Figure 3: Representative MRM chromatograms of (a) blank plasma, (b) plasma sample spiked with flucloxacillin and cefazolin at 0.2 mg/L, (c) plasma sample spiked with flucloxacillin and cefazolin at 12.5 mg/L, (d) plasma sample from a patient after intravenous administration of cefazolin (cefazolin concentration = 6.5 mg/L) and (e) plasma sample from a patient after intravenous administration of flucloxacillin (flucloxacillin concentration = 17.4 mg/L). In all cases, except blank plasma, the internal standard butobarbitone concentration was 0.2 mg/mL.