High Concentration of Ciprofloxacin in Urine Invalidates EMIT Results

Published: Journal of Analytical Toxicology, Volume 20, Number 5, September 1996, pp. 334.

Letter to the Editor:

High Concentration of Ciprofloxacin in Urine Invalidates EMIT Results
C. Lora-Tamayo, T. Tena, and A. Rodriguez

To the Editor:
During the development of a routine EMIT urine drug-screening procedure in a forensic case of a drug-related death, a sample with an excessively high absorbance value was found. This fact made it impossible to obtain valid results. The urine pH was adjusted to 7.5, and the initial absorbance value with the opiate reagent in the Syva (Palo Alto, CA) system was 4440. No results, either positive or negative, could be obtained.

We proceeded to extract the urine (2.5 mL + 7.5 mL borate buffer [pH 9] + dichloromethane–isopropanol [85:15] in Bond Elut) and to analyze the extract by gas chromatography and gas chromatography–mass spectrometry. We identified morphine (2.15 µg/mL ), 6-monoacetylmorphine (0.13 µg/mL ), and codeine (0.68 µg/mL) in the extract. An acidic extract of the urine was analyzed by high-performance liquid chromatography and was found to contain ciprofloxacin (2200 µg/mL).

We prepared urines spiked with different concentrations of ciprofloxacin and tested them on the Syva ETS system. We found that ciprofloxacin was responsible for the absorbance problems when at high concentrations. Table I shows the different concentrations of ciprofloxacin assayed and its absorbance values.

Ciprofloxacin is an antibacterial drug that is very effective in the treatment of Streptococcus pneumoniae, Staphylococcus aureus, Staphylococcus pyrogenes, and many other gram-positive and gram-negative bacteria. It is also frequently used in the treatment of infections associated with the intravenous abuse of heroin.

C. Lora-Tamayo, T. Tena, and A. Rodriguez
Instituto Nacional de Toxicología
Ministerio de Justicia e Interior
Luis Cabrera 9
28002 Madrid, Spain

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