Authentic materials

Gourd or Calabash Curare. This type, exported in small gourds, is said to be made from Strychnos toxifera Schomb., and this was confirmed by King, who isolated from botanically authenticated material collected in British Guiana, an amorphous, quaternary alkaloid indistinguishable from curarine prepared from gourd curare, and Wieland et al. have isolated from this species alkaloids which they have also found in this type of curare. Other Strychnos spp. from the same territory examined by King contained alkaloids, but not of the curarine type. 

Propenyl)aniline (1, 1.0 g, 7.52 mmol), PdCl2(CH3CN)2 (0.195 g, 0.75 mmol), benzoquinone (0.812 g, 7.52 mmol), and LiCl (3.158 g, 75.2 mmol) were combined in THF (95 mL). After 5 h at reflux, the solvent was removed and the residue was stirred with ether and decolorizing charcoal for approximately 20 min and filtered. The filtrate was washed five times with 50-mL portions of 1 M NaOH. The solvent was removed by vacuum, and the residue was placed on a silica gel column and eluted with 3 1 petroleum ether/ether. 2-Methylindole (2, 0.818 g, 86%) was collected as a white, crystalline solid, identical with authentic material. ... 

The measurement of filth elements by microanalysis is a valuable adjunct in the enforcement of the Food, Drug, and Cosmetic Act and serves as an efficient means of evaluating conditions of cleanliness, decency, and sanitation in food-producing plants. This, of course, is in addition to the value of microanalytical methods in the determination of the fitness of foods as they reach the consumer. The techniques available, together with proficiency of manipulation, repeated references to authentic materials, and sound judgment in the interpretation of results, provide effective enforcement weapons in the constant war to prevent the production and interstate distribution of products which are unfit for the table of the American consumer. 

The PE extract (4.5 g) was pre-adsorbed on silica gel (10 g) and chromatographed over 50 g silica gel (70-230 mesh) using as eluants PE followed by mixtures of PE/CH2CI2 (1s1) and CHjCl,/acetone (10,20,40,80%), 100 ml fractions being taken. The PE fractions contained glycerides (1H NMR, MS). Fraction 5 (PE/CH Clj) was further purified by preparative TLC (PE/ether, 3 1, 2 x). The low polarity band contained glycerides and a more polar band provided phytol (la) which was shown to be identical with authentic material by Hi NMR and MS comparison. Fractions 6-8 (PE/C Clj) gave after further purification by preparative TLC (PE/ether, 19 1,... 

Fraction 22 was further separated by repeated preparative TLC (PE/ether, 2 1, 6 x) and CH-Cl,/acetone> 9 1) to give, besides 2 and 3, vanillin (7) which was Identified by H NMR and MS comparison with authentic material. The low polarity TLC bands contained traces of a mixture of aromatic compounds (Hi NMR, MS) which were not further investigated due to the lack of material. 

The infrared spectrum of neamine sulphate (formerly called neomycin A) also as a potassium bromide dispersion is illustrated in Fig. 4. All spectra are of authentic material supplied by The Upjohn Company, Kalamazoo. 

The sources of these standards include FM manufacturers, synthesis by researchers (especially in the case of NM metabolites), and specialty chemical catalogs. When possible, it is preferable to obtain these standards directly from the FM manufacturers in order to use the authentic material being discharged to wastewater treatment. In all cases, the purchased, synthesized, or obtained standards must be extensively analyzed to confirm the chemical structure and purity. 

It seems reasonable that polyester cyclics could be prepared by an extension of the /wendo-high-dilution [17] chemistry used for the preparation of cyclic carbonate oligomers [18, 19] however, such proved not to be the case. Brunelle et al. showed that the reaction of terephthaloyl chloride (TPC) with diols such as 1,4-butanediol did not occur quickly enough to prevent concentration of acid chlorides from building up during condensation [14]. Even slow addition of equimolar amounts of TPC and butanediol to an amine base (triethylamine, pyridine or dimethylaminopyridine) under anhydrous conditions did not form cyclic oligomers. (The products were identified by comparison to authentic materials isolated from commercial PBT by the method of Wick and Zeitler [9].)... 

General. Toluene, chlorobenzene, and o-dichlorobenzene were distilled from calcium hydride prior to use. 4-Dimethylaminopyridine (Aldrich Chemical Co) was recrystalled (EtOAc), and the other 4-dialkylaminopyridines were distilled prior to use. PEG S, PEGM s, PVP s, and crown ethers were obtained from Aldrich Chemical Co., and were used without purification. BuJ r and BU. PBr were recrystallized (toluene). A Varian 3700 VrC interfaced with a Spectraphysics SP-4000 data system was used for VPC analyses. A Dupont Instruments Model 850 HPLC (also interfaced with the SP-4000) was used for LC analyses. All products of nucleophilic aromatic substitution were identified by comparison to authentic material prepared from reaction in DMF or DMAc. Alkali phenolates or thiol ates were pre-formed via reaction of aqueous NaOH or KOH and the requisite phenol or thiophenol in water under nitrogen, followed by azeotropic removal of water with toluene. The salts were transferred to jars under nitrogen, and were dried at 120 under vacuum for 20 hr, and were stored and handled in a nitrogen dry box. 

