ABSTRACT
<p><b>OBJECTIVE</b>We aimed to establish a sensitive quantified method for the simultaneous determination of melamine and cyanuric acid residues in water and urine by hydrophilic interaction liquid chromatography coupled with electrospray tandem mass spectrometry (HILIC-ESI-MS/MS) with the pretreatment of hydrophilic functional silica gel and cation exchange resin mixed solid phase extraction column(MCT), and to investigate the melamine and cyanuric acid residues in 501 water and 216 urine from several province and city.</p><p><b>METHODS</b>About 100 ml water (or 10 ml urine) was adjusted to pH 3.0 with concentrated hydrochloric acid, and then mixed with the internal standard solution((15)N3-melamine and (15)N3-(13)C3 -cyanuric acid) and 100 ml acetonitrile (10 ml for urine). The solution was cleaned with MCT solid-phase extraction column, and eluted once by 3 ml methanol and twice by 2.5 ml methanol (containing 5% ammonia water). The effluent was collected and dried by N2 flow at 40 °C, and then diluted to 2 mmol/L ammonium acetate containing 90% volume fraction acetonitrile. The completely dissolved solution was then filtered with 0.22 µm organic membrane; and the filtrate was detected by high performance liquid chromatography-tandem mass spectrometry and quantified with internal standards. The repeatability and sensitivity of the assay were evaluated. Then we detected the melamine and cyanuric acid residues in 501 water and 216 urine samples collected from several province and city.</p><p><b>RESULTS</b>By the quantification of internal standard (15)N3-melamine and (15)N3-(13)C3-cyanuric acid, the melamine and cyanuric acid were linear in the range of 2.0-1000.0 µg/L with correlation coefficient of 0.9998 and 0.9997. The detection limits of the method were separately 0.4 ng/L (melamine) and 0.3 ng/L (cyanuric acid) for water, and 4.0 ng/L (melamine) and 3.0 ng/L (cyanuric acid) for urine. The average recovery rate was around 95.3%-100.1% with the relative standard deviation (RSD) was <4.02%. Out of the 501 water samples, melamine was detected out in 19.9% (100/501) and cyanuric acid was detected out in 5.2% (26/501). The content was around 0.03-5.00 g/L. Melamine or cyanuric acid was detected out in 24.5% of the urine samples (53/216), with the content around 0.01-1.00 g/L.</p><p><b>CONCLUSION</b>The established method of solid phase extraction-hydrophilic interaction liquid chromatography-electrospray tandem mass spectrometry can satisfy the requirement for detection of melamine and cyanuric acid residues in all sorts of water and urine. Meanwhile, the two substances widely existed in water and Chinese population.</p>
Subject(s)
Humans , Chromatography, Liquid , Methods , Environmental Monitoring , Methods , Mass Spectrometry , Solid Phase Extraction , Methods , Triazines , Urine , Urinalysis , MethodsABSTRACT
<p><b>OBJECTIVE</b>To evaluate the overall diet quality and diet model of labor workers in Shenzhen using Chinese Diet Balance Index (DBI).</p><p><b>METHODS</b>In May 2009, 14 canteens from Baoan, Longgang and Nanshan districts were selected by stratified random sampling and 60 workers were randomly selected from each canteen by using random number method. Diet measurements were carried out among the 840 labor workers. Diet quality was evaluated by using DBI scoring and evaluating system.</p><p><b>RESULTS</b>The median values of labor workers' food intakes of cereal and meat & poultry were 483.8 and 121.7 g/d, which were more than the recommended amounts of their intakes of Chinese residents (cereal: 250 - 400 g/d, meat & poultry: 50 -70 g/d). The median values of the labor workers' intakes of fruit, dairy and eggs were 37.3, 20.6 and 23.5 g/d,which were less than recommended amounts in fruits (200 - 400 g/d), dairy (300 g/d) and eggs (25 - 50 g/d). The DBI-HBS scores of males and females in Shenzhen migrant workers were 24.4 +/- 6.1 and 22.6 +/- 6.3, respectively with a statistically significant difference (t = 4.21, P < 0.01). DBI-HBS scores of < 20 age group, 20 - 29 age group, 30 - 39 age group and > or = 40 age group in labor workers were 12.7 +/- 5.9, 11.3 +/- 6.3, 12.8 +/- 6.4 and 11.2 +/- 5.6 respectively (F = 3.67, P = 0.01). There were 7 dietary patterns among labor workers in this survey. Nearly 8.2% (68/830) of them belonged to Pattern A. Pattern B and E were the main dietary patterns, which accounted for 37.3% (310/830) and 31.0% (257/830) of the total population.</p><p><b>CONCLUSION</b>DBI can describe and evaluate the overall dietary quality and the major problem of the dietary patterns in labor workers. It is necessary to strength nutritional education to increase the intake of fruits, milk and eggs to improve nutritional status in labor workers in Shenzhen.</p>