Kit and method for quantitative detection of steroids

1. A method for the quantitative detection of oxosteroids and hydroxy steroids in a sample, the method comprising:

i. reacting a first portion of the sample with a first member of a pair of quantitative charge tags of formula (I) or formula (II);

wherein R is hydrogen, C 1-4 alkyl or aryl, OR 1 or NR 1 R 2 ,

each R 1 and R 2 is C 1-3 alkyl or R 1 and R 2 together with the nitrogen atom to which they are attached form a 5- or 6-membered heteroalkyl ring;

each R 3 is independently C 1-3 alkyl; and

X is a halide ion;

ii. reacting a second portion of the sample with an agent capable of oxidising an OH group to a carbonyl group;

iii. reacting the product of step (ii) with a second member of a pair of quantitative charge tags of formula (I) or formula (II);

iv. combining the products of steps (i) and (iii);

v. conducting mass spectrometry on the combined product of step (iv) and determining the quantities therein of compounds labelled with the first and second members of the pair of quantitative charge tags, thereby providing quantitative detection of both oxosteroids and hydroxy steroids in a single analysis.

2. The method as claimed in claim 1 , wherein the first and second portions of the sample are of equal volume.

3. The method as claimed in claim 1 wherein the quantitative charge tags are differential mass tags and the mass spectrometry of step (v) is liquid chromatography-mass spectrometry (LC-MS) or HPLC-MS.

4. The method as claimed in claim 1 wherein the quantitative charge tags are isobaric mass tags and the mass spectrometry of step (v) is an MS/MS method.

5. The method as claimed in claim 1 wherein the sample is prepared from a body fluid, for example whole blood, plasma, serum, cerebrospinal fluid, sputum, tears, sweat or urine; or from a specimen of tissue, hair, nails by extraction of the steroids into a solvent.

6. A method for the quantitative detection of oxosteroids and hydroxy steroids in a sample, the method comprising:

i. reacting the sample with a first member of a pair of quantitative charge tags of formula (I) or formula (II)

wherein R is hydrogen, C 1-4 alkyl or aryl, OR 1 or NR 1 OR 2 ;

each R 1 and R 2 is C 1-3 alkyl or R 1 and R 2 together with the nitrogen atom to which they are attached form a 5- or 6-membered heteroalkyl ring;

each R 3 is independently C 1-3 alkyl;

and X is a halide ion;

ii. reacting a reference composition with a second member of a pair of quantitative charge tags of formula (I) or formula (II);

iii. combining the products of steps (i) and (ii);

iv. conducting mass spectrometry on the combined product of step (iii) and determining the quantities therein of compounds labelled with the first and second members of the pair of quantitative charge tags, thereby providing quantitative detection of both oxosteroids and hydroxy steroids in a single analysis.

7. The method according to claim 6 wherein both the sample and the reference composition are reacted with an agent capable of oxidising an OH group to a carbonyl group before reaction with the quantitative charge tags.

8. The method as claimed in claim 6 , wherein the sample and the reference composition are of equal volume.

9. The method as claimed in claim 6 wherein the quantitative charge tags are differential mass tags and the mass spectrometry of step (vi) is liquid chromatography-mass spectrometry (LC-MS) or HPLC-MS.

10. The method as claimed in claim 6 wherein the quantitative charge tags are isobaric mass tags and the mass spectrometry of step (vi) is an MS/MS method.

11. The method as claimed in claim 6 wherein the method is repeated for a further sample using the same or a different reference composition.

12. A method for the quantitative determination of oxosteroids and hydroxy steroids in a sample comprising:

i. reacting a first portion of the sample with a first member of a first pair of quantitative charge tags of formula (I) or formula (II);

wherein R is hydrogen, C 1-4 alkyl or aryl, OR 1 or NR 1 R 2 ;

each R 1 and R 2 is C 1-3 alkyl or R 1 and R 2 together with the nitrogen atom to which they are attached form a 5- or 6-membered heteroalkyl ring;

each R 3 is independently C 1-3 alkyl; and

X is a halide ion;

ia. reacting a first portion of a reference composition with a first member of a second pair of quantitative charge tags of formula (I) or formula (II);

ii. reacting a second portion of the sample with an agent capable of oxidising an OH group to a carbonyl group;

iia. reacting a second portion of a reference composition with an agent capable of oxidising an OH group to a carbonyl group;

iii. reacting the product of step (ii) with a second member of a first pair of quantitative charge tags of formula (I) or formula (II);

iiia. reacting the product of step (iia) with a second member of a second pair of quantitative charge tags of formula (I) or formula (II);

iv. combining the products of steps (i) and (iii);

v. conducting mass spectrometry on the combined product of step (iv) and determining the quantities therein of compounds labelled with the first and second members of the pair of quantitative charge tags, thereby providing quantitative detection of both oxosteroids and hydroxy steroids.

13. The method as claimed in claim 12 wherein the portions of sample and reference composition are of equal volume.

14. The method as claimed in claim 12 wherein the first pair of quantitative charge tags are differential mass tags and the second pair of quantitative charge tags are isobaric mass tags.

15. The method as claimed in claim 12 wherein the first pair of quantitative charge tags are isobaric mass tags and the second pair of quantitative charge tags are differential mass tags.

16. The method as claimed in claim 12 further comprising repeating steps (i) to (iii) with a further sample and a further pair of quantitative mass tags and combining the labelled further sample portions with the product of step (iv) before carrying out mass spectrometry.