Hydrolyzed sample

The acetylation of isopropanol by acetic anhydride is catalyzed by 4-dimethyl-aminopyridine (DMAP). The reaction kinetics can be followed titrimetrically by hydrolyzing samples at known times and titrating them with standard NaOH. A blank is carried out with the reagents but no alcohol. 

Many synthetic water-soluble polymers are easily analyzed by GPC. These include polyacrylamide,130 sodium poly(styrenesulfonate),131 and poly (2-vinyl pyridine).132 An important issue in aqueous GPC of synthetic polymers is the effect of solvent conditions on hydrodynamic volume and therefore retention. Ion inclusion and ion exclusion effects may also be important. In one interesting case, samples of polyacrylamide in which the amide side chain was partially hydrolyzed to generate a random copolymer of acrylic acid and acrylamide exhibited pH-dependent GPC fractionation.130 At a pH so low that the side chain would be expected to be protonated, hydrolyzed samples eluted later than untreated samples, perhaps suggesting intramolecular hydrogen bonding. At neutral pH, the hydrolyzed samples eluted earlier than untreated samples, an effect that was ascribed to enlargement... 

Flocculation was correlated with both adsorption density and estimated surface coverage for the nonionic and 33% hydrolyzed polyacrylamides. Maximum settling rate was obtained with the nonionic flocculent at 0.1 and with the hydrolyzed sample at 0.2 surface coverage. Supernatant clarity showed a maximum at a surface coverage of Na-kaolinite by the hydrolyzed polyacrylamide of 0.1. At higher surface coverages (such as 0.5) considered in the past to be optimum for flocculation, complete dispersion was obtained with both the nonionic and the anionic polymer. 

Purify the FMLPK-Fl on a Cjg reverse-phase HPLC column by isocratic elution with a solution of 30% acetonitrile and 0.2 M acetic acid. Monitor the effluent at 254 nm. The peak corresponding to FMLPK-Fl should be clearly resolved from unreacted FITC and its breakdown products. Confirm the identity of FMLPK-Fl by performing an amino acid analysis of an acid-hydrolyzed sample. 

Hjerde, T., Smidsrad, O., Christensen, B.E. (1998b). Acid hydrolysis of k- and i-carra-geenan in the disordered and ordered conformations characterization of partially hydrolyzed samples and single-stranded oligomers released from the ordered structures. Macromolecules, 31, 1842-1851. 

Terminal 3,6-dideoxyhexoses that occur in lipopolysaccharides from Salmonella and Yersinia (Pasteurella) species7 could be hydrolyzed off with a high degree of selectivity. They may, therefore, be located by methylation analysis of the original lipopolysaccharide and of a partially hydrolyzed sample. Thus, for the Salmonella typhi-murium 395 MS lipopolysaccharide, composed18 of oligosaccharide... 

Similarly, methylation analysis of a partially hydrolyzed sample of the Klebsiella type 38 capsular polysaccharide, composed of pentasaccharide repeating units (5), revealed that the terminal 3-deoxy-L-g/ycero-pentulosylonic acid group (6) was located at 0-3 of a D-galac-tosyl residue (7), as the 6-O-methyl-D-galactose in the methylation... 

Figure 25-4 Part of amino-acid chromatogram obtained by the method of automatic amino-acid analysis from a hydrolyzed sample of the enzyme ribonuclease. The component amino acids listed are present in the ratio Asp Thr Ser Glu Pro Gly Ala = 15 10 15 12 4 3 12, as determined by peak intensity. The volume of effluent is a measure of the retention time of the amino acids on the column.

PITC (phenylisothiocyanate) Aabs = 254 nm. Phenylthiocarbamyl amino acid derivatives are moderately stable at room temperature (1 day). PITC reacts well with both primary and secondary amino acids. Reaction time is approximately 5 minutes at room temperature. Excess reagent must subsequently be removed under vacuum. Also, for hydrolyzed samples, hydrochloric acid must be completely removed prior to derivatization. As a result, even though the actual reaction time is reasonably fast, the total time for various sample manipulations can add up to 2 hours. This is partially compensated by the extremely fast separation possible (12 minutes). Detection is by UV absorption only. Detection limits are typically in the high picomole range. Short column life can result due to unreacted PITC getting into the column. Unlike some of the other reagents, PITC quantifies tyrosine and histidine very well. PITC analysis is available as a commercially prepackaged system dubbed Pico-Tag by Waters Corporation. Representative references include 184-188. See Fig. 11 for a typical separation. 

The hydrolyzed samples were not completely soluble. The M -values represent the soluble part of the previously grafted PAN chains. From the M -values obtained for PAN, the number of anhydroglucose units per grafted PAN chain was calculated. Corrections were introduced for the weight of the anhydroglucose units of EC and HEC according to the degree of substitution. 

Water Retention of Hydrolyzed Samples. The water retention of the AN-grafted samples after hydrolysis in aqueous alkali were determined using three different methods ... 

A1. 0.5 g sample (on dry basis) was swollen in 100 ml distilled water for 10 minutes. The fiber suspension was poured into a sintered glass filter (porosity 1) and sucked at 700 mm Hg pressure. The volume of filtrate was measured and the water retention calculated as g of water per g of dry material. The measurement was repeated after drying the hydrolyzed sample in an oven at 60°C. 

The authors of the studies cited above found that the enzymes used during sample preparation could not completely hydrolyze sample proteins into amino acids. This is partly understandable as both proteinase K and subtilisin are known to show hydrolyzing preference for specific residues of proteins. Accordingly, they do not necessarily arrive at total hydrolysis. At the same time, neither pronase E nor protease XIV could always provide 100 percent extraction of Se from the samples (see Table 19.1). Therefore, alternative methods should be developed in the field of sample preparation to replace enzymatic methods. 

Analysis of the modem degraded samples showed evidence of oxidation in both the thermally degraded samples and the 100-Mrad irradiated sample but not in the original or acid-hydrolyzed sample. Turnbulls Blue test of the hydrolyzed sample, however, did indicate a small degree... 

Urine, kidney, Hydrolyze sample directly or Spectrophotometric No data No data... 

In studies performed by Arnold " and Sachs and Arnold, hair samples were treated with a solution of 1 M NaOH and boiled until the hair disintegrated. The hydrolyzed sample was neutralized with 1 M HCl. The same approach was employed by Kintz and Mangin. Hair digests were analyzed directly by the enzyme multiplied immunoassay technique (Emit , Syva Corporation, Palo Alto, CA) and fluorescence polarization immunoassay (FPIA, Abbott Laboratories, Abbott Park, IL). 

The overall average yield for the pre-hydrolyzed sample was 2.2310.51 nmol (Fig. 3). The overall average error was 6.5% (Fig. 4). The methodological breakdown of the data showed significant differences in error (Table ni). 

Figure 5. Comparison of errors for the intact rs. pre-hydrolyzed sample.

The pre-hydrolyzed sample, prepared by conventional HCl digestion, contained cystine as such, and a number of sites obtained values close to the theoretical value. The distribution of cystine values found by all the sites was very asymmetric. Clusters at -50% error and some very high values suggest that some of these errors are perhaps due to a misunderstanding of the terminology used in analysis of cystine and cysteine. It should be noted that Cys/2 (halfcystine), when reported as such, has double the molar amount that would be reported for cystine. Commercial standards usually contain equimolar amounts of half-cystine and the other amino acids, or stated in terms of cystine - half the amoimt. 

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