A method for the determination of phytol enantiomers in plant-based dairy products was established by gas chromatography-mass spectrometry (GC-MS). The pretreatment process was optimized, and the figures of merit of the proposed method such as linear relationship, precision, spiked recovery, limit of detection (LOD) and limit of quantitation (LOQ) were investigated. Results showed that in the concentration range of 0.0–1.0 μg/mL, the linearity of the method was good (r > 0.999). The LODs of E- and Z-phytanol were 0.03 and 0.04 mg/kg, respectively, and the respective LOQs were 0.09 and 0.10 mg/kg. The recoveries of E- and Z-phytanol in spiked samples were 78.6%–93.5% and 79.5%–94.7%, respectively with relative standard deviations (RSDs) less than 10%. This method is sensitive, accurate and repeatable, and can be used for the determination of phytol enantiomers in plant-based dairy products.

An analytical method for the determination of ethyl carbamate in fermented milk was established by gas chromatography-mass spectrometry (GC-MS). Sample pretreatment conditions were optimized. The analytical figures of merit of the proposed method including linear relationship, precision, spiked recovery, detection limit and quantitation limit were evaluated. Ethyl carbamate was quantitated using an external standard. The linearity of this method was good in the range of 0–200 ng/mL (r > 0.999), and the detection limit and quantitation limit of ethyl carbamate were 2.0 and 5.0 μg/kg, respectively. The recovery of the added ethyl carbamate ranged from 89.9% to 105.2%, with relative standard deviation (RSD) less than 10%. This method is sensitive, accurate and repeatable, and can meet the requirements for the determination of ethyl carbamate in fermented milk.

An analytical method was established by gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of the contents of 16 polycyclic aromatic hydrocarbons (PAHs) in infant formula. This method was applied to survey the levels of PAHs pollution of 45 infant formula samples sold online. The sample pretreatment procedure was optimized and the figures of merit of the method including linearity, precision and spiked recovery were examined. The external standard method was used for quantitation. The linearity of the method was good in the concentration range of 1–100 ng/ mL (r > 0.999), and the limit of detection (LOD) was 0.01–0.10 μg/ kg. The average recoveries at spiked concentration levels of 5, 10 and 50 μg/kg were in the range of 76.2%–103.1%, and the relative standard deviation (RSD) for precision was less than 10%. The detection rate of PAHs was 86.7% from 15 infant formula samples for babies of 0–6 months at levels of 0–1.12 μg/kg. The detection rate of PAHs was 80.0% from 15 infant formula samples for babies of 6–12 months at levels of 0–0.75 μg/kg. The detection rate of PAHs was 60% from 15 infant formula samples for babies of 12–36 months at levels of 0–0.60 μg/kg.

A method for the quantitation of formaldehyde in infant formula was established by gas chromatography (GC) and validated by gas chromatography-mass spectrometry (GC-MS). The level of formaldehyde pollution in 45 commercial infant formula samples was determined by the proposed method and the risk of dietary exposure to formaldehyde through the consumption of infant formula was evaluated. The sample pretreatment conditions were optimized and the analytical method was assessed in terms of linearity, precision, accuracy, limit of detection (LOD) and limit of quantitation (LOQ). Quantitation was performed using the external standard method. The results showed that the linearity of this method was good in the range of 0–10 μg (r > 0.999), the LOD was 0.1 mg/kg, and the LOQ was 0.3 mg/kg. The average recoveries at spiked levels of 0.3, 0.6 and 3.0 mg/kg were in the range of 88.33%–96.56%, with relative standard deviation (RSD) less than 10%. The formaldehyde content increased with increasing reconstitution temperature above 40 ℃. In order to simulate the actual consumption process, the infant formula samples were detected after being reconstituted with warm water at 40 ℃. It turned out that formaldehyde was found in all samples at levels of 0.38–2.72 mg/kg. The average formaldehyde exposure of infants of different ages was 20.40 μg/kg at 0–6 months, 21.11 μg/kg at 6–12 months and 26.74 μg/kg at 12–36 months.