Milk Powder Samples Research Articles

Simultaneous spectrophotometric determination of Cu(II), Co(II) and Ni(II) using ratio spectra-continuous wavelet transformation in some food and environmental samples

Ratio spectra-continuous wavelet transformation was used for the simultaneous determination of ternary mixtures of copper, cobalt and nickel without prior separation steps. The method is based on the complexation reaction of these cations with 1-(2-pyridylazo)-2-naphthol (PAN) in triton X-100 micellar media at pH 8.0. The results showed that Cu(II), Co(II) and Ni(II) could be determined simultaneously in the ranges 0.20-4.0, 0.20-4.0 and 0.50-7.0 mg L-1, respectively. Different mother wavelets from the family of continuous wavelet transforms were selected and applied under the optimal conditions for multi-component determinations. The method was tested by analyzing various synthetic ternary mixtures of Cu(II), Co(II) and Ni(II) ions. Under the working conditions, the proposed method was successfully applied for the simultaneous determination of these metals content evaluation in some real samples including multivitamin tablet, tea, barley, spinach, chocolate, milk powder, soil, sea water and tap water samples.

Method and proficiency test for analysis of toxic metals in livestock products by ICP/MS

The analytical method of trace toxic metals in livestock products was confirmed and validated through certified reference material (CRM) and the international proficiency tests. There are some difficulties to determine low levels of toxic metals in livestock products because of interferences due to the matrix. The recoveries of CRM (NIST 1577c) ranged from 73.9 to 119% for lead and from 86.4 to 111% for cadmium in bovine liver. The international proficiency tests were carried out with the milk powder and cocoa powder samples including metals provided by Food Analysis Performance Assessment Scheme (FAPAS , UK). The test samples were prepared by microwave digestion using solution of HNO :H O :H O (v/v/v = 5 : 2 : 4) and analyzed by ICP/MS. The analytical result of cadmium in milk powder was 121 µg/kg with -0.3 of the z-score compared to the assigned value of 131 µg/kg by FAPAS . The analytical results of lead and cadmium in cocoa powder were 29.2 µg/kg and 97.6 µg/kg, respectively, which satisfied the assigned values of 34.2 µg/kg for lead and 126 µg/kg for cadmium by FAPAS . It is verified that the analytical method is accurate and reliable to determine trace lead and cadmium in livestock products by microwave digestion and ICP/MS.

Determination of docosahexaenoic acid in milk powder by gas chromatography using acid hydrolysis

A method to determine docosahexenoic acid (DHA) in milk powder by gas chromatography was established. The milk powder samples were hydrolyzed with hydrochloric acid, extracted to get total fatty acids by Soxhlet extractor, then esterified with potassium hydroxide methanol solution to form methyl esters, and treated with sodium hydrogen sulfate. The optimal experiment conditions were obtained from orthogonal experiment L9(3(3)) which performed with three factors and three levels, and it requires the reaction performed with 1 mol/L potassium hydroxide solution at 25 degrees C for 5 min. The derivative treated with sodium hydrogen sulfate was separated on a column of SP-2560 (100 m x 0.25 mm x 0.20 μm), and determined in 55 min by temperature programming-gas chromatography. Good linearity was obtained in the range 5.0-300 mg/L with the correlation coefficient of 0.999 9. The relative standard deviations (RSDs) were 3.4%, 1.2% and 1.1% for the seven repeated experiments of 10, 50 and 100 mg/L of DHA, respectively. The limit of detection was 2 mg/kg, and the recoveries of DHA were in the range of 90.4%-93.5%. The results are satisfactory through the tests of practical samples.

Metals determination in milk powder samples for adult and infant nutrition after focused-microwave induced combustion

