Multiple techniques and instruments can be used for the detection of chemical substances/drugs e.g., Spectrophotometer, HPLC, GC-MS etc. The methods for the detection of all antibiotics/drugs are written in Pharmacopoeias (Books) like British Pharmacopoeia, United States Pharmacopoeia.

HPLC is my priority choice.

LC- MS/MS

i do not have access to LC-MS/MS. for HPLC i think i need to have a standard but in this case i have no idea if and what type of antibiotics is present  in the wastewater, so i dont know which statndard to use. can i use GC-MS and what is the best way to prepare/extract the sample for GC-MS

Check out these publications links  from DC Water and World Health Organization (WHO) which can give you a start on what to anticipate and test methods, the first link and last one has a table listing potential pharmaceuticals and tests:

https://www.dcwater.com/waterquality/PharmaceuticalsNACWA.pdf

http://www.who.int/water_sanitation_health/emerging/info_sheet_pharmaceuticals/en/

http://www.who.int/water_sanitation_health/publications/2012/pharmaceuticals/en/

http://apps.who.int/iris/bitstream/10665/44630/1/9789241502085_eng.pdf?ua=1

http://apps.who.int/iris/bitstream/10665/44630/1/9789241502085_eng.pdf?ua=1

Also check out the USEPA website.

thank you

Dear Victoria,

It is advisable you focus on specific antibiotic(s), because every research has scope and limitations (funny enough even PhD!). Meanwhile there are methods available for your  research as Dr. Thampi has generously offered links for you.