A simple one-step ultrasonic-assisted extraction and derivatization method coupling to high-performance liquid chromatographyfor the determination of ε-aminocaproic acid and amino acids in cosmetics.

Nowadays, the safety of cosmetics is a widespread concern. Amines are common cosmetic additives. Some of them such as amino acids are beneficial. Another kind of amines, however, ε-aminocaproic acid (EACA) is prohibited to add into cosmetics for its adverse reactions. In this study, a simple, rapid, sensitive and eco-friendly one-step ultrasonic-assisted extraction and derivatization (UAE-D) method was developed for determination of EACA and amino acids in cosmetics by coupling with high-performance liquid chromatography (HPLC). By using this sample preparation method, extraction and derivatization of EACA and amino acids were finished in one step in ultrasound field. During this procedure, 4-fluoro-7-nitrobenzofurazan (NBD-F)was applied as derivatization reagent. The extraction conditions including the amount of NBD-F, extraction and derivatization temperature, the ultrasonic vibration time and pH value of the aqueous phase were evaluated. Meanwhile, the extraction mechanism was investigated. Under optimized conditions, the method detection limits were 0.086-0.15 µg/L, and method quantitation limits were 0.29-0.47 µg/L with RSDs less than 3.7% (n = 3). The recoveries of EACA and amino acids obtained from cosmetic samples were in range from 76.9% to 122.3%. Amino acids were found in all selected samples and quantified in range from 1.9 ±â€¯0.9 to 677.2 ±â€¯17.9 µg/kg. And EACA was found and quantified with the contents of 1284.3 ±â€¯22.1 µg/kg in a toner sample. This UAE-D-HPLC method shortened and simplified the sample pretreatment as well as enhanced the sensitivity of analytical method. In our record, only 10 min was needed for the total sample preparation process. And the method detection limits were two orders of magnitude less than literature reports. Furthermore, we reduced the consumption of solvent and minimized the usage of organic solvents, which made our method moving towards green analytical chemistry. In brief, our UAE-D-HPLC method is a simple, rapid, sensitive and eco-friendly analytical method for the determination of EACA and amino acids in cosmetics.

In vitro effects of an extracorporeal membrane oxygenation circuit on the sequestration of ϵ-aminocaproic acid.

OBJECTIVE: To assess the in vitro effects of drug sequestration in extracorporeal membrane oxygenation (ECMO) on ϵ-aminocaproic acid (EACA) concentrations. METHODS AND DESIGN: This in vitro study will determine changes in EACA concentration over time in ECMO circuits. A pediatric dose of 2,500 mg was administered to whole expired blood in the simulated pediatric ECMO circuit. Blood samples were collected at 0, 30, 60, 360 and 1440-minute intervals after initial administration equilibration from three different sites of the circuit: pre-oxygenator (PRE), post-oxygenator (POST) and PVC tubing (PVC) to determine the predominant site of drug loss. The circuit was maintained for two consecutive days with a re-dose at 24 hours to establish a comparison between unsaturated (New) and saturated (Old) oxygenator membranes. Comparisons between sample sites, sample times and New versus Old membranes were statistically analyzed by a linear mixed-effects model with significance defined as a p-value <0.05. RESULTS: There were no significant differences in EACA concentration with respect to sample site, with PRE and POST samples demonstrating respective mean differences of 0.30 mg/ml and 0.34 mg/ml as compared to PVC, resulting in non-significant p-values of 0.373 [95% CI (-0.37, 0.98)] and 0.324 [95% CI (-0.34, 1.01)], respectively. The comparison of New vs. Old ECMO circuits resulted in non-significant changes from baseline, with a mean difference of 0.50 mg/ml, 95% CI (-0.65, 1.65), p=0.315. CONCLUSION: The findings of this study did not show any significant changes in drug concentration that can be attributed to sequestration within the ECMO circuit. Mean concentrations between ECMO circuit sample sites did not differ significantly. Comparison between New and Old circuits also did not differ significantly in the change from baseline concentration over time. Sequestration within ECMO circuits appears not to be a considerable factor for EACA administration.

Cyclic oligomers in polyamide for food contact material: quantification by HPLC-CLND and single-substance calibration.

Cyclic oligomers are the major substances migrating from polyamide (PA) food contact materials. However, no commercial standards are available for the quantification of these substances. For the first time the quantification of cyclic oligomers was carried out by HPLC coupled with a chemiluminescence nitrogen detector (CLND) and single-substance calibration. Cyclic monomer (MW = 226 Da) and dimer (MW = 452 Da) of PA66 were synthesised and equimolar N detection of CLND to synthesised oligomers, caprolactam, 6-aminohexanoic acid (monomers of PA6) and caffeine (a typical nitrogen calibrant) was proven. Relative response factors (UVD at 210 nm) referring to caprolactam were determined for cyclic PA6 oligomers from dimer to nonamer, using HPLC-CLND in combination with a UVD. A method for quantification of cyclic oligomer content in PA materials was introduced using HPLC-CLND analysis and caffeine as a single nitrogen calibrant. The method was applied to the quantification of cyclic PA oligomers in several PA granulates. For two PA6 granulates from different manufacturers markedly different oligomer contents were analysed (19.5 versus 13.4 g kg⁻¹). The elution pattern of cyclic oligomers offers the possibility of identifying the PA type and differentiating between PA copolymers and blends.

