Methanol, detection

In addition to enzyme activity, the concentration of an nonelectroactive substrate can be determined electrochemically by this technique. By keeping the substrate (analyte) the limiting reagent, the amount of product produced is directly related to the initial concentration of substrate. Either kinetic or equilibrium measurements can be used. Typically an enzyme which produces NADH is used because NADH is readily detected electrochemically. Lactate has been detected using lactate dehydrogenase, and ethanol and methanol detected using alcohol dehydrogenase... 

Liquid chromatography was carried out utilizing a Hitachi model 63M adsorbent Hitachi gel 3010, developing solvent methanol, detecting wavelength 280nm). 

Used to introduce chromophores into aldehydes and ketones in a solution of carbonyl-free methanol detection of the more common 17-keto steroids as their 2,4-dinitrophenyl derivatives from urine and plasma suggested potential for clinical use Reference 20... 

Figure 9.69 Chromatograms recorded in the assay of UDPGT toward 4-NP. (a) Assay without 4-NP. (b) Assay without UDPGA. (c) Assay with all ingredients. Chromatographic conditions column, Hitachi gel No. 3010,3 mm X 500 mm, mobile phase, 0.01 N HC1 in 65% (v/v) methanol detection, 300 nm flow rate, 0.8 mL/min pressure, 60 kg/cm2 column temperature, 40°C. (From Matsui and Nagai, 1980.)...

Measurement of the activity of this enzyme by the HPLC assay method requires separation of the hypoxanthine and the IMP, which can be easily accomplished by several methods, including reversed-phase or ion-exchange HPLC. Jahngen and Rossomando (1984) used a reversed-phase Ci8 column with a mobile phase of 10 mM potassium phosphate (pH 5.6), and 10% methanol. Detection was at 254 nm, and the separation obtained is shown in Figure 9.98. 

Adenosine kinase catalyzes the transfer of phosphate from ATP to adenosine (Ado) to form AMP and ADP. The separation of the reactants, Ado and ATP, from the products, AMP and ADP, can be accomplished by reversed-phase HPLC (Ci8) with isocratic elution with a mobile phase of 0.1 M potassium phosphate (pH 5.5) and 10% methanol. Detection depends on the substrate. In this assay, it is useful to replace the substrate adenosine with the fluorescent analog formycin A (FoA) and to monitor the column eluent with a fluorescence detector. Thus, ATP and any of its hydrolytic products will not be detected. 

Separation of 3 -phosphoadenosine 5 -phosphosulfate and adenosine 3, 5 -diphosphate is carried out on an Econosphere Ci8 column (4.6 mm x 250 mm, 5 fim) at ambient temperature. The mobile phase was water-methanol (88 12) containing 75 mM KH2P04, 1 mM 1-octylamine, and 100 mM ammonium chloride. The pH was adjusted to 5.45 with KOH before the addition of methanol. Detection was by measuring absorbance at 254 nm. 

Filtration at 0.45 pm ion chromatography post-column reaction with methanol detection by SPEC with DPC (Lab. 25)... 

Several anions have proven to be effective for indirect photometric detection, figure 6.16 shows an excellent separation of conunon anions with 2.0 mM potassium phthalate, pH 6.0, with indirect detection at 280 nm. By switching to 4.0 mM p-hydro-xybenzoic acid, pH 8.5 with 2.5 % methanol, detection at 310 nm, and reducing the column length to 10 cm, the same anions plus phosphate could be separated in only... 

Many acrylic copolymers are currently used in the textile industry as binders for nonwoven fabrics. The purpose of these fibers is to stabilize the material. In many instances, these copolymers are used in conjunction with amino resins. Casanovas and Rovira have done a study of methyl methacrylate-ethyl acrylate-N-methylol-acrylamide by PY/GC-MS. Among the products identified were methane, ethylene, propene, isobutene, methanol, propionaldehyde, ethanol, ethyl acetate, methyl acrylate, methyl isobutyrate, ethyl acrylate, methyl methacrylate, n-propyl acrylate, and ethyl methacrylate. In this sample, clearly monomer reversion is the primary degradation process occurring however, several other degradation mechanisms are at work. When the sample contains an amino resin in the mixture, acrylonitrile is observed in the pyrogram. Another effect of the amino presence was a marked increase in the amount of methanol detected. Other products detected were meth-oxyhydrazine, methyl isocyanate, and methyl isocyanide. 

Urine is acidified with 2 M acetate buffer (pH = 3.5) and extracted with CH2CI2 methanol (19 1) the organic layer is washed with saturated NaHC03, filtered, and evaporated at 40°C to dryness under N2 the residue is dissolved in methanol Detection limit 0.5 p-g/ml Quantitation limit 1 p-g/ml... 

Method of extraction depends on Both materials can be base. Extraction with methanol detected in UV is often possible, then centri- 254 nm. 3-Butoxyethyl fugingandTLCwith this extract, nicotinate also with using an amount corresponding Konigs reagent... 

Figure 6 Separation of tocopherol isomers on a C30 reversed-phase column. Chromatographic conditions Column, LiChrospher WP 200, 3 fim, 250 X 4.6 mm mobile phase methanol detection, UV, 295 nm. Peak identification 1, 5-tocopherol 2, y-tocopherol 3, P-tocopherol 4, a-tocopherol 5, a-tocopheryl acetate. (From Ref. 66.)...

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