Ammelide Research Articles

Twenty-four-hour temporal trend of melamine and its derivatives in urine in association with meal consumption: a panel study in Shanghai, China.

Timing of sampling is important for the exposure assessment of melamine (MEL) and its derivatives. This study aimed to investigate whether MEL and its derivatives in spot urine can effectively represent individual exposure levels throughout the day in adults and to explore their temporal trend before and after meal consumption for helping understand the timing of sampling and for assessing the potential exposure risk. This is a 2-day panel study with 43 college students being enrolled to provide urine specimens in 24 h (from the morning of the first day to the second day) and to answer a questionnaire on demographic characteristics, physical measurements, and time of having meal. Spearman correlation and Wilcoxon rank-sum test were used to examine the associations of the urinary concentrations of MEL and its derivatives in different sampled times and compare the concentrations' differences before and after meal consumption. Urinary concentrations of MEL and its derivatives (ammeline (AMN), ammelide (AMD), and cyanuric acid (CYA)) in the first-morning urine at the second day and randomly selected spot urine were positively associated with the average concentrations in the previous 24-h urine (all P ≤ 0.002). Urinary MEL concentration increased rapidly after meal consumption, reaching a maximum at approximately 3 h and then decreased gradually towards baseline (P = 0.006). Two subjects (4.65%) had a cumulative daily intake exceeding the severest tolerable daily intake. MEL and its three derivatives in spot urine can effectively represent the average concentrations in the previous 24-h urine in adults. Meal consumption is still a notable source of exposure to MEL for humans. These findings are important for choosing a better sampling strategy of performing exposure assessment. Meanwhile, the acute elevation in urinary MEL concentration following meal consumption may pose a potential health risk.

Exposure to melamine and its derivatives in Chinese adults: The cumulative risk assessment and the effect on routine blood parameters

Melamine (MEL) and its derivatives, ammeline (AMN), ammelide (AMD), cyanuric acid (CYA) are widely existed in environmental media. Animal studies have reported the cumulative risk assessment (CRA) of simultaneous exposure to MEL and its derivatives and explored the associations between exposure and routine blood parameters. Such information is largely unknown in human studies. In this study, we detected the urinary concentrations of MEL and its derivatives in 239 Chinese adults to conduct the CRA by evaluating their hazard quotients (HQ) and hazard Index (HI), and also explored the possible associations between exposure and measured routine blood parameters in study population. The detectable frequencies of MEL, AMN, AMD and CYA were 96.65%, 41.00%, 97.91% and 97.07%, respectively. The median values of creatinine (Cr)-adjusted MEL, AMN, AMD, CYA and the total concentrations of MEL and its derivatives (∑MEL) were 11.41 μg/g Cr, not detected (ND), 2.64 μg/g Cr, 15.30 μg/g Cr, 35.02 μg/g Cr, respectively. There were 9 (3.77%) participants with estimated daily intakes (EDIs) of CYA exceeding the tolerable daily intake (TDI) of 2500 ng/kg bw/day, and 12 (5.02%) participants with HI of ∑MEL exposure exceeding 1 based on the strictest TDI value. Urinary concentrations of MEL and its derivatives were positively associated with specific routine blood parameters, including hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, white blood cell, neutrophil count (P < 0.05). Meanwhile, exposure to MEL and its derivatives increased the risk of red blood cell abnormality (P < 0.05). Our study is the first study to provide evidence-based data on the CRA of exposure to MEL and its derivatives in Chinese adults, and to propose a possible association between such exposure and routine blood parameters in human.

Determination of four melamine and its derivatives in urine by ultra-performance liquid chromatography-tandem mass spectrometry

To establish a method for simultaneous detection of melamine(MEL), ammeline(AMN), ammelide(AMD) and cyanuric acid(CYA) in urine by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). After the urine sample was added to the internal standard, they were mixed by acetonitrile, ultrasonic extraction and centrifugation, enriched by MCX or MAX solid phase extraction column, eluted with 5% ammoniated methanol or 2% formic acid methanol, dried under nitrogen at 40 ℃, separated by Amide chromatography column(2.1 mm×100 mm, 1.7 μm), qualitatively and quantitatively analyzed by mass spectrometer in the simultaneous scanning mode of positive and negative ions. Melamine and its derivatives were completely separated with great chromatography peak. The limit of detection(LOD) for melamine, ammeline, ammelide and cyanuric acid were 0.03, 0.04, 0.04 and 0.05 ng/mL, and the limit of quantification(LOQ) were 0.11, 0.12, 0.14 and 0.15 ng/mL, respectively. The recovery rate of standard addition samples of 0.2, 5, 50 and 200 ng/mL ranged from 94.6% to 106.5%, the intra-day precision was between 0.73% and 8.34%, and the inter-day precision was less than 6.80%(n=6). At low concentrations, AMD and CYA mainly showed matrix enhancing effect, while AMN showed matrix inhibitory effect with increasing concentration. The overall detection rate of melamine and its derivatives was 75.0% in 60 parcels of random urine. The average concentration of urinary melamine and its derivatives were higher in men. UPLC-MS/MS can simultaneously determine four melamine and its derivatives in urine. The LOD and LOQ of the current method were low with great accuracy and precision.

