Associations of Perchlorate, Nitrate, and Thiocyanate with Bone Mineral Density in the US General Population: A Multi-Cycle Study of NHANES 2011-2018.

BACKGROUND: Perchlorate, nitrate, and thiocyanate are widely recognized as endocrine disrupting chemicals, which are closely related to thyroid function. Animal and human studies show a correlation between thyroid hormone and bone mineral density (BMD). However, it remains unknown whether perchlorate, nitrate, and thiocyanate were associated with BMD. This study aimed to explore the association between perchlorate, nitrate, and thiocyanate exposure with BMD. METHOD: A cross-sectional analysis among 5607 participants from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) was conducted in the present study. Perchlorate, nitrate, and thiocyanate were detected in urine by ion chromatography. Survey-weighted generalized linear regression, restricted cubic splines, and qgcomp models were used to assess the association of BMDs with single and mixed perchlorate, nitrate, and thiocyanate exposures. In addition, age, gender, and BMI stratified these associations. RESULTS: Negative associations were found between perchlorate and nitrate with BMDs. Furthermore, based on the qgcomp model results, the combined association of perchlorate, nitrate, and thiocyanate exposure was negatively associated with BMDs (ß = -0.017, 95% CI: -0.041, -0.024 for total BMD; ß = -0.017, 95% CI: -0.029, -0.005 for lumbar BMD). Additionally, there was a significant effect after gender, age, and BMI stratification between perchlorate, nitrate, and thiocyanate with BMDs in the normal weight group (ß = -0.015, 95% CI: -0.020, -0.011 for total BMD; ß = -0.022, 95% CI: -0.028, -0.016 for lumbar BMD) and children and adolescents group (ß = -0.025, 95% CI: -0.031, -0.019 for total BMD; ß -0.017, 95% CI: -0.029, -0.005 for lumbar BMD). CONCLUSIONS: The present study indicated a negative correlation between BMDs and urinary perchlorate, nitrate, and thiocyanate levels, with nitrate being the main contributor to the mixture effect. People with normal weight and children and adolescents were more likely to be affected.

[Rapid determination of chlorate and perchlorate in tea by ion exchange chromatography-tandem mass spectrometry].

Ion exchange chromatography-tandem mass spectrometry (IEC-MS/MS) has recently become the preferred method for detecting ionic substances in tea. In this study, an IEC-MS/MS method was developed for the rapid determination of chlorate and perchlorate residues in tea samples. The optimal sample extraction process, pretreatment column, and chromatographic and mass spectrometric conditions were systematically investigated. In the optimal process, the tea samples were ultrasonically extracted with methanol-water (13∶7, v/v), and a PRiME HLB SPE column was used to purify the sample extract. An AceChrom Hybri-A IEC column (150 mm×2.1 mm, 5.0 µm) was used for separation, and 100 mmol/L ammonium acetate-acetonitrile (40∶60, v/v) was used as the mobile phase for isocratic elution. The flow rate was 0.3 mL/min, the column temperature was 40 ℃, and the injection volume was 5.0 µL. The mass spectrometric data were collected in negative electrospray ionization mode combined with multiple reaction monitoring (MRM) mode to achieve the rapid and accurate separation and qualitative analysis of the desired chemical components. Quantification was performed using the internal standard (IS) method. The measurement results showed a good linear relationship when the mass concentrations of chlorate and perchlorate were between 2.00-200 and 1.00-100 µg/L, respectively, with correlation coefficients (r2) greater than 0.9990. The average recoveries of chlorate and perchlorate at three spiked levels of low, medium, and high ranged from 88.54% to 97.25% with relative standard deviations (RSDs, n=7) of 3.2%-5.2%. The limits of detection for chlorate and perchlorate were 12.0 and 8.0 µg/kg, respectively, while the limits of quantification were 40.0 and 26.6 µg/kg, respectively. The results of tests conducted to assess the linearity, specificity, accuracy, precision, and applicability of the method to the analysis of chlorate and perchlorate in 15 tea samples collected from a local market demonstrated its validity for the routine analysis of tea samples. The proposed method is simple, rapid, sensitive, and accurate, and can meet requirements for the rapid screening and quantitative analysis of residual trace chlorate and perchlorate in large quantities of tea samples.

Comparative effects of ammonium nitrogen on perchlorate degradation performance under heterotrophic condition with different carbon sources.

