Immunoaffinity chromatography purification and ultra-high-performance liquid chromatography-tandem mass spectrometry determination of four ß-agonists in beef.

A highly selective and sensitive method was developed for the simultaneous determination of four ß-agonists (clenbuterol, salbutamol, ractopamine and terbutaline) in beef by immunoaffinity chromatography purification coupled to ultra-high-performance LC-MS/MS. The MS/MS conditions, ultra-high-performance LC mobile phase, injection solution, sample purification process and matrix effect were studied to optimise the operation conditions. The limits of detection (LODs) of the instrument for the studied ß-agonists ranged from 0.20 to 0.25 µg l(-1), and the LODs of the method for the studied ß-agonists ranged from 0.20 to 3.00 µg kg(-1) for beef. Calibration curves were constructed using a standard solution diluted with blank beef matrix. The linear ranges of the calibration curves ranged from 5 to 100 µg kg(-1) and the coefficients of determination were >0.9942 (n = 10) for all four ß-agonists. Samples spiked at 5, 10 and 50 µg kg(-1) showed recoveries >72% and RSDs <6.6%. The method is suitable for the simultaneous detection of four ß-agonists at trace levels in beef.

Migration of silver from nanosilver-polyethylene composite packaging into food simulants.

An analytical method for the determination of silver in food simulants (3% (w/v) aqueous acetic acid or 95% (v/v) aqueous ethanol) was developed based on inductively coupled plasma mass spectrometry (ICP-MS). Recoveries ranged from 87% to 109% and RSDs ranged from 0.7% to 7.8%. The procedure was applied to determine the migration of silver from nanosilver-polyethylene food packaging film into food simulants at different temperatures and migration times. Results indicated that the maximum migration ratios were 1.70%, 3.00% and 5.60% for 3% (w/v) aqueous acetic acid at 20, 40 and 70 °C, respectively, while for 95% (v/v) aqueous ethanol the maximum migration ratios were 0.24%, 0.23% and 0.22% at 20, 40 and 70 °C.

Kinetic migration of isothiazolinone biocides from paper packaging to Tenax and Porapak.

Migration investigations were carried out on paper packaging materials in contact with solid food simulants. The aim was to investigate the migration behaviour of a series of isothiazolinone biocides (2-methyl-3-isothiazolinone (MI), 1,2-benzisothiazolinone (BIT) and 2-octyl-3-isothiazolinone (OIT)) as potential contaminants in paper materials, at varying temperatures and migration times, for the food simulants Tenax and Porapak. Based on the migration results, Tenax was found to be a good food simulant, and was more suitable than Porapak at high temperature. Petri dishes were found to be suitable for use as migration cells when the compounds to be evaluated were non-volatile. The amount of migration gradually increased with time and increasing temperature, finally reaching a steady value. When the temperature was higher than the boiling point of OIT, the migration rate decreased because of volatilization. The maximum migration rates were 3.4% for MI, 2.2% for BIT and 10.6% for OIT at high temperature (≥100 °C). Two kinds of paper packaging for food were tested with the method that was developed. OIT in the papers migrated into the food simulants but the amount that migrated was less than 0.14 µg kg(-1).

Determination of silver in nano-plastic food packaging by microwave digestion coupled with inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry.

The detection of silver in nano-plastic food packaging by microwave digestion coupled with either inductively coupled plasma atomic emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Microwave digestion was optimised by trialling different acid mixtures. Both ICP-AES and ICP-MS showed good reproducibility, repeatability and recovery. For ICP-AES the limit of detection of the method (LODm) was 25.0 µg g(-1), the limit of detection of the instrument (LODi) was 30.0 ng ml(-1), the linear range was 0.10-10.0 µg ml(-1). The average recoveries for blank samples spiked with silver at 100, 250 and 500 µg g(-1) ranged from 82.53% to 87.60%, and the relative standard deviations (RSDs) were from 1.79% to 8.30%. For ICP-MS analysis the LODm was 0.75 µg g(-1), the LODi was 0.04 ng ml(-1), the linear range was 0.20-500.0 ng ml(-1), the RSDs were 2.26-4.79%, and the recoveries were 78.09-92.72% (spiked concentrations of 2.5, 5.0 and 10.0 µg g(-1)). These results indicate that the proposed method could be employed to analyse silver in nano-plastic food packaging.

Analysis of isothiazolinone biocides in paper for food packaging by ultra-high-performance liquid chromatography-tandem mass spectrometry.

A novel and simple method to detect isothiazolinone-type biocides (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT) and 2-octyl-3-isothiazolinone (OIT)) in paper used for food packaging by ultrasonic extraction coupled with UPLC-MS/MS was developed. Parameters affecting process efficiency such as extraction solvents, UPLC mobile phase, gradient elution procedure and MS/MS conditions were studied to optimise the operating conditions. Using the optimised gradient elution procedure, the retention time was less than 6 min. The limits of detection (LODs) were found to be between 0.001 and 0.010 mg kg⁻¹, which was validated using actual concentrations. After diluting the standard solution with a blank matrix, the linear calibration curve ranges were 0.002-1.000 mg kg⁻¹ for BIT and OIT, 0.005-1.000 mg kg⁻¹ for MI, and 0.020-1.000 mg kg⁻¹ for CMI, with correlation coefficients higher than 0.9985 (n = 6). A good level of precision with a mean recovery greater than 81.3% and a relative standard deviation (RSD) less than 6.2% were also obtained. A methodology has been proposed for the analysis of isothiazolinones in paper.

A multisectoral approach to primary health care in Fujian, China.

The government of Yongan in Fujian province has developed a multisectoral primary health care program in the rural community of Dahu with the aim of reaching "Health for All" by 1993. In keeping with the spirit of the Alma Ata declaration and the tradition of local self-reliance in China, the program has involved the entire community and is financed almost exclusively at the local level. Community leaders were trained in the importance of primary health care so that they could serve as role models. The project includes school health education, domestic hygiene education, reconstruction of homes to separate the kitchen, toilet and animals pens, road construction to eliminate dust, environmental sanitation, occupational health, and the upgrading of health care facilities. A number of local ordinances regarding construction, zoning and smoking have also been instituted. The results of the project's first year of implementation in two villages indicate that construction of the new road is near completion, and access to clean water is almost universal. Gains are also reported in the percentage of the population receiving physical examinations, the number of health stations that now meet state standards, and the number of homes that are constructed according to the new guidelines.

Coumarin 120 laser pulses close to the Fourier transform limit from a simplified resonant cavity.

Using a simplified resonant cavity consisted of an optical parallel glass plate and a diffraction grating at near grazing incidence and the appropriate laser parameters, coumarin 120 laser pulses close to the Fourier transform limit have been obtained. These laser pulses have a spectral linewidth of 600 +/- 40 MHz and a pulse width of 1.5 +/- 0.2 ns. The laser wavelength tuning range is from 4280 to 4600 A.