Abstract：
A simple and time-saving colorimetric method was developed to quantify sulfonamides (SAAs) in milk via inhibition of the human carbonic anhydrase II (hCAII)-like activity of ZIF-8 that can hydrolyze p-nitrophenyl acetate (pNPA) to p-nitrophenol (pNP), following the color change from yellow to colorless. Effects of different reaction conditions, including pH, temperature, amount of ZIF-8, and incubation time, were investigated. The value of Michaelis-Menten constant (Km) is measured to be 0.15 mM, which exhibits high affinity to pNPA. The IC50 (0.17, 0.24, and 0.60 mM) and inhibition constant (Ki) (0.09, 0.13, and 0.33 mM) of sulfamethazine (SD), sulfadimethoxine (SDM), and sulfathiazole (ST) on ZIF-8 were measured, respectively. Moreover, the activity of ZIF-8 remains more than 90.0% of its initial activity after 30 days\' storage. The colorimetric method for SD, SDM, and ST determination was established at the linear ranges of 6.3-750.0 μM (1.75-208.75 mg/kg), 6.3-750.0 μM (1.96-232.75 mg/kg), and 5.0-1250.0 μM (1.28-319.15 mg/kg) with limit of detection of 4.3, 3.2, and 3.9 μΜ (1.2, 0.99, and 0.96 mg/kg), respectively. In addition, the spiked recoveries of SAAs in milk sample are in the range of 81.6%-106.7% with RSD less than 6.5%. In short, the developed colorimetric method can achieve rapid analysis of SAAs in milk with simple operations.
摘要：
开发了一种简单而省时的比色法，通过抑制ZIF-8的人碳酸酐酶II（hCAII）样活性来定量牛奶中的磺胺类（SAAs），该活性可以将对硝基苯基乙酸酯（pNPA）水解为对硝基苯酚（pNP），颜色从黄色变为无色。不同反应条件的影响,包括pH值,温度,ZIF-8的量和孵育时间，被调查了。米氏-Menten常数（Km）的值被测量为0.15mM，对pNPA表现出高亲和力。磺胺二甲嘧啶（SD）的IC50（0.17、0.24和0.60mM）和抑制常数（Ki）（0.09、0.13和0.33mM），磺胺二甲氧嘧啶(SDM),对ZIF-8上的磺胺噻唑（ST）进行了测量，分别。此外，储存30天后，ZIF-8的活性仍超过其初始活性的90.0%。SD的比色法，SDM,和ST测定在6.3-750.0μM（1.75-208.75mg/kg）的线性范围内建立，6.3-750.0μM（1.96-232.75mg/kg），和5.0-1250.0μM（1.28-319.15mg/kg），检出限为4.3、3.2和3.9μM（1.2、0.99和0.96mg/kg），分别。此外,牛奶样品中SAAs的加标回收率在81.6％-106.7％之间，RSD小于6.5％。总之,所开发的比色法操作简单，可实现牛奶中SAAs的快速分析。
