Keywords: 
• gel microcolumn assay /
• IgM and IgG /
• ceftazidime /
• drug-coated red blood cells

Abstract: Objective To observe the effect on gel microcolumn assay of ceftazidime IgM and/or IgG in human serum with red cells packed by drug under different pH. Methods Drug-coated red blood cells were prepared by incubating 10 volumes of ceftazidime in the barbital buffer solution(pH=7.0,8.0,9.6) for 2 hour at room temperature.600 human serum samples were prepared for the drug-coated red cells test which the incubation pH was 9.6,and 10 samples were selected according to the Results .Among 10 samples three were positive,four were negative,the others were week positive All were tested by the drug-coated red cells which the incubation pH was 7.0 or 8.0. Results In the three week positive samples,one of them becomes negative when the incubation was pH8.0;all of them become negative when the incubation was pH7.0.The other seven were no different between the incubation pH was 9.6 or 8.0 or 7.0. Conclusion The Results of gel microcolumn assay of ceftazidime IgM and /or IgG in Human Serum may be false negative when the incubation pH is lower than 9.6.