Current Spike Test

Inhibition enhancement validation testing is performed on each raw material and finished product as part of the validation for bacterial endotoxin analysis in accordance with the current USP and the FDA Guidelines. Limits are determined from USP monographs or the FDA Guidelines and are used in calculating the maximum valid dilution (MVD). Serial dilutions are performed of spiked and unspiked product in order to determine the dilution required to overcome inhibition or enhancement (DROIE). If the DROIE does not exceed the MVD, the test is determined to be valid. Confirmation of the DROIE is performed on three finished product or raw material lots in order to complete the product validation. Products are tested at a dilution greater than the DROIE but less than the MVD. 

Fig. 29.17 TIC and SIR recordings collected from blank and spiked milk samples with 2 ppb of the various tested corticosteroids. From top to bottom total ionic current m/z 313, tp 17 97/18 13 min for dexamethasone (IS) m/z 310, tp 17 99/18 14 min for dexamethasone m/z 328, tp 17 86/18 01 min for flumethasone m/z 298, tp 18 34 min for prednisolone m/z 312, tp 18 73 min for methylprednisolone m/z 296, tp 17 97 min for isoflupredone. (Reprinted from Ref. 527, with permission from Elsevier Science.)...

The current penalty system is strict, clear, and straightforward however, it does not allow for minor errors. In fact, minor errors are treated equally to a false negative result, as demonstrated with the following example Laboratory 1 failed to identify one of the spiking chemicals in a test. Laboratory 2 found all spiking chemicals however, it made a minor reporting error in the identification of one of them the evidence provided was adequate to indicate the presence of the particular chemical, however, did not fulfill all the reporting requirements. 

A study on the feasibility of the enhanced EK-Fenton process for the remediation of hexachlorobenzene (HCB) in a low-permeability soil was conducted by Oonnittan, Shrestha, and Sillanpaa (2008). In that work, kaolin was spiked with HCB and treated by the EK and EK-Fenton processes. )3-cyclodextrin was used to enhance the solubility of HCB in pore fluid. Two EK experiments were conducted to observe the suitability of j8-cyclodextrin as a flushing solution for these processes. Another test conducted was the EK-Fenton test using )3-cyclodextrin as an enhancing agent. Results showed that the type of flushing solution, system pH, electric current, and EO flow are of significance for HCB removal. 

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