Sodium acetate, calibrant

Procedure To an aliquot of the sample solution containing 12.5 - 305 p.g of platinum(IV) were added 5 ml of hydrochloric acid - sodium acetate buffer of pH 2.1, 1 ml of O.IM Cu(II) sulphate solution, and 3.0 ml of 0.5% propericiazine solution. The solution was diluted to 25 ml with distilled water, mixed thoroughly, and the absorbance measured at 520 nm against a reagent blank solution after 10 min. The platinum concentration of the sample solution was determined using a standar d calibration curve. 

The preliminary precipitation of proteins from milk is realized through the addition of solutions of acetic acid (1,7 mol/1) and sodium acetate (lmol/1) at t = 40-45°C before chromatographic isolation of OxTC. The precipitated proteins are separated by filtration. OxTC is detenuined in filtrate after its isolation on chromatographic column. Contents of OxTC was determined on calibration curve which is linear within concentration range 0,01-1,0 p.g/ml. 

A calibration curve for the range 0.2-10 mg fluoride ion per 100 mL is constructed as follows. Add the appropriate amount of standard sodium fluoride solution, 25 mL of 2-methoxyethanol, and 10 mg of a buffer [0.1 Af in both sodium acetate and acetic (ethanoic) acid] to a 100 mL graduated flask. Dilute to volume with distilled water and add about 0.05 g of thorium chloranilate. Shake the flask intermittently for 30 minutes (the reaction in the presence of 2-methoxyethanol is about 90 per cent complete after 30 minutes and almost complete after 1 hour) and filter about 10 mL of the solution through a dry Whatman No. 42 filter paper. Measure the absorbance of the filtrate in a 1 cm cell at 540 nm (yellow-green filter) against a blank, prepared in the same manner, using a suitable spectrophotometer. Prepare a calibration curve for the concentration range 0.0-0.2 mg fluoride ion per 100 mL in the same way, but add only 10.0 mL of 2-methoxyethanol measure the absorbance of the filtrate in a 1 cm silica cell at 330 nm. 

The most important type of mixed solution is a buffer, a solution in which the pH resists change when small amounts of strong acids or bases are added. Buffers are used to calibrate pH meters, to culture bacteria, and to control the pH of solutions in which chemical reactions are taking place. They are also administered intravenously to hospital patients. Human blood plasma is buffered to pH = 7.4 the ocean is buffered to about pH = 8.4 by a complex buffering process that depends on the presence of hydrogen carbonates and silicates. A buffer consists of an aqueous solution of a weak acid and its conjugate base supplied as a salt, or a weak base and its conjugate acid supplied as a salt. Examples are a solution of acetic acid and sodium acetate and a solution of ammonia and ammonium chloride. 

Row 45, item pH A value of 4.8 in a series of values around 6.2 is highly suspicious if the calibration of the electrode involves the use of an acetic acid/sodium acetate buffer (pK = 4.6)... 

Fletsch and Richards [51] determined fluoride in seawater spectrophotometri-cally as the cerium alizarin complex. The cerium alizarin complex and chelate was formed in 20% aqueous acetone at pH 4.35 (sodium acetate buffer) and, after 20-60 min, the extinction measured at 625 nm (2.5 cm cell) against water. The calibration graph was rectilinear for 8-200 ig/l fluoride the mean standard deviation was 10 xg/l at a concentration of 1100 ig/l fluoride. 

One problem encountered with the NH probe was that its calibration drifted with time, thus requiring frequent recalibration of the probe. For this reason the probe was abandoned when the measurements with sodium acetate were made. 

The assay is more or less the same as that described for the paracetamol tablets except that the tablets are extracted with 0.05 M sodium acetate buffer pH 4.4. The calibration standard solutions are prepared so that they contain both aspirin and paracetamol in 0.05 M sodium acetate buffer pH 4.4 in the concentration range 1.0-1.5 mg/100 ml. 

A chromatographic mobile phase consisting of acetonitrile/0.1 M sodium acetate buffer pH 4.0 (70 30) is prepared. Separate stock solutions in 250 ml of chromatographic mobile phase containing miconazole nitrate (200 20 mg) and econazole nitrate (200 20 mg) (internal standard) are prepared. 25 ml of econazole nitrate stock solution is transferred to five 100 ml volumetric flasks and varying amounts of miconazole stock solution 15, 20, 25, 30 and 35 ml are added to the five flasks. The flasks containing the calibration series are diluted to volume with mobile phase. A sample of cream containing 20 mg miconazole nitrate is shaken with 25 ml... 

