Separation of N2-ethyl-2'-deoxyguanosine-5'-monophosphate and four native deoxyribonucleoside monophosphates using capillary zone electrophoresis with polyethylene glycol as buffer additive

Evaluation of Type-A Endonucleases for the Quantitative Analysis of DNA Damage due to Exposure to Acetaldehyde Using Capillary Electrophoresis

The substrate selectivities of three endonucleases were studied quantitatively using capillary zone electrophoresis to find one giving N²-ethyl(Et)-2'-deoxyguanosine-5'-monophosphate (5'-dGMP) and cyclic 1,N²-propano(CPr)-5'-dGMP from DNAs damaged by acetaldehyde (AA). Six 2'-deoxyribonucleoside-5'-monophosphates to be quantified in the hydrolysis solutions of DNAs, namely, Et-5'-dGMP, CPr-5'-dGMP, and four authentic ones, were completely separated using a 100 mM borate running buffer solution having an optimized pH of 9.67. Using the present method, nuclease reactions of nuclease S1 (NS1), nuclease P1 (NP1), and nuclease Bal 31 to 2'-deoxyribonucleoside-5'-monophosphates from damaged Calf thymus (CT-) DNAs were monitored. The CT-DNAs were prepared by treatment with AA to generate Et-guanine or CPr-guanine internally. Bal 31 hydrolyzed the damaged CT-DNAs to yield Et-5'-dGMP and CPr-5'-dGMP quantitatively. The two 5'-dGMP adducts were not detected in the hydrolysis solutions using NS1 or NP1. Bal 31 can be a suitable nuclease for analyzing DNA damages caused by AA.

Capillary electrophoresis-based methods for the determination of lipids--a review

Capillary electrophoresis (CE) is a high-resolution technique for the separation of complex biological and chemical mixtures. CE continues to emerge as a powerful tool in the determination of lipids. Here we review the analytical potential of CE for the determination of a wide range of lipids. The different classes of lipids are introduced, and the different modes of CE and optimization methods for the separation of lipids are described. The advantages and disadvantages of the different modes of CE compared to traditional methods like gas chromatography (GC) and liquid chromatography (LC) in the determination of lipids are discussed. Finally, the potential of CE in the determination of lipids in the future is illustrated.

Separation procedures capable of revealing DNA adducts

Detection and quantification of DNA adducts are very important in relation to diseases such as cancer. Both high sensitivity and high selectivity are required for the detection of DNA adducts because the content of adducts in DNA is very small compared with those of normal bases and only small amounts of DNA samples are available for analysis in general cases. In this paper are described separation procedures such as liquid chromatography, gas chromatography and capillary electrophoresis combined with a detection and identification method such as 32P-postlabeling, mass spectrometry, electrochemical detection, fluorescence detection and immunoassay. The merits and demerits of the procedures are also discussed.

Analysis of DNA adducts of acetaldehyde by liquid chromatography-mass spectrometry

A highly sensitive method using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) was developed for the analysis of DNA adducts of acetaldehyde (AA). AA, which is the primary oxidative metabolite of ethanol, is considered to possess carcinogenic activity. AA reacts with the exocyclic amino group of guanine in DNA to form N2-ethylguanine (Et-Gua) and 1,N2-propanoguanine (Pr-Gua) adducts. With the present method, such adducts were detected as the base forms from DNA chains using depurination in the pretreatment process. In our measurement with LC-ESI-MS, the limits of detection (LODs) of the Et-Gua and Pr-Gua adducts of the base forms were 3.0 x 10(-10) and 1.0 x 10(-9) M, respectively, and the LODs are about two orders of magnitude lower than those of the nucleoside forms. Calf thymus DNA samples treated with AA and NaBH3CN were analyzed by this method. Et-Gua was clearly detected and, in the absence of NaBH3CN, Pr-Gua was detected predominantly. Furthermore, the method was also applied to study whether or not these two adducts are formed in DNA of cultured HL-60 cells during exposure to AA for 24 h. Pr-Gua was clearly detected and traces of Et-Gua were also detected in the DNA of the cells. Although the sensitivity of this method is lower by at least oneorder of magnitude than the 32P-postlabeling assay, currently the most sensitive method, our method does not involve complex enzymatic reactions for the postlabeling and the use of troublesome radioactive materials. Furthermore, it enables structural identification of guanine adducts. The present method would be a useful tool for studies of Et-Gua and Pr-Gua adducts in connection with carcinogenesis.

