TABLE 2.

Conditions of assay of β-lactams by HPLC

Drug	Elution buffer (vol/vol)a	Reference	λ detector (nm)b	Range of linearity in μg (r2)	Intraday Covc (%)
Aztreonam	TBAHSO4, 5 mM, pH 4.2; acetonitrile (80:20)	27	254	1-400 (0.999)	0.5
Piperacillin	NH4 acetate, 70 mM, pH 5; acetonitrile (78:22)	2	220	1-100 (0.999d)	3d
Azlocillin	Na acetate, 20 mM, pH 5; acetonitrile (80:20)	19	220	1-10 (0.999)	1.4
Mezlocillin	Na acetate, 20 mM, pH 5; acetonitrile (76:24)	19	220	1-10 (0.999)	3.2
Ceftazidime	Na acetate, 10 mM, pH 4; acetonitrile (89:11)	13	258	0-400 (0.999)	0.3
Cefepime	Na acetate, 20 mM, pH 5; acetonitrile (95:5)	-e	258	50-200 (0.999)	0.6
Cefpirome	Na acetate, 20 mM, pH 5; acetonitrile (86:14)	-e	258	1-50 (0.998)	1.7
Imipenem	Gradient (12 min): Na borate, 200 mM, pH 7.2; acetonitrile (95:5 to 85:15)	15	220	1-10 (0.998)	1.9
Meropenem	NH4 acetate, 10.53 mM, pH 4; acetonitrile (90:10)	9	297	10-100 (0.993)	2.7
Faropenem	NH4 acetate, 10.53 mM, pH 4; acetonitrile (86:14)	-f	308	1-25 (0.999)	0.4

^aTBAHSO₄, tetrabutylammonium hydrogen sulfate.

^bλ of maximum absorbance, as shown by the instrument readings (diode-array photometer).

^cCOV, coefficient of variation.

^dSimilar values for piperacillin plus tazobactam (tazobactam was not eluted within the time frame of the piperacillin chromatographic run).

^eConditions were adapted from those of ceftazidime.

^fConditions were adapted from those of meropenem.