Preparation Of Calibration Standards Research Articles

A green and facile direct ink writing technique for preparation calibration standards in laser ablation inductively coupled plasma mass spectrometry analysis

BackgroundLaser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful tool for microanalysis of solid materials. Nevertheless, one limitation of the method is the lack of well-characterized homogeneous reference materials (RMs), such as BaF2 crystal and BaCO3 ceramics samples, making direct quantification difficult. This work presents a novel Direct Ink Writing (DIW) method to produce RMs for microanalysis. The Mg, Cr, Fe, Co, Ni, Cu, Y, Mo, Pr, Gd, Dy, Ho, Er, Tm, Yb, and Lu solutions were gravimetrically doped into BaCO3 by mixing with the dispersant and then cured with DIW techniques. (94) ResultsBaCO3 powder was combined with a dopant analyte to produce a printable slurry, aided by the use of a dispersant and cellulose. The resulting mixture was then printed using DIW equipment. The retention rates of the doped elements were investigated by internal and external standard method, and the results showed that they were completely dispersed in the solid material. After further optimization, it was found that there was no significant heterogeneity among the printed samples. LA-ICP-MS was used to analyze printed samples, to evaluate micro-scale homogeneity. The mass concentration of the doped element was determined by ICP-MS, verify its move closer to nominal value. Compared with the traditional reference materials preparation methods, the DIW technology greatly increased the sample homogeneity and the accuracy of the desired concentration. (132) SignificanceAs far as we know, there are few reports on the application of DIW method to prepare calibration standards. In brief, it is proved that the proposed method of preparing calibration standard by DIW technique to quantify analytes is valid and robust. This procedure provides great potential for LA-ICP-MS in-situ analysis in the field of well-prepared products, such as ceramic and crystal samples.(63)

Study on the effect of calibration standards prepared with different matrix on the accuracy of bile acid quantification using LC-MS/MS

The transition from relative to absolute quantification of metabolites is the future development trend of mass spectrometry-based metabolomics research, which could fundamentally solve the problem of comparability of data between different laboratories. However, absolute quantification of endogenous molecules is largely hampered by the lack of analyte-free matrix, leading to uncertainty and inconsistency in the preparation of calibration standards. Bile acids (BAs) are an important class of biomarkers that play a key role in disease progression. In this paper, the quantitative accuracy of calibration curves prepared in neat solvent (NSCCs), charcoal stripped matrix (SMCCs) and authentic matrix (AMCCs) were validated using quality control samples (QCs) prepared in authentic matrix. Results suggested that AMCCs could largely minimize the confidence interval (C.I.) and the deviation in accuracy compared with NSCCs and SMCCs when measured concentration is higher than 20% of the background level. In addition, experimental data demonstrated that two-step calibration strategy proposed here is a promising and reliable alternative strategy to quantify endogenous BAs in biological sample.

Stability of 10 Beta-Lactam Antibiotics in Human Plasma at Different Storage Conditions.

Recently, several studies have assessed the effects of therapeutic drug monitoring of frequently prescribed beta-lactam antibiotics, for which they were quantified in human plasma samples. Beta-lactams are considered unstable, leading to extra challenges in quantification. Therefore, to ensure sample stability and minimize sample degradation before analysis, stability studies are crucial. This study investigated the stability of 10 frequently used beta-lactam antibiotics in human plasma at relevant storage conditions for clinical use. Amoxicillin, benzylpenicillin, cefotaxime, ceftazidime, ceftriaxone, cefuroxime, flucloxacillin, imipenem, meropenem, and piperacillin were analyzed using ultraperformance convergence chromatography tandem mass spectrometry and liquid chromatography tandem mass spectrometry. Their short-term and long-term stabilities were investigated by measuring quality control samples at low and high concentrations against freshly prepared calibration standards. Measured concentrations at each time point were compared with the concentrations at T = 0. Antibiotics were considered stable if recovery results were between 85% and 115%. Short-term stability results indicated ceftriaxone, cefuroxime, and meropenem to be stable up to 24 hours at room temperature. All evaluated antibiotics, except imipenem, were stable on ice in a cool box for 24 hours. Amoxicillin, benzylpenicillin, and piperacillin were stable for 24 hours at 4-6°C. Cefotaxime, ceftazidime, cefuroxime, and meropenem were stable at 4-6°C up to 72 hours. Ceftriaxone and flucloxacillin were stable for 1 week at 4-6°C. Long-term stability results showed that all antibiotics were stable up to 1 year at -80°C, except imipenem and piperacillin, which were stable for 6 months at -80°C. Plasma samples for amoxicillin, benzylpenicillin, cefotaxime, ceftazidime, flucloxacillin, and piperacillin may be stored for a maximum of 24 hours in a cool box. Refrigeration is suitable for plasma samples of amoxicillin, benzylpenicillin, meropenem, and piperacillin for up to 24 hours and cefotaxime, ceftriaxone, ceftazidime and cefuroxime for 72 hours. Plasma samples for imipenem should be frozen directly at -80°C. For long-term storage, plasma samples can be stored at -80°C for a maximum of 6 months for imipenem and piperacillin and 12 months for all other evaluated antibiotics.

