Direct thermal decomposition mercury analysis is an efficient technique for determination of mercury in facial whitening creams. The analysis can be performed without any sample preparation. The samples can be weighed and placed directly into the analyzer. Thus there is no chemical waste produced in sample preparation. The time and energy used in sample digestion are saved as well. The calibration curve between mercury absorbance in terms of peak height and weight of standard mercury in the range of 0.1-10 ng was created. The calibration curve was linear followed the equation y=2.003x10-2X– 5.14x10-4 with coefficient of determination (R2) 0.9991. The precision in term of repeatability were 14% and 5.9% rsd (n=3) at 1.2 and 868 µg kg-1 respectively. The recoveries were between 88-110%. The detection limit (LOD) was 0.1 µg kg-1 (3sd/m n=10). The amount of mercury detected in 12 whitening cream samples sold in Chonburi province during the year 2019 were within the safety standard permitted in general cosmetics under the notification of the Ministry of Public except two samples were over the permitted standard.

The aim of this research was to study the influence of sucrose on the degradation of anthocyanins in makiang jam. Makiang flesh was prepared by three different methods. In the first method makiang flesh was mixed with sucrose at three different raitos (2:1 3:1 and 4:1) in the second method makiang flesh was soaked in sucrose solution (35 Brix) at three different ratios (1:1 1:1.5 and 1:2) and in the last method makiang flesh was prepared without addition of sucrose. After the jam processing makiang jams were stored at two different temperatures (the ambient temperature and 40 C) for 30 days to measure the degradation of anthocyanins. The results showed that the anthocyanins content in makiang jam decreased with increasing the storage time. The degradation of anthocyanins in makiang jam prepared by makiang flesh without addition of sucrose was higher than those prepared by mixing makiang flesh with sucrose or soaking makiang flesh in sucrose solution. Mixing makiang flesh with sucrose had lower anthocyanins degradation than soaking makiang flesh in sucrose solution. Makiang jam stored at the ambient temperature had lower anthocyanins degradation compared to those stored at 40 C.