Sample vial

Although chloroform is an analyte, it also can be interferent. Due to its volatility, chloroform present in the laboratory air may diffuse through the sample vial s Teflon septum, contaminating the samples. How can we determine whether samples have been contaminated in this manner ... 

Why is it necessary to collect samples such that there is no headspace (layer of air overlying the liquid) in the sample vial ... 

The basic instrumentation for capillary electrophoresis is shown in Figure 12.41 and includes a power supply for applying the electric field, anode and cathode compartments containing reservoirs of the buffer solution, a sample vial containing the sample, the capillary tube, and a detector. Each part of the instrument receives further consideration in this section. 

Injecting the Sample The mechanism by which samples are introduced in capillary electrophoresis is quite different from that used in GC or HPLC. Two types of injection are commonly used hydrodynamic injection and electrokinetic injection. In both cases the capillary tube is filled with buffer solution. One end of the capillary tube is placed in the destination reservoir, and the other is placed in the sample vial. 

Hydrodynamic injection uses pressure to force a small portion of the sample into the capillary tubing. To inject a sample hydrodynamically a difference in pressure is applied across the capillary by either pressurizing the sample vial or by applying a vacuum to the destination reservoir. The volume of sample injected, in liters, is given by the following equation... 

Electrokinetic injections are made by placing both the capillary and the anode into the sample vial and briefly applying an electric fleld. The moles of solute injected into the capillary, nj, are determined using... 

The clear filtrate is collected in a tightly capped sampling vial for later analysis. Freezing the filtrate will better preserve the existing condition. 

Impurities from solvents, reagents, or sample vials are present. 

Sample solution instability or incomplete extraction/separation would show up if several aliquots from the same sample work-up were put in a series of vials that would be run in sequence that would cover at least the duration of the longest sequence that could be accommodated on the autosample/instrument configuration. For example, if an individual chromatogram is acquired for 5.5 minutes, postrun reequilibration and injection take another 2.75 minutes, and 10 repeat injections are performed for each sample vial in the autosampler, then at least 15 60/(5.5 -I- 2.75)/10 = 11 vials would have to be prepared for a 5 P.M. to 8 A.M. (=15 hour) overnight run. If there is any appreciable trend, then the method will have to be modified or the allowable standing time limited. 

Uniformly labeled C-8-D with a specific activity of 2.99 juc/mg was administered orally to pregnant females at 2 /xg/kg/day from 6-15 days of gestation. Three females were sacrificed on alternate days during days 6-20 of pregnancy. Triplicate samples of fetus, placenta, blood, brain, abdominal fat, and sartorius muscle were procured from each female. The samples were dissolved in 1 ml of Soluene (Packard Instruments) to which 15 ml of Aquasol were added. Each sample vial was counted for 30 min in a Nuclear Chicago Mark I liquid scintillation counter. 

Special attention needs to be given to collecting samples for VOC analysis. The VOC vial should be filled slowly until a convex meniscus is present above the sample vial lip. Carefully cap the sample vial, invert and tap to check for bubbles. If bubbles are present, then a new sample vial should be filled. 

To fortify a sample, the label from a fortification sampling vial was removed and secured to the pre-labeled sample jar. Spike vials were individually shaken before use. The cap was discarded, the contents of the vial were poured into the sample jar and then the vial was dropped into the sample. The sample jar was capped with a Tefion-lined lid, hand shaken to mix, placed in a Kapak bag and sealed. Jars were placed immediately in storage freezers. In all cases, quality control samples were transported and stored with their corresponding field plot samples throughout sample handling and shipment to the analytical facility. 

Graduated cylinders Kimax brand. Red Stripe, glass, 100- and 500-mL and 1-L HPLC sample vials HP Amber with Teflon/silicone/Teflon septa, capacity 2-mL Volumetric flasks, 200-mL... 

Solution Activation 50 mg of supported Pt20 DEN was mixed with a solvent/acid mixture (see Table 1) in a 50 ml round bottom flask and refluxed for 2 - 6 hrs. Solid samples were separated from solution by vacuum filtration and dried in vacuum oven at 50°C overnight. To prepare sample 6 (see Table 1), supported Pt20 DENs were mixed with HN03/H20 (volume pore volume of Si02) in a sample vial, heated to 70°C for 2hrs, and dried in a vacuum oven at 50°C overnight. 

