scholarly journals Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with VitaminB6Deficiency

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Chi-Fen Chen ◽  
Tsan-Zon Liu ◽  
Wu-Hsiang Lan ◽  
Li-An Wu ◽  
Chin-Hung Tsai ◽  
...  
Keyword(s):  
Spectrophotometric Method ◽  
Solid Phase ◽  
Correlation Coefficients ◽  
Urinary Metabolites ◽  
Hplc Method ◽  
Small Scale ◽  
Extraction Column ◽  
Xanthurenic Acid ◽  
Activation Coefficient ◽  
Coefficient Method

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan (n=80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15 μmole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC’s AST/B6functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6deficiency-associated hyperhomocysteinemic condition.

scholarly journals Improved fluorometric quantification of urinary xanthurenic acid

1996 ◽  
Vol 42 (3) ◽  
pp. 397-401 ◽  
Author(s):  
M Liu ◽  
G R Wang ◽  
T Z Liu ◽  
K J Tsai
Keyword(s):  
Clinical Laboratory ◽  
Solid Phase ◽  
Correlation Coefficients ◽  
Hplc Method ◽  
Extraction Column ◽  
Xanthurenic Acid ◽  
Vanillylmandelic Acid ◽  
Fluorometric Method ◽  
Tryptophan Metabolites ◽  
Vitamin B6 Deficiency

Abstract Measurement of urinary xanthurenic acid (XA) has been used clinically to study a variety of disorders caused by vitamin B6 deficiency. To obviate some cumbersome steps of current methods for measuring XA in human urine, we have developed a simple fluorometric method. We apply the urine sample to a solid-phase extraction column containing trimethylaminopropyl group bound to silica, which enables us to purify and concentrate the XA from the urine without contamination from various tryptophan metabolites. The XA in the acidic eluate can then be quantified fluorometrically. The linearity of the proposed method extends from 0.2 to 10.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled control specimens (1.08 and 1.90 mg/L) of 1.2% and 2.6%, respectively. Correlation studies with an established HPLC method and with a spectrophotometric procedure showed correlation coefficients of 0.99 and 0.98, respectively. Interference from vitamin C, uric acid, salicylate, acetaminophen, vanillylmandelic acid, and homovanillic acid was insignificant. The proposed method for urinary XA is rapid, simple, and suitable for routine use in the clinical laboratory.

Clinical measurement of serum amiodarone and desethylamiodarone by using solid-phase extraction followed by HPLC with a high-carbon reversed-phase column

1993 ◽  
Vol 39 (3) ◽  
pp. 496-500 ◽  
Author(s):  
M A Jandreski ◽  
W E Vanderslice
Keyword(s):  
Serum Proteins ◽  
Clinical Laboratory ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Reversed Phase ◽  
Hplc Method ◽  
Extraction Column ◽  
Assay Precision ◽  
Phase Column ◽  
Reversed Phase Column

Abstract We describe a rapid, simple HPLC method routinely used in our clinical laboratory for determining amiodarone and its metabolite desethylamiodarone. These compounds are released from serum proteins by pretreatment with an acidic solution and then extracted onto a C2 reversed-phase clean-up column. After elution from the extraction column, the compounds are separated and quantified by HPLC with a C18 reversed-phase column and spectrophotometric detection. The standard curves for the drug and metabolite are linear up to 20.0 mg/L, with a lower limit of detection of 0.16 mg/L. The CVs for intra-assay precision were 5.0% at 0.58 mg/L and 2.9% at 5.96 mg/L; for inter-assay precision, they were 9.6% at 0.52 mg/L and 6.1% at 2.09 mg/L. Lipemia, hemoglobin, and bilirubin up to 300 mg/L do not interfere with this assay. None of > 550 cardiac patients' samples tested contained a compound that interferes with this assay.

scholarly journals Rapid Analysis of Metanephrine and Normetanephrine in Urine by Gas Chromatography-Mass Spectrometry

2002 ◽  
Vol 48 (2) ◽  
pp. 332-337 ◽  
Author(s):  
David K Crockett ◽  
Elizabeth L Frank ◽  
William L Roberts
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Solid Phase ◽  
Correlation Coefficients ◽  
Hplc Method ◽  
Gas Chromatography Mass Spectrometry ◽  
Internal Standards ◽  
Rapid Decomposition ◽  
Chromatography Mass Spectrometry ◽  
Deming Regression

Abstract Background: Widely used HPLC methods for quantification of metanephrine and normetanephrine in urine often have long analysis times and are frequently plagued by drug interferences. We describe a gas chromatography-mass spectrometry method designed to overcome these limitations. Methods: Metanephrine and normetanephrine conjugates were converted to unconjugated metanephrine and normetanephrine by acid hydrolysis. To avoid the rapid decomposition of the deuterated internal standards (metanephrine-d3 and normetanephrine-d3) under hydrolysis conditions, the internal standards were added after hydrolysis. Solid-phase extraction was used to isolate the hydrolyzed metanephrines from urine. Samples were concentrated by evaporation, then derivatized simultaneously with N-methyl-N-(trimethylsilyl)trifluoroacetamide and N-methyl-bis-heptafluoro-butryamide at room temperature. Results: The assay was linear from 25 to 7000 μg/L. The intraassay CVs were <5% and the interassay CVs <12%. Comparison with a routine HPLC method (n = 192) by Deming regression yielded a slope of 1.00 ± 0.02 μg/L, an intercept of −5.8 ± 7.8 μg/L, and Sy|x = 50.6 μg/L for metanephrine and a slope of 0.94 ± 0.03, intercept of 19 ± 11 μg/L, and Sy|x = 60 μg/L for normetanephrine. The correlation coefficients (r) were calculated after log transformation of the data and gave r = 0.97 for metanephrine and r = 0.97 for normetanephrine. Interference from common medications or drug metabolites was seen in <1% of samples. The time between sequential injections was <7 min. Conclusions: This new gas chromatography-mass spectrometry assay for total fractionated metanephrines is rapid, compares well with a standard HPLC assay, and avoids most drug interferences that commonly affect HPLC assays for urine metanephrines.

