HPLC/ELCD

HPLC on a Cosmosil 5 Cis column, using a perchloric acid-acetonitrile eluent (pH 7.6), followed by CLD in the presence of hydrogen peroxide and bis(2,4,6-trichlorophenyl) oxalate (42), was applied to the determination of 1-aminopyrene (43a) and various diaminopyrenes (43b-d). Ascorbic acid was added to avoid oxidative degradation of the aminopyrenes in the presence of metals LOD in the sub-fmol range (SNR 3)147. A fast (less than 10 min) HPLC-ELCD method was proposed for determination of dopamine (19b) and its metabolites in microdialysates, using packed fused silica capillary columns LOD 0.05 Xg/L of dopamine in a 2 XL sample, RSD 3% (n = 10)148. 

Otto, F., G. Leupold, H. Pariar, R. Rosemann, M. Bahadir, and H. Hopf. 1998. Chlorinated diphenoquinones a new class of dioxin isomeric compounds discovered in fly ashes, slags, and pyrolysis oil samples by using HPLC/ELCD and HRGC/MS. Anal. Chem. 70 2831-2838. 

Pharmaceutical analysts often have no experience in direct polarographic or voltammetric methods, but almost all will have used high-performance liquid chromatography (HPLC) for the determination of drugs and/or metabolites in biological matrices or drugs and/ or their degradation products in pharmaceutical formulations. Spectroscopy (ultraviolet and fluorescence) is the most common detection method in HPLC, but for molecules that do not possess a suitable chromophore or when increased sensitivity or specificity is required, electrochemical detection offers a suitable alternative. ELCD is applicable to any molecular species capable... 

DNP = dinitrophenol ELCD = electrochemical detection FID = flame ionization detection GC = gas chromatography HPLC = high pressure liquid chromatography HRGC = high resolution gas chromatography MS = mass spectrometry PAD = pulse amphrometric detection PID = photodiode array detection UV = ultraviolet detection... 

The most sensitive HPLC-method has been described by Schmidtke and Seifert (1990). When using l-(2-methoxy-phenyl)-piperazine (MPP) for derivatization and a column switching technique, detection limits of 1 ng/m and 30 ng/m could be achieved by electrochemical (ELCD) and UV monitoring, respectively. However, the MPP-ELCD method is very susceptible to trouble and therefore hardly suitable for routine analysis. 

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