In this study, a recently sample preparation method based on focused microwave-induced combustion (FMIC) is proposed for milk powder digestion (for adult and infant nutrition) for subsequent determination of Ba, Ca, Co, Cr, Cu, Fe, Mg, Mn, Sr, V and Zn by inductively coupled plasma optical emission spectrometry (ICP OES). Combustion was carried out under oxygen flow rate (2 to 15lmin−1) using ammonium nitrate (50μl of 6moll−1 solution) as ignition aid. Samples were pressed as pellets (up to 3g) and placed on a quartz holder positioned inside the glass vessel. The concentration of the absorbing solution was investigated using nitric acid in the range of 2 to 14moll−1. Sample digestion was also performed by microwave-assisted wet digestion (MAWD) and by microwave-induced combustion (MIC). Agreement higher than 95% was obtained for all analytes by comparison with certified reference materials of milk powder after FMIC using diluted nitric acid (2moll−1) and by comparison of the results obtained by MAWD and MIC. The main advantage of FMIC when compared to MAWD and MIC is the possibility to digest higher sample masses (up to 3g) achieving better limits of detection. It was possible to use diluted nitric acid solution for analytes absorption and digests were suitable for determination of metals by ICP OES avoiding the use of more expensive instrumentation as inductively coupled plasma mass spectrometry.

Correction of radiation absorption on biological samples using Rayleigh to Compton scattering ratio

The aim of this work was to develop a method to correct the absorbed radiation (the mass attenuation coefficient curve) in low energy (E<30keV) applied to a biological matrix based on the Rayleigh to Compton scattering ratio and the effective atomic number. For calibration, scattering measurements were performed on standard samples of radiation produced by a gamma-ray source of 241Am (59.54keV) also applied to certified biological samples of milk powder, hay powder and bovine liver (NIST 1557B). In addition, six methods of effective atomic number determination were used as described in literature to determinate the Rayleigh to Compton scattering ratio (R/C), in order to calculate the mass attenuation coefficient. The results obtained by the proposed method were compared with those obtained using the transmission method. The experimental results were in good agreement with transmission values suggesting that the method to correct radiation absorption presented in this paper is adequate for biological samples.

C18-coated stir bar sorptive extraction combined with high performance liquid chromatography–electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder

A simple, rapid, sensitive, inexpensive and less sample consuming method of C18-stir bar sorptive extraction (SBSE)–high performance liquid chromatography (HPLC)–tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C18 silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C18-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C18 stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C18 coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9–10.5μg/L for milk and 2.7–31.5μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained.

Determination of Melamine in Infant Milk Formula, Milk Powder and Basaa Fish Samples by HPLC/DAD

Thirty two samples were collected of milk powder for baby and human consumption and Basaa fish 8 infant milk formula, 8 growing up milk formula purchased from pharmacy in Saudi Arabia, 6 Sweetened Full Cream Milk Powder purchased from China and 10 fish samples (Basaa fish) Ui Tnam purchased from popular markets in Saudi Arabia. The samples were analyzed and determination for Melamine (MEL) by HPLC/DAD. The incidence of MEL in powder milk and in fish, was about 100 and 80 % respectively. High concentrations were found in growing up milk formula. Melamine was detected in 28 out of 32 samples with varying concentrations. Of the 28 melamine positive samples, samples had a melamine concentration higher than 258 mg/kg (the median). The lowest and the highest concentrations were found to be 7.5 and 258 mg/kg, respectively in all samples. This application note describes an efficient and simple method for preparing milk powder and fish samples coupled to an HPLC/DAD method for rapid analysis of melamine in these samples. The purpose of the survey was to determine levels of melamine and to monitor the effectiveness of the controls in place to limit consumer exposure to melamine.

An analytical method for estrogens in milk powder by pseudo template imprinted polymer coated fiber coupled with HPLC

This paper reports a novel molecularly imprinted polymer (MIP) coated fiber for extraction of estrogens. A rationally designed 17-ethylestradiol (ED) that exhibits resemblance to estrogens has been synthesized and used as a pseudo template. A DFT-based computational simulation method was proposed to choose the best functional monomer. The MIP coated fiber was fabricated by using silica fiber as substrate, ED as pseudo template, 2-(trifluoromethyl) acrylic acid (TFMAA) and acrylic acid (AA) as composite functional monomers, and ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent. A series of investigations indicated that the MIP coated fiber possessed excellent stability, rebinding capacity, selectivity and kinetics. An analytical method for the determination of estrogens in milk powder samples, combining molecularly imprinted solid phase micro-extraction (MISPME) with high performance liquid chromatography-ultraviolet (HPLC-UV), was developed. The limits of detection were in the range of 0.83–2.5 ng mL−1, the recoveries were 86–92%, 88–97%, 90–93% and 95–99% with RSD < 6.7% for estrone, 17β-estradiol, estriol and 17-ethynylestradiol, respectively.

