Biomedical subjects

A Parczewski

Publications and source records attributed to A Parczewski.

7 recordsLinked to original sources

PubMed2005

Basic and neutral route specific impurities in MDMA prepared by different synthesis methods. Comparison of impurity profiles.

In this work, the neutral and basic impurities found in the precipitate of MDMA(*)HCl are presented. MDMA.HCl was prepared by the most popular synthesis methods used in clandestine manufacture, i.e. safrole bromination, Leuckart method and reductive amination with various reducing agents: Al/Hg, NaBH(4), NaBH(3)CN. 3,4-Methylenedioxyphenyl-2-propanone (MDP-2-P), the starting material in Leuckart reaction and reductive amination, was prepared by two different synthesis methods, i.e. by isosafrole oxidation and MDP-2-nitropropene reduction. The extraction of impurities was performed under alkaline and neutral conditions. Impurity profiles were obtained using GC/MS. Each synthesis method is characterised by its own route specific impurities. The influence of pH on the extraction of synthesis markers from 3,4-methylenedioxymethamphetamine (MDMA) samples is discussed and comparison of the profiles of basic and neutral impurities is presented.

Journal Article↗

PubMed2005

Application of false discovery rate procedure to pairwise comparisons of refractive index of glass fragments.

This study was undertaken to apply a new method of controlling type I error when performing pairwise comparisons. The Benjamini and Hochberg false discovery rate (FDR) controlling procedures have proved to be very powerful tools in solving many practical problems but have not yet been applied to pairwise comparisons of refractive index of glass samples. Students t-test and Welch test (unequal variance Student's t-test) were applied to all possible pairwise comparisons. The comparisons were made on the basis of refractive index values of 72 glass fragments from different car windows and 69 different fragments from one windscreen. The type I error was controlled by the use of Benjamini and Hochberg false discovery rate (FDR) controlling procedure. To illustrate the importance of controlling type I error when using pairwise comparisons, results of pairwise comparisons with the FDR controlling procedure were compared to those comparisons made without any controlling procedure. Significantly fewer false negative results (false rejection of H0) were found during the use of FDR procedure in the comparison of refractive indices from the same windscreen than when comparing without controlling type I error. The results of application of FDR method were also compared to the results of other post-hoc tests, such as Tukey HSD test and Bonfferoni test. The FDR method has higher power than Bonferroni method and Tukey HSD method and control errors better than comparing without controlling type I error. The method of choice, for pairwise comparison of glass fragments on the basis of refractive index is Welch test with FDR adjustment. The method gave type I errors at level about 5.3% and type II error at about 3.7%.

Journal Article↗

PubMed2005

Determination of synthesis method of ecstasy based on the basic impurities.

MDMA was prepared by five different synthesis routes, i.e. by dissolving metal reduction (Al/Hg), cyanoborohydride reduction (NaBH(3)CN), borohydride reduction in low temperature (NaBH(4)), Leuckart reaction and safrole bromination. MDP-2-P was prepared by two different synthesis methods, i.e. by isosafrole oxidation and MDP-2-nitropropene reduction. Each of the synthesis routes was repeated three times in order to establish variation in qualitative composition of route specific impurities between different batches. The analysis of impurities in MDP-2-nitropropene, MDP-2-P, bromosafrole and MDMA was performed with GC-MS. GC/MS was used also in the analysis of impurities in starting materials: safrole, isosafrole and piperonal. As a result of our study the way of determination of MDMA synthesis route determination based on qualitative composition of impurities is proposed.

Journal Article↗

PubMed2005

Determination of synthesis route of 1-(3,4-methylenedioxyphenyl)-2-propanone (MDP-2-P) based on impurity profiles of MDMA.

