## 3 Selected Applications of GBMs in Key Miniaturized Techniques
### Dispersive Micro Solid-Phase Extraction  
Aligned with introducing alternative technologies to conventional SPE, d-\(\mu\)-SPE emerged as a potential analytical approach for sample preparation [106]. This miniaturization strategy involves dispersing the sorbent into the sample matrix to enhance the kinetic interaction between the sorbent particles and the target analyte(s) [107; 108]. The close contact between the sorbent particles and the analytes creates an advantageous condition reflecting improved extraction achievement. The enhanced adsorption capacity of this method relies on retaining matrix components while the analyte remains in the liquid phase, achieved through the introduction of the dispersed sorbent [109]. Given the critical role of the dispersion sorbent in enhancing analytical performance, evaluating the assisted dispersion approach primarily involves studying the utilization of external energy sources (such as mechanical stirring) or chemicals [110]. Employing GBMs as dispersion sorbents in d-\(\upmu\)-SPE has proven to be a versatile strategy for tackling the analysis of complex matrices [21]. Recently, [PERSON] [111] outlined the utilization of GO nanosheets in conjunction with complexing reagents such as neocuproine or batoucuproine as the dispersion sorbent for assessing trace-level metal ions in food samples, followed by inductively coupled plasma-optical emission spectrometry (ICP-OES). According to the results, the utilization of both neocuproine and batoucuproine reagents enhanced the adsorption of GO by forming cationic complexes with metal ions. Furthermore, a significant achievement was made regarding the preconcentration factor of the GO/neocuproine and GO/batoucuproine systems. Both sorbents exhibited preconcentration factors ranging from 10 to 100 and 20 to 200, respectively. Moreover, LOQ values ranged from 0.035 to 0.84, with recovery values over 90% for evaluating heavy metals in food. The developed method was demonstrated as a promising analytical tool for assessing heavy metals in food matrices. Another heavy metal detection was proposed by [PERSON] et al. [112] focusing on Cadmium (Cd), using a d-\(\upmu\)-SPE protocol with a GO dispersive sorbent in rose dry wine samples, analyzed by solution anode glow discharge optical emission spectrometry (SAGD-OES). The authors thoroughly investigated the sorption of Cd in comparison to common ions found in the matrix, such as Na+, K+, Mg2+, and Ca2+. The results revealed the remarkable adsorption capability of the GO phase, attributed to its functional groups (e.g., -COOH, -OH, =O, and epoxy) acting as electron pair donors, forming strong covalent bonds with metal ions. While most ions were adsorbed onto the GO phase, the analysis emphasized the superior affinity of the GO sorbent towards Cd ions over alkali and alkaline metals. This observation suggests that the strength of covalent bonds with d-block metals like Cd surpassed that of other ions, indicating the GO sorbent's pronounced selectivity towards Cd ions. While adopting GBMs as dispersion sorbents has yielded significant advantages for d-\(\upmu\)-SPE, a notable drawback persists: their tendency to aggregate in such applications [110]. This aggregation tendency can diminish analyte adsorption, reducing the available contact area between the sorbent and analyte. As demonstrated in this review, using biosorbents like chitosan can mitigate this aggregation trend, offering a promising solution to enhance the efficacy of d-\(\upmu\)-SPE methodologies. As evidenced by literature examples, biosorbents have already found application in d-\(\upmu\)SPE methodologies. For instance, [PERSON] et al. [113] utilized green hairy basil seed mucilage biosorbent for d-\(\upmu\)-SPE extraction of tetracyclines in bovine milk. This study showcased the biosorbent's ability to enhance contact between sorbent and analytes, resulting in remarkable recovery values ranging from 83.1% to 109.9%. Moreover, there's a growing emphasis on developing environmentally friendly biosorbents based on GBMs.