Injection peak

Figure 7A shows the timeeourse of [ H]MDA accumulation and clearance from rat brain after a subcutaneous injection. Peak concentration, which was reached at 45 minutes, was equivalent to 165 (36 trg/g). To... 

Figure 7 Flow injection peaks of hydrochorothiazide standards and samples, showing reproducibility. (Reprinted from Ref. 59, with permission from, and copyright, Elsevier Science.)...

Mirex is rapidly absorbed and distributes to the plasma and liver after intraperitoneal injection. Peak concentrations were seen at 3 hours in the plasma and 6 hours in the liver following single or multiple doses of mirex (4 mg/kg) injected intraperitoneally into mice (Charles et al. 1985). 

Fig. 11. Separation of a mixture of organic solvents using 50 cm long 100 (left) and 320 pm i.d. (right) monolithic capillary columns (Reprinted with permission from [112]. Copyright 2000 Wiley-VCH). Conditions temperature gradient 120 - 300 °C, 20 °C/min, inlet pressure 0.55 MPa, split injection. Peaks methanol (1), ethanol (2), acetonitrile (3), acetone (4), 1-propanol (5), methyl ethyl ketone (6), 1-butanol (7),toluene (8), ethylbenzene (9),propylbenzene (10),butyl-benzene (11)...

The origin of the electron injection peak at the end of the dissolution of an oxide film is not understood in detail. Silicon interface atoms with three Si-O bonds and a single Si-Si bond are proposed to be responsible for the effect [Mai]. On the other hand, during the dissolution process silicon interface atoms with one Si-O bond and three Si-Si bonds lead to a configuration identical to the one for which electron injection is observed during divalent dissolution (Fig. 4.3, step 2). In any case, the injected charge exceeds by a factor of 3 to 5 the charge expected... 

The last critical region in the chromatogram (region 3 in Figure 5) is around the injection peak. A polar compound might not be retained by the stationary phase, and as a consequence, elutes at the time of the injection peak. For this type of problem, a CE method can be an alternative. For example, Herrero et al. succeeded in distinguishing several polar compounds, which were not retained by RPLC, by the use of a CE method. 

Where RPLC often fails in separating polar compounds from the injection peak, ordinary CE mostly succeeds efficiently. As a consequence, it can be very useful to add at least one CE method to an orthogonal chromatographic set. ... 

Pharmacokinetics Onset of analgesic effect occurs 15 minutes after IM injection, peaks in about 1 hour, and persists up to 6 hours. When given IV, the time to onset and peak is shortened. 

EPO can be administered intravenously or, more commonly, by subcutaneous (s.c.) injection. Peak serum concentrations are witnessed 8-24 h after s.c. administration. Although they are lower than the values achieved by i.v. administration, the effect is more prolonged, lasting for several hours. In healthy individuals, less than 10% of administered EPO is excreted intact in the urine. This suggests that the kidneys play, at best, a minor role in the excretion of this hormone. 

Antimonials are irritating to the intestinal mucosa and therefore are administered by intramuscular or slow intravenous injection. Peak blood concentrations occur in 2 hours. These drugs bind to cells, including erythrocytes, and are found in high concentrations in the liver and spleen. As compared with the trivalent antimonials, which are no longer used, the pentavalent antimonials bind to tissue less strongly. This results in higher blood levels, more rapid excretion, and lowered toxicity. Pentavalent antimonials are rapidly excreted in the urine, with up to one-half of the administered dose excreted in 24 hours. 

Fig. 29.1 HPLC-PDA of (a) MSPD extract of control bovine kidney, (b) MSPD extract of bovine kidney fortified at the 20 ppm level, and (c) synthetic mixture of standards at levels of 15 ng per component injected. Peaks 1, spectinomycin 2, hygromycin B 3, streptomycin 4, dihydrostreptomycin. (Reprinted from Ref. 19 with permission from Elsevier Science.)...

TABLE 5.3 EQUATIONS FOR RESPONSE FACTOR IN TERMS OF WEIGHT (M) OF COMPOUND INJECTED, PEAK WIDTH (W), AND FLOW (F). 

Administration of succinylcholine is followed by a transient increase in intraocular pressure that is manifested less than 60 seconds after intravenous injection, peaks at 2-4 minutes, and declines after... 

The 2.2.2 column is especially advantageous in the determination of fluoride ion, which in traditional IC often elutes so early as to be masked by the injection peak. [32] In similar fashion, Tsai and Shih [33] derivatized polystyrene/divinylbenzene resin with cryptand 2.2.2 for the ion chromatographic separation of cations or anions. 

Final sample concentrations ranged from 0.05% to 1.0% (by weight), depending on latex particle size, In order to generate chromatographic signals in the linear range of the detector. Diluted samples were placed in a low power ultrasonic bath (Ultrasonics, Plainview, New York) for 60 seconds just prior to injection. Peak areas were determined for each injection. Each sample was injected until three consecutive areas differed by less than two percent from one value to the next. 