Enhancing the quantification accuracy for selected endocrine disruptors in different tea samples by GC–MS using matrix matching calibration strategy

This study was focused on enhancing the accuracy of quantifying twelve endocrine disruptors in green and black tea samples. The analytes included seven pesticides, two hormones, and three phenolic compounds. An optimized dispersive liquid–liquid microextraction method was used to preconcentrate the analytes from the tea samples for determination by gas chromatography-mass spectrometry. The matrix of the tea samples caused an enhancement effect on the extraction method and this yielded percent recoveries higher than 180% when calculated using the external calibration method. Matrix dilution and matrix matching calibration were used to prevent the formation of tea particle layers and enhance quantification accuracy, respectively. Similar tea matrices were used to prepare calibration standards and these were used to quantify the spiked analytes. The percent recovery results calculated for the analytes using matrix matching ranged between 92 and 105%. Both repeatability and reproducibility precision tests produced percent relative standard deviations below 10%.

Method of preparation of heterogeneous height standards for measurements by means of interferometry

The results of the practical implementation of a method for preparing calibration standards based on magnetron sputtering of a chromium film on the surface of the standard are presented. This film is an electrically conductive layer that preserves the topography of relief elements and allows scanning without charge accumulation in the sample. The results obtained showed that the sputtering of thin chromium films on the surface of height standards, the relief elements of which have different reflection coefficients, makes it possible to measure the heights of such standards with a fairly low error.

A novel strategy for preparing calibration standards for laser-induced breakdown spectroscopy using beeswax as a substrate: A case study with cosmetic and lubricant oil samples

A new calibration strategy based on the use of beeswax as a substrate for producing a synthetic multi-elemental calibration standard is proposed for laser-induced breakdown spectroscopy (LIBS). This approach was demonstrated by determining the Fe, Mg, Si, Ti, and Zn in lubricant and cosmetic samples. Besides an external standard calibration, we also proposed calibration strategies with and without the adjustment of mineral oil present in the calibration standards and three other different internal standard calibrations: C I 505.50 nm emission line and C2 516.4 and 545.7 nm emission bands. Concerning the lubricant oil samples, the best results were obtained by using the C2 emission band at 516.4 nm, which was used as an internal standard for determining Si and Zn. The C I emission line at 505.50 nm was the most adequate for Mg quantification, while for Fe quantification, the C2 emission band at 516.4 and 545.7 nm yielded similar results. Regarding the samples of cosmetic products, Si and Ti were quantified adequately by using the C2 emission band at 516.4 nm as an internal standard, while for Mg quantification, better results were achieved by using the C I emission line at 505.50 nm. Finally, for Fe quantification in face foundation and liquid lipstick samples, better results were obtained by employing the C I emission line at 505.50 nm and the C2 emission band at 516.4 nm, respectively. For all elements mentioned above, there was an agreement of between 90 and 110% comparing LIBS with inductively coupled plasma optical emission spectroscopy (ICP OES) and/or inductively coupled plasma mass spectrometry (ICP-MS). All the calibrations curves (using external and internal standards) showed a coefficient of determination (R2) higher than 0.95 and detection limits, in μg g−1, between 4 and 18 for Fe, 4 and 6 for Mg, 8 and 24 for Si, 4 and 14 for Ti, and 4 and 8 for Zn.

