Plasma collection device

Plasma collection tubes with a variety of additives are commercially available (e.g., heparin, EDTA, sodium citrate). These additives have the potential to cause interference with some analytical assays. Thus, interference testing should be performed prior to implementing sample collection procedures. It should be noted that the collection tubes intended to generate plasma contain the optimal amount of the appropriate additive for the indicated sample volume. If tubes are not filled to this indicated volume, the concentration of additive will be higher than recommended and could pose problems during downstream analysis. After collection, sample tubes should be mixed by gentle inversion several times to ensure proper mixing of additive with the blood. 

---

Compared to other drugs of abuse, analysis of cannabinoids presents some difficult challenges. THC and 11-OH-THC are highly lipophilic and present in low concentrations in body fluids. Complex specimen matrices, i.e., blood, sweat, and hair, may require multi-step extractions to separate cannabinoids from endogenous lipids and proteins. Care must be taken to avoid low recoveries of cannabinoids due to their high affinity to glass and plastic containers, and to collection devices for alternate matrices (Blanc et al. 1993 Bloom 1982 Christophersen 1986 Joern 1992). THC and THCCOOH are predominantly found in the plasma fraction of blood, where 95% to 99% are bound to lipoproteins. Only about 10% of either... 

Plasma Collection. Blood samples were collected from all animals at 0, 2, 4, 6, 12, 18 and 24 hours after the devices were inserted, then once daily until Day 10. On Days 13, 18, and 21, blood samples were withdrawn again followed by weekly collections between Day 21 and Day 84. Blood samples were subsequently taken on Days 86, 88 and Day 90, and then daily until the end of the in-life study when all the devices had been depleted. Approximately 10 mL of blood was collected from all animals in VACUTAINER tubes containing heparin at each sampling point. The blood was immediately centrifuged at 2(XX) rpm for ten minutes and the plasma was stored frozen until extraction. 

Based on a similar principle, Yang et al. [9] have developed a microfluidic device for continuous, real-time blood plasma separation from whole blood. The device is composed of a blood inlet, a bifurcating region which leads to a purified plasma outlet, and a concentrated blood cell outlet. They have precisely designed flow rate ratios at each bifurcation so that no blood cells (erythrocytes, leukocytes, or platelets) flow into the side channels, while blood plasma is skimmed into the purified plasma collection channels. The experimentally determined plasma selectivity with respect to blood hematocrit level was almost 100 % regardless of the inlet hematocrit (Fig. 7a). The total plasma separation volume percent varied from 15 % to 25 % with increasing inlet hematocrit (Fig. 7b). 

A method for the fractionation of plasma, allowing albumin, y-globulin, and fibrinogen to become available for clinical use, was developed during World War II (see also Fractionation, blood-plasma fractionation). A stainless steel blood cell separation bowl, developed in the early 1950s, was the earhest blood cell separator. A disposable polycarbonate version of the separation device, now known as the Haemonetics Latham bowl for its inventor, was first used to collect platelets from a blood donor in 1971. Another cell separation rotor was developed to faciUtate white cell collections. This donut-shaped rotor has evolved to the advanced separation chamber of the COBE Spectra apheresis machine. 

Figure 15.1—Inductively coupled plasma torch. A radiofrequency current (between 27 and 50 MHz) that induces circulation of the electrons in the inert gas drives the torch. The argon serves as an auxiliary gas, a cooling gas and the nebulisation gas. In the upper right is shown an optic device used to collect emitted light in the longitudinal axis of the plasma. Lower down, plasma generated by microwave.

In a follow-up study, the same authors examined the applicability of the same device for relevant protein samples and investigated the main contributions to band broadening [82]. As a consequence of the small depth of the beds, zone spreading caused by Joule heating was shown to be negligible (see Sect. 3.1.1). Cross fields of up to 100 V/cm were applied for the separation of human serum albumin, ribonuclease A and bradykinin. The feasibility of fraction collection was demonstrated with four collected fractions of a whole rat plasma sample. Off-line analysis of these four isolated fractions by CE indicated the separation of serum albumins and globulins. 

