Development and Validation of a Quantitative Method for Determination of Carmine (E120) in Foodstuffs by Liquid Chromatography: NMKL Collaborative Study

ThimA liquid chromatographic method for quantitative determination of carmine (E120) in different foodstuffs is described. Qualitative and semiquantita- tive methods for analysis of carmine and other related dyes are well established. However, quantitative methods available are based mainly on enzymatic reactions that are time-consuming or specific for analysis of carminic acid in yoghurt. In the method developed and validated here, carminic acid is extracted by boiling the sample with HCI, purified on a solid-phase extraction cartridge, and injected on a Cis analytical column. The method was evaluated by an internal analytical quality control and a collaborative study in which 11 laboratories from the Nordic countries participated. The food samples analyzed were fruit jelly, liqueur, juice, yoghurt, and ice cream. Materials were distributed to participants as uniform level and split level. Validation showed that the proposed method is well suited for quantitative determination of carmine. The detection limit is 0.1 mg/L. The mean relative standard deviation for reproducibility varies from 7.9 to 11.7%. The proposed method is simple and relatively fast compared with previously published methods.

Liquid Chromatographic Determination of Residual Nitrite/Nitrate in Foods: NMKL Collaborative Study

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.

Re-evaluation of potassium nitrite (E 249) and sodium nitrite (E 250) as food additives

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re‐evaluating the safety of potassium nitrite (E 249) and sodium nitrite (E 250) when used as food additives. The ADIs established by the SCF (1997) and by JECFA (2002) for nitrite were 0–0.06 and 0–0.07 mg/kg bw per day, respectively. The available information did not indicate in vivo genotoxic potential for sodium and potassium nitrite. Overall, an ADI for nitrite per se could be derived from the available repeated dose toxicity studies in animals, also considering the negative carcinogenicity results. The Panel concluded that an increased methaemoglobin level, observed in human and animals, was a relevant effect for the derivation of the ADI. The Panel, using a BMD approach, derived an ADI of 0.07 mg nitrite ion/kg bw per day. The exposure to nitrite resulting from its use as food additive did not exceed this ADI for the general population, except for a slight exceedance in children at the highest percentile. The Panel assessed the endogenous formation of nitrosamines from nitrites based on the theoretical calculation of the NDMA produced upon ingestion of nitrites at the ADI and estimated a MoE > 10,000. The Panel estimated the MoE to exogenous nitrosamines in meat products to be < 10,000 in all age groups at high level exposure. Based on the results of a systematic review, it was not possible to clearly discern nitrosamines produced from the nitrite added at the authorised levels, from those found in the food matrix without addition of external nitrite. In epidemiological studies there was some evidence to link (i) dietary nitrite and gastric cancers and (ii) the combination of nitrite plus nitrate from processed meat and colorectal cancers. There was evidence to link preformed NDMA and colorectal cancers.

Re-evaluation of sodium nitrate (E 251) and potassium nitrate (E 252) as food additives

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re-evaluating the safety of sodium nitrate (E 251) and potassium nitrate (E 252) when used as food additives. The current acceptable daily intakes (ADIs) for nitrate of 3.7 mg/kg body weight (bw) per day were established by the SCF (1997) and JECFA (2002). The available data did not indicate genotoxic potential for sodium and potassium nitrate. The carcinogenicity studies in mice and rats were negative. The Panel considered the derivation of an ADI for nitrate based on the formation of methaemoglobin, following the conversion of nitrate, excreted in the saliva, to nitrite. However, there were large variations in the data on the nitrate-to-nitrite conversion in the saliva in humans. Therefore, the Panel considered that it was not possible to derive a single value of the ADI from the available data. The Panel noticed that even using the highest nitrate-to-nitrite conversion factor the methaemoglobin levels produced due to nitrite obtained from this conversion would not be clinically significant and would result to a theoretically estimated endogenous N-nitroso compounds (ENOC) production at levels which would be of low concern. Hence, and despite the uncertainty associated with the ADI established by the SCF, the Panel concluded that currently there was insufficient evidence to withdraw this ADI. The exposure to nitrate solely from its use as a food additive was estimated to be less than 5% of the overall exposure to nitrate in food based on a refined estimated exposure scenario. This exposure did not exceed the current ADI (SCF, 1997). However, if all sources of exposure to dietary nitrate are considered (food additive, natural presence and contamination), the ADI would be exceeded for all age groups at the mean and the highest exposure.

Analysis of Nitrite and Nitrate in Foods: Overview of Chemical, Regulatory and Analytical Aspects

In this chapter, several factors that should be considered for selecting and developing suitable analytical methods for determining nitrite/nitrate are presented. Nitrite and nitrate occurrence and suitability are a controversial issue. Nitrite is an approved additive considered a foremost curing ingredient for the preservation of meat products. Nitrate is a natural constituent of the human diet that, however, raises fears for its suggested potential harmfulness related to carcinogenesis and environmental contamination. Chemical, regulatory, and analytical aspects are discussed in the light of the need to obtain reliable data of nitrite and nitrate for law enforcement purposes, exposure estimates, and investigation of their physiological role in the human body. In addition, current metrological aspects to ensure the "fitness for purpose" of the selected method are suggested and discussed.

Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation

The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products.

