Measurement uncertainty assessment of magnesium trisilicate column for determination of Sudan colorants in food by HPLC using C8 column.

This study aimed to conduct measurement uncertainty assessment of a new method for determination of Sudan colorants (Sudan I, II, III and IV) in food by high performance liquid chromatography (HPLC). Samples were extracted with organic solvents (hexane, 20% acetone) and first purified by magnesium trisilicate (2MgO·3SiO2). The Sudan colorants (Sudan I-IV) were also initially separated on C8 by gradient elution using acetonitrile and 0.1% (v/v) formic acid aqueous solution as the mobile phases and detected with diode-array detector (DAD). The uncertainty of mathematical model of Sudan I, II, III and IV is based on EURACHEM guidelines. The sources and components of uncertainty were calculated. The experiment gave a good linear relationship over the concentration from 0.4 to 4.0 µg/mL and spiked recoveries were from 74.0% to 97.5%. The limits of determination (LOD) were 48, 61, 36, 58 µg/kg for the four analytes, respectively. The total uncertainty of Sudan colorants (Sudan I, II, III and IV) was 810±30.8, 790±28.4, 750±27.0, 730±50.0 µg/kg, respectively. The recovery uncertainty was the most significant factor contributing to the total uncertainty. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in food samples. The sources of uncertainty have been identified and uncertainty components have been simplified and considered.

[Spatial regression analysis of relationship between schistosome infection rate of Oncomelania hupensis snails and climate factors].

OBJECTIVE: To explore the relationship between the schistosome infection rate of O. hupensis snails and the climate factors in endemic areas of schistosomiasis, so as to provide the evidence for improving the snail control. METHODS: The snail and climate data of 18 counties in Hubei Province in 2009 were collected to obtain the infection rate of O. hupensis snails and to fit the spatial regression models. RESULTS: The multiple linear regression model showed that the residuals were autocorrelated (Moran's I = 0.182 8, P < 0.01) and the spatial regression was necessary. The spatial lag model (SLM) was selected according to the results obtained by Lagrange multiplier statistics. The spatial parameter ρ of SLM was significant (p= - 0.151 5, P < 0.05) and the infection rate of O. hupensis snails was positively correlated with the annual average temperature (P < 0.05). The correlations between the infection rate of O. hupensis and the annual average relative humidity, precipitation and sunshine duration were not significant respectively (all P > 0.05). CONCLUSIONS: The spatial regression models could be well applied in the analysis of the relationship between the O. hupensis snails and climate factors. The annual average temperature is the primary climate factor influencing the infection of O. hupensis snails.

[Discussion of indoor quality control method of MPAIA antibody test of Schistosoma japonicum].

OBJECTIVE: To explore the scientific and effective indoor quality control method to ensure the results of Magnetic Particle Antibody Immunoassay (MPAIA) antibody test of Schistosoma japonicum reliable. METHODS: The MPAIA antibody test indoor quality control work was performed with the combination of the crubbs method, Z-scores figure and Westgard multi-rules quality control method. RESULTS: The crubbs test entered the quality control condition state from the third times, after 20 times, the test switched to Z-scores conventional quality control, and the Westgard multi-rules quality control method could help analyze the type of errors. From the third to fortieth test, 186 samples were completed and the tests of 9 samples among 2 batches needed to be re-done because of the failure of quality control. The test results of other 177 samples were acceptable. CONCLUSION: The combination of the crubbs method, Z-scores figure and Westgard multi-rules quality control method can effectively accomplish the indoor quality control of MPAIA antibody test of Schistosoma japonicum.

[Preventive effect of plant cercaricide Fangyouling for schistosome infection].

OBJECTIVE: To evaluate the preventive effect of Fangyouling (a plant cercaricide) for schistosome infection in the field. METHODS: Villagers contacting schistosome infested water in 3 administrative villages in Hubei Province were randomly selected, and the villagers rubbing Fangyouling before they contacted with the infested water were divided into Group I (159 cases) and those not rubbing Fangyouling before they contacted with the infested water were divided into Group II (172 persons). All the villagers were investigated by questionnaire, and their infections of schistosome were tested by sera and fecal examinations. RESULTS: There were no differences of constituent ratios of gender, age, occupation, time and type of infested water contact between the two groups (all P values > 0.05). The positive rates of sera and fecal examinations were 3.14% and 1.87%, respectively in Group I , and the positive rates of sera and fecal examinations were 9.30% and 6.40%, respectively in Group II, and there were significant differences between both the results of sera and fecal examinations of Group I and Group II (both P values < 0.05). In Group I , there were 110 people who completely embrocated Fangyouling, and their positive rates of sera and fecal examinations were 0.91% and 0, respectively. There are 42 people who incompletely embrocated Fangyouling, and their positive rates of sera and fecal examinations were 8.16% and 6.12%, respectively, and there were significant differences (both P values < 0.05). CONCLUSIONS: The preventive effect of schistosome infection of Fangyouling is significant. Incomplete embrocating may be one of the possible reasons for people still being infected with schistosome after rubbing the protective agent.