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Analytical methods based on the mass balance approach were developed for the purity evaluation of tetracycline hydrochloride, a representative salt compound used in pure veterinary drug analysis. The purity assignment method was used to quantify individual classes of impurities via independent analytical techniques. The mass fraction of the free base or salt form contained in a high-purity organic compound with a hydrochloride salt can be determined. The chloride content by ion chromatography-conductivity detector (IC-CD) and general classes of impurities, including structurally related impurities by liquid chromatography–ultraviolet (LC-UV) detector, water by Karl Fischer (KF) coulometric titration, residual solvents by headspace sampler gas chromatography/mass spectrometry (HS-GC/MS), and non-volatiles by thermogravimetric analyzer (TGA), were considered to calculate the purity of the mass fraction. The chloride content of the salt compound can be considered the main impurity in the mass fraction of the free base in the salt compound. A purity assay using quantitative nuclear magnetic resonance (q-NMR) as a direct determination method was performed to confirm the results of the mass balance method. The assigned purities of the tetracycline free form and its salt form in mass fraction were (898.80 ± 1.60) mg/g and (972.65 ± 1.58) mg/g, respectively, which are traceable to the international system of units (SI). Thus, the procedure for evaluating the purity of the free base and salt forms in the salt compound is newly demonstrated in this study. [ABSTRACT FROM AUTHOR]

Trichloroacetic acid is known as one of the harmful disinfection byproducts with chlorine of tap water and is regulated according to legally binding standards in Japanese Drinking Water Quality Standards. We developed a high-purity trichloroacetic acid reference material, NMIJ CRM 4074-a, with certified purity as a traceability source of standard solution supplied under the Japan Calibration Service System (JCSS). As trichloroacetic acid is hygroscopic, water could be the main impurity. Although all impurities in the sample can be possibly detected by the freezing point depression method (FPD), it was unclear for trichloroacetic acid whether water was detected by FPD owing to evaporation of water from the sample during fusion. Therefore, we confirmed that water in trichloroacetic acid was detected as an impurity by FPD. The procedure was validated from an increment of purity by FPD due to reduction of water content and an agreement of purity by FPD with those by neutralization titrimetry (NT) and mass balance approach (MBA), both methods were based on different measurement principles from FPD. The certified value was determined to be (0.999 ± 0.003) kg kg−1 from the purity assay by FPD and NT, and uncertainties due to the homogeneity and stability of the CRM were included in the expanded uncertainty. The reliability of the certified value was verified by the agreement of purities by FPD, NT, and MBA. [ABSTRACT FROM AUTHOR]

The assessment of primary calibrator purity is critical for establishing traceability to the International System of Units (SI). Recently, quantitative nuclear magnetic resonance (qNMR) has been used as a purity determination method for reference material development, and many related measurement techniques have been designed to acquire accurate and reliable results. This review introduces the recent advances in these techniques (including multidimensional methods), focusing on the application of qNMR to reference material preparation. [ABSTRACT FROM AUTHOR]

Live biotherapeutic products (LBPs), commonly referred to as probiotics, are typically preparations of live bacteria, such as Lactobacillus and Bifidobacterium species that are considered normal human commensals. Popular interest in probiotics has been increasing with general health benefits being attributed to their consumption, but there is also growing interest in evaluating such products for treatment of specific diseases. While over-the-counter probiotics are generally viewed as very safe, at least in healthy individuals, it must be remembered that clinical studies to assess these products may be done in individuals whose defenses are compromised, such as through a disease process, immunosuppressive clinical treatment, or an immature or aging immune system. One of the major safety criteria for LBPs used in clinical studies is microbial purity, i.e., the absence of extraneous, undesirable microorganisms. The main goal of this project is to develop recombinant phage lysins as reagents for improved purity assays for LBPs. Phage lysins are hydrolytic enzymes containing a cell binding domain that provides specificity and a catalytic domain responsible for lysis and killing. Our approach is to use recombinant phage lysins to selectively kill target product bacteria, which when used for purity assays will allow for outgrowth of potential contaminants under non-selective conditions, thus allowing an unbiased assessment of the presence of contaminants. To develop our approach, we used LysA2, a phage lysin with reported activity against a broad range of Lactobacillus species. We report the lytic profile of a non-tagged recombinant LysA2 against Lactobacillus strains in our collection. We also present a proof-of-concept experiment, showing that addition of partially purified LysA2 to a culture of Lactobacillus jensenii (L. jensenii) spiked with low numbers of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus ) effectively eliminates or knocks down L. jensenii, allowing for clear detection of the contaminating strains. With continued identification and characterization of phage lysins, we hope that the use of recombinant phage lysins in purity assays for products containing live microbials may offer additional tools to help advance product development of LBPs.

