Color ruler to confirm spectrophotometer results for nitro compound content in acidic wastewater from TNT processes

This study aimed to find an additional analytical reference procedure to verify the accuracy of single beam Spectrophotometer results that used to determine the concentration of nitro compound pollutants such as TNT, DNT, and MNT (Tri Nitro Toluene, Di Nitro toluene, and Mono Nitro Toluene respectively) in treated acidic wastewater generated from TNT manufacturing. This procedure was tested and confirmed to be a reference for a single-beam spectrophotometer. In this study 10 samples with known concentrations were taken and prepared for colorimetric analysis, the concentrations gradient from 10mg/L up to 60mg/L to make a ruler with gradient color, this ruler was suitable for high concentration samples but to specify the low concentration samples the procedure depended on adding a known concentration to the unknown concentration sample then this added concentration transferred the samples from unspecified color to specified color on the ruler consisted by known concentration mentioned above, the concentration of unknown concentration samples were specified by taking the concentration corresponding to the ruler color a subtracting the value of added concentration and the value of the remains was sample concentration. This study proved the reliability of this procedure to confirm single-beam spectrophotometer results, determining low concentration value of unknown concentration sample of TNT acidic wastewater, and then it can be used as a substituent of spectrophotometer in the event of malfunctions.

Hawk-Seq™ differentiates between various mutations in Salmonella typhimurium TA100 strain caused by exposure to Ames test-positive mutagens

A precise understanding of differences in genomic mutations according to the mutagenic mechanisms detected in mutagenicity data is required to evaluate the carcinogenicity of environmental mutagens. Recently, we developed a highly accurate genome sequencing method, ‘Hawk-Seq™’, that enables the detection of mutagen-induced genome-wide mutations. However, its applicability to detect various mutagens and identify differences in mutational profiles is not well understood. Thus, we evaluated DNA samples from Salmonella typhimurium TA100 exposed to 11 mutagens including alkylating agents, aldehydes, an aromatic nitro compound, epoxides, aromatic amines, and polycyclic aromatic hydrocarbons (PAHs). We extensively analysed mutagen-induced mutational profiles and their association with the mechanisms of mutagens. Hawk-Seq™ sensitively detected mutations induced by all 11 mutagens, including one that increased the number of revertants by approximately two-fold in the Ames test. Although the sensitivity for less water-soluble mutagens was relatively low, we increased the sensitivity to obtain high-resolution spectra by modifying the exposure protocol. Moreover, two epoxides indicated similar 6-dimensional or 96-dimensional mutational patterns; likewise, three SN1 type alkylating agents indicated similar mutational patterns, suggesting that the mutational patterns are compound category-specific. Meanwhile, an SN2 type alkylating agent exhibited unique mutational patterns compared to those of the SN1 type alkylating agents. Although the mutational patterns induced by aldehydes, the aromatic nitro compound, aromatic amines, and PAHs did not differ substantially from each other, the maximum total base substitution frequencies (MTSFs) were similar among mutagens in the same structural groups. Furthermore, the MTSF was found to be associated with the carcinogenic potency of some direct-acting mutagens. These results indicate that our method can generate high-resolution mutational profiles to identify characteristic features of each mutagen. The detailed mutational data obtained by Hawk-Seq™ can provide useful information regarding mutagenic mechanisms and help identify its association with the carcinogenicity of mutagens without requiring carcinogenicity data.

Detection of Non-nitro Compounds by Amplified Fluorescence Polymer (AFP): An Opportunity for Breath-Based Disease Diagnosis

Amplified fluorescence polymers (AFP) are a set of unique polymers known for their ability to detect trace nitro explosives. The prior knowledge in the AFP field indicates that the functional group variation on the polymer backbone is responsible for the selectivity of an analyte. The mechanism of analyte detection is believed that only compounds with nitro functional groups are detected by AFP. Usually, AFP functional groups varied to detect nitro compounds and the non-nitro compound detection and the mechanism of the AFP were not completely understood. In this work, the AFP polymer was kept constant and studied with 136 analytes with different functional groups for analyzing few non-nitro compounds. Among the 136 compounds analyzed, about fourteen have been detected by AFP. It was observed that most of the fourteen compounds were non-nitro compounds. The mechanism proposed originally for nitro compounds and associated hypothesises the existence of a parking space on the polymer backbone. Present study suggested that the possibility of only nitro compounds interacting with AFP due to the three-dimensional shape of the analyte as the detrimental factor. The discovery of non-nitro compound detection by AFP opens up the use of AFP for gas-phase disease volatile organic compound detection. Future studies of functional group variation on the AFP backbone in relation to the analyte detection could provide insights into the relation of analyte detection by AFP and the parameters to optimize for obtaining the selectivity and specificity.

Prototype of Nitro Compound Vapor and Trace Detector Based on a Capacitive MIS Sensor

A prototype of a nitro compound vapor and trace detector, which uses the pyrolysis method and a capacitive gas sensor based on the metal–insulator–semiconductor (MIS) structure type Pd–SiO2–Si, was developed and manufactured. It was experimentally established that the detection limit of trinitrotoluene trace for the detector prototype is 1 × 10−9 g, which corresponds to concentration from 10−11 g/cm3 to 10−12 g/cm3. The prototype had a response time of no more than 30 s. The possibility of further improving the characteristics of the prototype detector by reducing the overall dimensions and increasing the sensitivity of the MIS sensors is shown.