Coupling liquid chromatography/mass spectrometry detection with microfluidic droplet array for label-free enzyme inhibition assay

The Analyst ◽  
2014 ◽  
Vol 139 (1) ◽  
pp. 191-197 ◽  
Author(s):  
Xiu-Li Wang ◽  
Ying Zhu ◽  
Qun Fang
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Enzyme Inhibition ◽  
Free Enzyme ◽  
Label Free ◽  
Inhibition Assay ◽  
Liquid Chromatography Mass Spectrometry ◽  
Mass Spectrometry Detection ◽  
Droplet Array ◽  
Enzyme Inhibition Assay

Plasma methotrexate as determined by liquid chromatography, enzyme-inhibition assay, and radioimmunoassay after high-dose infusion.

1980 ◽  
Vol 26 (6) ◽  
pp. 734-737 ◽  
Author(s):  
S K Howell ◽  
Y M Wang ◽  
R Hosoya ◽  
W W Sutow
Keyword(s):  
Liquid Chromatography ◽  
Enzyme Inhibition ◽  
Plasma Concentrations ◽  
Cross Reactivity ◽  
High Dose ◽  
Maximum Plasma ◽  
Inhibition Assay ◽  
Dose Infusion ◽  
Enzyme Inhibition Assay ◽  
Related Compounds

Abstract Three techniques for measuring methotrexate show various cross reactivities with methotrexate-related compounds: “high-pressure” liquid chromatography, by principle, is virtually specific for methotrexate; the enzyme-inhibition assay quantitates methotrexate, methotrexate diglutamate, and methotrexate triglutamate equally well, but has a 10% cross reactivity with 4-amino-4-deoxy-N10-methylpteroic acid and 1% with 7-hydroxymethotrexate; radioimmunoassay shows an equal cross reactivity with methotrexate, 4-amino-4-deoxy-N10-methylpteroic acid, methotrexate diglutamate and triglutamate, and a 5 to 10% cross reactivity with 7-hydroxymethotrexate. Radioimmunoassay almost always yielded the highest values for methotrexate, followed by enzyme-inhibition assay then liquid chromatography. The presence of two methotrexate-related compounds, 7-hydroxymethotrexate and 4-amino-4-deoxy-N10-methylpteroic acid, was confirmed in human urine samples and quantitated in patients’ plasma by liquid chromatography, the respective maximum plasma concentrations being 250 and 16 mumol/L. Materials cross reacting with methotrexate in radioimmunoassay of chromatographic fractions from plasma were also noted in fractions corresponding to methotrexate diglutamate and triglutamate peaks, in quantities estimated to be 47 and 30 nmol/L methotrexate equivalents, respectively. 7-Hydroxymethotrexate is eliminated more slowly than methotrexate and its production increases with dosages of methotrexate.

A label-free double-amplification system for sensitive detection of single-stranded DNA and thrombin by liquid chromatography-mass spectrometry

2014 ◽  
Vol 50 (69) ◽  
pp. 9846-9848 ◽  
Author(s):  
Wenbo Zhao ◽  
Zhen Qin ◽  
Chengsen Zhang ◽  
Meiping Zhao ◽  
Hai Luo
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Dna Probe ◽  
Sensitive Detection ◽  
Label Free ◽  
Liquid Chromatography Mass Spectrometry ◽  
Single Stranded Dna ◽  
Exonuclease Iii ◽  
Amplification System ◽  
Adenine Thymine

A label-free double amplification system has been developed by using a ternary DNA probe containing the poly(adenine-thymine) sequence assisted by exonuclease III degradation.

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