Live biotherapeutic products (LBPs), commonly referred to as probiotics, are typically preparations of live bacteria, such as Lactobacillus and Bifidobacterium species that are considered normal human commensals. Popular interest in probiotics has been increasing with general health benefits being attributed to their consumption, but there is also growing interest in evaluating such products for treatment of specific diseases. While over-the-counter probiotics are generally viewed as very safe, at least in healthy individuals, it must be remembered that clinical studies to assess these products may be done in individuals whose defenses are compromised, such as through a disease process, immunosuppressive clinical treatment, or an immature or aging immune system. One of the major safety criteria for LBPs used in clinical studies is microbial purity, i.e., the absence of extraneous, undesirable microorganisms. The main goal of this project is to develop recombinant phage lysins as reagents for improved purity assays for LBPs. Phage lysins are hydrolytic enzymes containing a cell binding domain that provides specificity and a catalytic domain responsible for lysis and killing. Our approach is to use recombinant phage lysins to selectively kill target product bacteria, which when used for purity assays will allow for outgrowth of potential contaminants under non-selective conditions, thus allowing an unbiased assessment of the presence of contaminants. To develop our approach, we used LysA2, a phage lysin with reported activity against a broad range of Lactobacillus species. We report the lytic profile of a non-tagged recombinant LysA2 against Lactobacillus strains in our collection. We also present a proof-of-concept experiment, showing that addition of partially purified LysA2 to a culture of Lactobacillus jensenii (L. jensenii) spiked with low numbers of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) effectively eliminates or knocks down L. jensenii, allowing for clear detection of the contaminating strains. With continued identification and characterization of phage lysins, we hope that the use of recombinant phage lysins in purity assays for products containing live microbials may offer additional tools to help advance product development of LBPs. [ABSTRACT FROM AUTHOR]

A mass balance method for purity assessment of thermolabile organic reference materials was established by combining several techniques, including liquid chromatography with UV/VIS detector (LC-UV), Karl-Fischer (K-F) Coulometry, and thermal gravimetric analysis (TGA). This method was applied to three fluoroquinolones like enrofloxacin, norfloxacin and ciprofloxacin. LC-UV was used to analyze structurally related organic impurities based on UV/VIS absorbance spectra obtained in combination with LC separation. For all three organic reference materials, the UV/VIS spectra of the separated impurities were similar to that of the major component of the corresponding materials. This indicates that the impurities are structurally related to the respective reference material sharing common chromophores. Impurities could be quantified by comparing their absorbances at the wavelength of maximum absorbance (λmax). The water contents of the reference materials were measured by K-F Coulometry by an oven-drying method. The total inorganic impurities contents were assayed from ash residues in TGA analysis with using air as a reagent gas. The final purities estimated from results of those analytical techniques were assigned as (99.91 ± 0.06), (97.09 ± 0.17) and (91.85 ± 0.17)% (kg/kg) for enrofloxacin, norfloxacin and ciprofloxacin, respectively. The assigned final purities would be applied to the reference materials which will be used as calibrators for the certification of those compounds in matrix CRMs as starting points for the traceability of their certified values to SI units. [ABSTRACT FROM AUTHOR]

A reversed-phase high performance liquid chromatography (RP-HPLC) method for the purity assay of Sn-ADAM (2-((2-((Dimethylamino)methyl)phenyl)thio)-5-(tri-n-butyltin)-phenylamine) was developed and validated. Sn-ADAM is a precursor and free ligand of 1-123-ADAM (1-123-2-([2-({dimethylamino}methyl)phenyl]thio)-5-iodophenylamine) that is a SPECT imaging agent for serotonin transporters (SERTs). The chromatographic separation for Sn-ADAM was achieved on a RP-18 column with an eluent consisting of methanol-acetonitrile-ammonium acetate (pH 7.0, 10 mM; 58.8 : 39.2 2, v/v/v). The absorbance at 220 nm against the concentration of Sn-ADAM was linear over the range of 9.9-317.8 ppm, with a correlation coefficient (r) of 0.99997. Method validation parameters, including specificity, linearity, precision, accuracy, LOD/LOQ, stability, robustness and suitability were evaluated, indicating the potential of this method in pharmaceutical quality control. Moreover, present results of precursor to product ion transitions of Sn-ADAM and 1-127-ADAM by LC/ESI/MS/MS provided evidence for identification of fragmentation ions and proposition of the pathways of Sn-ADAM, 1-127-ADAM and 1-123-ADAM. [ABSTRACT FROM AUTHOR]

