A multiresidue analysis of pesticides in tea using supercritical fluid extraction (SFE) and GC-MS was developed. The preprocessing using SFE shortened the total analysis time. The SFE extract contained less matrices than the extract obtained with organic solvents. However, these matrices disturbed instrumental analysis. So, the extract was cleaned up with ENVITM-Carb/NH2 and InertSepTM SI cartridge. A recovery test was carried out for 245 pesticides spiked in samples at the level of 0.1 μg/g. Recovery rates of 178 pesticides ranged from 70 to 120%, the relative standard deviations (RSDs) were less than 15%, and quantitation limits were between 0.01 and 0.05 μg/g. Based on these results, this method is considered to be useful for multiresidue analysis of pesticides in tea samples.
In order to investigate cadmium contents in foods sold in Japan, cadmium levels in 40 seafood samples and 30 chocolate samples were measured by means of atomic absorption spectrometry and ICP-OES. We first confirmed the validity of the method according to the guidelines of the Ministry of Health, Labour and Welfare. Among 40 seafood samples investigated, cadmium was detected in 31 samples, in which the concentration exceeded half the LOQ (0.025 mg/kg), and the level was ranged from 0.03 to 0.38 mg/kg. We could not find any sample containing cadmium in excess of 2 mg/kg, which the Codex Alimentarius sets as the maximum standard value. Among 30 chocolate samples, cadmium was detected in 21 samples, and the level ranged from 0.025 to 0.54 mg/kg.
To evaluate LC methods with UV or MS detection for simultaneous analysis of deoxynivalenol (DON) and nivalenol (NIV) in wheat, an interlaboratory study was conducted in 11 laboratories. DON and NIV were purified using a multifunctional column, and their concentrations were determined using LC-UV or LC-MS(/MS). No internal standards were used. Three fortified wheat samples (0.1, 0.5 and 1 mg/kg), one naturally contaminated wheat sample, and one blank wheat sample were used. The recoveries ranged from 90% to 110% for DON and from 76% to 83% for NIV. For DON, the relative standard deviations for repeatability (RSDr) ranged from 1.1% to 7.6%. The relative standard deviations for reproducibility (RSDr) ranged from 7.2% to 25.2%. For NIV, the RSDr ranged from 2.0% to 10.7%, and the RSDr ranged from 7.0% to 31.4%. Regardless of sample and detector, the HorRat values for DON and NIV ranged from 0.4 to 1.4. Both LC-UV and LC-MS(/MS) methods were considered to be suitable for application as an official method.