The assay is carried out according to Baum et al. [ 1 ]. Each plate contains a calibration curve using the nitrocatechol solution at absolute concentrations of 5 nmol (5 pi), 10 nmol (10 pi), 20 nmol (20 pi), 50 nmol (50 pi), and 100 nmol (100 pi). All standards are run in duplicate and the volume for each well is adjusted to 150 pi with demineralized water. A substrate blank that does not contain leukocyte homogenate is included for both incubation times. In addition, a patient blank (no substrate buffer) and one plate blank (sodium acetate buffer only) is included in the assay. 

Include with the five sets of termination tubes a series of five tubes to be used to establish the calibration curve. Place in the calibration tubes 0, 5, 10, 15, and 20 pi of 1 mM galacturonic acid. Then add 20 mM sodium acetate to bring the volume to 0.1 ml and add 1 ml BCA working reagent (final volume 1.1 ml/tube). 

Effect of pH on the addition reactions was studied from pH 4 to 10. For pH values below 7, the reaction was buffered with a 25 mM sodium acetate solution whereas for pH values above 7, a 25 mM disodium tetraborate solution was used the pH was adjusted by adding either HC1 or NaOH. The combination electrode used for the determination of experimental pH, was calibrated with National Bureau of Standards (NBS) buffers for Milli-Q water (36) and tris(hydroxymethyl)aminomethane (TRIS) buffers for seawater (37) and NaCl solutions (38) on the pHF (free proton) scale. Since the addition of reactants caused a small pH change in the buffered medium, the experimental pH values shown in the results were measured after the reactants were added to reaction bottle. Samples from low pH reaction series were adjusted topH 9 by addition of a strong borate buffer just prior to HPLC analysis. Inis was necessary because thiol analysis using o-phthalaldehyde requires this pH for optimum derivatization. 

Ash is a measure of residual sodium acetate. A simple method consists of dissolving the PVA in water, diluting to a known concentration of about 0.5 wt %, and measuring the electrical conductivity of the solution at 30°C. The amount of sodium acetate is established by comparing the result to a calibration curve. A more lengthy method involves the extraction of the PVA with methanol using a Soxhlet extractor. The methanol is evaporated and water is added. The solution is titrated using hydrochloric acid in order to determine the amount of sodium acetate. 

A. Methyl y,M-diahlorocarbamate. A 2-L, two-necked, round-bottomed flask equipped with a magnetic stirrer, gas inlet and gas outlet is charged with 84 g (1.1 mol) of methyl carbamate, 210 g (2.6 mol) of sodium acetate, 21 g (0.35 mol) of glacial acetic acid and 400 mL of water and cooled to -10° to -15°C (Note 1). About 175 g (2.5 mol) of chlorine is condensed in a calibrated Schlenk tube (Note 2) cooled with dry ice/methanol. The cooling bath is replaced by an ice-water bath (Note 3) and chlorine is passed slowly... 

Perbromic acid and perbromates are most readily assayed by determination of their oxidizing power after reduction with hydrogen bromide, as described earlier in this article. Traces of fluoride in the acid or salts may be determined potentio-metrically, using a fluoride-sensitive electrode (Orion Research, Inc.) and an expanded-scale pH meter. Acid or alkaline solutions should be neutralized or buffered with acetic acid and sodium acetate before the determination. The electrode response should be calibrated against similar solutions of known fluoride content. 

Phenylthiocarbamoyl-/3-alanine was purified by chromatography on a LiChrosphere 100 C18 column (4.6 mm x 250 mm, 5 /xm), using a mobile phase of 50 mM sodium acetate (pH 6.0) containing 15% acetonitrile. The effluent was monitored at 245 nm. Standard samples of /3-alanine taken through the derivatization and chromatography procedures were used to prepare a calibration curve. 

