Department of Mechanical Engineering, Iowa State University, Ames, IA, 50011, USA.
Materials Analysis and Research Laboratory, Iowa State University, Ames, IA, 50011, USA.
Mikrochim Acta. 2023 Jan 3;190(1):43. doi: 10.1007/s00604-022-05615-9.
Nitrite is an important food additive for cured meats; however, high nitrite levels pose adverse health effects to humans. Hence, monitoring nitrite concentration is critical to comply with limits imposed by regulatory agencies. Laser-induced graphene (LIG) has proven to be a scalable manufacturing alternative to produce high-performance electrochemical transducers for sensors. Herein, we expand upon initial LIG studies by fabricating hydrophilic and hydrophobic LIG that are subsequently converted into ion-selective sensors to monitor nitrite in food samples with comparable performance to the standard photometric method (Griess method). The hydrophobic LIG resulted in an ion-selective electrode with improved potential stability due partly to a decrease in the water layer between the electrode and the nitrite poly(vinyl) chloride-based ion-selective membrane. These resultant nitrite ion-selective sensors displayed Nernstian response behavior with a sensitivity of 59.5 mV dec, a detection limit of 0.3 ± 0.1 mg L (mean ± standard deviation), and a broad linear sensing range from 10 to 10 M, which was significantly larger than currently published nitrite methods. Nitrite levels were determined directly in food extract samples of sausage, ham, and bacon for 5 min. These sensor metrics are significant as regulatory agencies limit nitrite levels up to 200 mg L in finished products to reduce the potential formation of nitrosamine (carcinogenic compound). These results demonstrate the versatility of LIG as a platform for ion-selective-LIG sensors and simple, efficient, and scalable electrochemical sensing in general while demonstrating a promising alternative to monitor nitrite levels in food products ensuring regulatory compliance.
亚硝酸盐是腌制肉类中的一种重要食品添加剂；然而，高亚硝酸盐水平对人类健康有不利影响。因此，监测亚硝酸盐浓度对于遵守监管机构规定的限制至关重要。激光诱导石墨烯（LIG）已被证明是一种可扩展的制造替代品，可以生产用于传感器的高性能电化学换能器。在此，我们通过制造亲水性和疏水性 LIG 扩展了最初的 LIG 研究，然后将其转化为离子选择性传感器，以监测食品样品中的亚硝酸盐，其性能可与标准比色法（Griess 法）相媲美。疏水性 LIG 导致离子选择性电极的电位稳定性得到改善，部分原因是电极和基于聚氯乙烯的亚硝酸盐离子选择性膜之间的水层减少。这些所得的亚硝酸盐离子选择性传感器表现出 Nernstian 响应行为，灵敏度为 59.5 mV dec，检测限为 0.3±0.1 mg L（平均值±标准偏差），线性传感范围从 10 到 10 M，明显大于目前发表的亚硝酸盐方法。直接在香肠、火腿和培根的食品提取物样品中测定亚硝酸盐水平，只需 5 分钟。这些传感器的指标非常重要，因为监管机构将成品中亚硝酸盐的含量限制在 200 mg L 以内，以减少亚硝胺（致癌化合物）的潜在形成。这些结果表明 LIG 作为离子选择性 LIG 传感器平台的多功能性，以及一般简单、高效和可扩展的电化学传感，同时展示了一种有前途的替代方法来监测食品中亚硝酸盐水平，以确保法规遵从性。