Initially, plasma and oral fluid specimens from patients (n = 21) on different antidepressant treatment were collected twice to assess if any of the studied analytes was likely to show a good correlation. The best results were obtained for venlafaxine (%CV for plasma/oral fluid concentrations ratio (f OF/PL) <21%). Therefore, the study was extended for this antidepressant by analysis of oral fluid and plasma specimens from five patients on venlafaxine treatment collected on four occasions. Daily doses of venlafaxine retard formulations were 75 mg for two patients, and 150 mg for the remaining participants. Collection of oral fluid (direct spitting into polypropylene tubes) and plasma (heparinized tubes) specimens was performed, when possible, before the next dose to ensure the drug was in the elimination phase. The dose and the time of collection was the same on the four different occasions for each patient. For the analysis, oral fluid and plasma specimens were centrifuged at 14 x 103 rpm, and 0.2 mL of the supernatant were extracted. In addition, correlation between the concentrations in the plasmatic free fraction and in oral fluid was also evaluated. Plasmatic proteins were eliminated by filtering 0.5 mL of plasma samples using Microcon filter devices Ultracel YM-3 (Millipore Corp., Billerica, MA, USA). 

This detector is based on the collective oscillations of the free electron plasma at a metal surface. Typically a prism is coated with a metal film and the film coated with a chemically selective layer. The surface is illuminated by a laser and the amount of material adsorbed by the coating affects the angle of the deflected beam. This platform is theoretically similar in sensitivity to a quartz crystal microbalance. This is another platform whose selectivity is based on the coating. The typical coating is using bound antibodies thus, this device becomes a platform for immuno-sensors (12). 

Thermionic converters are high temperature devices which utilize electron emission and collection with two electrodes at different temperatures to convert heat into electric power directly with no moving parts. Most thermionic converters operate with a plasma of positive ions in the interelectrode space to neutralize space charge and permit electron current flow. Both the plasma characteristics and the surface properties of the electrodes are controlled by the use of cesium vapor in thermionic diodes. 

DPI and three different doses using the EHD device. The nominal doses were 1000 pg for the DPI and 150, 250, and 400 pg for the EHD device. Multiple blood samples were collected from each subject up to 8 h after dosing to measure plasma drug concentration. An interval of 1 week was used between administration of the four doses. 

A potential problem with the analysis of biological fluids, especially plasma samples from in vivo studies, is the risk of clogging of SPE cartridges and/or analytical columns. Therefore, filtration of such samples prior to LC or SPE is recommended. Combined filtering and protein precipitation in 96-well plate format was described [97-98]. The samples are collected and stored frozen in sealed 96-well polypropylene filter plates. Prior to SPE and LC-MS analysis, the seals are removed and the plate is placed on top of a 96-well SPE manifold As the plasma thaws, it passes through the filter and into the SPE device. 

An examination of the numerous types of electrical discharges mentioned in this collection of symposium papers revealed that each almost without exception has the three elements illustrated in -Figure 1. That is, they are sustained by a source of electrical power (1), this power being delivered by means of a coupling mechanism (2), to a plasma environment (3), associated with the particular device. This simplified picture is rapidly obfuscated when one realizes that the number of combinations of power sources, coupling mechanisms, and plasma environments can be quite large, not to mention the variety of device geometries and modes of operation that are possible. 

The mode of coupling is resistive for those devices which have electrodes in direct contact with the ionized gas or plasma environment. In these devices the electrical field necessary to sustain the plasma is caused by positive and negative charge accumulations both within and at the boundaries (walls, electrodes, etc.) of the plasma region. A finite potential difference at the gas-electrode boundary always exists as a consequence of the accumulated charges. This potential supports a number of collision processes (ionization, excitation, electron emission or collection, etc.) which act to sustain the discharge. 

---