Search

Selective catalytic reduction (SCR) utilizing urea hydrolysis to generate ammonia (NH 3) is the most efficient technology to reduce the emission of nitrogen oxides (NO x). NH 3 detection is crucial in the closed-loop feedback system for the precise urea injection. In this work, a high-temperature NH 3 sensor using a BaZr 0.8 Y 0.2 O 3-δ (BZY) proton conductor as the electrolyte and a BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) H+/e–/O2– triple conductor as the sensing electrode (SE) is reported. The effect of the micromorphology of the BCFZY SE on the sensing performance is investigated by varying the sintering temperature of SE. The sensor shows high sensitivity to NH 3 with response currents of 0.39, 1.31, 3.03, and 1.81 μA/ppm at 350, 400, 450, and 500 °C, respectively. Furthermore, the sensor shows excellent selectivity and repeatability. This work demonstrates that the BCFZY-based sensor has great potential for the high-temperature NH 3 detection. • BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ triple conductor was used as the sensing electrode for ammonia detection. • A novel ammonia sensor was proposed based on the BZY proton electrolyte. • The influence of the morphology of BCFZY on the sensing performance was investigated. [ABSTRACT FROM AUTHOR]

Yttrium-doped BaZrO 3 (BZY) shows great potential as a new solid electrolyte for high-temperature NH 3 sensing applications. However, it is difficult to obtain a dense BZY electrolyte due to the refractory nature of this material. For this paper, an amperometric NH 3 sensor based on a BaZr 0.8 Y 0.2 O 3-δ (BZY20) electrolyte was proposed, and volatile B 2 O 3 was added to improve the density of BZY, which was essential to enhance the sensitivity and stability of the sensor. The effects of B 2 O 3 on the density, morphology, and conductivity of the electrolyte were investigated. Furthermore, the influence of the density of BZY20 on the sensitivity and stability of the sensor was analyzed. It was found that the sensitivity and stability were significantly improved by the enhancement of the conductivity. In addition, the sensor could reach a detection limit as low as 2.5 ppm for NH 3 at 450 ℃ and showed good selectivity, repeatability, and long-term stability. [Display omitted] • An NH 3 sensor was studied based on a dense BaZr 0.8 Y 0.2 O 3-δ electrolyte using volatile B 2 O 3 as a sintering additive. • The stability and sensing performance of the sensor improved with an increase in the density of BZY20. • The sensing mechanism and stability of the dense BZY20-based NH 3 sensor was analyzed by EIS. [ABSTRACT FROM AUTHOR]

Poisoning with diquat (DQ) and paraquat (PQ) herbicides has been a public health problem. Unfortunately, rapid detection in biofluids remains challenging. Herein, a hyphenated approach of electro-enhanced adsorption, solid-phase microextraction, and surface-enhanced Raman spectroscopy (EE−SPME−SERS) was exploited for rapid and sensitive in situ analysis of DQ and PQ in human urine and plasma. A porous Ag fiber with an Au layer (p-Ag/Au fiber) was fabricated with multi-functions (SERS substrate, SPME sorbent, and working electrode). Clear trends could be observed between signal intensity and concentration of DQ or PQ with high reproducibility. The method detection limits (MDLs) calculated from the characteristic peak of DQ were 0.064 ppb and 0.65 ppb in urine and plasma, respectively. Corresponding MDLs for DQ and PQ in urine and plasma were 0.036 ppb and 0.35 ppb, respectively. The whole process of "extracting and detecting" was completed within 4 min with satisfactory recoveries. Notably, the EE−SPME−SERS technique could easily realize in situ analysis of DQ and PQ in biofluids with good selectivity, which is practical in clinical diagnosis. This EE−SPME−SERS method provides a potential avenue for efficient pretreatment and in situ poison detection in biological samples. [Display omitted] • Ultrafast EE-SPME-SERS method for in situ analyzing diquat and paraquat in biofluids. • Low detection limits ranging from 0.034 ppb to 0.65 ppb. • Good selectivity based on electrochemical adsorption. • p-Ag/Au fiber to realize hyphenation of enrichment, extraction, and SERS detection. [ABSTRACT FROM AUTHOR]

Bromadiolone is the most frequently detected anticoagulant rodenticide in human biofluids, resulting in increased cases of poisoning. Here, we present a portable kit that could realize rapid fingerprint detection of DQ in human biofluids. This strategy was based on surface-enhanced Raman scattering (SERS) and salt-induced liquid-liquid phase separation (SILLPS) using a gold/silver core-shell nanoparticle (Au@Ag NPs) substrate. The kit included a portable Raman spectrometer and five tubes that contained Au@Ag NPs colloid, KI solution, saturated NaCl solution, acetonitrile, and Mg(NO 3) 2 solution. This strategy did not require pretreatment for urine samples. For blood samples, a 2-min SILLPS method was proposed with satisfactory recovery, providing unique insights into efficient pretreatment of complex biomatrix. The detection limits for urine and blood were calculated to be 3.21 ppb and 6.86 ppb, respectively. A clear trend could be observed between signal intensity and logarithmic concentration of bromadiolone ranging from 0 to 2 ppm with high reproducibility. Such a portable kit based on SILLPS-SERS can rapidly provide fingerprint information of poison. This simple-yet-practical "Pretreat & Detect" SERS kit may open up new opportunities for point-of-care detection of poisons and has great potential as a tool in field applications. [Display omitted] • Simple-yet-practical "Pretreat & Detect" SERS kit for rapid detection of bromadiolone in urine and blood. • Portable, easy to operate kit suitable for point-of-care testing. • Salt-induced liquid-liquid separation enables rapid pretreatment of blood. • Quantitative detection of bromadiolone concentrations in the range, 10 ppb to 2 ppm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrasensitive SERS-based method for rapid detection of Cr(VI) in water. • Portable, easy to operate detection system suitable for on-site testing. • Quantitative detection of Cr(VI) concentrations in the range, 2 ppb to 50 ppm. • Low detection limit of 0.72 ppb. • Good recovery in real water samples. Hexavalent chromium (Cr(VI)), a highly toxic heavy metal ion, poses a serious threat to human health, and the demand of rapid detection still on-going. Herein, we propose a surface-enhanced Raman spectroscopy (SERS)-based method for rapid and cost-effective quantification of Cr(VI) in aqueous solutions with direct signal of Cr(VI) rather than indirect signals of Raman reporter molecules exploited in previous studies. This method demonstrates high sensitivity (the detection limit of 0.72 ppb), high reproducibility (the batch-to-batch variation was less than 10 %), and excellent selectivity. The results of this proposed method are fairly in good agreement (R2 = 0.991) with those of the UV colorimetric method promulgated by the United States Environmental Protection Agency (USEPA). We demonstrated the potential of our novel method for practical application in determining Cr(VI) concentrations in drinking and environmental water samples, in which adequate recovery, and high interference resistance were observed. This method has the advantages of being faster and suitable for on-site inspection as no pretreatment process is required and the equipment is portable. The excellent performance promises a great prospective toward a rapid, reliable, and on-site detection for Cr(VI). [ABSTRACT FROM AUTHOR]