Conditions for the formation of dilysyl-dipyrrolones A and B, and novel yellow dipyrrolone derivatives formed from xylose and amino acids in the presence of lysine.

Foods derived from plants contain pentose in addition to hexose. It is well known that pentose contributes more to browning by the Maillard reaction than hexose does. We have recently found novel yellow compounds formed from xylose and lysine under weakly acidic conditions, named dilysyldipyrrolones (dilysyl-DPLs) A and B. We indicate in this study that dilysyl-DPLs were specifically formed under weakly acidic conditions from pentose, but not hexose. Moreover, we found novel DPL derivatives which were formed from xylose and such amino acids as alanine, arginine, aspartic acid, glutamic acid, isoleucine, leucine, phenylalanine, serine, and valine in the presence of lysine.

Simultaneous determination of active ingredients in an ophthalmic solution by isocratic tandem-mode HPLC connected reverse phase column and strong cation exchange column.

A tandem-mode high performance liquid chromatography (HPLC) system is described here, which employs reversed phase liquid chromatography (RPLC) followed by strong cation exchange liquid chromatography (SCX), was used to determine the mixture of six ingredients in an ophthalmic solution. As a result of investigations, isocratic HPLC methods that using two columns in tandem-mode; Atlantis dC18 (75 mm x 4.6 mm i.d., 3 microm, ODS) and CAPCELL PAK SCX UG80 (75 mm x 4.6 mm i.d., SCX), which have different separation modes, and control of mixture of methanol/ammonium dihydrogenphosphate buffer as used for the eluent, allowed for six target ingredients to be determined simultaneously. And all ingredients separated perfectly and were determined efficiently and rapidly. Validation of the method was accomplished with respect to linearity (r>0.999), recovery (99.4-100.4%), precision (R.S.D. 0.1-0.9%) and specificity. These results suggest that the fusion of different separation modes can be used for the simultaneous determination of ingredients in ophthalmic solutions, and this can be accomplished rapidly and with high precision.

The effects of ultrafiltration on e-aminocaproic acid: an in vitro analysis.

Blood conservation strategies have become a standard of practice in cardiac surgery, with the use of antifibrinolytic agents and ultrafiltration two popular techniques. The purpose of this study was to evaluate the effects of continuous ultrafiltration on e-aminocaproic acid (EACA) utilizing functional coagulation analysis. A fibrinolytic assay was developed to detect EACA using the thromboelastograph (TEG) and urokinase (0.138 units 0.360 mL(-1)). Fresh bovine blood (23 +/- 1% hematocrit) was pumped (100 mL min(-1)) through an ultrafiltrator (HPH 400) at 37 degrees C with a transmembrane pressure of 280 mmHg. EACA (0.065 mg mL(-1)) was circulated for 10 minutes before initiating ultrafiltration. Samples (pre- and postultrafiltrator) were obtained at baseline, 5, and 10 min of ultrafiltration and analyzed via the fibrinolytic assay for EACA determination. TEG profiles significantly decreased from concentrations of 0.065 mg to 0.0325 mg of EACA mL(-1) blood (maximum amplitude MA, 75.4 +/- 4.0 versus 63.3 +/- 2.9, p < .05, TEG index 5.4 +/- 0.7 versus 4.0 +/- 0.3, p < .05). Fibrinolysis at 30 min increased as EACA concentrations declined (0.065 mg, 0% versus 0.032 mg, 16.4 +/- 2.8%, p < .05). During ultrafiltration the MA increased significantly from baseline to 10 min postultrafiltrator (68.2 +/- 3.0 versus 75.8 +/- 10.0, p < .05) and from 5 min pre- to 10 min postultrafiltrator (69.7 +/- 4.2 versus 75.8 +/- 10.0, p < .05). The TEG index showed no significant change, and no fibrinolysis was detected at 30 min from any datapoint during ultrafiltration. In conclusion, this study demonstrates that the antifibrinolytic properties of EACA are maintained during ultrafiltration with a 25% reduction in total circulating volume.

Interaction of a group A Streptococcus within human plasma results in assembly of a surface plasminogen activator that contributes to occupancy of surface plasmin-binding structures.

