Archives

  • 2018-07
  • 2018-10
  • 2018-11
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • Introduction Histamine H Imidazol yl ethanamine mol

    2022-01-21

    Introduction Histamine (2-(1H-Imidazol-4-yl)ethanamine), mol.w. 111.15 g/mol belongs to biogenic amines, which arise in foodstuffs from amino acids by action of microorganism´s or tissue enzymes. Histamine (HA) is formed from the amino NVP-LCQ195 L-histidine by action of enzyme histidine decarboxylase (EC number: 4.1.1.22). HA is the most important biogenic amine responsible for allergies and/or intoxications. It is associated with so-called “scombroid poisoning” after ingestion of some fish species such as mackerel, sprats, anchovy (scombroidae fish). Most of foodborne intoxication related to HA can cause headaches, hypotension and digestive problems [1]. So that the estimation of HA level is important with respect to human safety issue and quality of food. An increased HA content in food is a sign of improper processing of food raw material. HA like other biogenic amines usually occur in fermented foods such as beer, wine, fermented meat and fish products, cheeses and fermented vegetables [[2], [3], [4]]. Grilled, fried or fermented food (seafood, vegetables or meat) have higher levels of histamine comparing with raw or boiled food [5]. HA in food are extensively studied; a lot of information on formation and occurrence of histamine and the biogenic amines in foods is given in recently published papers [3,6,7]. There are plenty of methods for HA analysis in food such as chromatography or capillary electrophoresis [[7], [8], [9], [10], [11]]. Because of HA has no chromophore NVP-LCQ195 or fluorophore a derivatization procedure (pre- or post-column) has been usually applied. There are only few published methods without derivatization step, viz., ion chromatography with conductometric detection [12], capillary zone electrophoresis with conductivity (CZE-COND), amperometric or electrochemiluminescence detection [9,[13], [14], [15]], capillary isotachophoresis (cITP-COND) with conductivity detection [16,17], and cITP-CZE with UV detection at 280 nm [18]. More than one decade ago we published simple and quick CZE method for the determination of biogenic amines including HA in various food [13]. We have successfully applied this method on many food samples for HA analysis. The only disadvantage of this method was the insufficient sensitivity in the case of salty samples (due to high sodium content in such samples the acidic extract had to be more diluted). A significant increase of sensitivity of CZE method can be smartly achieved by on-line combination of CZE and cITP using a capillary-coupled electrophoretic analyser [[19], [20], [21], [22]]. This arrangement utilizes advantages of both techniques, i.e., high loading capacity of cITP and high resolution capacity of CZE. In the first, isotachophoretic step, a large amount of sample (up to hundreds of microliters) is injected into the first (wider) capillary. Isotachophoretic step allows analysis of ionic minor constituents (sub micromole) in a large excess (up to 106-times) of sample ionic matrix. In this stage the ionic constituents are separated into stack of zones with minor constituents focused into narrow bands. The minor analyte(s) concentrated (and cleaned up) from bulk components are transferred into an analytical (narrower) capillary for CZE separation. The CZE step exhibits high resolution power (HETP ≈ 10 μm) within short time of analysis (<15 min) and enhanced selectivity (the 2nd dimension of separation). Already published electrophoretic methods do not unfortunately provide sufficient sensitivity for high salt samples. Such samples (e.g. 2% of the salt represents ca 350 mM of sodium) must be diluted at least 50-times prior to analysis, to ensure complete separation of histamine from sodium. For cITP-COND method [17] the limit of detection of histamine 2 mg/L is given, which, after the recalculation to the dilution corresponds to 100 mg/kg. For the cITP-CZE method with UV detection [18] histamine LOD of 0.35 mg/L is reported, that corresponds after taking into account the dilution to 17 mg/kg. Relatively low sensitivity reported of this cITP-CZE-UV method is due to very low molar absorption coefficient of histamine at 280 nm (˜102 L/mol/cm). Similar sensitivity was provided by our CZE method [13]. With respect to histamine health limit 100 mg/kg in selected foods [23], the sensitivity of published electrophoretic methods [[16], [17], [18]] is inadequate for salty samples (necessary dilution 100-times or more) and therefore we were forced to develop more sensitive method.