Citrate-phosphate, buffer

Fig. 10.3.1 Bioluminescence spectrum of the centipede Orphaneus brevilabiatus (left panel), and the influence of pH on the luminescence of the exudate of the same centipede in 0.1 M potassium citrate/phosphate buffers (right panel). From Anderson, 1980, with permission from the American Society for Photobiology.

Assay conditions. 700 pL citrate-phosphate buffer pH 5.0, 100 pL enzyme solution (dilution if required) and 200 pL mandelonitrile stock solution (60 mmol L in citrate-phosphate buffer pH 3.5) were mixed in a cuvette with 1 cm pathlength and the increase of absorbance at 280 nm was measured for 2 min. 

Cellulase solution - dissolve 6.25 g cellulase from Trichoderma viride (Merck Ltd) in 1 I citrate-phosphate buffer, pH 4.6, immediately before use. 

Homogenization with MeOH, CH2CI2 addition of citrate-phosphate buffer centrifugation filtration... 

Figure 2. Heat stability of nisin after treatment at 100°C at pH 4.0, 6.0, and 8.0. Nisin was obtained from culture supernatant broth of Lc. lactis 11454 and resuspended in citrate-phosphate buffer.

Figure 3. Heat stability of bacteriocins from Lc, lactis FS 84, FS 90, FS 91-1, and FS 97 In citrate-phosphate buffer at pH 4.0 and 8.0.

Citrate/phosphate-buffer 1.78 g Na2HP04-2H20 (Merck) is dissolved in 50 ml demineralized water and the pH is adjusted to 5.0 with citrate solution. Subsequently, demineralized water is added until a total volume of 100 ml is obtained. 

Substrate buffer 3.79 mg 4-methylumbelliferyl-N-acetyl-a-D-glucosaminide (Moscerdam Substrates) is dissolved in 10 ml citrate/phosphate buffer. For faster dissolution, the mixture is sonicated (1 min). The substrate buffer is stored at -20°C and protected from light. 

Figure 3. Germination of lettuce and Lepidium seeds held in darkness at 25° and 20° C., respectively, after moistening with various concentrations of gibberellin A3, dissolved in unbuffered or dilute citrate phosphate buffer...

Following adjustment to pH 6.0, the solution is applied to a SP-Sephadex C-25 column in the sodium form. Amino acids are then eluted with 0.2 M citrate phosphate buffer, pH 8.0, and the effluent evaporated to dryness at 50 °C. The residue is dissolved in 0.1 N hydrochloric acid and applied to the amino acid analyser. Amino acids are separated by passing 0.2 M, pH 8 sodium citrate solution down the column. The S-methylmethionine content can then be obtained from the chromatogram, as illustrated in Fig. 8.1. The results obtained agree reasonably well with those obtained by thin-layer chromatography [13]. 

Kieselguhr, impregnated with citrate-phosphate buffer pH 5.5 containing 10% glycerine... 

RP 8 acetonitrile (96 4) pH adjusted to 8.4 with ammonia citrate-phosphate buffer (pH 2.20)-acetonitrile (65 35)... 

Add peroxidase substrate dissolved in acidic citrate/phosphate buffer and incubate 20 min (maximum) in the dark. 

Fig. 2.11. Cyclic voltammograms of a poly(aniline)-coated glassy carbon electrode (deposition charge ISO mC, geometric area 0.38 cm2), recorded at 5 mV s 1 in oxygen-free 0.1 mol dm 3 citrate/phosphate buffer at pH 5 in the absence (—), and in the presence (—), of 1 mmol dm-3 NADH. Before each scan the electrode was held at -0.3 V for 3 min to ensure complete reduction of the film.

Fig. 2.12. Plot of the current as a function of time for the oxidation of 4 mmol dm- 1 NADH at 0.2 V at a poly(aniline)-coated rotating disc electrode (area 0.38 cm2, deposition charge ISO mC) in 0.1 mol dm 1 citrate/phosphate buffer, pH 5. The rotation speed of the electrode was increased in the sequence I, 4, 9, 16, 25, 36 and 49Hz and reduced in sequence back to 1 Hz. The broken line connects segments of the curve corresponding to the different rotation speeds. Note The current decays more rapidly at the higher rotation speeds and responds rapidly to changes in rotation speed.

Fig. 2.17. Plots of the current at +0.1 V for a poly(aniline)/poly(vinylsulfonate)-coated glassy carbon electrode (deposition charge 150 mC, geometric area 0.38 cm2) rotated at 9 Hz in 0.1 mol dm- 1 citrate/phosphate buffer at pH 7 as a function of the NADH concentration showing the stability of the electrode response. Four replicate calibration curves recorded in succession over 4h using the same electrode are shown ( ) run 1 ( ) run 2 (A) run 3 and (O) run 4. The solid line is drawn as a guide for the eye.

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