Sodium hydroxide cleaning solution

M NaOH. Carefully pour the sodium hydroxide (NaOH) solution into the acid in the foam cup. Cautiously without splashing, stir the solution with a clean stirring rod. 

Rezk et al. [74] developed and validated a reversed-phase HPLC assay method for the simultaneous quantitative determination of omeprazole and its three metabolites in human plasma. The method provides excellent chromatographic resolution and peak shape for the four components and the internal standard within a 17-min run time. The simple extraction method results in a clean baseline and relatively high extraction efficiency. The method was validated over the range of 2-2000 ng/ml. The resolution and analysis for the four analytes omeprazole, hydroxyome-prazole, omeprazole sulfone, and omeprazole sulfide and the internal standard utilized a Zorbax C18 (15 cm x 3 mm, 5 /im) with a Zorbax C18 (12.5 cm x 4.6 mm) guard column. The mobile phase consisted of two components. Mobile phase A was 22 mM phosphate monobasic, adjusted to a pH of 6 with diluted sodium hydroxide. This solution was filtered through a 0.45-/im membrane filter, then mixed as 900 ml buffer to 100 ml methanol. Mobile phase B was composed of 100 ml of the phosphate buffer as mobile phase A, mixed with 800 ml of acetonitrile, 100 ml of methanol, and 100 /A of trifluoroacetic acid with an initial flow-rate of 0.55 ml/min and detection at 302 nm. 

PMMA itself does not possess ready-to-use fiinctional groups for covalent binding with biological molecules. The amine-terminated PMMA were often produced by immersing the freshly cleaned PMMA substrate into a 1.0 M ethylenediamine in dimethyl sulfoxide (DMSO) solution for 15 min at room temperature (115) or coated with a thin layer of polyethyleneimine (PEI) or polyallylamine hydrochloride (PAH). This was first treated in 1 N sodium hydroxide (NaOH) solution at 55 C for 30 min and then immersed in a PEI or PAH solution (0.2%, pH 7) at room temperature for 1 h (117). Tsai and Lin (2005) demonstrated that PEI-derivatized PMMA was used for the determination of alpha-fetoprotein by quartz crystal microbalance (QCM) (118). Furthermore, the amine-terminated PMMA could be generated by reacting with 10% hexamethylene diamine (HMD) (reaction shown in scheme 8.2) or 1,3-diaminopropane (DAP) in 100 mM borate buffer pH 11.5 for 2 h (119) or exposing to -lithioethylenediamine (120) (reaction shown in scheme 8.3). 

Obtain in a clean, dry beaker about 50. mL of approximately 0.1 M sodium hydroxide, NaOH, solution from the reagent bench. Record the exact concentration of the base in TABLE 16.1C. Rinse your buret with about 10. mL of the standard base. Then add a few milliliters of the standard base to the buret, fill the buret tip completely by manipulating the stopcock or pinch clamp, check to be certain that there are no air bubbles in the buret tip, and add the rest of your standard base to the buret. 

It is preferable to use Tollen s ammoniacal silver nitrate reagent, which is prepared as follows Dissolve 3 g. of silver nitrate in 30 ml. of water (solution A) and 3 g. of sodium hydroxide in 30 ml. of water (solution B). When the reagent is requir, mix equal volumes (say, 1 ml.) of solutions A and JB in a clean test-tube, and add dilute ammonia solution drop by drop until the silver oxide is just dissolved. Great care must be taken in the preparation and use of this reagent, which must not be heated. Only a small volume should be prepared just before use, any residue washed down the sink with a large quantity of water, and the test-tubes rinsed with dilute nitric acid. 

Mix intimately in a mortar 100 g. of sodium laevulinate, 250 g. of phosphorus sulphide (1) and 50 g. of clean dry sand. Place the mixture in a flask fitted with a condenser for distillation and a receiver (2). Heat the flask with a free flame until the reaction commences, and then remove the flame. When the reaction subsides, continue the heating until distillation ceases. Wash the distillate with 10 per cent, sodium hydroxide solution to remove acidic by-products and steam distil. Separate the crude 2-methyltliiophene from the steam distillate, dry over anhydrous calcium sulphate, and distil from a little sodium. Collect the pure compound at 113° the yield is 30 g. 

