A color test for the convenient identification of an ingested surface activating agent

Overview

Color tests are easy, simple and inexpensive methods for the qualitative identification of chemicals. A color test was applied to the stomach contents of a forensic autopsy case. The result of the test, using bromophenol blue reagent, indicated the ingestion of a commercial cleaning product containing a cationic surface activating agent. Our findings suggest that forensic investigators should consider the additives used in commercial chemical products, such as surface activating agents, when determining the cause of death.

Keywords:
color test – surface activating agent – screening – stomach contents

Screening tests for identifying the chemicals ingested in suspected suicide, accident or homicide cases provide important results for forensic diagnosis (1). Color tests are often the first tool used for the qualitative identification of the causative chemical (2). Here we report the application of a color test for the toxicological screening of an ingested household cleaning chemical.

CASE REPORT

A Japanese woman in her eighties (height: 150cm, weight: 66kg) was found dead on a mountain at the end of December. Subsequent investigation by the authorities revealed that the deceased had been missing for 5 days. A half-empty bottle of toilet-bowl cleaner Sanpoll^®, which contains 9.5% hydrochloric acid (HCl) and cationic surface activating agent (3)), was found nearby.

A medico-legal autopsy was performed. External examination revealed abrasions and contusions on her head and upper and lower extremities, but they were not considered to be the cause of death. Internal examination showed that the stomach wall and surrounding tissues were discolored and dark brown, and that the stomach wall was thinned but without perforations (Figure 1). The stomach contained approximately 140 ml of a dark brown fluid; this fluid had no unusual odor, and a pH of approximately 3 as measured using pH test paper. A drug screening test using a Triage^TM panel (Biosite Diagnostic Inc., San Diego, CA, USA) provided negative results. No ethanol was detected in the blood or urine.

The autopsy findings and the results of subsequent investigation by the authorities suggested that the victim had ingested Sanpol^® cleaner.

MATERIALS AND METHODS

A color test for cationic surface activating agent and a spectrophotometric analysis were performed as described previously (4). In brief, the stomach contents were centrifuged (3000 rpm, 5 min), then the supernatant was analyzed. Bromophenol blue reagent (2 ml, 0.002% bromophenol blue in acetate buffer solution, pH 3.6) was added to 1 ml of sample and mixed gently. A dark green color provides a visual positive result, which indicates the existence of cationic surface activating agent in the sample by the reaction with bromophenol blue. Spectrophotometric analysis was performed using a Shimadzu UV-1700 (Kyoto, Japan).

RESULTS AND DISCUSSION

Color tests provide an easy and convenient way for identifying chemical agents (2). They are simple to perform, require no extensive training, and give an immediate visual result (2) that may help identify the chemicals involved in forensic cases.

Figure 2 shows the results of the color test used in the present case. The right column is the sample (stomach contents), the middle column is the positive control (Sanpoll^®), and the left column is the control (distilled water). A positive result was observed for the stomach contents. Figure 3 shows the absorption spectrum of each sample. Both the stomach contents (red line) and Sanpoll^® (blue line; positive control) show a peak at 605 nm. The color test using bromophenol blue reagent indicates the presence of a cationic surface activating agent in the stomach contents; this observation is supported by the results of spectrophotometric analysis. Since the concentration of chemicals in the stomach may be quite high in cases of chemical ingestion or drug overdose (5), the stomach contents are useful for preliminary screening (1,6,7).

The identification of ingested chemicals during forensic investigations is generally focused on identifying the main component of the causative agent, with little attention paid to identifying additives(8). Here we focused on the cationic surface activating agent (alkyl trimethylammonium salt), which is used as an additive in Sanpoll^® (3). As HCl, the main component of Sanpoll^®, is present in the stomach gastric juices, it is impossible to distinguish its various origins using chemical methods. In contrast, identification of the cationic surface activating agent in the stomach contents may be a good indicator of Sanpoll^® ingestion. From the autopsy findings, the investigation by the authorities, and the results of the color reaction test and spectroscopic analyses, we concluded that the victim ingested the toilet cleaner, Sanpoll^®.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest regarding the publication of this paper.

Correspondence address:

Dr. H. Kinoshita,

Department of Forensic Medicine

Faculty of Medicine, Kagawa University

1750-1, Miki, Kita, Kagawa 761-0793, Japan

tel.: +81-87-891-2140

fax: +81-87-891-2141

e-mail: kinochin@med.kagawa-u.ac.jp