Development and validation of an ultra-high performance liquid chromatography coupled to tandem mass spectrometry method for the quantification of the antileishmanial drug paromomycin in human skin tissue

Bioanalytical assay development and validation procedures were performed to quantify antiprotozoal drug paromomycin in human skin tissue by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. Paromomycin, an aminoglycoside drug, is administered intra-muscularly and used in the treatment of multiple clinical presentations of the neglected tropical disease leishmaniasis. It is currently studied in the treatment of post-kala-azar dermal leishmaniasis, a disease where the Leishmania parasites divide and reside in the skin. We present a target-site bioanalytical method to accurately quantify paromomycin in human skin tissue, with the clinical purpose of quantifying paromomycin in skin biopsies from post-kala-azar dermal leishmaniasis patients originating from Sudan. Enzymatic digestion using collagenase A incubated at 37 °C overnight was employed as homogenization method to produce skin tissue homogenates. Further sample preparation was performed by protein precipitation using trichloroacetic acid and a dilution step. Final extracts were injected onto a C18 analytical column and isocratic heptafluorobutyric acid ion-pair separation and elution were employed. The chromatography system was coupled to a triple quadrupole mass spectrometer for detection. The method was validated in digestion solution over a linear range from 5 to 1000 ng/mL (r2 ≥ 0.9967) with the assay performance of accuracy and precision within acceptable criteria values as stated by the EMA guidelines. Furthermore, matrix effects were observed in human skin tissue and were corrected by the multiple deuterated paromomycin internal standard. No substantial IS-normalized matrix effect was detected along with relatively high sample preparation recovery. Consequently, digestion solution matrix serving as the preparation of calibration standards can be used as surrogate matrix for human skin tissue, which is convenient given the limited availability of control matrix. Finally, paromomycin was accurately quantified in skin of post-kala-azar dermal leishmaniasis patients originating from clinical trials in Sudan.

Nontoxic Enantiomeric Reference Materials for Saxitoxins.

Saxitoxin (STX) is a potent neurotoxin that is biosynthesized by toxic dinoflagellates and accumulated in shellfish via the food chain. STX and its various analogues are now monitored in shellfish by the hygiene authorities in many countries with instrumental analytical methods, which require calibration with standards. Unfortunately, STX is registered as a chemical warfare agent in Schedule 1 of the Chemical Weapons Convention, and this has made it difficult to import calibration standards into some countries. We aimed to avoid violation of the Chemical Weapons Convention and facilitate analyses by preparing calibration standards based on unnatural nontoxic antipodal STXs (ent-STXs) with the same physicochemical properties as natural STXs. Our findings demonstrate that the nontoxic ent-STXs can be safely utilized as alternative reference materials of STXs in the routine monitoring program by the local authorities and consequently can lead to reduced usage of STX.

A simple method for the preparation of homogeneous and stable solid powder standards: Application to sulfide analysis by LA-ICP-MS

A simple method for immobilizing powder samples was proposed to prepare calibration standards for the analyses of bulk elemental compositions of solid samples by LA-ICP-MS. Upon mixing with epoxy resin, the multielement doped powder was transformed into a stable and mechanically resistant target. Using this method, a sulfide standard, RPSS (resin preserved silver sulfide), was developed that contains 47 different elements, including PGE, chalcophile elements, siderophile elements, lithophile elements, and REE. The homogeneity of most elements in the original sulfide powder pressed pellet and RPSS was better than 10% (RSD, one sigma) at a microscale of larger than 24 μm. The mass fractions of most elements in the RPSS determined by LA-ICP-MS analyses, calibrated against the pressed pellet, agreed well with that of solution ICP-MS analyses. This result indicates no significant matrix effect between the RPSS target and the original powder pellet. The proposed method is convenient for quickly preparing homogenous and stable solid powder standards for LA-ICP-MS analysis. It is particularly suitable for the development of sulfide standards because it prevents them from oxidation when exposed to air; thus, the target can be preserved for long periods of time.

