Acid adjustment

The most important property of the solution is its low acidity. Such solutions can be treated by liquid-liquid extraction using both the collective and selective methods after an appropriate acidity adjustment. 

Procedure. Place 10.0 mL of the working lead solution in a 250 mL separatory funnel, add 75 mL of the ammonia-cyanide-sulphite solution and then by the cautious addition of dilute hydrochloric acid adjust the pH of the solution to 9.5 (pH-meter). This operation must be carried out slowly if the pH of the solution falls even temporarily below 9.5, HCN may be liberated and so use of a fume cupboard is necessary. Now add 7.5 mL of the dithizone reagent to the separatory funnel, followed by a further 17.5 mL of chloroform. Shake for 1 minute, allow the layers to separate, then remove the chloroform layer. Measure the absorbance of this against a blank solution, using a 1 cm cell and a wavelength of 510 nm (green filter). 

Reverse osmosis plants also are not immune from silica fouling, and where the raw water source naturally contains relatively high levels of silica, good pretreatment of the RO FW is a prerequisite. To reduce fouling of RO membranes by silica, pretreatment by acid adjustment, alum coagulation, and filtration usually is provided. 

Table III. Gelation by Acidity-Adjusted Redox Reactions Polymer = Flocon 2000 ppm in 2% NaCl Cr(III) = 90 ppm...

Similar species are formed from both the acid-adjusted redox and the Cr(III) salt - NaOH reactions. A comparison is given in Table IV. The pH of each corresponding pair at the same Cr concentration is very close, futher supporting this theory. The UV absorption at -400 nm of the redox products shifted to shorter wavelength when the starting redox mixture was made more acidic, suggesting that less hydrolyzed Cr was formed at higher acidity. This trend was observed in the preparation of Cr dates by the nNaOH + Cr(N0d reaction (Table I). 66... 

In case, the sample is acidic, adjust the pH to 6.0 with dilute ammonia solution carefully,... 

In the final method, the BGE recipe has to be described unequivocally and it is preferred to have the precise composition over pH adjustments, e.g., 0.100 mol/1 phosphoric acid, 0.090 mold triethanolamine, resulting in pH 3.0 instead of 0.100 mol/l phosphoric acid adjusted to pH 3.0 with triethanolamine. ... 

Methanesulfonic acid adjusted to pH 1.3 with triethanolamine and 60% acetonitrile. 

Running buffer 5X TBE 45mM Tris base, 45mM boric acid adjust to pH 8.0 with 0.5M EDTA. 

Prepare from a concentrated solution of sodium hydroxide that has been standardized. Standardize the diluted solution against 1 N acid. Adjust to 1 N, if necessary. 

Figure 1 Separation of impurities A, B, and C from the peak of interest (P) using seven different HPLC systems. Reprinted from [14], copyright 2004, with permission from Elsevier. (For each system the column temperature is 30°C, the detector is UV 254 nm and the gradient is a 60-min gradient from 5% to 95% organic modifier. Ml column 250 X 4.6 mm i.d. 5 pm Kromasil C4, mobile-phase acetonitrile/0.1% trifluoroacetic acid [pH 1.9] M2 column 100X4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile-phase acetonitrile/0.1% acetic acid adjusted to pH 3.5 with ammonium hydroxide M3 column 100 X 4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile-phase acetonitrile/10 mM ammonium acetate [pH 7.0] M4 column 100 X 4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile phase THF/10 mM ammonium acetate adjusted to pH 5.0 with glacial acetic acid M5 column 150 X 4.6 mm i.d. 3 pm Spherisorb ODSl, mobile-phase methanol/10 mM ammonium acetate [pH 7.0] M6 column 150 X 4.6 mm i.d. 5 pm Monitor Cl8, mobile-phase methanol/0.1% acetic acid adjusted to pH 3.5 with ammonium acetate M8 column 100 X 4.6 mm i.d. 4 pm YMC J Sphere ODS H80, mobile-phase acetonitrile/0.1% formic acid [pH 2.1] [M7 is a variation on the M8 gradient and is not shown].)...

Hupka et al. [29] developed a method for the determination of morphine and its phase II metabolites, morphine-3-beta-D-glucuronide and morphine-6-beta-D-glucuronide in the blood of heroin victims. The method is based on immunoaffinity SPE, RP-HPLC isocratic separation (mobile phase 90% lOmmol KH2PO4, 2mmol 1-heptanesulfonic acid, adjusted to pH 2.5 with H3PO4 and 10% acetonitrile flow rate 1.5 mL/min), and laser-induced native fluorescence detection. 

