Barbiturates detection

Mueller, M. A., and Wang, R. I. H. Comparison of Radioimmunoassay with Thin-Layer and Gas-Liquid Chromatographic Methods of Barbiturate Detection in Human Urine Clin. Chem. (Winston-Salem, N. C.) 21(6) 672-675 (1975) CA 83 ... 

While barbiturate metabolites are more intensely colored by the mercury(I) nitrate reagent (q.v.) the unaltered barbiturates react more sensitively to the mercury(II) diphenylcarbazone reagent the detection limits lie between 0.05 pg (Luminal ) and 10 pg (Prominal ) per chromatogram zone [6]. 

The ZwKKER reaction involving Co salts is frequently used for the detection of barbituric acid derivatives [31-35], but some purine, pyridine and piperidine derivatives and heterocyclic sulfonamides also yield colored derivatives. The Zwkker reaction is particularly sensitive when it is possible to form a tetrahedral complex [Co(Barb)2 Xj] (X = donor ligand, e.g. amine) [4]. 

Thormartn, W., Meier, R, Marcolli, C., and Binder, F., Analysis of barbiturates in human serum and urine by high-performance capillary electrophoresis-micellar electrokinetic capillary chromatography with on-column multiwavelength detection, /. Chromatogr., 545, 445, 1991. 

It is sometimes possible to improve detection by changing the pH of the eluent, or by the use of photochemical reactions. The common barbiturates used in therapy are weak acids that are easily separated in their acid (unionised) forms. Because the conjugate bases are much stronger chromophores than the acids, barbiturates have been detected by post-column mixing with a pH 10 borate buffer followed by uv absorption at 254 nm. An example of the second approach is the detection of cannabis derivatives in body fluids involving the conversion of cannabis alcohols to fluorescent derivatives on subjecting the column effluent to intense uv radiation. 

The bioslurry treatment successfully removed several of the PhC to non-detectable levels after 26 days three histamine H2-receptor antagonists (ranitidine, famotidine, cimetidine), two (1-blockers (atenolol, sotalol), one barbiturate (butalbital) and one antidiabetic compound (glibenclamide). The elimination of the sulfonamide antibiotics sulfapyridine (100%), sulfamethazine (91.0%) and... 

On the other hand, the analgesic phenylbutazone, the antidepressant paroxetine, tetracycline antibiotics doxycycline and chlorotetracycline, the antibiotics tilmico-sin, danofloxacin, enoxacin, nifuroxazide, the (3-blockers betaxolol, carazolol, pindolol, the (3-agonist clenbuterol, barbiturates, the antihypertensive lisinopril, and the drug to treat cancer tamoxifen were never detected. 

Waste or leachate (EPA Method 901OA) Reflux-distillation of acidified sample absorption of released HCN in NaOH treatment with AgNOs and an indicator (titrimetric) or chloramine-T/pyridine-barbituric acid (colorimetric) Titrimetric or colorimetric detection (total and amenable cyanide) 0.1-0.2 mg/L titrimetric) 0.02 mg/L (colorimetric) (Titrimetric) 94-99 (total cyanide), 87-97 (amenable cyanide) EPA1992d... 

Ma H, Liu J. 1992. Flow-injection determination of cyanide by detecting an intermediate of the pyridine-barbituric acid chromogenic reaction. Anal Chim Acta 261(l-2) 247-252. 

B27. Broughton, P. M. G., A rapid ultraviolet spectrophotometric method for the detection, estimation and identification of barbiturates in biological material. Biochem. J. 63, 207-215 (1956). 

Monitoring Perform baseline and follow-up LFTs (10 to 14 days) to detect hepatic dysfunction resulting from therapy. Perform a CBC and serum chemistries. Dependence and addiction Alcoholism may accompany or be followed by dependence on narcotics or sedatives. Barbiturates have been coadministered with disulfiram without untoward effects, but consider the possibility of initiating a new abuse. 

Drugs such as 2-thiobarbituric acid are oxidized in the presence of iodide mediators. In aqueous media, an electroio-dination process occurs and the resulting voltammetric signal allows quantitative determination [190]. A similar methodology with a limit of detection at ca. 40 gM level has been developed for barbiturates [191]. Also, catechin as a model system for polyphenols was studied in the presence of an iodide redox mediator [192]. 

The uses of constant-current coulometry for the determination of drugs in biological fluids are few, basically due to sensitivity restriction. Monforte and Purdy [46] have reported an assay for two allylic barbituric acid derivatives, sodium seconal and sodium sandoptal, with electrogenerated bromine as the titrant and biamperometry for endpoint detection. Quantitative bromination required an excess of bromine hence back titration with standard arsenite was performed. The assay required the formation of a protein-free filtrate of serum with tungstic acid, extraction into chloroform, and sample cleanup by back extraction, followed by coulometric titration with electrogenerated bromine. The protein precipitation step resulted in losses of compound due to coprecipitation. The recoveries of sodium seconal and sodium sandoptal carried through the serum assay were approximately 81 and 88%, respectively. Samples in the concentration range 7.5-50 pg/mL serum were analyzed by this procedure. 

The fluorimetric determination of barbiturates has been examined by derivatization with DNS-C1 followed by HPLC [125]. The derivatives are formed under similar conditions to those used for the alkaloids. Therapeutic amounts (1.0 ppm) of barbiturates can be detected in as little as 20 Ail of blood. 

The limits of detection are ca. 2 ng of barbiturate per injection. DNS derivatives of aprobarbitone, barbitone, heptabarbitone, secobarbitone, butallylonal and talbutal can be analyzed by this technique. 

The nonspecific initial tests in a series are valuable for determining the presence or absence of a particular class of compounds. Colorimetric tests to detect the presence of phenothiazines would give initial information about a drug class present. This would be followed by more specific tests to identify the actual compound as well as provide quantitative data. Another example of a type of initial test would be an immunoassay that determines the presence of barbiturates. Confirmatory tests are mandatory to identify the particular drug within the class detected. 

Barbiturates Barbital, phenobarbital Separated on a C-18 high carbon loaded silica column mobile phase methanol-water detected by UV at 254 nm... 

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