Exposure to melamine and its derivatives in childcare facilities.

Melamine (MEL) and its derivatives are widely used in many consumer products, including furniture, kitchenware, and plastics. However, very limited knowledge exists on human exposure to MEL and its derivatives, especially in the indoor environment. Here, we determined the occurrence and distribution of 11 MEL derivatives in childcare facilities and estimated children's exposure through dust ingestion and dermal absorption. We analyzed dust and samples of nap mats, a commonly used item in many childcares, from eight facilities located in the United States. Eight MEL-based compounds were detected in dust, and total MEL concentrations ranged from 429 to 117,000ng/g. The most abundant compounds found in the dust samples were MEL, cyanuric acid (CYA), ammeline (AMN), and ammelide (AMD), with median concentrations of 1620, 585, 1060, and 299ng/g, respectively. MEL, CYA, AMN and 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine (TBMMAT) were also detected in nap mats with median concentrations of 45.6, 19.8, 1510 and 2.5ng/g, respectively. ΣMEL concentrations in mat covers (median 709ng/g) were significantly higher than those in mat foam (median 15.1ng/g). Estimated daily intakes (EDIs) of MEL and its derivatives via dust ingestion were two orders of magnitude higher than the EDIs through dermal absorption, but both were below the established tolerable daily intake levels. This is the first report on exposure to MEL and its derivatives in the childcare environment.

Rapid screening and quantification of cyromazine, melamine, ammelide, ammeline, cyanuric acid, and dicyandiamide in infant formula by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and triple quadrupole mass spectrometry

In the past few years, special concern for triazine pesticide cyromazine (CYRO) and its metabolites melamine (MM), ammelide (AMD), ammeline (AMN), cyanuric acid (CA), and dicyandiamide (DCD) residues has arisen in the food safety field on infant foods. In this work, screening and confirmation for infant milk powder samples were performed by quadrupole time-of-flight mass spectrometry (QTOF-MS). An accurate mass database was established. The matrix-matched internal standard calibration curves of UPLC–MS/MS were linear, with correlation coefficient (r2) higher than 0.994. The limits of quantification (LOQ) were 1.6, 5.0, 16.5, 10.0, 66.4, and 66.4 μg/kg for CYRO, MM, AMD, AMN, CA, and DCD, respectively. The average recoveries ranged from 64.8 to 103%. The retention time, intra- and inter-day precisions (relative standard deviation, RSDs) of 6 analytes were in the range of 0.02–0.05%, 2.4–6.1%, and 7.2–11.2%, respectively. CYRO and MM residues in some infant milk powder samples were confirmed. Quantitation of positive samples was performed using the internal standard method and six-point matrix-matched calibration curves. The content for CYRO in all 8 samples and MM in 4 samples were in the range of 3.5–45 μg/kg and 8–25 μg/kg, respectively. The method developed for the first time has high sensitivity, can be used as an effective tool for rapid screening and highly sensitive multiresidue determination of CYRO, MM and their metabolites AMD, AMN, and CA as well as DCD in milk powder samples.

Determination of Melamine and Derivatives in Foods by Liquid Chromatography Coupled to Atmospheric Pressure Chemical Ionization Mass Spectrometry and Diode Array Detection

Two liquid chromatographic methods based on atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) and diode array detection (DAD) are evaluated for the rapid determination of melamine (MEL) and structurally related compounds, including ammeline (AMN), ammelide (AMD), and cyanuric acid (CA) in foods. Both procedures used ion-exchange LC and isocratic elution. Samples were extracted by homogenization with acetonitrile/water/diethylamine. Specificity was demonstrated for LC-MS by the retention characteristics and MS spectra, by comparing with commercial standards. Specificity was only demonstrated in the case of LC-DAD for MEL and AMN, considering the retention characteristics and UV spectra. The recoveries obtained for spiked samples were satisfactory for all the analytes with LC-MS. The proposed procedure, LC-APCI-MS, was successfully applied to the analysis of different baby foods, including infant formula and breakfast cereal, and samples of rice flour, potato starch, soya drink, and coconut drink.

Detection of melamine in infant formula and grain powder by surface‐assisted laser desorption/ionization mass spectrometry

We have developed a method for the determination of melamine (MEL), ammeline (AMN), and ammelide (AMD) by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using gold nanoparticles (Au NPs). The major peaks for MEL, AMN, and AMD at m/z 127.07, 128.05, and 129.04 are assigned to the [MEL + H](+), [AMN + H](+), and [AMD + H](+) ions. Because the three tested compounds adsorb weakly onto the surfaces of the Au NPs through Au-N bonding, they can be easily concentrated from complex samples by applying a simple trapping/centrifugation process. The SALDI-MS method provides limits of detection of 5, 10, and 300 nM for MEL, AMN, and AMD, respectively, at a signal-to-noise ratio of 3. The signal variation for 150-shot average spectra of the three analytes within the same spot was 15%, and the batch-to-batch variation was 20%. We have validated the practicality of this approach by the analysis of these three analytes in infant formula and grain powder. This simple and rapid SALDI-MS approach holds great potential for screening of MEL in foods.