Sweeping: concentration mechanism and applications to high-sensitivity analysis in capillary electrophoresis

Sweeping in capillary electrophoresis (CE) involves the interaction of a pseudostationary phase (PS) in the separation solution and a sample in the matrix that is free of the PS used. The PS includes not only the PSs employed in electrokinetic chromatography, but also complexation reagents such as borate. The sample matrix could have a lower, similar, or higher conductance than the separation solution. Thus, the basic condition for sweeping is a sample matrix free of the additive. The accumulation of analyte molecules during the interaction makes this interesting phenomenon very useful as an on-line preconcentration method for CE. Preconcentration occurs due to chromatographic partitioning, complexation, or any interaction between analytes and PS. Contact between analyte and PS is facilitated by the action of electrophoresis and is independent of electroosmosis. The analyte, PS, or both should have electrophoretic velocities when an electric field is applied. The extent of preconcentration is dictated by the strength of the interaction involved. From tens to several thousand-fold improvements in detector response for many neutral and charged analytes have been achieved with this technique, suggesting sweeping as a general approach to on-line preconcentration in CE. The mechanism and applications of the sweeping phenomenon under different experimental conditions are discussed in this review, with particular emphasis on a better understanding of the sweeping mechanism under reduced electric field (high conductivity) in the sample zone.

Separation and on-line preconcentration by sweeping of charged analytes in electrokinetic chromatography with nonionic micelles

The separation and on-line preconcentration by sweeping of charged analytes in electrokinetic chromatography using a neutral pseudostationary phase is described. Under neutral or basic conditions, the electrophoretic migration of anionic analytes towards the anode is overcome by a high, cathode-directed electroosmotic flow; hence, they experience net migration towards the cathode, and the system is run at positive polarity mode. The separation and the retention factor, k, are dependent on both the analyte's electrophoretic mobility and its interaction with the pseudostationary phase. The versatility of the sweeping mechanism is then shown in this system. The charged analyte, prepared in a matrix free of the pseudostationary phase, penetrates the pseudostationary phase zone upon application of voltage. Analyte molecules are consequently accumulated and concentrated. As a demonstration, the separation and preconcentration of phenol derivatives using nonionic surfactants of the alkyl polyoxyethylene ether type (Brij 35 and Brij 58) yielded peak height enhancements up to 100-fold. The efficiency of sample stacking was also found to be improved with the use of a high viscosity background solution.

A handy detection cell for end-column electrochemical detection in capillary electrophoresis

A handy and simple detection cell was constructed using a mixing joint for end-column electrochemical detection in capillary electrophoresis (CE). The cell allows for positioning of the working electrode at the end of the separation capillary without the aid of micropositioners. The design facilitates the exchange of electrodes and capillaries without the need to refabricate the entire capillary-electrode setup. The cell can be assembled in a short period of time. Alignment with the joint screw proved to be reproducible for working electrodes of copper and gold. The advantages of reduced time and low cost make the device very attractive for the routine analysis of electroactive species, such as carbohydrates and their derivatives, purine bases and nucleosides, amino acids, and catecholamines etc. by CE with electrochemical detection.

Analysis of DNA adducts bases by capillary electrophoresis with amperometric detection

We have developed a method for the detection of DNA adducts by combining capillary electrophoresis (CE) with the specificity of amperometric detection. Guanine is the most easily damaged base of the four normal DNA bases and many adducts of guanine have been found in DNA. These guanine adducts are often electrochemically active, while the normal bases with the exception of guanine are not. Therefore, CE with amperometric detection will be a promising method to study DNA damage. The four normal deoxynucleosides and two damaged deoxnucleosides N2-ethyldeoxyguanosine (N2-ethyl-dG) and 8-hydroxydeoxyguanosine (8-OH-dG), were completely separated by micellar electrokinetic chromatography (MEKC). Deoxyguanosine and the two damaged deoxynucleosides were identified using amperometric detection. The sensitivity of our system was comparable to that of UV detection. Analysis of DNA hydrolysis products was also performed briefly using this method.