Determination of Potassium – 40 ( 40 k) Concentration in Some Powdered Milk Samples Consumed In Delta State, Nigeria

Determination of Potassium – 40 ( 40 k) Concentration in Some Powdered Milk Samples Consumed In Delta State, Nigeria

A water-soluble, 1,8-naphthalimide based aggregation induced synchronous emission system for selective and sensitive recognition of casein

A water-soluble 1,8-naphthalimide-based fluorescent probe 1, bearing two acetic carboxylic groups, exhibited high selectivity and sensitivity for recognition of casein in water based on aggregation induced synchronous emission (AISE) character. A new fluorometric method to detect casein content in PBS (pH 7.4) was developed by synchronous fluorescence spectra with wavelength intervals of 15 and 60 nm. The linear ranges of the calibration curves were 0.1–4.3 μg mL−1 (Δλ = 15 nm) and 0.1–10.1 μg mL−1 (Δλ = 60 nm) for casein, with a correlation coefficient of 0.9962 and 0.9971. The detection limits were estimated to be 5.6 and 7.5 ng mL−1. The proposed method has been applied to the determination of casein in skimmed milk powder samples and the results are in good agreement with those of the Biuret method.

Bovine milk powder adulteration with vegetable oils or fats revealed by MALDI-QTOF MS

Matrix-assisted laser desorption/ionisation-quadrupole time of flight mass spectrometry (MALDI-QTOF MS) allowed detection of bovine milk powder adulteration with vegetable oils or fats with high speed and reliability, requiring little sample preparation (n-hexane extraction) and no prior separation procedures. This technique was also able to identify the adulterated employed in this fraud. Hydrogenated soybean oil addition in bovine milk powder sample generate a similar TAG profile to that observed on adulterated milk samples apprehended by the Brazilian Federal Police. In this sense, a robust method for high throughput forensic screening of milk powder adulteration by exogenous oils and fats is showed.

Quantitative Determination and Confirmation of Five Synthetic Glucocorticoid Residues in Milk Powder by Gel Permeation Chromatography–Liquid Chromatography–Tandem Mass Spectrometry

A new method for multi-residue determination of five synthetic glucocorticoids (betamethasone, dexamethasone, prednisone, prednisolone, and hydrocortisone) in milk powder is developed. The glucocorticoids in the samples were extracted with tert-butyl methyl ether under ultrasonication incubation, and then cleaned up through gel permeation chromatography. After C18 LC gradient elution separation using acetonitrile with 0.1% formic acid as a mobile phase, the eluents were determined by liquid chromatography–tandem mass spectrometry with multiple reaction monitoring and positive ionization modes. The effective separation for the five glucocorticoids was achieved. The limit of quantification of the method for testing five glucocorticoids in milk powder was in the range from 0.2 to 0.5 μg kg−1, which was lower than the maximum residue limits established by European Union for glucocorticoids in foods. Experiments on spiked samples of milk powder showed that the mean recoveries at addition level of 1.0, 3.0, and 5.0 μg kg−1 were in the range of 71.2% and 103%, and the relative standard deviation ranged from 4.7% to 16.8%. The calibration curves for these drugs between 1.0 and 100 μg l−1 showed good linearity, with correlation coefficient (r) more than 0.999. The real sample test showed that this method is sensitive and accurate. It can be used for qualitative and quantitative determination of studied glucocorticoid residues in milk powder samples.

Fast quantitative determination of melamine and its derivatives by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

A simple, sensitive and fast method for the determination of melamine and its derivatives in milk powder using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was developed. Neither time-consuming sample preparation, nor special target plates, or other extra equipment are necessary. The common matrix sinapinic acid (SA) was used with a dried-droplet preparation. Detection limits (signal-to-noise (S/N) ratio = 3) for standard solutions of melamine, ammeline and cyanuric acid were 10, 25 and 10 µg/L, respectively. The limit of quantification (LOQ) for melamine was 25 µg/L and excellent linearity (R(2): 0.9990) was maintained over the range of 10-2000 µg/L. Ammeline and cyanuric acid were analyzed with an LOQ of 50 µg/L and also excellent linearity (R(2): 0.9997 and R(2): 0.9998). Good accuracy and precision were obtained for all concentrations within the range of the standard curve. The developed method was successfully used for the determination of melamine, ammeline and cyanuric acid in milk powder samples with a simple sample preparation. The LOQ of melamine was 0.5 µg/g. Ammeline and cyanuric acid were detectable at 0.5 and 5 µg/g. This method showed excellent accuracy, precision and linearity and significantly reduces the needed analysis time, as only approximately 10 s/sample measuring time is required. To the authors' knowledge, this is the first published method to quantify melamine and derivatives by MALDI-TOF-MS.

