Abstract: Antibiotic β-lactams with a C6 side-chain [e.g., penicillin X(I) and benzylpenicillin(II)] were pre-derivatized with imidazole and a salt of Ni(II), Zn(II), Ag+, Cd(II), Au+ or Hg(II) (HgCl2 best) before analysis by HPLC on a column (20 cm x 4.6 mm) of Spherisorb C18 (5 µm) with aqueous 0.01 M NaH2PO4 buffer (pH 6.5) - acetonitrile (4:1), 0.01 M in complexing agent (EDTA, NaCN or Na2S2O3), as mobile phase (1.5 mL min-1) and detection at 325 nm. Although NaCN was the best complexing agent, the less toxic ones were preferred. With use of EDTA and HgCl2 calibration graphs based on peak area were rectilinear for up to 50 µg mL-1 of I and II; for determination of 25 µg mL-1 of I, the coefficient of variation was 2% (n = 10). With Na2S2O3, the detection limits were 0.5 µg mL-1 for I and II. β-Lactams with a primary amino-group, e.g., 6-aminopenicillanic acid(III) and cephamycin C(IV), were separated on a column (20 cm x 4.6 mm) of Spherisorb C8 with acetonitrile - 0.01 M phosphate buffer of pH 5.5 containing 0.01 M butylammonium hydroxide and 0.2% of acetic acid (1:19) as mobile phase (1.5 mL min-1), post-column derivatization with phthalaldehyde and 2-mercaptoethanol and fluorimetric detection at 450 nm (excitation at 350 nm). Hydrolysis on a column of Amberlite IRA-120 before derivatization improved sensitivity for, e.g., III. Calibration graphs for (IV) and adicillin (V) were rectilinear in the range 0 to 100 µg mL-1. In analysis of a sample containing 100 µg mL-1 of (IV) the coefficient of variation was 2% (n = 20). The detection limits for (IV) and V were 0.5 to 1.0 µg mL-1 and for ampicillin, cephalexin and cephradine were 26, 14 and 8 µg mL-1, respectively.

Abstract: Immobilized enzymes have found widespread application in analytical chemistry within the past years. The use of immobilized enzyme reactors in flow-injection analysis (FIA) has several advantages compared with the conventional FIA technique, where usually a chemical reaction is performed by mixing reagents and substrate in a reaction coil and the reaction product is measured by a detector. The modular construction and the use of a versatile microcomputer interface for total flow-injection control considerably extend the applicability of the immobilized enzyme reactor-flow injection analysis (IMER-FIA) system beyond merely β-lactam analysis. Minor modifications of the instrumental setup and of the controlling microcomputer programs permit automated determinations of a wide spectrum of other different compounds, such as sugars, peptides, proteins, esters, carboxylic acids, and urea, for which selective and sensitive enzymes are available. These determinations can be performed either in direct or in subtractive mode according to the detection system employed.

Abstract: A broad range of compounds containing the β-lactam ring were screened for enhancement of luminol chemiluminescence. A selection of these compounds were found to enhance the chemiluminescence of luminol. A high performance liquid chromatographic method for the analysis of some β-lactams employing post-column chemiluminescence was developed via flow injection analysis studies.