Perchlorate (ClO4-) mainly exists in the form of ammonium perchlorate in industrial production. However, the degradation mechanisms of different concentrations of ammonium nitrogen (NH4+-N) and ClO4- mixed pollutants in the environment are not well understood. This study aims to explore the potential of different types of carbon sources for ClO4- and NH4+-N biodegradation. Experimental results showed that the concentration and type of carbon sources are decisive to simultaneous removal of NH4+-N and ClO4-. Under condition of C(COD)/C(ClO4-) ratio of 21.15 ± 4.40, the simultaneously removal efficiency of ClO4- and NH4+-N in acetate (Ace) was relatively higher than that in methanol (Met). C(NH4+-N)/C(ClO4-) ratio of 9.66 ± 0.51 and C(COD)/C(ClO4-) ratio of 2.51 ± 0.87 promoted ClO4- reduction in glucose-C (Glu-C). However, high concentration of Glu could cause pH decrease (from 7.57 to 4.59), thereby inhibiting ClO4- reduction. High-throughput sequencing results indicated that Proteobacteria and Bacteroidetes have made a major contribution to the simultaneous removal of NH4+-N and ClO4-. They are two representative bacterial phyla for participating in both ClO4- reduction and denitrification. Notably, the abundance of main ClO4- degrading bacteria (such as Proteobacteria, Chloroflexi, and Firmicutes) significantly increased by 528.57 % in Glu-C. It can be inferred that the concentration of carbon source and NH4+-N were the most important factors determining the removal efficiency of ClO4- by influencing changes in the core microbial community. This study will provide new techniques and mechanistic insights for the simultaneous removal of mixed ClO4- and nitrogen pollutants, which can also provide theoretical support for innovation in future biological treatment processes.

Perchlorate in foodstuffs from South China and its implication for human dietary exposure.

Perchlorate, an aqueous-soluble compound resistant to degradation, is mainly used in the synthesis of pyrotechnics, herbicides, and other products. It serves as a pivotal component in the production of fireworks, rocket fuel, and explosives. Perchlorate was recognized as a pollutant owing to the potential toxic risk to thyroid function, which could pose a potential threat to the nervous system of infants and pregnant women. Some study had found that perchlorate existed in food, water and air. This study aimed to investigate the levels of perchlorate in six types of foods (n = 570) from South China, and evaluate potential exposure risks for residents. Vegetables were found to have the highest median levels of foods, attributed to elevated water content in leafy vegetables and facile solubility of perchlorate in water. The relatively low levels of perchlorate in food compared to other studies could attribute to the fact that the period of food we purchased in this study was during the wet season while the contaminants, such as perchlorate, were diluted. The maximum hazard quotient (HQ) values for all residents consuming different foods and water were all higher than 1 This suggested that there is a potential health risk of perchlorate to residents in South China. Those may be attributed to the high levels of perchlorate in some individual samples of meat and eggs. However, the 95th percentile of HQ values in all residents was less than 1, indicating that there is no potential health risk of perchlorate to most residents in South China.

Effects of temperature, chloride and perchlorate salt concentration on the metabolic activity of Deinococcus radiodurans.

The extremophile bacterium Deinococcus radiodurans is characterized by its ability to survive and sustain its activity at high levels of radiation and is considered an organism that might survive in extraterrestrial environments. In the present work, we studied the combined effects of temperature and chlorine-containing salts, with focus on perchlorate salts which have been detected at high concentrations in Martian regolith, on D. radiodurans activity (CO2 production rates) and viability after incubation in liquid cultures for up to 30 days. Reduced CO2 production capacity and viability was observed at high perchlorate concentrations (up to 10% w/v) during incubation at 0 or 25 °C. Both the metabolic activity and viability were reduced as the perchlorate and chloride salt concentration increased and temperature decreased, and an interactive effect of temperature and salt concentration on the metabolic activity was found. These results indicate the ability of D. radiodurans to remain metabolically active and survive in low temperature environments rich in perchlorate.

Investigating the mechanisms of action of thyroid disruptors: A multimodal approach that integrates in vitro and metabolomic analysis.

