Site Loader
Rock Street, San Francisco

Metamorphosis of drug is that, the process by which drugs are transformed in the organic structure to a signifier that is more readily evacuated, the metabolic destiny of specific drug in footings of designation and quantification of the metabolites is request to cognize that, if its usage it will non do more jobs than the medical status it is merchandise to bring around the patient. In add-on, it is really of import to the drug companies to see how it works and assist to supply drugs with more efficient.

Drug metamorphosis ( or biotransformation ) is the path which drug are made more water-soluble to subserve their removing from the organic structure. There is a broad latitude of different drug construction, while there are merely proportionately little figure of chemical reaction lead to the production of metabolites.

What is Liquid chromatography/Mass spectroscopy ( LC/MS ) ?

As it is named, it is an of import method conjoins two separation processs: Liquid chromatography ( LC ) and Mass spectroscopy ( MS ) . Both of these techniques are known for rather long clip and they have been developed and used widely.

Liquid chromatography

LC is explained as that, it is a physical green goods of separation in which the compound to be separated is apportioned between two stages, foremost one is stationary ( the stationary stage ) , while the other ( the nomadic stage ) travel in define way. Any modern chromatographic system may be include four constituent parts which are:


Device for sample debut.

A nomadic stage.

A stationary stage.

A sensor.

These four constituents are used in different figure of chromatographic techniques. For illustration, the injector in gas chromatography used to present the sample is of great importance and have to be selected in visible radiation of the fortes of the analyte under probe ( their stableness and volatility ) and the quantum of the analyte nowadays, right pick will give a successful analysis. In LC the injector is used to let debut of the analyte into the liquid watercourse. The nomadic stage which are conjoint with the separation that occurs in a chromatographic system are the nomadic stage and stationary stage.

Mass spectroscopy

It is known as an instrument which can organize, dividing and detection, either atomic or molecular, based on their mass-to-charge ratio. A mass-to-charge ratio of an ion is frequently abridge as m/z. A mass spectroscopy can be contained four constituent parts which are:

A method of sample debut.

A method of ion production.

A method of ion separation.

Facilities for ion sensing and information use.

Tandem Mass spectroscopy:

It is a technique which can supply both the molecular weight of the analyte and the information refering the construction of the molecule. However, the ionisation technique is widely used for LC-MS, are designative ‘soft ionisation ‘ in that make chiefly molecular species with atomization.

Tandem mass spectroscopy ( MS-MS ) is a method which cover a figure of techniques in one phase of mass spectroscopy. It is non needfully that, the first phase is isolate an ion of involvement and a 2nd phase is used to examine the regard of this ion with others. The two stairss of mass spectroscopy are related in certain ways in order to supply the intended analytical information.

There are a considerable figure of different MS-MS experiments that can be carried out but there are four which most widely used and these are:

The merchandise ion scan.

The precursor-ion scan.

The constant-neutral-loss scan.

Selected decomposition monitoring.

-Instrument of MS-MS:

In this portion there is one Instrument which will be mentioned and that is the Ternary Quadrupole.

The Ternary Quadrupole:

This one is most widely used in MS-MS instrument. As it is named, it contains three of sets of quadrupole rods in series. The 2nd set of rods is non used as a mass separation device but as hit cell, while the atomization of ions transmitted by the first set of quadrupole rods is carried out and the 3rd set is used as a device for concentrating any produced ions. By commanding both sets of rods to let the passage of ions of a individual m/z ratio or a scope of m/z values to give the intendment analytical information.

Fig.1. Schematic of a ternary quadrupole mass spectrometer. ( Ardrey,2003 ) .

Technique of MS-MS:

In this portion besides merely one technique of MS-MS will be mentioned which is Selected Reaction Monitoring. In this technique, the atomization of a chosen precursor ion to a chosen merchandise ion is monitored. This is carried out by revising each of the stairss of mass spectroscopy to direct a individual ion ( i.e. the precursor ion by MS1 and the merchandise ion by MS3 ) .

-Desorption electrospray ionisation ( DESI ) and Direct analysis in existent clip ( DART ) techniques:

DESI and DART are atmospheric force per unit area desorption ionisation techniques, which they can merchandise ions of diverse chemical nature straight from solid surface for MS/MS analysis. These techniques are widely used and they give an ability to analyses samples by simple measure, which is positioning a surface near the trying recess of an APIequipped.


Fig.2. ( DART and DESI ) ( Elsevier,2008 )

A paradigm of API MS was evolved to used for analysis in nonlaboratory environments. The paradigm API MS used a compact vacuity system and smaller pump to suit into a 0.1m-3 box and weight & A ; lt ; 45 Kg. In this technique the instrument can capable of tandem MS analyses because of the CIT ( capillary isotachophoresis ) mass analyser and nowadayss result which similar to those generated utilizing benchtop API3D quadrupole ion trap instrument. DART and DESI are used for analysis molecules from over-thecounter drug and explosives.

