Investigation into the method for stable isotope analysis of water in apple using laser spectroscopic to assist in verifying the geographical origin of products

Abstract

This study aim at the development of a cryogenic vacuum extraction method for extracting water in apple following the determination of stable isotope composition of hydrogen (ð²H) and oxygen (ð¹⁸O) of water in apple from the United State and New Zealand using a laser LWIA - 24D - Los Gatos spectrometer for tracing the geographical origin of products. Results of extracting - weighing and checking t-test at the significance level α=5% and p<0.05 showed that the extraction method functioned stably, the amount of water collected ensured no fractionation of deuterium and oxygen-18,  there are no statistical difference between the mean values of water amount collected from different extraction batches of the same sample. The standard deviation among extraction batches less than or equal to 0.03 (g). The analytical results on laser spectroscopy showed that the stability and reliability met the manufacturers' criteria for the analysis of isotopic composition ð²H and ð¹⁸O with the standard deviation of all samples be less than 0.3‰ and standard errors less than 0.3‰. The results of the stable isotope analysis of water in apple samples from the US and New Zealand showed the difference in the composition of hydrogen and oxygen in apple’s water so that it is believed that there is a basis to support the assessment of the authenticity of the products.