scholarly journals Development of Flow Injection Spectrophotometric Method for 1-Napthylthiourea Using Sodium Nitrite and Sulphanilic Acid Diazotization Reaction

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Muhammad Asghar ◽  
Mohammad Yaqoob ◽  
Sami Ullah ◽  
Samar Ali ◽  
Nusrat Munawar ◽  
...  
Keyword(s):  
Flow Injection ◽  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Hplc Method ◽  
Calibration Equation ◽  
Sulphanilic Acid ◽  
Paired Student ◽  
Relative Standard ◽  
Hydrolysis Of

A simple spectrophotometric method in conjunction with flow injection analysis is developed for the quantitative analysis of 1-napthylthiourea (ANTU). The reaction is based on the alkaline hydrolysis of ANTU to 1-naphthylamine at 30°C, coupled with diazotized sulphanilic acid resulting in 4-(sulphophenylazo)-1-naphthylamine which is monitored at 495 nm. The limit of detection (S/N = 3) is 0.01 mg/L with a sampling throughput of 45/h. The method is linear over the range of 0.05–120 mg/L (R2=0.9995,n=7), with calibration equation y = 0.031x−0.018 (y = absorbance; x = mg/L) and relative standard deviation (n=3) 1.8–3.6%. Experimental variables are optimised, and the interfering effects of different pesticides, organic compounds, cations, and anions at environmentally relevant concentrations are investigated. The analysis of ANTU in spiked water samples is extracted with solid phase procedure using disposable Sep-Pak C18 cartridges, and the recovery was 93 ± 1.9–110 ± 3.0%. The results of the proposed method are compared with the HPLC method by applying the F-test and paired Student t-test at 95% confidence level.

scholarly journals Determination of urinary free cortisol by HPLC

1997 ◽  
Vol 43 (8) ◽  
pp. 1386-1391 ◽  
Author(s):  
Ursula Turpeinen ◽  
Helene Markkanen ◽  
Matti Välimäki ◽  
Ulf-Håkan Stenman
Keyword(s):  
Solid Phase Extraction ◽  
Mobile Phase ◽  
Solid Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Hplc Method ◽  
Extraction Column ◽  
Phase Extraction ◽  
Free Cortisol

Abstract We here report a reversed-phase HPLC method for the determination of free cortisol in human urine, using methylprednisolone as the internal standard. Before chromatography, samples were extracted with a C18 solid-phase extraction column and the steroids were separated on a LiChrospher 100 C18 column with a mobile phase of methanol/acetonitrile/water (43/3/54 by vol). Linearity, precision, and accuracy of the method were established. The detection limit was 10 pmol of cortisol, and total CVs were <8%. With various solid-phase extraction columns the recovery of cortisol was 36–97%; recovery of the internal standard was 43–85%. Study of interference by 6 other steroids and metabolites and 24 drugs showed that carbamazepine and digoxin partly overlapped with cortisol, but this interference could be reduced by modification of the mobile phase. The HPLC method was compared with an RIA and an automated immunoassay method. The results obtained by HPLC averaged 40% of the RIA values.

scholarly journals Development of a kinetic spectrophotometric method for insecticide diflubenzuron determination in water and baby food samples

2018 ◽  
Vol 72 (5) ◽  
pp. 305-314 ◽  
Author(s):  
Emilija Pecev-Marinkovic ◽  
Zora Grahovac ◽  
Aleksandra Pavlovic ◽  
Snezana Tosic ◽  
Ivana Rasic-Misic ◽  
...  
Keyword(s):  
Spectrophotometric Method ◽  
Solid Phase ◽  
Kinetic Method ◽  
Inhibitory Effect ◽  
Food Samples ◽  
Hplc Method ◽  
Baby Food ◽  
Relative Standard ◽  
Concentration Interval ◽  
Kinetic Spectrophotometric

A kinetic spectrophotometric method for determining residues of insecticide diflubenzuron 1(4-chlorphenyl)-3-(2,6-diflubenzoyl)urea (DFB) has been developed and validated. Kinetic method was based on the inhibitory effect of DFB on the oxidation reaction of sulfanilic acid (SA) by hydrogen peroxide in the presence of Co2+ ions in a phosphate buffer, which was monitored at 370 nm. DFB can be measured in the concentration interval 0.102 ? 3.40 ?g mL-1 and 3.40 ? 23.80 ?g mL-1. The detection and quantification limits of the method were calculated according to the 3? criteria and found to be 0.077 ?g mL-1 and 0.254 ?g Ml-1, respectively. The relative standard deviations for five replicate determinations of 0.102, 1.70 and 3.40 ?g mL-1 DFB were 2.08, 1.22 and 1.21 %, respectively, for the first concentration interval, and the recovery percentage values were from 94.12 to 97.35 %. HPLC method was used as a parallel method to verify results of the kinetic method. The kinetic method was successfully applied to determine diflubenzuron concentrations in spiked water and baby food samples after solid phase extraction of the samples. The F and t values at 95% confidence level are lower than the theoretical ones, confirming agreement of the developed and the HPLC method.

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