Syringe handling

Syringe handling techniques for injection of liquid samples... 

Syringe handling Slow movement of the plunger can almost eliminate the pressure wave but results in enhanced discrimination of sample components. Rapid injection using the hot needle or solvent flush method is preferred. Autosamplers capable of high speed and reproducible injection times provide improved performance. 

Unfortunately, the preset split ratio differs from the true sample ratio in a complex manner, which is dependent on parameters such as sample volume, solvent, and volatility, syringe handling, and injector and column temperatures. When the sample is volatilised, it produces a pressure wave, which introduces some sample onto the column before the pressure falls back. During the second phase, little sample enters the column and most is vented. The splitter ratio in fact controls the magnitude of the pressure wave, and through this the actual sample size. Thus if the same amount of sample is injected in different volumes of solvent, sample peak areas may not be the same. 

Sample Handling System. Venous or capillary blood, urine, and cerebrospinal fluid are specimens routinely used in medical diagnostic testing. Of these biological fluids, the use of venous blood is by far the most prevalent. Collection devices such as syringes and partial vacuum test tubes, eg, Vacutainer, are used to draw ten milliliters or less of venous blood. At collection time, the test tubes are carefully labeled for later identification. 

Diethyl chlorophosphate, supplied by Aldrich Chemical Company, Inc., was used by the submitters without purification and was handled in a glove bag under an atmosphere of dry nitrogen in a well-ventilated hood. The reagent was distilled and stored under nitrogen by the checkers. Aliquots were withdrawn with a syringe as needed. 

Distilla lion of the starting materials prior to use and reactions arc carried out under nitrogen or argon with exclusion of moisture. 47.5 g (0.25 mol) of titanium(lV) chloride are added dropwise to a solution of 213 g (0.75 mol) of tetraisopropoxytitanium in 250 mL of anhyd hexane cooled by an ice-bath. The mixture is allowed to warm to r.t. and brought to a total volume of 1.0 L by dilution with hexane. The flask is sealed by a scrum cap and the stock solution handled with a syringe when used. 

Always observe aseptic technique when handling syringes and needles. 

Toluene, the major solvent, was stirred for three days with several portions of sulphuric acid, washed, dried, and stored over calcium hydride on a vacuum rack. The toluene was distilled out immediately prior to the reaction. The dichlorides were vacuum distilled at the time of the reaction into three fractions, and the middle fraction, about 60% of the total, used. The dichlorides were obtained from Petrach, stored in a nitrogen glove bag and handled by syringe. 

This compound was found, on investigation of an explosion in a syringe during transfer, to have a decomposition energy equivalent to that of commercial explosives. Slow decomposition, even at room temperature, becomes explosive above 100°C. Shock sensitive. Stable as hydrocarbon solution below 25% concentration. Recommended that this and related compounds be handled only in such solution. See FLUORINATED ORGANOLITHIUM COMPOUND... 

Triethoxysilane and especially trimethoxysilane are rather toxic compounds (they may cause blindness if allowed to get into contact with eyes) and therefore care must be taken in their handing. Both need to be manipulated very carefully with suitable gloves, eyes face protection, in a well ventilated fume-hood. However, both can be handled without problems via syringe techniques. 

Soil solution samples from saturated soils can be obtained by simple filtration. Simple gravity filtration is preferable to vacuum filtration methods because vacuum filtration can lead to distortions in the composition of analyte composition in filtrates. Syringe filters are usually not capable of handling soil and so are not recommended. Also, some filters can retain analytes of interest. 

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