Determination, validation and standardization of a CMV DNA cut-off value in plasma for preemptive treatment of CMV infection in solid organ transplant recipients at lower risk for CMV infection

BACKGROUND

Valganciclovir preemptive therapy guided by the viral load is the current strategy recommended for preventing CMV disease in CMV-seropositive Solid Organ Transplant Recipients (SOTR) at lower risk for developing CMV infection. However, universal viral load cut-off has not been established for initiating therapy.

OBJECTIVES

Our goal was to define and validate a standardized cut-off determined in plasma by real-time PCR assay for initiating preemptive therapy in this population.

STUDY DESIGN

A prospective cohort study of consecutive cases of CMV-seropositive SOTR was carried out. The cut-off value was determined in a derivation cohort and was validated in the validation cohort. Viral loads were determined using the Quant CMV LightCycler 2.0 real-time PCR System (Roche Applied Science) and results were standardized using the WHO International Standard for human CMV.

RESULTS

A viral load of 3983 IU/ml (2600 copies/ml) was established as the optimal cut-off for initiating preemptive therapy in a cohort of 141 patients with 982 tests and validated in a cohort of 252 recipients with a total of 2022 test. This cut-off had a 99.6% NPV indicating that the great majority of patients at lower risk will not develop CMV disease without specific antiviral therapy. The high sensitivity and specificity (89.9% and 88.9%, respectively) and the relatively small numbers of patients with CMV disease confirm that real-time PCR was optimal.

CONCLUSIONS

We have established a cut-off viral load for starting preemptive therapy for CMV-seropositive SOT recipients. Our results emphasized the importance of a mandatory follow-up protocol for CMV-seropositive patients receiving preemptive treatment.

Levels of nitrate in Swedish lettuce and spinach over the past 10 years

Monitoring of nitrate in Swedish-produced lettuce and spinach over the past 10 years (1996-2005) showed that more than 95% of the samples were below the maximum levels established by the European Commission in 1997. The good agricultural practices used by Swedish farmers may partly explain these results. Analytical results of organic farming production of lettuce from 2000 showed low nitrate levels compared with conventional production. The 10 years of Swedish experience has shown good compliance with the European Union maximum levels, but even lower nitrate levels may be achieved by organic farming methods, at least regarding fresh lettuce grown under cover.

Liquid chromatographic determination of residual nitrite/nitrate in foods: NMKL collaborative study

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.

[Non fermentative gram negative bacilli isolated in a hospital laboratory]

OBJECTIVE

To report a prospective study on non fermentative gramnegative bacilli, excluded Pseudomonas aeruginosa, isolated at Dr. Julio C. Perrando Hospital in Resistencia (Argentina). The goal of this study was to know their frequency and antimicrobial susceptibility.

MATERIAL AND METHODS

For bacterial identifications we used biochemical tests.

RESULTS

The greatest percentages of non fermentative gramnegative bacilli isolates were found in blood samples (25%), respiratory secretions and urine (23.9%). Acinetobacter baumannii (34.7%), Pseudomonas fluorescens/Pseudomonas putida (15.2%), Stenotrophomonas maltophilia (9.7%) and Burkholderia cepacia (8.7%) were the non fermentative gramnegative bacilli species most commonly isolated. Distribution of microorganism strains according to samples and area is also assessed. Antimicrobial sensitivity of most commonly isolated non fermentative gramnegative bacilli strain analyzed.

CONCLUSIONS

We concluded that non fermentative gramnegative bacilli are most frequently present in hospitalized that in outpatients and antibacterial therapy must be provided according to bacteriological information.

Characterization and distribution of HLA-B*5002 in a Spanish population sample

HLA-B45, in contrast to B44, does not show molecular polymorphism. We have found a group of Caucasian Spanish individuals, serologically typed as B45, showing an unexpected HLA-B12 PCR-SSO subtyping pattern. Complete coding region sequencing and B45 subtyping by PCR-SSO demonstrated that the B45 serologic specificity is constituted by two molecular alleles: B*4501 and B*5002. B*5002 is recognized by polyclonal and monoclonal allosera against B12 and B45, whereas it is not detected by B21, B49, or B50 reagents, providing a new example of poor correlation between serology and structure. B*5002 explains an important subset (18%) of the B45-positive individuals of the Spanish population studied, and almost half are included in a very infrequent haplotypic association, Cw6-B*5002-DRB1*0406-DQA1*03-DQB1*0402.

Development and validation of a quantitative method for determination of carmine (E120) in foodstuffs by liquid chromatography: NMKL Collaborative Study

A liquid chromatographic method for quantitative determination of carmine (E120) in different foodstuffs is described. Qualitative and semiquantitative methods for analysis of carmine and other related dyes are well established. However, quantitative methods available are based mainly on enzymatic reactions that are time-consuming or specific for analysis of carminic acid in yoghurt. In the method developed and validated here, carminic acid is extracted by boiling the sample with HCl, purified on a solid-phase extraction cartridge, and injected on a C18 analytical column. The method was evaluated by an internal analytical quality control and a collaborative study in which 11 laboratories from the Nordic countries participated. The food samples analyzed were fruit jelly, liqueur, juice, yoghurt, and ice cream. Materials were distributed to participants as uniform level and split level. Validation showed that the proposed method is well suited for quantitative determination of carmine. The detection limit is 0.1 mg/L. The mean relative standard deviation for reproducibility varies from 7.9 to 11.7%. The proposed method is simple and relatively fast compared with previously published methods.