The Collection of Biotechnological-Interest Microorganisms of the CIGB includes several bacteria and yeast strains used in gene manipulation by means of genetic engineering and the production of recombinant proteins. The E. coli host collection contains all the strains used in the research projects of the institution. This microorganism is an important tool for genetic engineering and molecular research. Accuracy of results depends on the quality of the microorganism banks, which it is determined by the storage conditions and the evaluation strategies of these microorganisms. The complexity of the management of this collection is influenced by the fact that a great number of contaminants may grow in the propagation media and they are difficult to identify. The more similar is the pollutant to the strain of interest, the harder it is to obtain pure banks with reliable stability and conservation. This work describes how quality control is ensured in the E. coli banks. The verification methods and strategies described here have been developed in our laboratory. [ABSTRACT FROM AUTHOR]

We developed and validated a reverse-phase high performance liquid chromatography (RP-HPLC) method for the purity assay of BZM. BZM is a precursor and free ligand of [231I]IBZM (iodobenzamide) that is a SPECT imaging agent for striatal dopaminergic D2/D3 receptor (D2R). The chromatographic separation was achieved on a Zorbax Eclipse XDB-C18 column with a gradient mobile phase consisting of 10mM ammonium acetate buffer, pH 7.0 and acetonitrile at a flow rate of 0.5 mL/min. The absorbance at 254 nm against the concentration of BZM over the range 0.5-5.5 μg was linear, with a correlation coefficient above 0.9997. The limit of detection (LOD) and quantification (LOQ) of major impurity (impurity A, tR = 3.85 mm) in BZM were 0.028% and 0.094%, respectively. Method validation parameters, including specificity, precision, accuracy, linearity, LOD/LOQ, robustness and solution stability were evaluated, indicating the potential of this method in pharmaceutical quality control. Moreover, the most sensitive precursor to product ion transitions for the identification of BZM and 'cold' IBZM by LC-ESI-MS/MS were found to be m/z 279.0-112.0 and 405.0-112.0, respectively. The present results allow identification of fragmentation ions and proposition of the pathways of BZM and 'cold' IBZM, showing that the feasibility of this method for quantification of free ligand BZM in SPECT imaging agent [123I]IBZM injection. [ABSTRACT FROM AUTHOR]

Bispecific IgG asymmetric (heterodimeric) antibodies offer enhanced therapeutic efficacy, but present unique challenges for drug development. These challenges are related to the proper assembly of heavy and light chains. Impurities such as symmetric (homodimeric) antibodies can arise with improper assembly. A new method to assess heterodimer purity of such bispecific antibody products is needed because traditional separation-based purity assays are unable to separate or quantify homodimer impurities. This paper presents a liquid chromatography-mass spectrometry (LC-MS)-based method for evaluating heterodimeric purity of a prototype asymmetric antibody containing two different heavy chains and two identical light chains. The heterodimer and independently expressed homodimeric standards were characterized by two complementary LC-MS techniques: Intact protein mass measurement of deglycosylated antibody and peptide map analyses. Intact protein mass analysis was used to check molecular integrity and composition. LC-MS(E) peptide mapping of Lys-C digests was used to verify protein sequences and characterize post-translational modifications, including C-terminal truncation species. Guided by the characterization results, a heterodimer purity assay was demonstrated by intact protein mass analysis of pure deglycosylated heterodimer spiked with each deglycosylated homodimeric standard. The assay was capable of detecting low levels (2%) of spiked homodimers in conjunction with co-eluting half antibodies and multiple mass species present in the homodimer standards and providing relative purity differences between samples. Detection of minor homodimer and half-antibody C-terminal truncation species at levels as low as 0.6% demonstrates the sensitivity of the method. This method is suitable for purity assessment of heterodimer samples during process and purification development of bispecific antibodies, e.g., clone selection.