Comparison of three methods for detection of melamine in compost and soil

Recent product recalls and food safety incidents due to melamine (MM) adulteration or contamination have caused a worldwide food security concern. This has led to many methods being developed to detect MM in foods, but few methods haves been reported that can rapidly and reliably measure MM in environmental samples. To meet this need, a high performance liquid chromatography (HPLC) with UV detection method, an enzyme-linked immunosorbent assay (ELISA) test kit, and an enzyme-linked rapid colorimetric assay (RCA) test kit were evaluated for their ability to accurately measure MM concentrations in compost and soil samples. All three methods accurately detected MM concentrations if no MM degradation products, such as ammeline (AMN), ammelide (AMD) and cyanuric acid (CA), were present in an aqueous sample. In the presence of these MM degradation products, the HPLC yielded more accurate concentrations than the ELISA method and there was no significant (P>0.05) difference between the HPLC and RCA methods. However, if samples were purified by SPE or prepared with blocking buffer, the ELISA method accurately measured MM concentrations, even in the presence of the MM degradation products. The HPLC method generally outperformed the RCA method for measuring MM in soil extracts but gave similar results for compost extracts. The number of samples that can be analyzed by the ELISA and RCA methods in a 24-hour time period is much greater than by the HPLC method. Thus the RCA method would seem to be a good screening method for measuring MM in compost and soil samples and the results obtained could then be confirmed by the HPLC method. The HPLC method, however, also allows simultaneous measurement of MM and its degradation products of AMD, AMN and CA.

A 100% Water Mobile Phase HPLC-PDA Analysis of Meamine and Related Analogues

This paper describes a reserved-phase high performance liquid chromatographic method for detecting melamine (MEL) and related analogues, cyanuric acid (CYA), ammeline (AML), and ammelide (AMD), using a 100% water mobile phase. Chromatographic separation was performed an Inertsil? ODS-4 (250 × 4.6 mm, 5 μm) with a water mobile phase and a photodiode-array detector. The monitoring wavelength was adjusted to 210 nm which represents an average maximum for all the analytes. The total run time was < 8 min. The method shows high stability, significant linearity and satisfactory sensitivity. The detection limits were established in the range 23 - 46 ng.mL–1. An inexpensive and harmless method for the simultaneous detection of MEL, CYA, AML, and AMD was developed and may be further applied to the quantification in foods.

Determination of melamine, ammeline, ammelide and cyanuric acid in infant formula purchased in Canada by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry-based isotope dilution method was developed for the analysis of the triazine compounds melamine (MEL), ammeline (AMN), ammelide (AMD) and cyanuric acid (CYA) in infant formula samples purchased in Canada in 2008 for the purpose of a combined exposure and risk assessment. Infant formula samples were extracted with 1:1 acetonitrile–water, cleaned up on disposable ion-exchange solid-phase extraction cartridges, and analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. MEL and CYA were detected in almost all infant formula products: the highest concentrations observed were 0.32 mg kg−1 MEL and 0.45 mg kg−1 CYA. Samples that were relatively high in MEL in this survey tended to be low in CYA, and vice versa. Concentrations of AMN and AMD were very low in all samples. The total of MEL-related compounds (sum of all four analytes) in all samples was below the interim standard of 0.5 mg kg−1 for infant formula products established by Health Canada.

Highly sensitive detection of melamine and its derivatives by capillary electrophoresis coupled with online preconcentration techniques

Two kinds of online preconcentration techniques including large-volume sample stacking-sweeping and selective-exhaustive injection-sweeping (SEI-S) were employed in CE to develop a rapid, simple and sensitive method for determination of melamine (MM) and its derivatives such as ammeline (AMN), ammelide (AMD) and cyanuric acid (CA) in liquid milk products. Though the sensitivity of large-volume sample stacking-sweeping is not particularly high, it can be used to detect all the four compounds simultaneously. However, it is very difficult to improve the sensitivity of these four compounds by using single SEI-S method directly, owing to their completely different extents of protonation or deprotonation. Grouping can solve this problem perfectly. After the four compounds are divided into two groups (MM/AMN and AMD/CA), cation-SEI-S or anion-SEI-S can be applied for their online stacking. In cation-SEI-S, the detection limits for MM and AMN were both 0.01 ng/mL based on the signal-to-noise ratio of 3. In anion-SEI-S, the detection limits were 0.05 and 0.02 ng/mL for CA and AMD, respectively. Results of this study show a great potential for the SEI-S method to be a useful tool for the rapid and sensitive determination of MM and its derivatives in liquid milk products.