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Chemical Analysis
Published in Rudolf Puffr, Vladimír Kubánek, Lactam-Based Polyamides, 2019
Božena Lánská, Jaroslav Stehlíček
A quantitative determination of the content of acid or basic compounds in caprolactam is possible by using conductometric or Potentiometrie titrations.5,11 Basic impurities, mainly amines which are determined in caprolactam by titration with a strong mineral acid, are all due to the production process. On the contrary, the content of acid compounds (with the exception of aminocaproic acid) determined by titration with a strong base indicates the oxidation of caprolactam. Hence, pH of the aqueous solution of caprolactam is its essential characteristic. For pure caprolactam this value should be virtually 7.5 Present-day high-quality industrial caprolactams give a weakly alkaline reaction corresponding to a base content of 10–4 mol/kg at most. Caprolactam having an acid reaction is generally regarded as completely low-quality. The pH value of caprolactam is best determined potentiometri-cally.5,11 The conductometric titration can also be used in the determination of the content of weak salts of weak acids, i.e., a value which virtually represents the content of aminocaproic acid in caprolactam.11 In the determination of carboxylic acids, the titration base should be free of carbonates.
Polycondensation Polymers (Step-Reaction Polymerization)
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Interestingly, Carothers and his group had considered a number of routes to produce the polyamides, including 6-aminocaproic acid. In their attempts to form nylon 6 from 6-aminocaproic acid, they obtained a waxy material that they believed to be oligomeric polyamide along with a cyclic material. The cyclic material was caprolactam. Carothers published the results, noting that this cyclic amide could not give polyamides. This paper cost DuPont a lot of money because chemists at I. G. Farben scoured the literature looking for ways to break DuPont's hold on the production of nylon 66 because any company using nylon 66 had to pay royalties to DuPont. This paper appeared to galvanize efforts at I. G. Farben to polymerize caprolactam. They found that the “secret” was the presence of a little water that allowed the decyclization of caprolactam forming nylon 6. Incidentally, caprolactam was the same product that Beckmann produced in his reaction with oximes years before in 1886.
Process Affinity Chromatography
Published in Juan A. Asenjo, Separation Processes in Biotechnology, 2020
Before dealing with the chromatographic applications of this technique, it is worth remembering that the affinity concept can be applied to batch procedures and used at any scale. Batch adsorption can be performed in at least three different ways: (1) the adsorbent is added loose in the bulk volume of the sample, and subsequent steps are performed on a filter or in a column; (2) the adsorbent is confined in a porous “bag” or “belt” and is added to the sample in this form; and (3) the adsorbent is placed in a fluidized bed. Batch affinity adsorption has been used to purify plasminogen from human plasma on agarose-immobilized lysine (Eketorp, 1982). When coupled to agarose, this amino acid can be regarded as an analog of ε-aminocaproic acid, a strong inhibitor of the activation of plasminogen to plasmin. The batch-adsorbed plasminogen was recovered from the affinity sorbent packed in a column upon elution with 0.1 M of ε-aminocaproic acid. Similarly, purification of human antithrombin III (also known as heparin cofactor) was effected by batch adsorption on heparin-Sepharose CL-6B followed by elution with 2 M sodium chloride (Eketorp, 1982). However, in most cases the affinity adsorbent is packed in a column, and it is in this form that the technique finds most applications. These include, but are not limited to, human plasma protein/enzyme processing, removing trace amunts of contaminants from substances intended for medical use, and preparing interferons, growth factors, monoclonal antibodies, therapeutic enzymes, lectins, oxidoreductases, and restriction endonucleases (Clonis, 1987a) (Table 3).
Room-temperature-storable chemiluminescence freeze-drying mixes for detection of SARS-CoV-2 neutralizing antibody
Published in Drying Technology, 2022
Qihan Zhang, Liuyu Gong, Yewei Zhang, Ya Shen, Lin Shen, Liangli Cao, Guocheng Han, Fangrong Hu, Feijun Zhao, Zhencheng Chen
We purchased sodium chloride (NaCl, 99%), Sucrose (C12H22O11, 99%), Trehalose (C12H22O11, 99%), Bovine serum albumin (BSA, 98%), Equine serum albumin (HAS, 96%), Amgiotensin converting enzyme-2 (ACE2, 95%), SARS-COV-2 spike receptor-binding domain (SARS-CoV-2 S1 RBD, 95%), N-methylmorpholine (C5H11NO, 99%), MAL-dPEG®24-TFP ester (C64H108F4N2O29, 90%), 2-iminothiolane (C4H7NS·HCl, 98%), Alkaline phosphatase (ALP, 98%), Glycol-2000 (H(OCH2CH2)nOH, 99%), ProClin™300 (pkg of 50 mL), BRONIDOX-L (C4H6BrNO4, 99%), N-ethylmaleimide (C6H7NO2, 99%), Glycine (C2H5NO2, 99%), 6-Aminocaproic acid (C6H13NO2, 99%), L-Lysine (C6H14N2O2, 99%), Polyvinylpyrrolidone (PVP, K30 and K360), Pullulan ((C37H62O30)n, GPC), Xylitol (C5H12O5, 99%), Sorbitol (C6H14O6, 99%), Mannitol (C6H14O6, 99%), Glycerol (C3H8O3, 99%), Glucan 200000 ((C6H10O5)n, 95%), Sodium benzoate (NaC6H5O6, 99%), Sodium azide (NaN3, 99.5%), Tween-20 (10% (wt/vol)) from Sigma-Aldrich (Shanghai) Co., Ltd. (Shanghai, China).