Acetate Salts. Sodium acetate and sodium trifluoracetate clusters were used and produce useful reference peaks for both positive and negative ESI [10,11,23] 0.5% acetic acid in ammonium acetate solutions can be used for calibration in ESI-MS. This calibration solution, which is volatile, produces cluster ions up to m/z 1000. Therefore, it does not produce any source contamination or memory effects. Replacing acetic acid by trifluoroacetic acid (TEA) furtlier enlarges file mass range to m/z 4000, but TEA produces some memory effects and ion suppression, especially in negative-ion mode. 

Indapamide can be analyzed in blood, plasma and urine by HPLC and fluorescence methods. A specific and sensitive assay method for the analysis of indapamide in urine, blood and plasma was developed (31). The method uses a 250 x 4.6 mm i.d. Zorbax ODS (5 pm particle size) column and a mobile phase of 0.1 M sodium acetate buffer (pl =3.6)/acetonitrile at a ratio of 65/35 (v/v). This method uses an internal standard of sulfanilanilide. Calibration curves obtained by plotting the ratio of the peak height of indapamide to that of sulfanilanilide versus the concentration of indapamide were linear over the concentration ranges of 25-200 ng/mL for plasma and 50-400 ng/mL for blood and urine using UV detection at 241 nm. Another publication reports a high performance liquid chromatographic assay method for monitoring indapamide and Its major metabolite in urine (32). 

Figure 19.6 Typical ccdibration curve of an ISE by direct potentiometry. The calibration curve of the specific electrode for the chloride ion has almost an ideal slope value. The range of linear response for the different ISE extends over 4 to 6 orders of magnitude depending on the ion. Expression 19.5 leads to the estimation that an uncertainty of 0.2 mV on E leads to an inexactness of 0.8 per cent in the concentration (for a monovalent ion). Here, the TISAB consists of NaCl 1 M for adjusting the ionic force, a complexing agent for metals and a hufler mixture of acetic acid/sodium acetate.

Figure 4. Zone-length calibration of CMC and sodium acetate. Reproduced with permission from Ref. 11. Copyright 1986 Elsevier.

A 100-ml intake was used for analysis. Extraction was performed with 50 ml NaOH and 2 ml sodium acetate/acetic acid (2 mol 1 ) in 10 ml hexane. Cleanup was carried out using silica gel, followed by preconcentration over a N2 stream to a volume of 1 ml. Derivatization was performed with 10% NaBE4 in acetic acid at pH 4. Separation was by CGC (column of 30 m length, 0.32 mm internal diameter, DB-5 as stationary phase, 0.25-/rm film thickness He as carrier gas air/H2 as make-up gases injector temperature at 80°C). Detection was by QFAAS at 283.3 nm (detector temperature at 750°C). Calibration was by standard additions, using M3PbCl provided by SM T. 

Three phenylpropanoid glucosides (coniferin, kalopanaxin, syringin) were used to identify subspecies of Viscum album. These were extracted from powdered leaves and stems and separated on a C]g column (A = 264 nm). Baseline resolution and complete elution were achieved in 25 min using a 73.5/20/6.5 water/methanol/ water (0.1 M sodium acetate) mobile phase [397]. Calibration curves fi m 300 to 750ng/mL were used. 

In preparation of the samples to be measured, 0.1 mL (0.1 g) aliquot of the sample is placed into 25-mL volumetric flask followed by the addition of 5 mL of 0.01 M sodium acetate buffer and 1 mL of the iodine reagent (BCIs). The solution is then diluted to volume with deionized water to give a dilution factor of 250. The calibration standards are also prepared in the same manner from a stock calibration solution. The concentration of the KHI standards that fell in the linear range of calibration are 20 mg/L, 40 mg/L, 80 mg/L, and 120 mg/L. 

Procedure—Add a freshly prepared stock solution of ascorbic acid successively to a supporting electrolyte, consisting of an acetate buffer pH 4-7, containing 0-2 M acetic acid and 0-2 M sodium acetate and 0-005 per cent gelatin. Deaerate the solution with an indifferent gas and record the anodic curves (Fig. 36). Then plot the heights of the waves on a graph to show the dependence of the diffusion current with the concentration of ascorbic acid (Fig. 37). Finally transfer the samples to be analysed into the same supporting electrolyte as that used for the construction of the calibration curve. 

---