The accuracy of the method is assessed by preparing multiple samples (e.g., three) at multiple concentration levels (usually at 80%, 100%, and 120% of the nominal concentration). For DP methods, the sample solutions are also spiked with placebos. Similar experiments should also be conducted for impurities when authentic materials become available. 

The synthesis of pheromones remains an important cornerstone of pheromone research and development. The initial synthesis of an insect pheromone serves not only to confirm the structural identification, but also provides authentic material for either laboratory or field bioassay. Oftentimes, larger quantities of the pheromones are desired for the development of monitoring and pest control methods. The scale up of the synthesis of complex pheromone compounds is often a major bottleneck in the practical application of pheromones. Also, the unusual structure of some pheromone compounds beckons synthetic chemists to apply new methodology in order to show off their methods. 

The (2R,3R,4R) diastereomer results from partial racemization of one or both of the allenylmetal intermediates. This point was confirmed by comparison to authentic material as the (S)-MPA ((S)-(2-methoxy)phenylacetic acid-Mosher s acid) derivative. The optical rotations of these compounds are small, and thus correlation by comparison of [ajp... 

The hydrate formed by photolysis of this substance is one of the few such products (the others are uracil hydrate, 5-fluorouracil hydrate, and uridine hydrate) that have actually been isolated and compared with authentic material of known structure.7 It is nearly the only product formed in the photolysis, is definitely stable at room temperature and neutral pH, and the thermal reversal to dimethyluracil is nearly quantitative. These properties, as Moore observed, make the reaction ideal for mechanistic investigation. Burr and Park have investigated the reaction mechanism by measuring the photolysis rate of dimethyluracil in mixtures of water with several nonaqueous, nonreactive solvents as a function of water concentration.64 The photolysis rate for 10" iM DMU was found to be the same in water-saturated cyclohexane (about 5 x 10-3M in water) as in dry cyclohexane. The photolysis rate in dry, highly purified dioxane was quite insensitive to water, and it was observed that hydrate formation (measured by thin-layer chromatography and by thermal absorbance reversal) became appreciable only at water concentrations above 40%. 

The quality assurance sample used is an aliquot of a urine pool prepared by mixing equal proportions of 24-h samples from 20 men and women. Thus, the values obtained on GC-MS analysis should approximate true average steroid excretions. We use these values to adjust the calibration of steroids without authentic materials in the external standard. We have determined that the excretion of 18-OH-THA in the quality assurance sample should be 90 pg/24 h THAldo, 30 pg/24 h, and 18-oxo-THF, 5 pg/24 h. The amount of these steroids in clinical samples is thus calibrated against a normal excretion. 

Muehlstaedt et al. reported an unusual ring transformation in which the thermodynamically more stable 7-amino-6-cyano-l,2,4-triazolo[l,5-a]-pyrimidine (67) underwent an acid-catalyzed retro-Dimroth rearrangement to the thermodynamically less stable 7-amino-6-carboxamido-l,2,4-tria-zolo[4,3-a]pyrimidine (115) (70JPR254). The structure of this product was confirmed by comparison with authentic material obtained (70JPR254) from the acid hydrolysis of the known 7-amino-6-cyano-l,2,4-triazolo[4,3-a]pyrimidine (66) (Scheme 48). 

The detection of products derived from the N-oxygenation of C=N functionalities presents many problems, which illustrate difficulties that are associated with the isolation, identification and quantification of small amounts of water-soluble metabolites. Spectrophotometric methods19 as well as differential pulse polarographic techniques20 previously used to determine oximes, nitrones and N-oxides frequently lack sensitivity and/or specificity. Improved analytical methods for the quantification of these N-oxy compounds include chromatographic techniques taking into account the chemical peculiarities of the individual N-oxygenated C=N functionalities. These procedures usually require the chemical synthesis of authentic material for comparison with data obtained with the isolated metabolites, and also for the construction of calibration curves. 

Pentabromoethylbenzene was found by Hoh et al. [60] in gas- and particle-phase atmospheric samples collected in the summer of 2003 in Chicago. Its identity was verified by comparison of the unknown mass spectra and GC retention times with those of authentic material. 

Based on that of authentic material, the UV-detected chromatogram showed that the peak from fluticasone propionate eluted first and four impurity peaks (see below for structures) had later retention times of 20, 26, 30 and 36 min, respectively ... 