The thyroid gland, a vital component of the endocrine system, plays a pivotal role in regulating metabolic processes, growth, and development. To better characterize thyroid system disrupting chemicals (TSDC), we followed the next-generation risk assessment approach, which further considers the mechanistic profile of xenobiotics. We combined targeted in vitro testing with untargeted metabolomics. Four known TSDC, propyl-thiouracil (PTU), sodium perchlorate, triclosan, and 5-pregnen-3ß-ol-20-one-16α­carbonitrile (PCN) were investigated using rat in vitro models, including primary hepatocytes, PCCL3 cells, thyroid microsomes, and three-dimensional thyroid follicles. We confirmed each compound's mode of action, PTU inhibited thyroperoxidase activity and thyroid hormones secretion in thyroid cells model, sodium perchlorate induced a NIS-mediated iodide uptake decrease as triclosan to a lesser extent, and PCN activated expression and activity of hepatic enzymes (CYPs and UGTs) involved in thyroid hormones metabolism. In parallel, we characterized intracellular metabolites of interest. We identified disrupted basal metabolic pathways, but also metabolites directly linked to the compound's mode of action as tyrosine derivates for sodium perchlorate and triclosan, bile acids involved in beta-oxidation, and precursors of cytochrome P450 synthesis for PCN. This pilot study has provided metabolomic fingerprinting of dedicated TSDC exposures, which could be used to screen and differentiate specific modes of action.

Biogenic Palladium Improved Perchlorate Reduction during Nitrate Co-Reduction by Diverting Electron Flow in a Hydrogenotrophic Biofilm.

Microbial reduction of perchlorate (ClO4-) is emerging as a cost-effective strategy for groundwater remediation. However, the effectiveness of perchlorate reduction can be suppressed by the common co-contamination of nitrate (NO3-). We propose a means to overcome the limitation of ClO4- reduction: depositing palladium nanoparticles (Pd0NPs) within the matrix of a hydrogenotrophic biofilm. Two H2-based membrane biofilm reactors (MBfRs) were operated in parallel in long-term continuous and batch modes: one system had only a biofilm (bio-MBfR), while the other incorporated biogenic Pd0NPs in the biofilm matrix (bioPd-MBfR). For long-term co-reduction, bioPd-MBfR had a distinct advantage of oxyanion reduction fluxes, and it particularly alleviated the competitive advantage of NO3- reduction over ClO4- reduction. Batch tests also demonstrated that bioPd-MBfR gave more rapid reduction rates for ClO4- and ClO3- compared to those of bio-MBfR. Both biofilm communities were dominated by bacteria known to be perchlorate and nitrate reducers. Functional-gene abundances reflecting the intracellular electron flow from H2 to NADH to the reductases were supplanted by extracellular electron flow with the addition of Pd0NPs.

Occurrence, distribution characteristics and exposure assessment of perchlorate in the environment in China.

Recognizing the extent of perchlorate pollution in the environment is critical to preventing and mitigating potential perchlorate harm to human health. The presence and distribution of perchlorate in Chinese environmental matrixes (water, atmosphere, and soil) were systematically investigated and comprehensively analyzed, and cumulative perchlorate exposure at the regional level was assessed using a combined aggregate exposure pathway method. The results showed that perchlorate is ubiquitous in the environment of China with significant regional differences. The total perchlorate exposure levels in each region of China ranked as South China > Southwest China > East China > North China > Northeast China > Northwest China. Although the average exposure dose of 0.588 (95 %CI: 0.142 -1.914) µg/kg bw/day being lower than the reference dose of 0.70 µg/kg bw/day, it was observed that the intake of perchlorate in some regions exceed this reference dose. Oral ingestion was the primary route of perchlorate exposure (89.97-96.57 % of the total intake), followed by dermal contact (3.21-9.16 %) and respiratory inhalation. Food and drinking water were the main sources of total perchlorate intake, contributing 52.54 % and 31.12 % respectively, with the latter contributing significantly more in southern China than in northern China. In addition, perchlorate exposure from dust sources was also noteworthy, as its contribution was as high as 23.18 % in some regions. These findings will improve understanding of the perchlorate risk and serve as a critical reference for policymakers in crafting improved environmental management and risk mitigation strategies in China and other nations.

A study into the natural occurrence of inorganic ions relevant to forensic explosives investigations on human hands.

The natural occurrence of 16 inorganic ions relevant to forensic explosives investigations on human hands was studied to support the evaluation of activity-level propositions when such traces are found on the hands or in the fingerprints of a suspect. A total of 594 hand swab extracts from 297 participants throughout Europe and the United States of America were analyzed using Ion Chromatography - Mass Spectrometry. The data provides a reference framework for future covert investigations and forensic casework. The results indicate that thiocyanate, chlorate, nitrite, lithium, strontium, and barium are rarely detected on the hands of individuals who have had no direct contact with explosives (P<0.03) and in quantities below 6 µg. Perchlorate contamination sporadically occurs without deliberately handling perchlorates (P=0.03), albeit at low levels (<12 µg). It also seems that the presence of perchlorate on hands is generally related to professions that involve explosives. Detecting substantial amounts of any of these rare ions on a suspect's hands would require a specific explanation. Because legitimate activities exist that can also result in elevated levels of ions of interest on hands, the context surrounding their presence has to be carefully assessed for each individual case.

Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for molecular evolution on Mars.

Mars is a particularly attractive candidate among known astronomical objects to potentially host life. Results from space exploration missions have provided insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to its toxicity. However, it can also provide potential benefits, such as producing brines by deliquescence, like those thought to exist on present-day Mars. Here we show perchlorate brines support folding and catalysis of functional RNAs, while inactivating representative protein enzymes. Additionally, we show perchlorate and other oxychlorine species enable ribozyme functions, including homeostasis-like regulatory behavior and ribozyme-catalyzed chlorination of organic molecules. We suggest nucleic acids are uniquely well-suited to hypersaline Martian environments. Furthermore, Martian near- or subsurface oxychlorine brines, and brines found in potential lifeforms, could provide a unique niche for biomolecular evolution.

Microbial preference for chlorate over perchlorate under simulated shallow subsurface Mars-like conditions.

The Martian surface and shallow subsurface lacks stable liquid water, yet hygroscopic salts in the regolith may enable the transient formation of liquid brines. This study investigated the combined impact of water scarcity, UV exposure, and regolith depth on microbial survival under Mars-like environmental conditions. Both vegetative cells of Debaryomyces hansenii and Planococcus halocryophilus, alongside with spores of Aspergillus niger, were exposed to an experimental chamber simulating Martian environmental conditions (constant temperatures of about - 11 °C, low pressure of approximately 6 mbar, a CO2 atmosphere, and 2 h of daily UV irradiation). We evaluated colony-forming units (CFU) and water content at three different regolith depths before and after exposure periods of 3 and 7 days, respectively. Each organism was tested under three conditions: one without the addition of salts to the regolith, one containing sodium chlorate, and one with sodium perchlorate. Our results reveal that the residual water content after the exposure experiments increased with regolith depth, along with the organism survival rates in chlorate-containing and salt-free samples. The survival rates of the three organisms in perchlorate-containing regolith were consistently lower for all organisms and depths compared to chlorate, with the most significant difference being observed at a depth of 10-12 cm, which corresponds to the depth with the highest residual water content. The postulated reason for this is an increase in the salt concentration at this depth due to the freezing of water, showing that for these organisms, perchlorate brines are more toxic than chlorate brines under the experimental conditions. This underscores the significance of chlorate salts when considering the habitability of Martian environments.

Preservation of Bacillus subtilis' cellular liquid state at deep sub-zero temperatures in perchlorate brines.

Although a low temperature limit for life has not been established, it is thought that there exists a physical limit imposed by the onset of intracellular vitrification, typically occurring at ~-20 °C for unicellular organisms. Here, we show, through differential scanning calorimetry, that molar concentrations of magnesium perchlorate can depress the intracellular vitrification point of Bacillus subtilis cells to temperatures much lower than those previously reported. At 2.5 M Mg(ClO4)2, the peak vitrification temperature was lowered to -83 °C. Our results show that inorganic eutectic salts can in principle maintain liquid water in cells at much lower temperatures than those previously claimed as a lower limit to life, raising the prospects of active biochemical processes in low temperature natural settings. Our results may have implications for the habitability of Mars, where perchlorate salts are pervasive and potentially other terrestrial and extraterrestrial, cryosphere environments.

Environmental perchlorate, thiocyanate, and nitrate exposures and bone mineral density: a national cross-sectional study in the US adults.

Associations of perchlorate, thiocyanate, and nitrate exposures with bone mineral density (BMD) in adults have not previously been studied. This study aimed to estimate the associations of individual and concurrent exposure of the three chemicals with adult BMD. Based on National Health and Nutrition Examination Survey (NHANES, 2011-2018), 1618 non-pregnant adults (age ≥ 20 years and 47.0% female) were included in this study. Survey-weighted linear regression models were used to estimate individual urinary perchlorate, thiocyanate, and nitrate concentrations with lumbar spine BMD and total BMD in adults. Then, weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models were conducted to evaluate associations of co-occurrence of the three chemicals with adult BMD. In all participants, nitrate exposure was inversely associated with lumbar spine BMD (ß = - 0.054, 95%CI: - 0.097, - 0.010). In stratification analyses, significant inverse associations were observed in female and participants older than 40 years old. In WQS regressions, significant negative associations of the weighted sum of the three chemicals with total and lumbar spine BMD (ß = - 0.014, 95%CI: - 0.021, - 0.007; ß = - 0.011, 95%CI: - 0.019, - 0.004, respectively) were found, and the dominant contributor was nitrate. In the BKMR models, non-linear dose-response associations of nitrate exposure with lumbar spine and total BMD were observed. These findings suggested that environmental perchlorate, thiocyanate, and nitrate exposure may reduce adult BMD and nitrate is the main contributor.