A method for quantitative analysis of gases evolving during formation applied on LiNi0.6Mn0.2Co0.2O2 ∣∣ natural graphite lithium ion battery cells using gas chromatography - barrier discharge ionization detector

To understand the overall processes behind the decomposition of state-of-the-art organic liquid electrolytes in lithium ion batteries (LIBs), it is necessary to investigate and quantify the permanent gases and light hydrocarbons evolving during electrolyte decomposition. In this work a convenient way of sampling gas from pouch cells without any previous preparation of the cell as well as a comprehensive gas chromatographic (GC) investigation of the gas phase is shown. A barrier discharge ionization detector (BID) was utilized for gas quantification and a multi component gas standard in combination with a gas mixing device was implemented to prepare calibration standards for validation. Therefore, sensitivity, linearity and reproducibility as well as the limits of detection (LOD) and limits of quantification (LOQ) were determined.Gas samples from pouch cells using LiNi0.6Mn0.2Co0.2O2 as cathode material and natural graphite (NMC622 ∣∣ NG) as anode material were analysed after formation. Gas volume and gas composition are key factors for a sufficient formation of LIBs and of interest for research with respect to the development of new materials and additives.

Assessment of strategies for the formation of stable suspensions of titanium dioxide nanoparticles in aqueous media suitable for the analysis of biological fluids.

Due to their omnipresence in consumer products, there is a growing concern about the potential effects of nanoparticles on human health. Toxicological assessment and NP end-product studies require proper quantification of these materials in biological fluids. However, their quantifications in these media require stable predispersed NP solutions in aqueous media to enable the fortification in the matrices of interest or the preparation of calibration standards. In this study, a sample preparation scheme was developed by studying various dispersion media (polyvinylpyrrolidone and polyethylene glycol) and sonication strategies (bath and ultrasonic probe) to ensure homogeneous dispersion of titanium dioxide nanoparticles. Optimization of the various parameters was performed using SRM NIST 1898 NP reference material, composed of rutile and anatase phases. Number-based size distribution for titanium dioxide NPs was determined by dynamic light scattering and single-particle inductively coupled plasma mass spectrometry to evaluate the procedure efficiency. Changes in mean size and most frequent size distribution were also studied to determine if the agglomeration of nanoparticles occurs at the various dispersion conditions tested. Among the different dispersion parameters tested herein, the use of polyvinylpyrrolidone combined with a sonication process generated by a probe leads to a significant improvement in terms of suspension efficiency and stability over 72h. The dispersion efficiency of the proposed methodology was assessed by single-particle inductively coupled plasma mass spectrometry with spiked biological fluids such as urine and blood. Graphical abstract.

A Tool for Automatic Correction of Endogenous Concentrations: Application to BHB Analysis by LC-MS-MS and GC-MS.

Several substances relevant for forensic toxicology purposes have an endogenous presence in biological matrices: beta-hydroxybutyric acid (BHB), gamma-hydroxybutyric acid (GHB), steroids and human insulin, to name only a few. The presence of significant amounts of these endogenous substances in the biological matrix used to prepare calibration standards and quality control samples (QCs) can compromise validation steps and quantitative analyses. Several approaches to overcome this problem have been suggested, including using an analog matrix or analyte, relying entirely on standard addition analyses for these analytes, or simply ignoring the endogenous contribution provided that it is small enough. Although these approaches side-step the issue of endogenous analyte presence in spiked matrix-matched samples, they create serious problems with regards to the accuracy of the analyses or production capacity. We present here a solution that addresses head-on the problem of endogenous concentrations in matrices used for calibration standards and quality control purposes. The endogenous analyte concentration is estimated via a standard-addition type process. This estimated concentration, plus the spiked concentration are then used as the de facto analyte concentration present in the sample. These de facto concentrations are then used in data analysis software (MultiQuant, Mass Hunter, etc.) as the sample's concentration. This yields an accurate quantification of the analyte, free from interference of the endogenous contribution. This de facto correction has been applied in a production setting on two BHB quantification methods (GC-MS and LC-MS-MS), allowing the rectification of BHB biases of up to 30 μg/mL. The additional error introduced by this correction procedure is minimal, although the exact amount will be highly method-dependent. The endogenous concentration correction process has been automated with an R script. The final procedure is therefore highly efficient, only adding four mouse clicks to the data analysis operations.

Proposed selection strategy of surrogate matrix to quantify endogenous substances by Japan Bioanalysis Forum DG2015-15.

