Syringe injection

So far, two principles of sampling have been applied in high-performance LC (HPLC) syringe and valve injection. Both types, conmercially available or custom-made, are discussed in detail below. 

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Injector The sample, typically 5-200 )J,L, is placed in the carrier stream by injection. Although syringe injections through a rubber septum are used, a more common means of injection is the rotary, or loop, injector used in ITPLC and shown in Figure 12.28 of Chapter 12. This type of injector provides reproducible injection volumes and is easily adaptable to automation, a feature that is particularly important when high sampling rates are desired. 

Generation of test atmospheres of organic vapours by the syringe injection technique Generation of test atmospheres of organic vapours by the permeation tube method On-site validation of sampling methods... 

Sorbent tube standards preparation by the syringe injection technique... 

Sample injection system. Introduction of the sample is generally achieved in one of two ways, either by using syringe injection or through a sampling valve. 

The injection device is also an important component in the LC system and has been discussed elsewhere (2,18). One type of injector is analogous to sample delivery in gas chromatography, namely syringe injection through a self-sealing septum. While this injection procedure can lead to good column efficiency, it generally is pressure limited, and the septum material can be attacked by the mobile phase solvent. 

For higher pressures, stopped flow injection has been used in which a valve releases the pressure in the column to atmosphere, at which point syringe injection at the top of the column (without septum) takes place. There has, however, been a trend in recent years to use valve injectors because of their generally high pressure capabilities and their ability to deliver large... 

Successful use of modern liquid chromatography in the clinical laboratory requires an appreciation of the method s analytical characteristics. The quantitative reproducibility with respect to peak height or peak area is quite good. With a sample loop injector relative standard deviations better than 1% are to be expected. The variability of syringe injection (3-4% relative standard deviation) requires the use of an internal standard to reach the 1% level (2,27). 

Table 4.17 Characteristics of various syringe injection methods...

Injectors introduce the sample into the mobile phase under high pressure. There are several approaches to injection in HPLC, such as syringe injection via septum, a combination of a septum and syringe or a valve injection. Valve injection is the method of preference in up-to-date HPLC instrumentation. 

The CPA or "Snake Pen" consists of a pen body containing a porous wick, such as that used in felt pens, and a solution ofDMSO and any number of toxins. When the wick is touched to the victim s skin he receives a fatal dose of poison. The CPA is built from a correction fluid pen, available at any office supply store. These pens have a soft, flexible body and are easy to modify. Unscrew the top from the son pen body, squeeze out the correction fluid and flush the interior with solvent to remove all traces of its original contents. Note that most of these pens have a left-hand thread on the body. The tip of the pen is sawed off and the valve stem carefully removed. Ream out the pen tip to fit the wick. A felt tip marker pen works well as a wick, after being soaked and rinsed in sol vent to remove traces of ink. It may be necessary to trim the wick to fit. Press the wick into the pen tip until about 3/8 " protrudes and seal around it with silicone sealer. When the sealant is dry, put on rubber gloves and, using a hypodermic syringes, inject the DMSO solution into the pen barrel until it is about 3/ 4 full. Be sure not to squeeze the pen while accomplishing this. Coat the barrel threads with a little silicone sealer, screw on the cap and allow the pen to dry in a vertical position. Line the inside of the cap... 

The checkers used a syringe, injecting through a rubber septum. 

Draw 2 ml (0.8 mg) of naloxone into syringe. Inject 0.5 ml (0.2 mg) while needle is still in vein, observe patient for 30 sec for withdrawal signs or symptoms, if no evidence of withdrawal, inject remaining 1.5 ml (0.6 mg) observe patient for additional 20 min for withdrawal signs or symptoms. Subcutaneous Inject 2 ml (0.8 mg) of naloxone observe patient for 45 min for withdrawal signs or symptoms. 

Route of administration The reconstituted product must be administered intravenously by either direct syringe injection or drip infusion. Kogenate and Kogenate FS must be administered within 3 hours after reconstitution. 

Vapor phase components are quantified through the syringe injection of a head space vapours at controlled rates directly into the ion source. Into a syringe barrel are deposited a few drops of... 

Injection Syringe injection, analytical volume 0.5 mL and preparative volume 100 mL. ... 

Syringe injection—Injection of a volatile liquid at a known rate into an air stream of known flow rate is a convenient method for producing vapor mixtures of known composition. Since the rate of delivery of the syringe drive may be accurately determined by weighing the amount of liquid delivered over a known period of time and by measuring the dilution air flow rate, very good accuracy may be obtained with this method. 

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