The cyclization of aminyl radical 5, produced by decomposition of tetrazene 4 (Scheme 1), was investigated, and products were analyzed by GC/MS comparisons to authentic materials. The results are summarized in Table 1 (83JA7759). It is important to note that no piperidine products were detected and that a 1 1 ratio of cyclic-to-acylic disproportionation... 

The structure (29) of epirubijervine was deduced mainly on the basis of XH and 13C n.m.r. data, and was confirmed by direct comparison with authentic material.62... 

Phosphoglucomutase (EC 2.7 5.l) slowly converts R-l-P to ribose-5-phosphate. A mixture of 35 mM R-l-f O J-P, 17mM R-l-[ L 0l(]-P and less than lmg glucose-1,6-diphosphate at pH 7 33 was equilibrated with phosphoglucomutase (Sigma, P3397, rabbit muscle), at 25°C for 3 Hr. The 31p NMR spectrum was recorded at pH 7 37- The enzyme converted ca. 20 to a mixture of ribose-5-phosphate l Ol (resonance identified by addition of authentic material) and I80I803 species. This demonstrated that the enzyme catalyzed formation of the 0-P bond. 

Methylation of stachyose and subsequent hydrolysis, by Onuki,20 gave 2,3,4,6-tetra-O-methyl-D-galactose (identified as the crystalline anilide), a tri-O-methyl-D-galactose and a tri-O-methyl-D-glucose (which were converted into the 2,3,4,6-tetra-O-methyl derivatives, and characterized as the crystalline anilides), and 1,3,4,6-tetra-O-methyl-D-fructose, a sirup which agreed in properties with the authentic material. 

In an attempt to correlate pharmacological activity with the rate of biotransformation, Beckett and Morton have studied the metabolism of a series of indole alkaloids and related model systems by a variety of enzyme preparations of mammalian origin (39, 40, 57-59). Of the systems studied, rabbit liver microsomes were effective in performing O-demethylation liver microsome preparations from rat and guinea pig were not very effective in transforming alkaloids 4-7 and 9-19 (but vide infra) (40). In the case of corynantheidine (4), the product of metabolism was identified as the 0-( 17)-demethyl compound 8 by TLC comparison with authentic material. 

The anodic fluorination of 1,4-difluorobenzene (22) using BDD electrodes was reported more than a decade ago and represents the first synthetic use of BDD anodes. NEt4F.4HF was employed as electrolyte. The electrochemical conversion was monitored by gas chromatography and the identity of the product 23 found by comparison with authentic material. The electrolysis was conducted at constant voltage conditions with 2.75 V (vs Ag/Ag+) at the BDD anode. Further preparative details for the formation of 3.3.6.6-tetrafluoro-1,4-cyclohexadiene (23) were not provided [66] (Scheme 11). 

In actual practice, final identification of a sugar by partition chromatography involves chromatographing the unknown on the same paper with authentic material. The test should be repeated with at least... 

However, there are circumstances where only one of the above claims is actually of practical relevance. For example if we have manufactured a batch of crude drug for sale, the purchaser will demand some statement as to its minimum purity, but will hardly insist that we guarantee that it does not contain more than a particular amount of the authentic material. What we can do in such a case is to calculate what is initially a 90 per cent confidence interval for true drug content, which will generate two statements ... 

Where limits for minor components are specified in the column entitled Other Requirements in the above tabular specifications for flavor chemicals, analysts should use authentic materials to confirm the retention times of minor components. Determine the quantity of components following the instructions below under Calculations and Methods. 

Lignin Models. l-(4-Hydroxy-3-methoxyphenyl)-2-(2-methoxyphcnoxy)propan-1,3-diol (VII). The 4-benzyloxy-a-keto precursor to VII was prepared as previously described (16), Treatment of this compound (70 mg, 0.17 mmole) in THF(2 mL)/H2O(0.1 mL) with 10% Pd/C under H2 (balloon), with stirring, for 3 hours gave a colorless oil (49 mg, 91%) which was shown to be VII by comparison (TLC and NMR) with authentic material. A 70 30 erythroAhreo ratio was indicated by 13C-NMR. The XH and 13C-chemical shifts (CDCI3) have been previously published (17), Compound VII enriched with 13C at Ca was prepared from labeled acetovanillone, which was prepared from guaiacol and acetic acid-l-13C by a procedure analogous with that described previously (16), The 7-13C enriched compound was made by simply utilizing 13C-formaldehyde in the synthesis. 

The remainder of the ozonolysis mixture was distilled from 22 °C (0.4 mm) to 55°C (0.03 mm) to give 0.549 gram of product. The crude product was distilled at 27°C (0.25 mm) to give 0.376 gram of a liquid. Analysis of this material by GPC showed that 70% of it was methyl ethyl ketone diperoxide (30% yield) identified by comparison with authentic material. The diperoxide had m.p. 7°-8°C. The remainder of the product was not identified. 

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