Micellar electrokinetic capillary chromatography (MECC) of UV-absorbing constituents in normal urine: a chemometric optimisation of the separation

Capillary electrophoresis of human follicular fluid

Some of the major serum proteins that are also found in follicular fluid, including transferrin, alpha-macroglobulin and albumin, are thought to play a role in oocyte maturation. This study set out to identify proteins in human follicular fluid by capillary zone electrophoresis and to investigate their relationship to follicular/oocyte maturity and fertility outcome. 176 individual follicular fluid samples, from 30 women undertaking in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), were run using an optimized capillary zone electrophoresis method that gave a good separation of sixteen peaks in most samples. Nine of the peaks were identified and quantified but seven remain unknown and require further proteomic identification. Of the identified protein peaks, levels of each were corrected for follicular volume and total content calculated. No significant difference in protein levels was found with regard to oocyte recovery and fertilization. Protein concentrations tended to decrease as the follicular sphere increased whilst total content in follicular fluid increased in proportion to size. This is consistent with simple transudation across a sphere surface area which does not increase in proportion to the follicular fluid. This is not true of the concentration and content pattern of other proteins/biomolecules which are produced by follicular cells locally. In conclusion, neither concentration nor absolute levels of nine major proteins identified in follicular fluids correlated with oocyte presence and fertility outcome. Future work to remove more concentrated proteins (e.g. albumin) would enhance separation of smaller peaks and identification of the unknown molecules.

Urinary electrophoretic profiles from chronic fatigue syndrome and chronic fatigue syndrome/fibromyalgia patients: a pilot study for achieving their normalization

Aim of our study was to determine if there were distinct, disease-related patterns of urinary analytes in chronic fatigue syndrome (CFS) and chronic fatigue syndrome/fibromyalgia (CFS/FM) compared to normal controls (NC). Urine was collected from these subjects for two consecutive 24 h periods and aliquots were submitted to micellar electrokinetic chromatography (MEKC). To compensate for the differences in peak migration times, these were normalized from the 35 min duration of run to a 100-point scale, and each peak was assigned its normalized time measure. Peak heights were also normalized by dividing the mAU by that of the internal standard (creatinine) and multiplying by 100. MEKC with normalization for peak height and migration time generated comparable results within each of the patient groups. CFS/FM and CFS had significant differences in peaks compared to NC that may be of significance as biomarkers of illnesses.

Capillary electrophoresis for detection of inherited disorders of purine and pyrimidine metabolism: a selective approach

We developed a capillary electrophoresis method as a diagnostic tool for purine and pyrimidine metabolic disorders. Optimal conditions allowed the separation of the major diagnostic metabolites in urine samples within an analysis time of 10 min and with a separation efficiency of about 350,000 theoretical plates/m. The diagnostically important metabolites (adenine, adenosine, 2-deoxyadenosine, 2-deoxyguanosine, 2,8-dihydroxyadenine, guanosine, hypoxanthine, orotidine, orotic acid, and creatinine) were detectable at concentrations of 1.0-5.7 micromol/L. The method gives a linear calibration curve for tested purine and pyrimidine derivatives within the range of 5-500 micromol/L (r > 0.996) The coefficients of variation for the within- and between-day imprecisions were less than 3.2 and 5.8%, respectively. Characteristic abnormalities were detected in the electropherograms of urine samples from patients with purine and pyrimidine enzyme deficiencies. We provide electrophoretic and spectral characteristics of intermediates in purine and pyrimidine metabolism and possible artifacts from medication and their UV-absorbing compounds. Our method allows the detection of the majority of inborn errors of purine and pyrimidine metabolism.

Optimised separation of endogenous urinary components using cyclodextrin-modified micellar electrokinetic capillary chromatography

In this study both native and chemically modified cyclodextrins (CDs) were investigated as buffer additives to improve the micellar electrokinetic capillary chromatography (MEKC) separation of endogenous bioanalytes in human urine. The following CDs were investigated: alpha, beta, gamma-CDs; hydroxypropyl-alpha-CD, hydroxypropyl-beta-CD, methylated beta-CD, sulphated beta-CD, sulphobutyl ether-beta-CD and hydroxypropyl-gamma-CD. The separations were compared to MEKC without additives. The best improvement in peak resolution and separation of urine components was observed with the sulphated beta-CD. A four-factor three-level full factorial design study was conducted on voltage, temperature, pH and sulphated beta-CD molarity. The optimum conditions were 25 mM sodium tetraborate, pH 9.5, 75 mM sodium dodecyl sulphate (SDS) and 6.25 mM sulphated beta-CD and were able to resolve 70 peaks from a urine pool in 12 min. These optimum conditions have been successfully applied to a number of clinical samples.

A rapid urine creatinine assay by capillary zone electrophoresis

Using capillary zone electrophoresis, the urine creatinine (uCr) assay was validated in extemporaneous diluted urine, both in healthy subjects and athletes, with the uCr concentration as a reference value to compare excretion rates of other metabolites in the same samples. The electrokinetic sample injection was carried out at 10 kV per 10 s; UV absorbance detection was at 254 nm. Using standard samples, the creatinine migration mean time in 100 mmol/L acetate buffer, pH 4.4, was 3.3+/-0.2 min; the repeatability for absolute migration mean time was 0.6% and peak height repeatability was 2.9%. The correlation coefficient of the standard curve was r = 0.999 and the detection limit was 23.1 micromol/L. Intra- and interassay coefficients of variation (CV) were 3.0 and 3.6%, respectively; recovery was 99+/-3% and linearity was r= 0.98. Normal urine samples were diluted 1:80 in run buffer. The present CE urine creatinine assay showed a good correlation with HPLC and with Jaffe methods (r = 0.98 and r = 0.97, respectively; p < 0.0001). The uCr in the morning urine samples of 34 healthy males (M), 38 healthy females (F), and 83 male athletes (A) was 10.4+/-6.1 mmol/L, 10.8+/-8.1 mmol/L and 13.2+/-6.5 mmol/L, respectively. The uCr difference (p < 0.02) between M and A and a correlation (p < 0.05) with age in A were observed.

Analysis of compounds containing carboxyl groups in biological fluids by capillary electrophoresis

Capillary electrophoresis (CE) is one of the suitable separation techniques used to analyze drugs or metabolites in complicated sample matrices such as plasma, serum and urine. It sometimes requires only a simple process of sample pretreatment, deproteinization, dilution or extraction for biological fluids, otherwise no pretreatment is necessary. Various metabolic disorders concerning the compounds which possess carboxyl groups such as organic acids have been monitored by CE. Drug metabolism in the body can be monitored by the same technique. Recent publications suggest the feasibility of an automated system for diagnosis based on CE technique.

Determination of allantoin in biofluids using micellar electrokinetic capillary chromatography

A micellar electrokinetic chromatographic method is described for the determination and quantitation of allantoin, an end-product of purine metabolism in mammals that is applicable to biofluids of different mammal species and man. The method was optimised following a study on the effect of pH and sample preparation procedure. Final conditions were 30 mM sodium tetraborate, pH 9.5, 75 mM sodium dodecyl sulphate, 20 kV and 20 degrees C. Allantoin was well resolved from endogenous compounds and could be determined in horse, dog, mouse and rabbit urine. No allantoin could be found in man. No complicated sample treatment was necessary, thus the developed method was rapid (< 5 min), sensitive (5 microM) and simple. Results from this work will permit the determination of allantoin in man as a measure of free radical generation reactions as well as its presence in the plasma and other biofluids with modification of the sample preparation procedures.