Metagenomic profiling of halites from the Atacama Desert: an extreme environment with natural perchlorate does not promote high diversity of perchlorate reducing microorganisms.

We surveyed the presence of perchlorate-reducing microorganisms in available metagenomic data of halite environments from the Atacama Desert, an extreme environment characterized by high perchlorate concentrations, intense ultraviolet radiation, saline and oxidizing soils, and severe desiccation. While the presence of perchlorate might suggest a broad community of perchlorate reducers or a high abundance of a dominant taxa, our search reveals a scarce presence. In fact, we identified only one halophilic species, Salinibacter sp003022435, carrying the pcrA and pcrC genes, represented in low abundance. Moreover, we also discovered some napA genes and organisms carrying the nitrate reductase nasB gene, which hints at the possibility of cryptic perchlorate reduction occurring in these ecosystems. Our findings contribute with the knowledge of perchlorate reduction metabolism potentially occurring in halites from Atacama Desert and point towards promising future research into the perchlorate-reducing mechanism in Salinibacter, a common halophilic bacterium found in hypersaline ecosystems, whose metabolic potential remains largely unknown.

Oxidation of organics in water by active chlorine performed in microfluidic electrochemical reactors: a new way to improve the performances of the process.

Wastewater polluted by organics can be treated by using electro-generated active chlorine, even if this promising route presents some important drawbacks such as the production of chlorinated by-products. Here, for the first time, this process was studied in a microfluidic electrochemical reactor with a very small inter-electrode distance (145 µm) using a water solution of NaCl and phenol and a BDD anode. The potential production of chloroacetic acids, chlorophenols, carboxylic acids, chlorate and perchlorate was carefully evaluated. It was shown, for the first time, up to our knowledge, that the use of the microfluidic device allows to perform the treatment under a continuous mode and to achieve higher current efficiencies and a lower generation of some important by-products such as chlorate and perchlorate. As an example, the use of the microfluidic apparatus equipped with an Ag cathode allowed to achieve a high removal of total organic carbon (about 76%) coupled with a current efficiency of 17% and the production of a small amount of chlorate (about 30 ppm) and no perchlorate. The effect of many parameters (namely, flow rate, current density and nature of cathode) was also investigated.

Determination of phosphorus in commercially available milk using ion chromatography with perchloric acid deproteinization.

Suppressed ion chromatography with perchloric acid deproteinization was developed for the determination of phosphorus in commercially available milk. Although the perchloric acid deproteinization method is widely used in the medical field, it sees limited application in the food industry. Herein, the concentration of perchloric acid and hydrolysis conditions were examined, specifically regarding perchloric acid deproteinization, which was used as a deproteinization method in this study. The calibration curve constructed from the peak area of orthophosphoric acid (monohydrogen phosphate ion: HPO42-) was linear, with a correlation coefficient of 0.999. The relative standard deviation of the peak area of 50 mg/L of HPO42- from six replicates was 0.35%. The detection and quantitative limits of HPO42-, calculated from its signal-to-noise ratio were 0.033 mg/L and 0.100 mg/L, respectively. The proposed method was applied to the analysis of phosphorus in commercially available milk. Perchloric acid deproteinization has proved to be useful in the food industry.

Bioprospecting of extremophilic perchlorate-reducing bacteria: report of promising Bacillus spp. isolated from sediments of the bay of Cartagena, Colombia.

