ABSTRACT
Objective To evaluate the automatic biochemical analyzer when used to detect urinary vanilmandelic acid (VMA), and to compare it with manual method. Methods The automatic biochemical analyzer using homogenous enzyme immunoassay technology was compared with the manual method on accuracy, precision, linear range, recovery rate, anti-interference capability and etc when used to detect VMA.The comparison was also carried out on positive rate and etc when the two methods were used to test the urine specimens of the healthy subjects and suspected patients of hypertension, hyperthyroidism and hypothyroidism. Results The two methods both had the results on accuracy, precision, linear range, recovery rate, anti-interference capability meet the requirements described in the instruction of reagent kit, while the analyzer gained advantages over the manual method.The positive rates by the two methods for testing urine specimens were similar,while the analyzer behaved better in diagnosing the patient with critical value.Conclusion The analyzer proves better than the manual method when used to detect VMA,and thus is worthy promoting in clinical trial.
ABSTRACT
Objective To establish a method for detecting urinary vanillylmandelic acid (VMA), homovanillic acid (HVA) and creatinine (Cr) simultaneously by high performance capillary electrophoresis (HPCE). Methods The separations were carried out using a 120 mmol/L phosphate buffer (pH 6.80) in a fused-silica capillary tube of 47 cm×75 μm I.D. by capillary zone electrophoresis (CZE). Injections were made by using the pressure mode for 4 s at 1 p. s. i. after samples were centrifuged and diluted. The detections were monitored by a diode-array detector (DAD) at 200 nm after samples were separated at a voltage of 20 kV. The method developed was validated systematically and applied to urine samples from healthy adults (n = 100) and children (n = 100) for establishing the reference ranges of VMA/Cr and HVA/Cr, respectively. Results Under these conditions, the separations of VMA, HVA and Cr could be completed within 13 min. The linearity ranges of VMA, HVA and Cr were 0-500, 0-500 and 0-4 000 μmol/L, respectively, with the correlation coefficients (r) between 0.997 2 and 0. 999 1 (P < 0.01). The detection limits (S/N= 3) were 1.0 μmol/L for VMA, 1.0 μmol/L for HVA and 50.0 μmol/L for Cr. The mean within-run (n = 10) CVs of migration time for VMA, HVA and Cr in urine were 0.58%, 0.56% and 0.25% respectively, while the mean between-run (n = 10) CVs of migration time were 0.95%, 1.00% and 0.48% respectively. The mean within-run (n = 10) CVs of peak area for VMA, HVA and Cr were 3.78%, 3.97% and 2.76% respectively, while the mean between-rim (n = 10) CVs of peak area were 4.60%, 4.08% and 4.42% respectively. The average recoveries were 98.36% for VMA, 93.56% for HVA and 98.85% for Cr. Other compounds in human urine such as catecholamines, 5-hydroxytryptamine and albumen didn't interfere with the assay. The correlation between CE method and HPLC method was good. And the correlation coefficients (r) of VMA and HVA were 0.954 9(P <0.01) and 0.945 1 (P < 0.01), respectively. Skewness distributions were presented for VMA/Cr and HVA/Cr in random urine from both adults and children, and the 95% reference ranges were established by the percentile method. For adults, the reference ranges of VMA/Cr and HVA/Cr were 0-4. 26 and 0-1.69 (μmol/mmol), respectively. For children, the reference ranges of VMA/Cr and HVA/Cr were 0-10.39 and 0-4.31 (μmol/mmol), respectively. Conclusions The CE method devised here for direct measurement of urinary VMA, HVA and Cr is simple, fast,precise and automatic with good repeatability. It is an ideal method for routine detection and mass screening of pheochromocytoma and neuroblastoms.
ABSTRACT
Objective To establish an HPLC-FLD method for simultaneous determination of homovanillic acid(HVA) and vanilmandelic acid(VMA) in human urine.Methods After being filtered with 0.45 ?m membrane,the samples of urine were injected directly into an ODS column(250 mm?4.6 mm,5.0 ?m) at the room temperature.The samples of urine were carried with the mobile phase comprised of methanol-0.1mol/L phosphate buffered solution(20:80,V/V).The flow rate was 1 ml/min,the injection volume was 10 ?l,the detection was taken at ?ex=277 nm,?em=320 nm.Results The determination was finished in 15 min,the retention time was 3.18 min for VMA and 6.72 min for HVA respectively.The detection limit of HVA was 0.15 ?g/ml,the linear range was 0-25 ?g/ml,the recovery rates were between 84.53%-106.1%,the relative standard deviation(RSD)