# Quantification of Microplastics in Plastic-Bottled Chinese Baijiu Using Micro-FTIR in Imaging Mode
## 3 Results
### Distribution of the Size and Shape of Microplastics  
The analysis of size distribution demonstrated that microplastics, which were present in the plastic-bottled Chinese baijiu samples, had sizes ranging from 25 \(\upmu\)m to 5 mm. The majority of them fell in the category of 50-300 \(\upmu\)m. The instruments used to measure the size had a detection limit of 25 \(\upmu\)m, and the filters employed had a mesh size of 0.4 \(\upmu\)m. Microplastics were segregated into six size classes (25-50 \(\upmu\)m, 50-100 \(\upmu\)m, 100-300 \(\upmu\)m, 300-500 \(\upmu\)m, 500-1000 \(\upmu\)m, and 1000-5000 \(\upmu\)m) and differentiated into two types: fibers and fragments.  
Figure 4 illustrates the distribution of microplastics in RedStar Erguotou Liquor by length. The majority of microplastics in this particular brand fall within the 50-100 \(\upmu\)m and 100-300 \(\upmu\)m length ranges, accounting for 26.1% and 44.2% of the total particles, respectively, followed by microplastics ranging from 300-500 \(\upmu\)m in length, which constituted 11.8% of the particles. In addition, RedStar Erguotou Liquor exhibited particle size distributions of 1000-5000 \(\upmu\)m and 25-50 \(\upmu\)m, accounting for 4.4% and 5.4% of the particles, respectively. It is noteworthy that the other five Chinese baijiu brands bottled in plastic showed similar particle size distributions.  
The analysis investigated the shapes of microplastic particles in the plastic-bottled Chinese baijiu samples. Figure 5 displays the distribution of microplastic shapes across the six brands of plastic-bottled liquors that were examined. The findings demonstrated that the types of microplastic particles differed among the various brands. Fibers were the most frequent type of microplastic particles identified, making up 88.2% of the total number of microplastic particles detected in Mao Pu pure grain wine. In Bu Lao Tan grain wine, the dominant microplastics were granules and fragments, making up 64% of all microplastic  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multicolumn{1}{c}{**Sample**} & \multicolumn{2}{c}{**Average Microplastic Abundance (Items/500 mL)**} & \multicolumn{2}{c}{**Total Microplastic**} & \multirow{2}{*}{**RSD (\%)**} \\  & & & **Abundance (Items/500 mL)** & & \\ \hline Bu Lao Tan grain wine (BLT) & Cellulose 147, PET 41, PS 68, PU18, PA 125, PVC 11 & 410 & 422 & 398 & 0.029 \\ Mao Pu Pure grain wine & Cellulose 833, PET 9, PU3, PA 56, PVC 43 & 942 & 1024 & 866 & 0.084 \\ Niu Lan Shan Erguotou & Cellulose 214, PET 16, PU14, PA 31, PVC 1 & 274 & 252 & 300 & 0.087 \\ Liquor (NLS) & Cellulose 89, PU17, PA 61, PVC 5, PP 1 & 178 & 143 & 198 & 0.161 \\ Hui Yi Erguotou Liquor (HY) & Cellulose 172, PET 8, PU10, PA40, PVC 1, PP 1 & 240 & 256 & 200 & 0.124 \\ Chun liang Liquor (CLYJ) & Cellulose 334, PET 3, PS 4, PU11, PA135, PVC 1, PP 20 & 496 & 538 & 490 & 0.051 \\ Blank (Milli-Q water) & Cellulose 4 & 4 & 4 & 4 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Microplastic abundance of six brands of plastic-bottled Chinese baijiu (items/500 mL).  
particles. Notably, fibers accounted for 35.9% of the microplastics in Bu Lao Tan grain wine. In Hui Yi Erguotou Liquor, the microplastic particles were predominantly fibers and fragments, with fibers representing 51% and fragments accounting for the remaining 49% of the total microplastic particles. These findings suggest that the shapes of microplastic particles in plastic-bottled Chinese baijiu may differ depending on the brand, revealing the range of sources and types of microplastics present in the samples.