Three extremophile bacterial strains (BBCOL-009, BBCOL-014 and BBCOL-015), capable of degrading high concentrations of perchlorate at a range of pH (6.5 to 10.0), were isolated from Colombian Caribbean Coast sediments. Morphological features included Gram negative strain bacilli with sizes averaged of 1.75 × 0.95, 2.32 × 0.65 and 3.08 × 0.70 µm, respectively. The reported strains tolerate a wide range of pH (6.5 to 10.0); concentrations of NaCl (3.5 to 7.5% w/v) and KClO4- (250 to 10000 mg/L), reduction of KClO4- from 10 to 25%. LB broth with NaCl (3.5-30% w/v) and KClO4- (250-10000 mg/L) were used in independent trials to evaluate susceptibility to salinity and perchlorate, respectively. Isolates increased their biomass at 7.5 % (w/v) NaCl with optimal development at 3.5 % NaCl. Subsequently, ClO4- reduction was assessed using LB medium with 3.5% NaCl and 10000 mg/L ClO4-. BBCOL-009, BBCOL-014 and BBCOL-015 achieved 10%, 17%, and 25% reduction of ClO4-, respectively. The 16 S rRNA gene sequence grouped them as Bacillus flexus T6186-2, Bacillus marisflavi TF-11 (T), and Bacillus vietnamensis 15 - 1 (T) respectively, with < 97.5% homology. In addition, antimicrobial resistance to ertapenem, vancomycine, amoxicillin clavulanate, penicillin, and erythromycin was present in all the isolates, indicating their high adaptability to stressful environments. The isolated strains from marine sediments in Cartagena Bay, Colombia are suitable candidates to reduce perchlorate contamination in different environments. Although the primary focus of the study of perchlorate-reducing and resistant bacteria is in the ecological and agricultural realms, from an astrobiological perspective, perchlorate-resistant bacteria serve as models for astrobiological investigations.

Comparing the effects and potencies of perchlorate and nitrate on amphibian metamorphosis using a modified amphibian metamorphosis assay (AMA).

A modified amphibian metamorphosis assay was performed in which Nieuwkoop and Faber (NF) stage 47 Xenopus laevis larvae were exposed to different concentrations of either perchlorate (ClO4 -) or nitrate (NO3 -) for 32 days. Larvae were exposed to 0.0 (control), 5, 25, 125, 625, and 3125 µg/L ClO4 -, or 0 (control), 23, 71, 217, 660, and 2000 mg/L NO3 -. The primary endpoints were survival, hind limb length (HLL), forelimb emergence and development, developmental stage (including time to NF stage 62 [MT62]), thyroid histopathology, wet weight, and snout-vent length (SVL). Developmental delay as evidenced by altered stage distribution and increased MT62, a higher degree of thyroid follicular cell hypertrophy, and an increase in the prevalence of follicular cell hyperplasia was observed at concentrations ≥125 µg/L ClO4 -. The no observed effect concentration (NOEC) for developmental endpoints was 25.0 µg/L ClO4 - and the NOEC for growth endpoints was 3125 µg/L ClO4 -. Exposure to nitrate did not adversely affect MT62, but a decreasing trend in stage distribution and median developmental stage at ≥217 mg/L NO3 - was observed. No histopathologic effects associated with nitrate exposure were observed. An increasing trend in SVL-normalized HLL was observed at 2000 mg/L NO3 -. Nitrate did not alter larval growth. The NOEC for developmental endpoints was 71 mg/L NO3 -, and 2000 mg/L NO3 - for growth endpoints. The present study provided additional evidence that the effects and potency of nitrate and perchlorate on metamorphosis and growth in X. laevis are considerably different.

[Determination of perchlorate and chlorate in drinks by ultra-performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a method for determination of perchlorate and chlorate in drinks by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) based on isotopic internal standard method. METHODS: The perchlorate and chlorate residue in liquid drinks were extracted with methanol, in solid drinks with acetic acid solution, then centrifuged. The supernatant was cleaned-up with PSA/C18 cleanup tube. The separation of perchlorate and chlorate was carried out on a Acquity CSH fluorophenyl column(100 mm×2.1mm, 1.7 µm) and the detection was performed with tandem mass spectrometry with internal standard method for quantification. RESULTS: The peak area ratio of perchlorate and chlorate had a good linear relationship with their mass concentration within their respective linear ranges, with correlation coefficients(r) greater than 0.999. The limits of detection of perchlorate and chlorate were 0.2and 1 µg/L respectively and the limits of quantification were 0.5 and 3 µg/L respectively. The mean recoveries of two compounds were from 84.0% to 105.5% with relative standard deviations from 4.2% to 17.0% and 82.7% to 112.1% with relative standard deviations from 5.5% to 18.4%(n=6), respectively. The perchlorates in 11 kinds of beverage samples were 0.53-4.12 µg/L, chlorates were 3.27-61.86 µg/L. CONCLUSION: This method is simple, sensitive, accurate and reliable, which is suitable for the determination of perchlorate and chlorate in drinks.