An autosampler using tapered mini-sample vials in a 54-well format. (Used for step 4)... 

If your sample is reluctant to dissolve in the chosen solvent, avoid adding more solvent for the reasons outlined above. Instead, try warming the sample vial carefully on a hotplate or with a... 

Remove the sample vial from the Processor, recap it, and save it for 7 days. 

The cervical-endocervical sample is collected by the clinician using either a broom or a brush as cervical sampling devices and rinsed in a vial filled with PrecervCyt Solution. The ThinPrep Sample vial is then properly capped, labeled with the patient s name and sent, together with a requisition form, to the laboratory, which is equipped with a ThinPrep 2000 Processor. After processing, the specimen will result in a thin layer of cells concentrated in a 20-mm diameter on a glass slide. 

Assign a gynecologic accession number to the PreservCyt Sample vial, requisition and clean, new slide. 

Remove the cap from the PreservCyt Sample vial and load it into the sample holder. 

The SPME process, adapted for solid or viscous matrix, is shown in Figure 10.1. A fused silica fibre, coated with a polymer, is installed inside a stainless steel hollow needle. In the first step, the needle is introduced in the sample vial through the septum. The fibre is then exposed to the headspace above the sample and the organic analytes adsorb to the coating of the fibre. After a variable sampling time, the fibre is drawn into the needle and the needle is withdrawn from the sample vial. Finally, in the same way, the fibre is introduced into the chromatograph injector where the analytes are thermally desorbed. 

Fig. 1.23. Monitor AW 2. In the foreground right Sample vial with measuring electrodes and resistance thermometer, behind to the left the control- and analysis unit. The storage of LN2 and its control valve are not shown. The resistance in the measuring head has to be large compared with the resistance to measure e. g. 1011 1 (photograph AMSCO Finn-Aqua, D-50354 Hiirth).

A Waters Acquity UPLC system with a cooling autosampler and column oven was used. The stationary phase was a Waters Acquity BEH C18 column (50 x 2.1 mm, 1.7 /.un particle size). The column was maintained at 40°C. The mobile phase consisted of water and acetonitrile, each containing 0.3% formic acid and was delivered at 0.35 mL/min in a gradient mode at 60% water from 0 to 1.5 min, linearly decreased to 10% water in 0.5 min, and then returned to 60% water. Sample vials were maintained at 4°C. 

Lercanidipine — Kalovidouris et al.57 applied UPLC-MS/MS to the determination of lercani-dipine in human plasma after oral administration of lercanidipine. A Waters Acquity UPLC system with cooling autosampler and column oven was coupled with a Waters BEH C18 column (50 x 2.1 mm, 1.7 jum). The mobile phase was composed of 70% acetonitrile in water containing 0.2% v/v formic acid, delivered at a flow of 0.30 mL/min. The column temperature was maintained at 40°C and sample vials at 5°C. 

Wet solids. Press out on filter paper, break up, let dry. The solid shouldn t stick to the sides of the sample vial. Tacky ... 

Electrokinetic (also called electromigration) injection is performed by placing the inlet of the capillary and an electrode in the sample vial. Following this a voltage is applied during a defined period of time. The sample constituents are actively carried into the capillary, and when present, the EOF also passively carries them into the capillary. For this reason, neutral compounds are also injected. The active migration is due to the effective electrophoretic mobilities of the constituents. The amount (B), in units of concentration injected into the capillary is expressed by [2,38]... 

Hydrodynamic injection can also be performed by using gravity to generate AP [41]. This injection mode is also called hydrostatic injection. The inlet of the capillary is placed in the sample vial and this is then raised during a period of time, creating a difference in height (Ah, in cm) between the inlet and the outlet of the capillary. The sample enters the capillary by siphoning. The amount and volume injected are derived from Eqs. 17.46 and 17.47, respectively, after substitution of AP with Eq. 17.48. 

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