In our study 1-(3,4-methylenedioxyphenyl)-2-propanone (MDP-2-P or PMK) was prepared by two different routes, i.e. by oxidizing isosafrole in an acid medium and by 1-(3,4-methylenedioxyphenyl)-2-nitropropene reduction. The final product-MDP-2-P was subjected to GC/MS analysis. The intermediates and reaction by-products were identified and the 'route specific' impurities were established. The following impurities are the markers of the greatest importance: 1-(3,4-methylenedioxyphenyl)-1-propanone (compound 10, Table 2), 1-methoxy-1-(3,4-methylenedioxyphenyl)-2-propanone (compound 11, Table 2) and 2,2,4-trimethyl-5-(3,4-methylenedioxyphenyl)-[1,3]dioxolane (compound 13, Table 2) (the 'oxidising isosafrole route') and N-cyclohexylacetamide (compound 3, Table 1), 3-methyl-6,7-methylenedioxyisoquinoline-1,4-dione (compound 15, Table 1) (the 'MDP-2-nitropropene reduction route'). Subsequently, MDMA was prepared by reductive amination of MDP-2-P using NaBH4 as reducing agent (so-called 'cool method'). Impurities were extracted with n-heptane under alkaline conditions. The impurity profiles were obtained by means of GC/MS, some reaction by-products were identified by means of the EI mass spectra including low energy EI mass spectra and 'route specific' impurities were established. 4-Methyl-5-(3,4-methylenedioxyphenyl)-[1,3]dioxolan-2-one (compound 22, Table 2), N-methyl-2-methoxy-1-methyl-2-(3,4-methylenedioxyphenyl)-ethaneamine (compound 18, Table 2), 3-methyl-6,7-methylenedioxyisoquinoline-1,4-dione (compound 15, Table 1) and N-cyclohexyloacetamide (compound 3, Table 1) were found to be the synthesis markers of greatest importance.

Journal Article↗

PubMed2003

Profiling of impurities in p-methoxymethamphetamine (PMMA) by means of SPE/TLC method. Examination of the influence of experimental conditions according to 2(4) factorial.

In the present paper profiling of impurities in p-methoxymethamphetamine (PMMA) by means of SPE/TLC is reported. PMMA was synthesised by Leuckart procedure. The influence of experimental conditions on the profile quality was investigated. The experiments were carried out according to a 2(4) factorial. The proposed characteristics of the profile quality (optimisation criterions) are based on a matrix presentation of TLC patterns. They take into account, simultaneously, the number of spots revealed, differences between R(f) values and intensity of fluorescence.

Amphetamines↗

PubMed2003

Synthesis of standards of the most important markers of Leuckart p-methoxymethamphetamine (PMMA). Examination of the influence of experimental conditions and a drug diluent on SPE/TLC profiling.

The synthesis of characteristic markers of PMMA obtained by Leuckart method was described. The effectiveness of a procedure of SPE/TLC screening profiling of impurities was studied on the basis of selected impurities. The influence of glucose (a drug diluent) on the profile quality was investigated. The intermediate product (characteristic for the Leuckart synthesis) N-formyl-p-methoxymethamphetamine (1) and by-products: N-formyl-p-methoxyamphetamine (2), p-methoxyamphetamine (3), N,N-dimethyl-p-methoxyamphetamine (4), (RS) and (RR/SS) diastereoisomers of bis(1-methyl-2-(4-methoxyphenyl)ethyl)amine (meso-5 and rac-5), (RS) and (RR/SS) diastereoisomers of N-methyl-bis(1-methyl-2-(4-methoxyphenyl)ethyl)amine (meso-6 and rac-6), N-methyl-1,3-bis(4-methoxyphenyl)propane-2-amine (7) were synthesized. The substrate p-methoxyphenylacetone and the impurities 1 and 4 were used in the study of influence of experimental conditions and glucose on the profiling process and results. The experiments were carried out according to a 2(4) factorial design. The proposed criterions of the profile quality are based on matrix presentation of TLC patterns. They take into account the number of spots revealed, differences between R(f) values and intensity of fluorescence, simultaneously.

Amphetamines↗

PubMed1979

[Not Available].

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Botany↗