Glutamic acid sensors

Glutamic Acid Sensor. A rapid automatic measurement of glutamic acid in fermentation media is required in fermentation industries. 

Another problem is the cahbration of BOD-sensor to enable the comparison with the conventional BOD. For cahbrating a BOD-sensor, a glucose-glutamic acid standard solution (the so-called GGA-standard), which is also used as standard solution for the BODj-method [71], or aqueous solutions of glucose or glycerol with a defined BODj [43,54] are used. 

The microbial sensor for acetic acid was applied to a fermentation broth of glutamic acid. The concentration of acetic acid was determined by the microbial sensor and by a gas chromatographic method. Good agreement was obtained the regression coefficient was 1.04 for 26 experiments. 

The concentrations of glutamic acid in some fermentation broths were determined by the microbial sensor and by the Auto-analyzer method. The results were in good agreement. The response of the sensor was constant for more than 3 weeks and 1500 assays. Thus the microbial sensor appears to be very attractive for the determination of glutamic acid. 

Figure 16.7 Schematic representation illustrating the selective diffusion of dopamine over glutamic acid and tyrosine into the mesopores of PLA-coated MSN-based fluorescence sensor system.

Sensors for particle size characterization used for crystallization include ultrasound attenuation measurement/ " laser diffraction/ and laser backscatteiing/ commercially called focused beam reflectance measurement (FBRM). Ultrasonic attenuation spectroscopy has been used to monitor the crystallization process parameters such as the crystal size distribution, concentration, and the onset of nucleation during batch crystallization of L-glutamic acid/ Off-line laser diffraction has been used to measure the crystal size distribution in the development of the crystallization process for a pharmaceutical intermediate/ ... 

Hikuma, M., Obana, H., Yasuda, I. . Karube, L, and Suzuki, S. (1980) A potentiometric microbial sensor based on immobilized Escherichia coli for glutamic acid. Analytica Chimica Acta, 116 (1), 61-67. 

Extensive research and development of microbial sensors has been carried out by Suzuki et al. (89-94) and Rechnitz et al. (95-97) (see Table III). Microbial sensors consisting of membrane-bound whole cells and an oxygen electrode were constructed for the determination of substrates such as assimilable sugars, acetic acid, alcohols and ammonia, and for the estimation of biochemical oxygen demand (BOD) (98-104). Glutamic acid was determined with a microbial sensor which consists of membrane-bound whole cells containing glutamate decarboxylase and a carbon dioxide gas electrode. These microbial sensors have been applied and evaluated for on-line measurements in fermentation processes (105,106). 

Recently, selective oxidases for L-lysine (EC 1.4.3.-) (Romette et al., 1983) and L-glutamate (EC 1.4.3.11) have been employed in enzyme electrodes. Wollenberger et al. (1989) developed a sensor based on glutamate oxidase from Streptomyces endus, which permits selective measurement of glutamic acid between 1 pmol/1 and 1 mmol/1 with a sample frequency of 120/h. In contrast, a sensor using an analogous... 

Fig. 110. Measuring curves of BOD sensors containing different microorganisms. Glucose-glutamic acid (GGA) standard solutions were used as BOD reference.

An assay for diagnosing type I diabetes mellitus based on the detection of anti-glutamic acid decarboxylase (GAD) antibodies in buffer by a Biacore 2000, is presented in [47,48]. Biotinylated GAD was immobihzed on a streptavidin-coated surface. The effect of mixed SAM composition (differing in ratios of hydroxyl- and carboxyl-terminated alkanethiols) on the sensitivity of the sensor was investigated. On SPR sensor chips prepared with the optimized SAM composition (10 1 ratio of 3-mercaptopropanol to 11-mercaptoundecanoic acid), a concentration of anti-GAD as low as... 

Response curves of Bacillus subtilis- and THchosporon cutaneum-based sensors to glucose-glutamic acid standard solution containing 22 mg/L biochemical oxygen demand (BOD). Reproduced from (420] with permission from Springer-Verlag. 

The next group of multimembrane systems comprises membranes sensitized biologically using immobilized enzymes or microorganisms. Species that are directly sensed by an ISE are produced in the enzymatic reaction of the analyte. Examples of such sensors are those used for determination of urea in milk, based on immobilized urease and measurement of a pH change. An example of the application of bacteria strains is the use of immobilized recombinant Escherichia coli coupled with a pH electrode. Such electrodes have been used for determination of cephalosporins. When this bacterial strain is coupled with a CO2 gas sensor, glutamic acid determination can be carried out. 

L-glutamine Glutaminase L-glutamine glutamic acid -E NH3 NEl4+-glass or polymer NEl3-gas sensor... 

Copper(ll) complexes of a glutamic acid derived diamido-diamino ligands 12 (Fig. 5c) containing anthracene units were also used as enantioselective sensors for a-hydroxy acids (in particular mandelate) and amino acids [68]. The ligand fluorescence was quenched by copper(ll) and recovered by addition of the analytes. A mechanism involving photoinduced electron transfer (PET) was proposed, and the conditional stability constants of the ternary complexes was found to be different for the two mandelate enantiomers (with KiJK = 15.2) in this study. 

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