high performance liquid chromatography (HPLC) and microfluidics. 

L. Brunt, Electrochemical detectors for high-performance liquid chromatography and flow analysis systems, in Trace Analysis, vol. I, Ed. J. Lawrence, Academic Press, 1981. 

H. W. van Rooijen and H. Poppe, An Electrochemical Reactivation Method for Solid Electrodes Used in Electrochemical Detectors for High-Performance Liquid Chromatography and Flow Injection Analysis. Anal. Chim. Acta, 130 (1981) 9. 

C.N. Svendsen, Multi-electrode array detectors in high-performance liquid chromatography A new dimension in electrochemical analysis. Analyst, 1993, 118, 123-129. 

The refiactive index detectitm (RID), often used in high-performance liquid chromatography (HPLC), is an interesting detection method in CE with a laser light source and a hmit of detection (LOD) in the micromolar range. Electrochemical detection (ECD) and pulsed amperometric detection (PAD) of sugars are common and effective methods used in HPLC. Some recait communications show that the sensitivity of these detection methods in CE have an approximately 1000-fold better LOD than RID. Unfortunately, these detectors (RID, ECD, and PAD) are not commercially available for CE at the moment... 

G. Forzy, J.L. Dhondt and J.M. Hayte, Comparison of 11 electrochemical detectors used in high performance liquid chromatography, Ann. Biol. Clin. (Paris), 1988, 46, 793-793. 

OPTIMIZATION OF AN ELECTROCHEMICAL DETECTOR USING A STATIC MERCURY DROP ELECTRODE IN HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY ANALYSIS OF THE ANTICANCER AGENT MITOMYCIN C IN PLASMA... 

High-performance liquid chromatography (HPLC) with a micellar mobile phase or with a selective pre-column or reaction detection system has also been used to determine alkylenebis(dithiocarbamaes). ° Zineb and mancozeb residues in feed were determined by ion-pair HPLC with ultraviolet (UV) detection at 272 nm. These compounds were converted to water-soluble sodium salts with ethylenediaminetetra-acetic acid (EDTA) and sodium hydroxide. The extracts were ion-pair methylated with tetrabuthylammonium hydrogensulfate (ion-pair reagent) in a chloroform-hexane solvent mixture at pH 6.5-8.S. The use of an electrochemical detector has also been reported. ... 

Nagaosa et al. [839] simultaneously separated and determined these elements in seawater by high-performance liquid chromatography (HPLC) using spec-trophotometric and electrochemical detectors. 

GC = gas chromatography EC = electrochemical (detector ECD = electron capture (detector HCD = Hall conductivity detector HFBA = heptafluorobutyric anhydride HPLC = high performance liquid chromatography NCI-MS = mass spectrometry in the negative chemical ionization mode NPD = nitrogen-phosphorus detector ppb = parts per billion UV = ultraviolet absorption SPE = solid phase extraction wt wt = weight weight... 

Direct determination of urea pesticides by high-performance liquid chromatography has been widely reported in the literature (10,32-36,127-130). Ultraviolet detection has often been used (32,33,35,36,60,127) with usually acceptable sensitivity, although this detector is nonspecific and the sensibility is, in general, low. To overcome this problem, several techniques have been assayed, such as precolumn enrichment (60), postcolumn derivatization (34,10), and the use of other detection techniques such as the electrochemical (129), photoconductivity (128,130), and fluorescence detectors (9,10,34). Table 9 summarizes representative papers using these techniques in HPLC analysis. 

We believe that this symposium on Recent Advances in Pesticide Analytical Methodology fulfills this plea. High-performance liquid chromatography (HPLC) has made the greatest advances. Chapters on HPLC cover subjects on metabolism studies automation of HPLC evaluation of LC columns the effect of the mobile phase on reversed-phase chromatography the electrochemical or amperometric detector and fluorogenic detection. 

Duan et al. reported the use of a rapid and simple method for the determination of acetylcholine and choline in mouse brain by high performance liquid chromatography, making use of an enzyme-loaded post column and an electrochemical detector [144]. Perchloric acid extracts of small brain tissue were injected onto the HPLC system with no prior clean-up procedure. Detection limits for both compounds were 1 pmol, and this method was successfully applied to the measurement of acetylcholine in discrete brain areas of the mouse. 

Poppe, H. Electrochemical detectors. In Instrumentation for High-Performance Liquid Chromatography, Huber, J.F.K., Ed. Elsevier Amsterdam, 1978, pp. 131-149. 

Reversed-phase high-performance liquid chromatography (RP-HPLC) is the usual method of choice for the separation of anthocyanins combined with an ultraviolet-visible (UV-Vis) or diode-array detector (DAD)(Hebrero et al., 1988 Hong et ah, 1990). With reversed-phase columns the elution pattern of anthocyanins is mainly dependent on the partition coefficients between the mobile phase and the Cjg stationary phase, and on the polarity of the analytes. The mobile phase consists normally of an aqueous solvent (water/carboxylic acid) and an organic solvent (methanol or acetonitrile/carboxylic acid). Typically the amount of carboxylic acid has been up to 10%, but with the addition of a mass spectrometer as a detector, the amount of acid has been decreased to as low as 1 % with a shift from trifluoroacetic acid to formic acid to prevent quenching of the ionization process that may occur with trifluoroacetic acid. The acidic media allows for the complete displacement of the equilibrium to the fiavylium cation, resulting in better resolution and a characteristic absorbance between 515 and 540 nm. HPLC separation methods, combined with electrochemical or DAD, are effective tools for anthocyanin analysis. The weakness of these detection methods is a lack of structural information and some nonspecificity leading to misattribution of peaks, particularly with electrochemical... 

Dopamine was quantitated by high-performance liquid chromatography (HPLC) with electrochemical detection with a detection limit of approximately 5 fmol/sample. An HPLC pump (LKB, Pharmacia) was used in conjunction with an electrochemical detector (Antec, Leiden) working at 625 mV versus an Ag/AgCl reference electrode. The analytical column was a Supelco Supelcosil LC-18 Column (3 pm particle size). The mobile phase consisted of a mixture of 4.1 g/1 sodium acetate (Merck), 85 mg/1 octane sulphonic acid (Aldrich), 50 mg/1 EDTA (Merck), 1 mM tetramethylammonium chloride (ACROS), 8.5 % methanol (Labscan) and ultra pure water (pH=4.1 with glacial acetic acid). 

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