Dear Gopi. Concerning your issue about the analysis of synthetic textiles dyes' metabolites using agilent LCMS LCQQQ 6460C. LCMS method is developed to separate, identify, and quantify a mixture of twenty two aromatic amines. A literature method for chemical reduction of the textiles samples was applied. A standard addition method was used for quantification wherein a standard mixture of the twenty two restricted aromatic amines were spiked into the sample at various increasing concentrations prior to reduction. This standard addition method for quantification accounts for recovery losses of the analyte during the reduction of textile samples. For more details,  I think the following below links may help you in your analysis:

http://www.chem-agilent.com/pdf/MP20_470.pdf

http://www.agilent.com/cs/library/applications/5991-5169EN.pdf

https://run.unl.pt/bitstream/10362/5656/1/Souto_2010.pdf

Thanks