Simultaneous Analysis of Nine Estrogens in Milk Powder with Ultra-Performance Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry

Abstract A rapid, sensitive, and specific method has been developed and validated for the simultaneous analysis of nine estrogens in milk powder, including estriol, β-estradiol, a-estradiol, equilin, 17a-ethinylestradiol, estrone, diethylstilbestrol, dienestrol, and hexestrol using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The milk powder was dissolved in water, the estrogens were extracted with acetonitrile using ultrasonication, and the fat in the extracted solution was removed by liquid-liquid extraction with n-hexane. Then, the estrogens were purified using a NH2-containing solid-phase extraction cartridge, separated on a Waters ACQUITY UPLC HSS T3 column (100 mm × 2.1 mm × 1.8 μm), and analyzed both qualitatively and quantitatively by UPLC-Q-TOF-MS. The overall analysis time of the proposed method was 13 minutes, and the linear range was between 0.001–0.5 mg L−1, with a correlation coefficient greater than 0.993. The limits of detection for the compounds were 0.11–0.30 μg kg−1, and the limits of quantification were within the range 0.37–1.0 μg kg−1. The mass errors between the theoretical and experimental masses obtained for the deprotonated molecules of the nine estrogens and the internal standard (β-estradiol-d3) were between −1.0 and 0.9 mDa. At the spiked levels of 1, 2, 10, and 100 μg kg−1, the average recoveries ranged from 61% to 137%, with relative standard deviations ranging between 1.0% and 22.6%, as determined by the matrix-matched internal-standard method. The results showed that the proposed method was suitable for the multiresidue detection of estrogens in milk powder and was successfully applied to the detection of estrogens in seven real milk powder samples.

Development of an Analytical Method Based in the Slurry Sampling for Iron Determination in Fortified Milk Powder by HR-CS FAAS

The use of slurry sampling as the procedure for sample preparation provides simplicity, speed, and low consumption of reagents in analytical methods. In this paper, a method based on slurry sampling for the determination of iron in samples of fortified milk powder by high-resolution continuum source flame atomic absorption spectrometry was developed. Multivariate design techniques were applied for the optimization of experimental conditions of the method for a sample mass of 100 mg, final volume of slurry of 10 mL, and using the absorbance signal as response. Initially, a two-level full factorial design was used for the preliminary evaluation of the variables involved in slurry preparation: concentration hydrochloric acid, Triton X-100 concentration, and sonication time. Then, the Doehlert matrix was applied for the determination of the critical conditions: 2.5 mol L−1 hydrochloric acid and sonication time of 20 min. External calibration technique with aqueous standard was used for the quantification of iron. This way, the method allowed iron determination with limits of detection and quantification of 0.9 and 3.0 μg g−1, respectively. The precision expressed as the relative standard deviation was evaluated under repeatability and reproducibility conditions, being 3.2% and 4.0%, respectively. Addition/recovery test was used for assessing the accuracy of the method, and the recovery values achieved were in the range of 90–110%. The method was applied for iron determination in eight samples of fortified milk powder, and the obtained concentrations varied from 95.4 to 295.6 μg g−1. The results were compared with those obtained after acid digestion, and no significant difference was observed applying t test at the 95% confidence level.

Enhancement of the chemiluminescence of permanganate-formaldehyde system by gold/silver nanoalloys and its application to trace determination of melamine

Gold/silver alloy nanoparticles (Au/Ag NPs) are shown to exert a beneficial effect on the chemiluminescence (CL) reaction of permanganate-formaldehyde in the presence of sodium dodecyl sulfate micelles. The Au/Ag NPs can be prepared by chemical reduction and display better catalytic properties than their monometallic counterparts. Transmission electron microscopy, energy dispersion X-ray spectrometry and UV–vis spectroscopy were used to characterize the Au/Ag NPs. Melamine at even ultratrace level inhibits the action of nanoparticles and therefore decreases the intensity of CL. This finding forms the basis for a method for the determination of melamine in the 0.01–35 ng mL−1 concentration range, with a detection limit of 8 pg mL−1. The method was successfully applied to the determination of minute concentrations of melamine in powdered milk samples.