It is important to select an appropriate surrogate matrix for preparing calibration standards and quality control samples while quantitatively assaying for endogenous substances, because a blank matrix that does not contain the endogenous substance cannot be derived from the species from which the target study samples are collected. This is because the assay results might be affected, depending on the characteristics of the analyte in the surrogate matrix. Our discussion group that participated in the Japan Bioanalysis Forum discussed the recommended selection strategies, focusing on large and small molecules in ligand binding assays and LC-MS, respectively. We established an efficient selection strategy for a surrogate matrix, with simple compositions as the first candidates stated in this article.

UHPLC-MS/MS bioanalysis of human plasma coproporphyrins as potential biomarkers for organic anion-transporting polypeptide-mediated drug interactions.

Coproporphyrins (CP-I and CP-III) have been identified as possible biomarkers to predict human hepatic organic anion-transporting polypeptides-mediated-drug-interactions for a new drug entering clinical development. The method is applicable to quantify plasma CP-I and CP-III within 0.078-15.0nM. The results identify and address a number of challenges encountered with porphyrin assays such as photodegradation and interferences. To overcome interferences from ubiquitous porphyrins, a surrogate matrix was used to prepare calibration standards. Quality controls were prepared in plasma and surrogate matrix to ensure parallelism between surrogate matrix and plasma. A robust UHPLC-MS/MS assay was developed and validated for CP-I and CP-III in plasma, and is currently applied to clinical studies to confirm suitability of Coproporphyrins as a potential substitute for drug-drug interaction study.

Spotting of external calibration standards on blank dried blood spots as a resource-sparing protocol.

Dried blood spots (DBS) offer significant ethical and scientific advantages; however preparation of calibration curves often times, off-sets some of these advantages. We have developed a methodology wherein small volumes of external calibration standards can be spiked on to blank DBS cards. A total of 2μl of stock solution spotted on to blank blood spots yielded concentrations that were comparable to those obtained using conventional DBS method. The stability of six analytes on 10-day-old blank spots was within 80-120%. The new methodology was successfully applied to a hydroxycholorquine mouse pharmacokinetics study. Blank DBS samples can be opportunistically prepared from overweight or satellite animals, be stored, and subsequently spiked with standards to prepare calibration standards.

SIMULTANEOUS EXTRACTION AND RAPID HPLC BASED QUANTIFICATION OF CROCIN AND SAFRANAL IN SAFFRON (CROCUS SATIVUS L.)

<p><strong>Objective</strong>:<strong> </strong>Saffron (<em>Crocus sativus</em> L.) is one of the most valuable crops with high medicinal values used in many diseases. The aim of the study was to establish the reliability and rapid HPLC method for analysis of crocin and safranal concentration present in stigmata of saffron in the market as well as field grown samples.</p><p><strong>Methods</strong>:<strong> </strong>Field grown and market stigmata of saffron were used for extraction of crocin and safranal. The linear dynamic ranges were established after validating the robustness of critical method parameters. The Agilent1260-Infinity Quaternary LC system was used for the preparation of calibration standards and quantification of crocin and safranal in <em>C. sativus</em> stigmata.</p><p><strong>Results</strong>:<strong> </strong>A good linearity was achieved in the range of 10-30 µg for each compound with the determination coefficient (R<sup>2</sup>). The calibration curves revealed linear regression (r. 0.997) for this rapid HPLC method and limit of quantifications (LOQs) were achieved in the range of 3.4 µg/ml for crocin and 10.2 µg/ml for safranal. The limit of detection (LODs) for all standards was ≤4.2 µg/ml. The range of crocin content (10.43-16.32 mg/g) and safranal (5.19-5.21 mg/g) was estimated in saffron samples.</p><p><strong>Conclusion: </strong>This method may serve the purpose of accurate quantification of crocin and safranal present in the stigmata of the plant in a quick time period.</p><p><strong>Keywords: </strong>Saffron, Crocin, Safranal, Extraction, Quantification, HPLC</p>

Analysis of small molecule antibody-drug conjugate catabolites in rat liver and tumor tissue by liquid extraction surface analysis micro-capillary liquid chromatography/tandem mass spectrometry.