Sodium hydroxide (NaOH) and potassium hydroxide (KOH) solutions do not dissolve tantalum, but tend to destroy the metal by formation of successive layers of surface scale. The rate of the destruction increases with concentration and temperature. Damage to tantalum equipment has been experienced unexpectedly when strong alkaline solutions are used during cleaning and maintenance. 

Sulphonphthaleins. These indicators are usually supplied in the acid form. They are rendered water-soluble by adding sufficient sodium hydroxide to neutralise the sulphonic acid group. One gram of the indicator is triturated in a clean glass mortar with the appropriate quantity of 0.1 M sodium hydroxide solution, and then diluted with water to 1 L. The following volumes of 0.1 M sodium hydroxide are required for 1 g of the indicators bromophenol blue, 15.0 mL bromocresol green, 14.4 mL bromocresol purple, 18.6 mL chlorophenol red, 23.6 mL bromothymol blue, 16.0 mL phenol red, 28.4 mL thymol blue, 21.5 mL cresol red, 26.2 mL metacresol purple, 26.2 mL. 

Dissolve a known weight (ca 0.5 g) of the steel by any suitable procedure. Treat the acidic sample solution (< 200 /jg Co), containing iron in the iron(II) state, with 10-15 mL of 40 per cent (w/v) sodium citrate solution, dilute to 50-75 mL and adjust the pH to 3-4 (indicator paper) with 2M hydrochloric acid or sodium hydroxide. Cool to room temperature, add 10 mL of 3 per cent (10-volume) hydrogen peroxide and, after 3 minutes, 2mL of the reagent solution. Allow to stand for at least 30 minutes at room temperature. Extract the solution in a separatory funnel by shaking vigorously for 1 minute with 25 mL of chloroform repeat the extraction twice with 10 mL portions of chloroform. Dilute the combined extracts to 50 mL with chloroform and transfer to a clean separatory funnel. Add 20 mL of 2M hydrochloric acid, shake for 1 minute, run the chloroform layer into another separatory funnel, and shake for 1 minute with 20 mL of 2M sodium hydroxide. Determine the absorbance of the clear chloroform phase in a 1 cm cell at 530 nm. 

Spills of endosulfan, according to FAOAVHO (1975a), should be cleaned up by first washing with 5% sodium hydroxide solution and then rinsing with large quantities of water. In addition, empty containers that held endosulfan residues should be rinsed two or three times with water while the sides are scrubbed, and once with 5% sodium hydroxide solution. Thus decontaminated, the empty containers can be recycled and used by pesticide manufacturers to package a chemical similar to endosulfan if the containers remain in good condition and if such reuse is not prohibited by federal, state, or local laws. 

Pretreatment of hair samples also includes an extraction, usually with an alkaline sodium hydroxide solution, followed by cleaning up with LLE with n-hexane/ethyl acetate. Instead of LLE, the employment of SPE is also possible. Furthermore, the solid phase microextraction (SPME) in combination with head-space analysis is usable [104-106]. In the case of using hair samples, possible external contamination (e.g., by passive smoking of Cannabis) has to be considered as false positive result. False positive results can be avoided by washing of the hair samples previous to extraction [107]. Storage of collected samples is another important fact that can cause false results in their content of A9-THC and metabolites [108-110]. 

It must be emphasised that there is no universal cleaning mixture. The student must take into account the nature of the substance to be removed and act accordingly. Thus if the residue in the flask is known to be basic in character, dilute hydrochloric or sulphuric acid may dissolve it completely similarly, dilute sodium hydroxide solution may be employed for acidic residues. If the residue is known to dissolve in a particular inexpensive organic solvent, this should be employed. 

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