Group A streptococcal isolate 187061 incubated in human plasma or serum reconstituted with fibrinogen but not plasminogen-depleted plasma or serum alone acquired a surface plasminogen activator activity. Assembly of the surface plasminogen activator was inhibited by the presence of neutralizing antibodies to streptokinase. Once assembled, the bacterial-associated plasminogen activator could generate plasmin when incubated in human plasminogen, plasmin or serum which could bind to bacterial surface plasmin-binding structures despite the presence of host physiological inhibitors. These studies provide evidence that the pathways by which group A isolates interact with human plasmin(ogen) are potentially linked and may provide a mechanism for bacteria to acquire host enzymatic activity efficiently in the infected host.

The detection of an early advanced glycation product which co-elutes with the Amadori product on aminophenylboronate affinity chromatography.

The production of an antiserum recognizing an early advanced glycation product of glycated human serum albumin (HSA) is reported. The antiserum was produced with the intention of recognizing the Amadori product, i.e. the monofructosamine derivative, of any glycated protein. In retrospect, however, the immunogen appears to have been transformed in vivo which led to the production of antibodies to an early advanced glycation product. Two-site immunometric and competitive ELISAs showed that the affinity-purified antibodies recognized glycated HSA only after it had been stored for several months. This recognition, by the antibody, was more specific for the transformed product than for the original hapten (1-amino-1-deoxy-D-fructose-6-aminohexanoic acid) used for immunization by a factor of more than 1,000. These antibodies also detected immunoreactive material present in the elution fraction after in vivo glycated HSA had been chromatographed on an aminophenylboronate affinity column, indicating that an early advanced glycation product can co-elute with the Amadori product of glycated HSA on aminophenylboronate affinity chromatography. This suggests that the antiserum recognized an early advanced glycation product that also contained cis-diols as does the Amadori product, and may prove useful in the early detection of clinical complications in diabetic patients.

High performance liquid chromatographic assay of Amicar, epsilon-aminocaproic acid, in plasma and urine after pre-column derivatization with o-phthalaldehyde for fluorescence detection.

A simple, reliable and highly sensitive procedure was devised for measuring the levels of Amicar in blood and urine. 100 microL of serum or urine sample was added to 10 microL of a 10% w/v zinc sulfate solution and 100 microL of methanol, as previously described (Lam et al., 1980) for the removal of proteins by precipitation. 50 microL of the supernatant was then mixed with 300 microL of 1 M borate buffer containing D-valine as the internal standard before derivatization with o-phthalaldehyde. The amino acids were then separated by a stereoselective reversed-phase system using a mobile phase containing 10% of acetonitrile in 2.5 mM Cu(II) complexes of L-proline. The chromatography is highly selective, resolving Amicar from L-valine which in turn is resolved from its unnatural D-antipode, the internal standard. The procedure including sample preparation and separation required a total of 15 min. As little as 50 ng/mL of Amicar in body fluids could be detected as the o-phthalaldehyde derivative by fluorescence.

[Preparation and testing of polymer drugs. 4. Water-soluble polymer drugs with a base of vinylpyrrolidone-maleic acid anhydride-copolymers]. / Darstellung und Testung von Polymerpharmaka. 4. Mitteilung: Wasserlösliche Polymerpharmaka auf der Basis von Vinylpyrrolidon-Maleinsäureanhydrid-Copolymeren.

Watersoluble polymeric drugs were synthesized on the basis of alternating copolymer of 1-vinyl-2-pyrrolidone and maleic anhydride. Benzocain served as model drug. The drug was bound directly as well as about epsilon-aminocapronic acid as spacer. The pancreatin catalyzed hydrolysis of these polymeric drugs was studied. No hydrolysis was noted, if the drug is directly bound on the copolymer. The polymeric drug with the epsilon-aminocapronic acid as spacer showed a small release. Possible reasons for these facts are discussed.

gamma-aminobutyric acid in the murine brain: mass fragmentographic assay method and post-mortem changes.

An improved mass fragmentographic assay method for the determination of gamma-aminobutyric acid (GABA) in the brain is described. Applicability of the method was examined in a study of the effect of semicarbazide on GABA levels and in a separate study to confirm post-mortem increase in GABA. The method itself is based on Cattabeni's procedure in which GABA is assayed as trimethylsilyl derivative. Three improvements were made: a) application of a more suitable mass spectrometry system for GABA determination; b) use of 6-aminocaproic acid as the internal standard; c) selection f a high intensive ion (m/z 174) for mass fragmentographic analysis. The mass spectrometer used is accurate to as little as 25 pg. GABA levels after semicarbazide treatment decreased 54.4% in rat whole brain and 44.2% in the dorsal hippocampus. Rapid post-mortem increases in GABA levels were confirmed by application of the improved assay method; decreases were most clearly observable following microwave irradiation. Post-mortem changes in GABA were observed within 3 min after death, as reported by other researchers.