Urine Heat with sulfuric acid adjust pH to 9.2 GC/MS 0.2 pmol per No data Rosenberg and... 

Reaction buffer 0.1 M acetate buffer pH 4.5 mix 43 ml 0.1 M sodium acetate stock solution with 57 ml 0.1 M acetic acid. Adjust the pH to 4.5 with either acetate or acetic acid. 

To verify the part played by yeasts in color fixation (48), we prepared a synthetic alcoholic mixture (10% alcohol, 5 grams/liter tartaric acid adjusted to a pH of 3.0 with concentrated sodium hydroxide) and added a solution of macerated Cabernet Sauvignon skins. We studied the... 

To an aqueous alcoholic solution (10% alcohol, 5 grams/liter tartaric acid, adjusted to pH 3 with concentrated sodium hydroxide), add (a) anthocyanins (abut 500 mg/liter), (b) tannins (about 5 grams/liter), (c) a mixture of both at the same concentration. Other conditions call for Fe3+ ions (5 mg/liter) and aeration (Table XV). 

Figure 4. Equilibrium-rate plots of the hydrogen ion concentration vs. time during the mutarotation of 0.8M, a- and /3-D-glucopyranose in 0.01 M boric acid adjusted to pH 7 with NaOH and 25°C...

Fig. 15 Separation of ropivacaine and propranolol enantiomers using an MIP plug composed of (S)-ropivacaine MIP and (S)-propranolol MIP. The capillary was 100 cm in total length and 91.5 cm in effective length. The electrolyte contained acetonitrile/2 mol L-1 acetic acid adjusted to pH 3 by the addition of triethanolamine (90/10, v/v). The separation voltage was 15 kV, and the capillary column was thermostated to 60 °C. The MIPs were injected hydrodynamically at 50 mbar for 6 s each, and the sample was composed of 50 pmol L 1 rac-propranolol (first eluting) and rac-ropivacaine injected electrokinetically at 16 kV for 3 s. Detection was performed at 214 (top) and 195 nm (bottom) [42]...

After feed acidity adjustment, plutonium and neptunium are recovered in the NPEX process, with high yields and sufficiently low impurity levels to make them suitable for MOX fuel fabrication. 

The raffinate of the NPEX process is fed, without acidity adjustment, to a TRUEX step, where the minor actinides and the REEs are recovered. 

RNA deprotection buffer, Thermo Scientific/Dharmacon (B-001000-DP-018)—100 mM acetic acid, adjusted to pH 3.8 with TEMED... 

The weights of the raw materials added must be recorded either manually or by printout from the scales display unit. The weighing units must be regularly checked and recalibrated if needed. The capacity of the scale must be of a suitable size for the material being added. The low quantity of acid adjustment material needed requires the use of a lower total capacity scale. 

Selected examples of analytical methods used for the determination of global profiling of lipids are listed in Table 5. Extraction is usually based on simple liquid extraction, using modified Folch or Blight and Dyer extraction (4,5). For more acidic lipids, such as PSs and phosphatidic acids, adjustment of the pH in the aqueous phase is required. The analysis is most typically performed with LC-MS in RPLC mode, with the UHPLC methods gradually replacing the conventional HPLC methods. HRMS systems, such... 

Figure 3. Tryptic maps of carbonic anhydrase (A), L-asparaginase (B) and myoglobin (C). Column Hy-Tach micropellicular C-18 silica, 105x4.6mm eluent A, 20 mM phosphoric acid adjusted to pH 2.8 with NaOH, eluent B, 60% (v/v) ACN, 20 mM phosphoric acid, pH 2.8 flow rate, 1.0 ml/min. temp., 50°C. Initial column inlet pressure, 278 bars. Protein samples were carboxymethylated and subsequently digested with trypsin following the procedure of Stone et. al.

Next, further need for sensory modification is determined in tasting, and acid adjustment or fining is done if needed to balance or soften the wine. The wine is checked to be sure its bitartrate and protein stability meet the winery s requirements. The amount of SO2 is adjusted, usually to 30-35 mg/L free S02 for bottling. 

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