ABSTRACT
Objective To establish a capillary gas chromatography method for the determination of trinitrotoluene (TNT) in workplace air.Methods Using dichloromethane as the eluent,the air was drawn through a glass fiber filter to collect TNT,TNT was extracted from the filter with dichloromethane by an ultrasonic shaker,and the sample was analyzed by OV-17 elastic quartz electron capture detector capillary gas chromatography.Results Under the optimal condition,the lowest detection limit was 0.006 ?g/ml,the lowest detection concentration was 0.001 3 mg/m~3 (based on 45 L air sample).When the concentration of standard solution was 0.040-2.0 ?g/ml,the linear equation was good,r=0.999 8,RSDs were between 0.66%-3.62%,the recovery rates were 90.4%-95.5%.When sample was collected by fiberglass filter paper,the efficiency of desorption was more than 90%,and was stable for at least 7 days at 2℃-8℃.Conclusion This method is applicable to the determination of trinitrotoluene in workplace air.
ABSTRACT
<p><b>OBJECTIVE</b>Children aged 3 - 6 years in the urban areas of China were surveyed for the first time to find out the state of child neglect (CN) as well as the major relevant risk factors so as to provide evidence for developing intervention measures.</p><p><b>METHODS</b>1163 children (of whom 49.6% were males and 4.5% were minority nationality) were randomly sampled under multistage stratification, from 25 cities which representing 15 provinces of China. Based on the Child Neglect Norms used by China, prevalence of CN was identified and SPSS-Windows 11.0 was employed for statistical analysis. Scores, frequency/degrees, age, sex and 5 types (physical, emotional, educational, medical and safety) of CN on every group of the regions, were calculated. Multifactorial analysis was conducted through Binary Logistic Regression and multiple linear regression to determine the relevant risk factors.</p><p><b>RESULTS</b>(1) The average degree of CN for the 3 - 6 year-olds was 42.2, with its prevalence as 28.0%. Degrees of CN for the groups of 3, 4, 5, 6-year-olds were 41.7, 42.2, 42.1 and 43.1 (F = 0.988, P > 0.05), with frequencies of 25.0%, 25.3%, 27.9% and 35.4% (chi(2) = 4.798, P > 0.05), respectively. Degrees for CN in males and females were 42.7 and 41.8 (F = 2.502, P > 0.05) with the frequencies as 32.6% and 23.7% (chi(2) = 6.585, P < 0.05), respectively. Degrees of CN for the five types were 39.4-43.4 with the frequencies as 5.1%-12.9%, respectively. No significant difference was found in the frequency of the types (with an exception on 'physical neglect') between males and females (P > 0.05). The highest frequency (42.9%) of CN was seen in the single-parent families and the lowest in large family with three generations (25.5%). (2) According to monofactorial chi(2) test, the possible risk factors of CN would include: educational background, occupation and decrease of income of the parents during last year, etc. (3) Binary Logistic regression analysis showed that the influential factors to the occurrence of CN would include: father's educational background, sex of the child and mother's occupation, etc. (4) Multiple linear regression showed that the influential factors to the degree of CN were: family structure, number of supporting family members, relationship between parents and children, etc.</p><p><b>CONCLUSION</b>The degree and frequency of CN among children aged 3 to 6 in the urban areas of China were high but similar among the four age groups. Male children had a higher frequency of neglect than females, but with similar degree. Children in single-parent families had the highest frequency. The major influential factors of CN would include: educational background, occupation, family structure, family income of the parents which were similar to the results reported from foreign literature.</p>