... metamizole (formylaminoantipyridine and aminoantipyridine), and two micobiological metabolites (1,5-dimethyl-1 , 2- dehydro-3-pyrazolone, 4-( 2- methylethyl )-1 ,5dimethyl-1 , 2- dehydro-3-pyrazole) were studied ... techniques, being to 10 ng/L in drinking water and surface water and 50 ng/L in wastewater.48 The authors recommended the use of LC-(+)ESI-MS/MS for the analysis of these polar molecules in the environment, ... GC-MS and down to ng/L using GC-IT-MS/MS Other authors also used GC-IT-MS/MS for the determination of eight acidic pharmaceuticals in water by SPE on RP-C18 In- port methylation in the GC using...