Glycine solution

Since formaldehyde solutions almost invariably contain formic acid, and amino-acids themselves are seldom exactly neutral, it is very important that both the formaldehyde solution and the glycine solution should before mixing be brought to the same pH (see footnote, p. 509), and for this purpose each solution is first madejWl alkaline to phenolphthalein by means of dilute sodium hydroxide solution. This preliminary neutralisation must not be confused with... 

Weigh out accurately about 2 g. of glycine, transfer to a 250 ml. graduated flask, dissolve in distilled water, make up to the mark, and mix well. Transfer 25 ml. of the solution to a conical flask, add 2 drops of phenolphthalein, and then again add dilute sodium hydroxide very carefully until the solution is just faintly pink. No v add about 10 ml. (/. ., an excess) of the neutralised formaldehyde solution the pink colour of the phenolphthalein disappears immediately and the solution becomes markedly acid. Titrate with AI io sodium hydroxide solution until the pink colour is just restored. Repeat the process with at least two further quantities of 25 ml. of the glycine solution in order to obtain consistent readings. 

Weight of glycine taken = 2 029 g. Glycine solution made up to 250 ml. 

What is the pH of a glycine solution in which the a-NHj group is one-third dissociated ... 

Remove the humidity chamber from the incubator, drain off the enzyme by tilting the slide on a paper towel. Inactivate the enzyme activity by putting the slides into a staining dish with 0.1 M glycine solution for 20 min. 

Employing experimental supersaturated solution diffusion coefficient data and the cluster di sion theory of Cussler (22), Myerson and Lo (27 attempted to estimate the average cluster size in supersaturated glycine solutions. They estimated an average cluster size on the order of two molecules. Their calculations indicated that while the average cluster size was small, large clusters of hundreds of molecules existed, only there were very few of them. Most of the molecular association was in the form of dimers and trimers. 

Water To 100 mL sample, add 2 mL glycine solution and mix. In a separate flask, place 5 mL buffer reagent and /V,/V-diethyl-p-phenylenediamine indicator solution and mix. Add 200 mg EDTA, disodium salt, and then add glycine-treated sample and mix. UVA/IS spectrometry >0.1 mg/L No data APHA1998 (Method 4500-CL02-D)... 

The stop buffer comprises 0.2 M Na2C03/glycine pH 10.5 Dissolve 21.2 g Na2C03 in 400 ml water. Dissolve 3.75 g glycine in 100 ml water. Titrate 400 ml of the Na2C03 solution with the glycine solution to pH 10.5. Add water to 1 L. This stop buffer is used in all assays unless indicated otherwise. When assays are adapted to microtiter plates, detergent (0.025% w/v Triton X-100) should be present in the stop buffers in order to minimize meniscus effects. 

Besides local toxicity, discussed above, there are numerous other modes of potential adverse interactions involving excipients (19,20). Many of these pose little threat provided the amounts of excipients are constrained to certain levels. Excessive amounts, however, can cause problems, particularly for patients who are intolerant of even modest levels. Commonly used phosphate buffers may cause calcium loss with formation of insoluble calcium phosphates when such buffers are administered in over-ambitious amounts (21). Calcium phosphate precipitation has been noted particularly in nutritional parenteral admixtures for neonates because of the high nutrient requirements. Similarly, renal toxicity has been associated with depletion of zinc and other trace metals caused by large parenteral doses of ethylenediaminete-traacetic acid (EDTA) (22). Excessive absorption of glycine solutions, when used as irrigants during transurethral resections, can cause hyponatremia, hypertension, and confusion (23). The use of preservatives has been associated with cardiac effects in a few patients (24). Premature neonates were found to be at risk for receiving toxic amounts of benzoic acid or benzyl alcohol in bacteriostatic solutions used to flush intravenous catheters (25). 

B 6. If you mix 1 mL of the 1 M glycine solution in Problem 4 with 9 mL of water, what is the final concentration of this diluted solution in mM3... 

Methionine and glycylmethionine interfered in the ammonia determination, and although color developed, no ammonia yields are reported for these compounds. A fine precipitate also appeared on nesslerizing some of the irradiated glycylglycine solutions, which prevented their analysis. The ammonia yields for glycine solutions were so low they were at the... 

Figure 3. Yield of ammonia from 2% glycyl-glycine solution as a function of temperature and dose...

The ammonia production in glycine solutions (G = 0.003) at room temperature was much lower than expected for this concentrated a solution (0.27M). G values of 0.1 to 3.0 were expected, based on the literature. However, Barron (1) has reported no detectable ammonia production in... 

HM glycine solutions and a G value of only 0.13 in a 0.1M oxygen-saturated solution using a dose of 0.05 megarad. 

Garetz, B. A., Malic, J., Myerson, A. S., Polarization switching of crystal structure in the nonphotochemical light-induced nucleation of supersaturated aqueous glycine solutions. Phys. Rev. Lett. 2002, 89. 

Fig. 4.—Dependence of Color Intensity of a D-Glucose-Glycine Solution on pH. (Curve A intensity of total color curve B intensity of color due to non-melanoidin products curve C color from melanoidin formation, by difference between A and B.164)...

An additional example for ion pair extraction of QTA (ipratropium) was described by Tang et al. mixing equine urine with alkaline saturated borax buffer prior to extraction with EE allowing to remove more lipophilic compounds. Subsequently, the EE layer was discarded and an alkaline potassium iodide-glycine solution was added to the aqueous phase. Afterwards, the ipratropium-ion pair complex was extracted twice with dichloromethane yielding in a recovery of 82 % [24] (Table 3). 

Supersaturated glycine solution + racemic a-amino acids... 

In glycine solutions at pH values below 6, the amino group is present in the positively charged form. This positive charge stabilizes the negatively charged carboxylate ion by electrostatic interaction. 

Dialyze samples against two changes of 100 vol of glycine solution overnight. 

Istre O, Jellum E, Skajaa K, Forman A. Changes in amino acids, ammonium, and coagulation factors after transcervical resection of the endometrium with a glycine solution used for uterine irrigation. Am J Obstet Gynecol 1995 172(3) 939M5. 

Norlen H, Dimberg M, Allgen LG, Vinnars E. Water and electrolytes in muscle tissue and free amino acids in muscle and plasma in connection with transurethral resection of the prostate. II. Isotonic 2.2% glycine solution as an irrigating fluid. Scand J Urol Nephrol 1990 24(2) 95-101. 

Place 2 ml of glycine solution and 2 ml of 10 per cent sodium nitrite solution in a test tube. In another tube place 2 ml of the nitrite solution and 2 ml of water. Hold both together in the left hand, and to each tube add 5 drops of dilute acetic acid, shake, and observe any reaction. What is the name of the product formed Write the equation for the reaction. 

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