Plasma assay

This assay was developed using an incubation temperature of 30°C, although 37°C is used in other centres [32]. The assay at 30°C is linear with 50 pi plasma/assay tube for at least 60 min, and with a assay time of 60 min with at least 100 pi plasma/assay tube. When insufficient plasma is available, the assay can be performed with 25 pi plasma/assay tube (+25 pi demineralised water) for 120 min. If an assay temperature of 37°C is preferred, the assay time with 50 pi plasma/assay tube should be reduced to 30 min. Normal values measured at 37°C [31, 32] are higher (theoretically 1.7 times) than those measured at 30°C (Table 3.7.2). 

A similar study of the reproducibility of collection of 14c 9 tetrahydrocannabinol in plasma assayed by liquid scintillation after extraction and reverse-phase HPLC was also conducted. The amounts recovered were proportional to the amounts injected, and the HPLC recovery efficiency of the drug in the heptane extract was 95.7%. 

Detection of either I or VI in HPLC eluent was found to be practical using UV light at 209 nm. Mobile phases used had to be compatible with monitoring at this wavelength to obtain the sensitivity needed for plasma assays. In the assay for I a 0.3% isopropanol in heptane solution as mobile phase met these criteria as did water acetonitrile in the assay for VI. The assay developed for I required the use of two tandem bonded-phase columns to adequately separate drug and endogenous plasma constituents. 

A stock solution of the internal standard was prepared as well by dissolving the standard in DMSO to a concentration of 1 mg/mL. The DMSO solution was diluted to 1 pg/mL with methanol for the plasma assay and a solution of 0.1 pg/mL was made up for the assay in urine. 

Standard point Samples Human blank plasma Assay buffer Iodinated APS-314d Mixture containing rabbit anti-Beraprost serum, sheep anti-rabbit y-globulins and rabbit y-globulins... 

Butyrylcholine iodide monohydrate (Calbiochem grade B) was used as the substrate for plasma assay, and the results are expressed as micromoles of butyric acid produced per milliliter of plasma per minute. 

Besides assay of phenytoin from the serum or plasma, assay from saliva has also been described in the literature (S269). 

Measurement of Arginine Vasopressin Numerous immunoassays for measuring AVP in plasma or urine have been described. However, their routine clmical application has been hampered because of method complexity and lack of assay sensitivity and specificity. With most plasma assays, a prefiminary extraction procedure is required, not only to concentrate die minute amount of hormone that is present in the specimen, but also to remove nonspecific interfering substances. 

The health services in India have a centralized administrative structure (Figure 52.1) with the Drug Controller General of India DCGI under the Ministry of Health for Clinical Trials and Imported Clinical Materials. Although export of biological samples, which included bloods, tissues plasma assay material must be also approved by the... 

Fourier transform filter 929, 981 Fourier transform IR spectroscopy 547 Fractionation factors 367 Fragmentation, metastable 275 Franck-Condon simulation 107 FRAP (ferric reducing abiUty of plasma) assay 857... 

Fig. 7. Standard plot for digoxin standards in human plasma. Assay conditions are the same as in Fig. 6. (Reprinted with permission from Wehmeyer et al., 1986. Copyright 1986, American Chemical Society.)... 

B. Plasma assay of salbutamol by means of high-performance liquid chromatography with ampero-metric determination using a loop column for injection of plasma extracts. Application to the evaluation of subcutaneous administration of salbuteimol. Ther.Drug Monit., 1992, 14, 243—248... 

Blood pressure can be regulated by receptor, enzyme, endogerous substance, and cell, such as bradykinin B2-receptor, ACE, 5-Hydroxytryptamine, and endothelia cell. Based on these facts, the human plasma assay [131], pulmonary hypertension assay [132], coronary arteries (CA) constriction assay [133], MCAO and HSPG assay [134], and temperature assay in awake subjects [135] are established. 

Standard curves were constructed by plotting the change in absorbance with time (dA/dt) versus concentration of ATI or ATF. Standards for the assay were prepared by dilution of stock solutions of ATI or ATF to the appropriate concentrations (0,25,50,100,175, and 250ng/mL for ATI 0,5,10,20,50, and lOOng/mL for ATF) with PBS (pH 7.4), with the addition of 1% (v/v) blank rat plasma. Assays were validated with respect to precision and accuracy, by analysis of QC samples at 25,100,250ng/ml for ATI and 5,20, lOOng/ml for ATF, respectively. Intra-assay and inter-assay variability were determined through the analysis of QC samples. 

Z5. Zucker, S., Lysik, R. M., DiMassimo, B. I., et al. Plasma assay of gelatinase B Tissue inhibitor of metalloproteinase (TIMP) complexes in cancer. Cancer 76, 700-708 (1995). 

Freed, C. R., and Asmus, P. A., 1979, Brain tissue and plasma assay of L-dopa and a-methyldopa metabolites by high-performance liquid chromatography with electrochemical detection,/. Neurochem. 32 163-168. 

Limits of detection for absorbance detectors (325 nm) with conventional (5 qm particle size) C18 columns and methanol water mobile phases are typically 0.35 pmol (0.1 ng) at a 5 1 signal noise ratio. Even low serum retinol concentrations as found in vitamin A deficiency (0.35 to 0.7 iM, i.e., 10 to 20 Ag/dL) require sample volumes of only 1 pL Nonetheless, fiuorescence detection can give even lower limits of detection (0.07 pmol, 20 pg in tear fluid (111) 5-pL sample sizes have been used for routine plasma assays (112). Electrochemical detection has also been used for simultaneous analysis of retinol and tocopherol (113,114). Microbore columns and smaller packing particle sizes could give improved limits of detection (115,116) but require low-dispersion fittings and detector cells. The requirements for plasma retinol quantitation are not so stringent that use of these techniques has become popular. 

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