Objective To study a method for determination of aluminum in food,and to ensure food safety and public health.Methods Microwave digestion-chrome azurol S spectrophotometric method was used to detect the aluminum content in fried dough sticks.Detection limit,linear range,precision,accuracy and maximum absorption wavelength were calculated.Results The method detection limit was 0.08 μg,precision was 0.60％-5.90％,and recovery rate was 96.0％-102.3％,maximum absorption wavelengnth was 620 mm.Aluminum content in 10 samples of fried dough sticks were all exceeded the standard,which were 709.5,980.8,1 010.3,1 151.5,1 214.0,1 243.7,1 318.1,1 374.0,1 435.0 and 1 479.4 mg/kg.Conclusion The method is simple,reliable,reproducible and easy to be used.

Objective To investigate the situation of food contamination by lead,cadmium,mercury,copper and aluminum in Ningxia Region.Methods Ten categories of food samples up to 712 copies including dairy,edible mushrooms,eggs,preserved egg,meat,organs,aquatic products,vegetables,grains and pasta from supermarkets of five administrative cities of Ningxia Autonomous Region were selected in 2010.The contents of lead,cadmium and mercury in food were detected in 646 samples of 9 categories of food,and copper content of the 30 meat samples were detected.Aluminum content in 66 samples of flour food was tested.According to the methods of national food safety standards (GB 5009.12-2010) and national food hygiene standards (GB/T 5009.13-2003,GB/ T 5009.15-2003 and GB/T 5009.17-2003),lead,copper,cadmium and mercury in various foods were tested.Aluminum was determined using the method for determination of spectrophotometry.Results The detection rates of lead,cadmium,mercury in the nine categories of food were 52.8％ (341/646),62.1％ (401/646),51.7％ (334/646);the detection rates of copper in the meat was 90.0％ (27/30);the aluminum in flour food was 84.8％ (56/66),respectively.Compared with the national standards,the eligible rates of lead,cadmium,mercury,copper and aluminum were 97.1％ (627/646),98.2％ (539/549),100.0％ (646/646),100.0％ (30/30) and 75.8％ (50/66),respectively.Food contaminated by lead and cadmium were mainly distributed in preserved egg [lead detection rate 9.5％ (2/21)],organs [lead detection rate 6.7％ (2/30),cadmium detection rate 30.0％ (9/30)],vegetables [lead detection rate 9.9％ (8/90)] and a small amount of food products [lead detection rate 4.7％ (7/150)].The levels of lead in fried flour food and fine dried noodles were higher [40.9％ (9/22),36.4％ (4/11)].Conclusions Food contamination by lead,cadmium,mercury and copper is not serious in Ningxia.The monitoring results of lead,cadmium,mercury and copper in food are satisfying in Ningxia.But there is aluminum contamination in flour food.It is important to do the risk evaluation of aluminum contamination in food as quickly as possible.

OBJECTIVETo investigate the method for uncertainty evaluation of determination of tin and its compounds in the air of workplace by flame atomic absorption spectrometry.

METHODSThe national occupational health standards, GBZ/T160.28-2004 and JJF1059-1999, were used to build a mathematical model of determination of tin and its compounds in the air of workplace and to calculate the components of uncertainty.

RESULTSIn determination of tin and its compounds in the air of workplace using flame atomic absorption spectrometry, the uncertainty for the concentration of the standard solution, atomic absorption spectrophotometer, sample digestion, parallel determination, least square fitting of the calibration curve, and sample collection was 0.436%, 0.13%, 1.07%, 1.65%, 3.05%, and 2.89%, respectively. The combined uncertainty was 9.3%.The concentration of tin in the test sample was 0.132 mg/m³, and the expanded uncertainty for the measurement was 0.012 mg/m³ (K=2).

CONCLUSIONThe dominant uncertainty for determination of tin and its compounds in the air of workplace comes from least squares fitting of the calibration curve and sample collection. Quality control should be improved in the process of calibration curve fitting and sample collection.

Air Pollutants, Occupational ; analysis ; Models, Theoretical ; Spectrophotometry, Atomic ; Tin ; analysis ; Uncertainty ; Workplace

objective To investigate the clinical relevance of antinuclear antibodies (ANA)in patients with systemic sclerosis(SSc).Methods Clinical data were collected from 283 patients with SSc admitted to Peking Union Medical College Hospital(PUMCH)from 1981 to 2009.A retrospective analysis was carried out.Results In the 283 patients,253(89.4%)were female.The mean age at onset was 35.9±12.6 years and mean disease duration 4.3 ±4.5 years.There were 125(44.2%)patients with diffuse SSc(dcSSc) and 158(55.8%)with limited cutaneous SSc(lcSSc).Of all the patients,96.8%were positive for ANA,54.4% for anti-Scl-70 antibodies,6.4%for anticentromere antibodies(ACA),23.7%for anti-ribonucleoprotein(RNP) antibodies,7.1%for anti-Sm antibodies,25.1%for anti-SSA antibodies,7.1%for anti.SSB antibodies,and 1.1%for anti-Jo-1 antibodies.No patients were positive for anti-rRNP antibodies.Only one patient was positive for both anti-Scl-70 antibodies and ACA.The positivity rate of ACA in patients with leSSe was higher thanthat in those with dcSSc(P<0.05).Conclusion The detection of antinuclear antibodies is helpful for the diagnosis,classification,prognosis evaluation and management of SSc.