The application:

Stanozolol ( 17_-hydroxy-17_-methyl-5_-androst-2-eno ( 3,2- degree Celsius ) -pyrazole ( Fig. 3, compound 1 ) is one of the doping, which is an amphetamine stimulation a batch. The abuse of stanozolol is usually showed by the mark exposing of the metabolite 3-hydroxy-stanozolol ( Fig. 3, metabolite 4 ) . The exposing of this compound can be done by Gas Chromatography-Mass Spectrometry ( GS-MS ) or by Liquid Chromatography-Tandem Mass Spectrometry ( LC-MS/MS ) . Stanozolol metabolisms to 19 metabolites and all of them can be detected by utilizing LC-MS/MS, but in this work merely four metabolites will be mentioned.

In this application of LC-MS/MS the merchandise of ion has been chosen to be at three place which are m/z 81,97 and 145. The merchandise ion at m/z 81 is selected as a particular for stanozolol metabolites without a alteration in A- or N-rings. Whereas, the merchandise ion at m/z 97, 145 for metabolites hudroxylated in N-ring and 4-hydroxy-stanozolol metabolites severally. With these status the parent drug and up to 15 metabolites are found in positive doping trial sample.

Fig.3. Proposed metabolic tract for stanozolol. ( Steroids, 2009 ) .

Sample readying:

Screening analysis:

Analysis of unconjugated constituent was done by altering the PH of the piss ( 5 milliliter ) to 9.2 by increase of about 0.3 g Na H carbonate: K carbonate ( 2:1, tungsten: tungsten ) . so, liquid- liquid extraction ( LLE ) was accomplished by adding 5 ml diethyl quintessence and commixture that about 20 min. After that, the sample was centrifuged and when the organic bed was appeared it separated and evaporated under O free N ( OFN ) at 40c0.

In regard of conjugated and unconjugated constituent, there was 1 milliliter of phosphate buffer ( PH7 ) added and 50 milliliter of the & A ; Icirc ; ?-glucuronidase solution was added to 5 milliliters urine. Then the sample was hydrolysed about 2.5 H at 56c0. Following, the sample was cooled to room temperature, extraction was accomplished as described for the uncojugated constituent.

Sing to LC-MS/MS analysis, the remnant was dissolved into 20 milliliter of methyl alcohol: H2O ( 50:50, V: V ) , so 20 milliliter of solution were straight injected into the system.

Precursor ion analysis ( QqQ ) :

Choosing the doing ion at m/z 81,97 and 145 was applied utilizing the ternary quadrupole instrument ( QqQ ) in precursor ion scan method. The hit energy for m/z 81 and 91 was 45 electron volt and for m/z 145 was 30 electron volt. The breadth of extremum was puting at 0.7 Da and the scan rate at 0.4 s/scan. Column, nomadic stage composing ( LC-MS/MS surveies ) were used.

selected-reaction monitoring ( SRM ) analysis:

A SRM mode utilizing the ternary quadruplicate instrument was promoted for LC-LC/MS sensing of stanozolol for each metabolite. The acquisition clip was set at 50 MS for each gesture.


Precursor ion scan and natural loss method were utile tools for sensing of steroid metabolites. Because of the lower sum of interventions the more specific the attack the higher figure of metabolites identified. Wherefore, specific ions were chosen for sensing of stanzolol metabolite. The ion at m/z 81 has been noted for stanzolol derived functions without any alteration in the N-ring, the ion at m/z 97 was reported for stanzolol derived functions with a hydroxyl group in the N-ring, while the ion at m/z 145 was noted to 4-hydrolysed-stanzolol derived functions. When human piss was applied no metabolites were found in non-hydrolysed piss, compatible with period reported consequences, which articulate that, less than 5 % of stanzolol metabolites are found in the uncojugated constituent. Whereas, after hydrolysis 15 metabolites were detected. By utilizing precursor ion scan of m/z 81 jointing an unchanged N-ring six compounds were detected. Five metabolites were detected utilizing the precursor ion of m/z 97 and four appeared utilizing the precursor ion scan of m/z 145. Some of these compounds were identify by utilizing the analysis of available criterions. As a consequence, compound 1 was assigned to stanozolol, metabolite 2 to 16 & A ; Icirc ; ?-hydroxy-stanozolol, metabolite 3 to 4 & A ; Icirc ; ?-hydroxy-stanozolol and metabolite 4 to 3-hydroxy-stanozolol.

Fig. 4. Precursor ion chromatogram at m/z 81 ( top ) , m/z 97 ( medium ) and m/z 145 ( below ) for ( a ) human urine declared negative and ( B ) human piss declared positive for stanozolol. Numbers within brackets refer to metabolites in Fig. 3. ( Steroids, 2009 ) .


LC-MS/MS QqQ in precursor ion scan is really utile method and allowed to observe 19 metabolites of stanozolol. As a consequence, LC-MS/MS can be used to expounding of drugs by utilizing sample of urine and make up one’s mind if that drug is good or non. In add-on, helps to look the failing of that drug and helps drug companies to supply and merchandise efficient drug.

Post Author: admin