Rapid-acting insulin reaches the blood within 15 minutes of injection, peak levels occur between 30 and 90 minutes, and the duration of action is usually 5 hours. 

Short-acting (regular) insulin reaches the blood within 30 minutes of injection, peaks in 2-4 hours and acts for 4—8 hours... 

Intermediate-acting (NPHand lente) insulin reaches the blood 2-6 hours after injection, peaks in 4-14 hours and acts for 14-20 hours. 

Disposition in the Body. Readily absorbed after oral administration bioavailability about 55%. Flupenthixol decanoate is very slowly absorbed from the site of intramuscular injection. Peak plasma concentrations are attained about 3 to 6 hours after oral administration and 3 to 7 days after intramuscular injection. The main metabolic reactions are sulphoxidation, side-chain N-dealkylation and glucuronic acid conjugation. AT-Desalkylflupen-thixol and flupenthixol sulphoxide are the major metabolites found in plasma (both are inactive). Numerous metabolites are excreted in the urine and faeces and there is evidence of enterohepatic circulation. 

Flaloperidol is well absorbed orally with a bioavailability of 60-65% due to first-pass hepatic metabolism. It has a reversible oxidation/reduction metabolic pathway it is metabolized via reduction to reduced haloperidol, which is biologically inactive. Both agents are rapidly absorbed after intramuscular injection, peaking within 10 min. Butyrophenones are metabolized in the liver to inactive metabolites. Concentrations of butyrophenones are found in the liver, central nervous system, and throughout the body. Flaloperidol is 92% protein bound. Haloperidol is 15% eliminated through the bile. The elimination half-life is 14-41 h. The half-life of droperidol is 2 h 10% is recovered unchanged in the urine. 

Loxapine is readily but incompletely absorbed. Due to first-pass metabolism, oral bioavailability is 30% less than bioavailability after intramuscular injection. Peak blood levels occur 1 or 2h after oral administration and 5 h after intramuscular injection. Loxapine is extensively metabolized in the liver through aromatic hydroxylation, N-demethylation, or N-oxidation. The metabolite amoxapine is active and marketed as an antidepressant. Loxapine is widely distributed throughout the body, including the central nervous system. The main metabolites are excreted both in the urine and feces, and 50% of a... 

The nature of the association process (inter- or intramolecular) can be revealed by mixing compounds of the same structure but different molecular mass [34, 37]. Because the mobility of the investigated compounds is mass-dependent, with intramolecular association the electropherogram of the mixture should indicate superimposition of the two single injection peaks. If intermolecular associates are predominantly formed, one single, sharp peak should appear for the mixture. Both cases could be realized in practice ... 

In many cases, despite some loss of resolution, column overloading is an economic and viable method for compound purification. In analytical LC, the ideal peak shape is a Gaussian curve. If under analytical conditions a higher amount of sample is injected, peak height and area change, but not peak shape or the retention factor. However, if more than the recommended amount of sample is injected onto the column, the adsorption isotherm becomes nonlinear. As a direct consequence, resolution decreases, and peak retention... 

The vagus nerve acts to decelerate heart rate via a cholinergic input to the sinoatrial node, and atropine blocks this action, leading to an increase in heart rate. Effects are noted at doses as low as 0.6 mg per 70 kg of body weight, and the maximum increase of 35 to 50 beats per min is achieved at doses of 2 to 3 mg per 70 kg of body weight. Heart rate begins to increase within 15 min of an IM injection, peaks at 60 to 90 min, and can persist for 4 hr (Penetar, 1990 Penetar, Haegerstrom-Portnoy, Jones, 1988). 

If the peak becomes smaller with every blind injection there is a high probability of sample carry over. Measures as explained above under Sample Carry Over . If the peak appears with more or less constant size it may be an injection peak (system peak). Measures can be difficult or impossible. The mobile phase must not be detector-active, i.e. the UV cutoff wavelength must be taken into consideration. Perhaps the peak disappears when a mobile phase from another batch or another manufacturer is used, especially in low UV and with acetonitrile or trifluoroacetic acid. Injected air can produce a peak. ... 

A sample of lower total ionic concentration than that of the eluent will create a zone of lower E concentration that will ultimately show up as a negative injection peak. The magnitude of the injection peak (either positive or negative) can be used to estimate the total ionic concentration of the sample compared with that of the eluent. Sometimes the total ionic concentration of the sample is adjusted to match that of the eluent in order to eliminate or reduce the size of the injection peak. 

In this example, the total ionic concentration of the initial sample zone was higher than that of the eluent. This zone of higher ionic concentration will be displaced by continued pumping of eluent through the column until it passes through the detector. This will cause an increase in conductance and a peak in the recorded chromatogram called an injection peak. If the total ionic concentration of the injected sample is lower than that of the eluent, an injection peak of lower conductance will be observed. The... 

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