Determination of 90Sr in milk and milk powder in Tehran and estimation of annual effective dose

Thirty-eight different milk and milk powder samples from Tehran-Iran were collected and analyzed for 90Sr activity using a method in which the daughter product of 90Sr decay (90Y) was extracted by tributyl phosphate from ashed milk. 90Y was then back extracted with water, and oxalate was precipitated . Following the sample analyzing, beta counting was performed with an ultralow-level liquid scintillation spectrometer. The quality control and assurance of the method were obtained by standard samples prepared with an IAEA-certified reference material. The mean determined 90Sr activity concentration in the analyzed milk and milk powder (0.225 ± 0.042 and 0.216 ± 0.024 Bq kg−1, respectively) showed that the radioactivity concentration in our samples was too low to induce biological hazards. These data can provide useful information of the background level of contamination, which in turn can be used in the following environmental monitoring programs.

Determination of quinolone residues in infant and young children powdered milk combining solid-phase extraction and ultra-performance liquid chromatography–tandem mass spectrometry

The present work describes a method based on solid-phase extraction (SPE) and ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) for the simultaneous determination of three quinolones (pipemidic acid, oxolinic acid and flumequine) and twelve fluoroquinolones (marbofloxacin, fleroxacin, pefloxacin, levofloxacin, norfloxacin, ciprofloxacin, enrofloxacin, danofloxacin, lomefloxacin, difloxacin, sarafloxacin, and moxifloxacin) in different infant and young children powdered milks. After suitable deproteination of the reconstituted powdered samples, a SPE procedure was developed providing recovery values higher than 84% (RSDs lower than 13%) for all the analytes, with limits of detection between 0.04 and 0.52 μg/kg. UPLC–MS/MS analyses were carried out in less than 10 min. Sixteen infant and young children powdered milk samples of different origin, type and composition bought at Spanish markets were analyzed. Residues of the selected antibiotics were not detected in any of the analyzed samples.

Fast determination of myo-inositol in milk powder by ultra high performance liquid chromatography coupled to tandem mass spectrometry

A simple and fast method has been developed and validated for the determination of myo-inositol in milk powder samples, using solid–liquid extraction with water (0.01% formic acid, v/v):methanol (1:1, v/v). The determination was carried out by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC−MS/MS) using an electrospray ionisation source (ESI) in positive mode. Chromatographic separation was carried out using as mobile phase water (0.01% formic acid, v/v) and methanol in gradient mode. Data acquisition under MS/MS was achieved by applying selected reaction monitoring, using 181.0→109.0 and 181.0→81.0 for quantification and confirmation purposes, respectively. The technique provides a sensitive and selective determination of myo-inositol in the analysed samples, with a run time of 4min. The limit of detection and quantification were 0.2 and 0.5mgkg−1, respectively. The method was applied to six fortified commercial milk powder samples containing myo-inositol amounts ranging from 290 to 2200mgkg−1.

A survey on the occurrence of aflatoxin M1 in raw and processed milk samples marketed in Lebanon

A survey was conducted to determine the occurrence of AFM1 in 77 cow and goat milk samples (38 raw milk, 25 pasteurized milk and 14 powder milk samples); obtained either from local small farms, or markets. The competitive enzyme – linked immunosorbent assay (ELISA) method was applied for this purpose positively detecting AFM1 in 64.9% of all tested milk samples. The revealed rates of AFM1 contamination were 73.6%, 68.0%, 35.7% for the raw, pasteurized and powder milk samples, respectively. The individual values, within each category of milk samples, ranged from 2.63 to 126 ng/l (average = 60 ng/l), 3.27–84.4 ng/l (average = 30.6 ng/l) and 9.18–16.5 ng/l (average = 13.7 ng/l) for the raw, pasteurized and powder milk samples, respectively. Of the positive samples, 29 were still below the permitted limit (50 ng/l) set by the European Commission whereas 21 exceeded the permissible limit. This work represents the data of the first survey on the occurrence of AFM1 in raw and processed milk marketed and consumed in Lebanon.