Sodium borate, solution preparation

Carbamate pesticides are best analyzed by HPLC using postcolumn deriva-tization technique. Some common carbamate pesticides are listed in Table 2.19.1. Compounds are separated on a C-18 analytical column and then hydrolyzed with 0.05 N sodium hydroxide. Hydrolysis converts the carbamates to their methyl amines which are then reacted with o-phthalaldehyde and 2-mercaptoethanol to form highly fluorescent derivatives. The derivatives are detected by a fluorescence detector. o-Phthaladehyde reaction solution is prepared by mixing a 10-mL aliquot of 1% o-phalaldehyde solution in methanol to 10 mL of acetonitrile containing 100 pL of 2-mercaptoethanol and then diluting to 1 L with 0.05 N sodium borate solution. 

Mobile phase MeOH buffer 50 50 (Prepare buffer by dissolving 6.183 g boric acid and 1.461 g NaCl in 500 mL water, adjust pH to 6.4 with sodium borate solution.)... 

Sodium borate (decahydrate, hydrated borax) [1303-96-4] M 381.2, m 75 (loses 5H2O at 60 ), d 1.73. Crystd from water (3.3mL/g) keeping below 55° to avoid formation of the pentahydrate. Filtered at the pump, washed with water and equilibrated for several days in a desiccator containing an aqueous solution saturated with respect to sucrose and NaCl. Borax can be prepared more quickly (but its water content is somewhat variable) by washing the recrystd material at the pump with water, followed by 95% EtOH, then Et20, and air dried at room temperature for 12-18h on a clock glass. 

From this material, samples are cut and swelled to constant weight in a buffered saline solution prepared from 8.43 g sodium chloride (NaCl), 9.26 g boric acid (H3BO3), 1.0 g sodium borate (Na3B03), and 0.1 g of the disodium salt of the dihydrate of ethylenediaminetetraacetic acid [Na2 EDTA -(/ 0)21 ini L of distilled water. 

Prepare a carboxylated QD solution in lOmM sodium borate, pH 7.4 (reaction buffer), at a concentration of 1 pM. The supplier of QDs usually will provide the reagent concentration as a molar quantity, which treats each particle as though it was a single molecule. A typical QD solution as obtained from a manufacturer may be about 8 pM starting concentration. 

Prepare a solution of TCPK-trypsin in 0.1 M sodium borate, pH 7.5, at a concentration of 400 ng/pl. Add 10 pi of the trypsin solution to each sample and incubate at 37°C for 12-16 hours or overnight with mixing. 

Tamsulosin was the IS. Stock solutions of doxazosine and tamsulosin (1 mg/mL) were prepared in water/acetonitrile (50 50 v/v) and stored at 4°C in the dark. Aliquots (0.5 mL) of plasma samples were spiked with 50 fiL of tamsulosin (250 ng/mL), mixed with 0.5 mL of 0.4M sodium borate buffer (pH 10) followed by 2 mL diethylether, vortexed for 5 min, and centrifuged at 3800 rpm for 5 min. The organic layer was collected, evaporated to dryness at 40°C under a gentle nitrogen stream, reconstituted with 100 ftL of water/acetonitrile (50 50 v/v), filtered through a 0.45 fim Mil-lipore PTFE hydrophilic filter, and assayed injection volume was 5 fiL. 

What molar ratio of salt/acid (sodium borate to boric acid) is required to prepare a buffer solution having a pH of 9.6 The pKa of boric acid is 9.24 at 25°C. 

Prepare an IgG solution of at least 3 mg/mL in sodium borate buffer. If the antibodies have been stored in sodium azide, the azide must be removed prior to conjugation. Dialyze extensively against the borate buffer (see Note 2). 

A boron analog - sodium borohydride - was prepared by reaction of sodium hydride with trimethyl borate [84 or with sodium fluoroborate and hydrogen [55], and gives, on treatment with boron trifluoride or aluminum chloride, borane (diborane) [86. Borane is a strong Lewis acid and forms complexes with many Lewis bases. Some of them, such as complexes with dimethyl sulfide, trimethyl amine and others, are sufficiently stable to have been made commercially available. Some others should be handled with precautions. A spontaneous explosion of a molar solution of borane in tetrahydrofuran stored at less than 15° out of direct sunlight has been reported [87]. 

Dialyze the phycobiliprotein into 50 mM sodium borate, 0.3 M NaCl, pH 8.5 (note commercial preparations of these proteins come as an ammonium sulfate suspension). After dialysis, adjust the protein solution to a concentration of 1 mg/ml. Higher protein concentrations may be used, but the amount of cross-linking reagent added to each milliliter of the reaction should be proportionally scaled up, as well. Protect the protein solution from undue exposure to light. 

Stock solutions (1000 mg/L in acetonitrile) of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 2,4-dinitrotoluene (2,4-DNT), and 4-amino-2,6-dinitrotoluene (4-Am-2,6-DNT) (Supelco). Sodium dodecyl sulfate (SDS) and sodium borate 10-hydrate. Standard solutions of the various explosives should be prepared daily (using the proper safety precautions) in an SDS-containing electrophoresis buffer. Platinum and silver wires, 0.1mm diameter. 

Titanium borides have been reviewed66,67 and optimum conditions given for then-preparation from boron and titanium oxides.68 Electrolysis of a solution containing cryolite, NaOH, sodium borate, NaCl, and rutile at 1100°C results in the crystallization of TiB2 at the cathode.69 Mixtures of boride and nitride phases are formed during the interaction of BN with TiB2 at 1200—2000 °C.70... 

The supporting electrolyte for all free-solution separations reported here was a borate buffer (pH 8.1 or 8.26, 0.10 M or 0.20 M), prepared from reagent-grade sodium borate decahydrate and boric acid (J.T Baker). 

This gel is usually prepared by adding 1 part of a 4 mass % aqueous sodium borate (borax) solution to 3 or 4 parts of a 4 mass % aqueous poly(vinyI alcohol) solution. 

Protein (approx. 3 mg/ml) is dissolved in 0.2 M sodium borate buffer pH 9.0. To 2.0 ml of this solution, at 0°C, is added a 50 pi aliquot of a freshly prepared solution of NaBH4 (40 mg/ml). Five consecutive increments of 1 pi of 18% (v/v) aqueous formaldehyde solution are then added at 5 min intervals. At the end of 30 min, the reaction mixture is transferred to dialysis tubing and exhaustively dialyzed against ice-cold deionized water at 4°C. The protein derivative is recovered by lyophilization. 

Sodium borate is used in pharmaceutical applications similarly to boric acid (see Boric Acid). It has been used externally as a mild astringent and as an emulsifying agent in creams. It has also been used in lozenges, mouthwashes, otic preparations (0.3% w/v), and ophthalmic solutions (0.03-1.0% w/v). Sodium borate has additionally been investigated in the prevention of crystal formation in freeze-dried solutions. Preparations of sodium borate in honey have historically been used as paints for the throat, tongue, and mouth, but such use is now inadvisable because of concerns about toxicity in such applications, see Section 14. Sodium borate is also used in cosmetics such as moisturizers, deodorants, and shampoos. 

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