[Bacterial contamination of infant urine samples obtained from filter papers used in neuroblastoma-screening tests. (6) Protective effects of preaddition of chlorhexidine digluconate in filter papers or containers for urine on bacterial break-down of creatinine, vanillylmandelic acid and homovanillic acid].

The effects of chlorhexidine digluconate preadded to urine samples for a neuroblastoma-screening test in preventing the break-down of creatinine (Cre), vanillylmandelic acid (VMA), and homovanillic acid (HVA) by creatinine-cleaving bacteria and the influence of the added disinfectant on the HPLC determination of urinary Cre, VMA, vanillillactic acid (VLA) and HVA. Laboratory or field experiments showed that preadded disinfectant (0.02% volume) nearly completely inhibited the growth of the bacteria and satisfactorily protected urinary Cre, VMA, and HVA from bacterial decomposition. Chlorhexidine digluconate was comparable to benzalkonium chloride in its inhibitory effects on the growth and activities of creatinine-cleaving bacteria. Unlike benzalkonium chloride, chlorhexidine digluconate added to urine samples gave no troubles in subsequent analytical processes. Addition of the disinfectant (0.02% volume) to standard Cre, VMA, VLA, and HVA solution did not affect retention times and sensitivities in HPLC analyses. To estimate influences of the added disinfectant on the serial HPLC determinations of VMA, VLA, and HVA on a large number of urine samples (40, 80, 120, 160, 200, or 5, 500), HPLC analyses were performed on standard VMA, VLA, and HVA solution with repeated injection of the disinfectant in great amounts into a column. The results showed no appreciable changes in the retention times and sensitivities of VMA, VLA, and HVA, and almost complete elution of the disinfectant retained on the column were possible with water-methanol (1:1, 2:8) or methanol washing.(ABSTRACT TRUNCATED AT 250 WORDS)