3 research outputs found
Comprehensive Identification and Ubiquitous Occurrence of Eight Classes of Rubber-Derived Vulcanization Accelerators in Urban Dusts
Vulcanization accelerators (VAs) serve as crucial additives
in
synthetic rubber on a global scale. Despite their widespread use,
the environmental presence, distribution, and associated exposure
risks of VAs remain poorly understood. This study compiled a target
list and conducted a screening for eight classes encompassing 42 VAs
in diverse urban dust samples from South China. A total of 40 of the
42 target VAs were detectable across all four studied regions, among
which 30 were identified for the first time in the environment. Among
the eight structure-classified VA classes, xanthates exhibited the
highest concentrations (median: 3810–81,300 ng/g), followed
by thiazoles, guanidines, sulfenamides, dithiocarbamates, thiurams,
thioureas, and others. The median total concentrations of all target
VAs (∑VAs) were determined to be 5060 ng/g in road dust, 5730
ng/g in parking lot dust, 29,200 ng/g in vehicle repair plant dust,
and 84,300 ng/g in household dust, indicating the widespread presence
of numerous rubber-derived VAs in various urban environments. This
study marked the first systematic effort to identify a wide range
of emerging rubber-derived VAs prevalent in urban environments. The
findings call for increased attention to these widely utilized but
less well-evaluated chemicals in future research and environmental
management efforts
Organophosphate Triesters and Diester Degradation Products in Municipal Sludge from Wastewater Treatment Plants in China: Spatial Patterns and Ecological Implications
Little
is known about the occurrences, distributions, sources,
and potential risks of organophosphate (OP) triesters and diester
degradation products in municipal sludge from wastewater treatment
plants (WWTPs). In this study, we conducted the first nationwide survey
to simultaneously determine a suite of 11 OP triesters and six diester
degradation products in sludge from WWTPs across China. All OP triesters
were detected and three diesters were identified for the first time
in sludge samples. Total concentrations of OP triesters and diester
degradation products were in the ranges of 43.9–2160 and 17.0–1300
ng (g of dry weight)<sup>−1</sup>, respectively, indicating
relatively low pollution levels in China compared with those of several
developed countries. A distinct geographical variation of higher concentrations
of OP triesters and diesters in East China than in Central and West
China was observed, suggesting that regional levels of organophosphate
esters are associated with the magnitudes of regional economic development.
Source analysis revealed nonchlorinated OP diesters are mainly derived
from degradation in WWTPs, while chlorinated OP diesters were largely
sourced from outside WWTPs. The estimated total emission fluxes of
OP triesters and diesters via land-application sludge in China were
approximately 330 and 134 kg/year, respectively. Further risk assessment
based on risk quotient values in sludge-applied soils indicated low
to medium risks for most OP triesters and diesters except trisÂ(methylphenyl)
phosphate. The significant accumulation of OP triesters and widespread
occurrence of diester degradation products in sludge raise environmental
concerns about these contaminants
Antibody-Free Colorimetric Detection of Total Aflatoxins in Rice Based on a Simple Two-Step Chromogenic Reaction
The prevalently used immunoassays
for fast screening of aftatoxins
(AFs) usually cannot meet the requirement for simultaneous determination
of total AFs (aflatoxin B<sub>1</sub> + aflatoxin B<sub>2</sub> +
aflatoxin G<sub>1</sub> + aflatoxin G<sub>2</sub>) due to the deficiency
of highly group-specific antibodies. This paper describes a two-step
chromogenic reaction based method to quantitatively detect total AFs
in rice using colorimetric measurement without antibody. In the method,
colorless AFs transform into green-colored indophenol products through
the reaction with sodium hydroxide and 2,6-dibromoquinone-4-chloroimide
(DBQC) successively, allowing selectively determining total AFs up
to 3.9 μg/kg over other competitive mycotoxins under optimal
conditions by a UV–vis spectrophotometer. In addition, the
colorimetric measurement results of the rice samples agree well with
that of a standard HPLC method, demonstrating the good reliability
and applicability of the method. Uniquely, the method has potential
for on-site detection of total AFs in rice when using a nylon membrane-based
device