Antibody-drug conjugates (ADCs) are some of the most promising antibody-related therapeutics. The fate of the cytotoxic moiety of ADCs in vivo after proteolytic degradation of the antibody needs to be well understood in order to mitigate toxicity risks and design proper first in patient studies. The feasibility of liquid extraction surface analysis micro-capillary liquid chromatography/tandem mass spectrometry (LESA-μLC/MS/MS) was tested for direct surface sampling of two possible ADC catabolites composed of synthetically modified maytansinoid (DM1) and 4-[N-maleimidomethyl]cyclohexane-1-carbonyl (MCC) from rat liver and tumor tissue. Moreover, the iMatrixSpray was incorporated to prepare calibration standards (Cs) and quality control (QC) samples by spraying analyte solution at different concentrations directly on blank tissue. Lys-MCC-DM1 sprayed on blank liver tissue was homogeneously distributed (12.3% variability). The assay was selective (inference ≤20%) and linear from 50.0 to 1000 ng/mL without any carry-over. Inter-run accuracy and precision were ≤2.3% and ≤25.9% meeting acceptance. Lys-MCC-DM1 was the only catabolite detected in liver and tumor tissue and was most likely responsible for the total radioactivity signal in liver tissue 72 h post-dose measured by quantitative whole body autoradiography (QWBA). Both analytical assays (LESA-μLC/MS/MS and QWBA) are complementary to each other and provide useful quantitative and qualitative information in spatial tissue distribution of ADCs and their related catabolites. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of fungal mycelia on the HPLC–UV and UV–vis spectrophotometric assessment of mycelium-bound epoxide hydrolase using glycidyl phenyl ether

The use of mycelia as biocatalysts has technical and economic advantages. However, there are several difficulties in obtaining accurate results in mycelium-catalysed reactions. Firstly, sample extraction, indispensable because of the presence of mycelia, can bring into the extract components with a similar structure to that of the analyte of interest; secondly, mycelia can influence the recovery of the analyte. We prepared calibration standards of 3-phenoxy-1,2-propanediol (PPD) in the pure solvent and in the presence of mycelia (spiked before or after extraction) from five fungi (Aspergillus niger, Aspergillus tubingensis, Penicillium aurantiogriseum, Penicillium sp. and Aspergillus terreus). The quantification of PPD was carried out by HPLC-UV and UV-vis spectrophotometry. The manuscript shows that the last method is as accurate as the HPLC method. However, the colorimetric method led to a higher data throughput, which allowed the study of more samples in a shorter time. Matrix effects were evaluated visually from the plotted calibration data and statistically by simultaneously comparing the intercept and slope of calibration curves performed with solvent, post-extraction spiked standards and pre-extraction spiked standards. Significant differences were found between the post- and pre-extraction spiked matrix-matched functions. Pre-extraction spiked matrix-matched functions based on A. tubingensis mycelia, selected as the reference, were validated and used to compensate for low recoveries. These validated functions were successfully applied to the quantification of PPD achieved during the hydrolysis of glycidyl phenyl ether by mycelium-bound epoxide hydrolases and equivalent hydrolysis yields were determined by HPLC-UV and UV-vis spectrophotometry. This study may serve as starting point to implement matrix effects evaluation when mycelium-bound epoxide hydrolases are studied.

Laser desorption sample transfer for gas chromatography/mass spectrometry.

Ambient mass spectrometry can detect small molecules directly, but complex mixtures can be a challenge. We have developed a method that incorporates small molecule separation based on laser desorption with capture on a solid-phase microextraction (SPME) fiber for injection into a gas chromatography/mass spectrometry (GC/MS) system. Samples on a metal target were desorbed by a 3 µm mid-infrared laser focused to a 250 µm spot and 1.2 mJ pulse energy. The desorbed material was aspirated into a metal tube suspended 1 mm above the laser spot and captured on a SPME fiber. The collected material was injected into a GC/MS instrument for analysis. We have developed a versatile approach for ambient laser desorption sampling onto SPME for GC/MS analysis. The performance of the laser desorption SPME capture GC/MS system was demonstrated for small molecule standards, a mixture of nitroaromatic explosives, and collected cigarette smoke. The utility of ambient laser desorption sampling onto SPME for GC/MS was demonstrated. The performance of the method was evaluated by preparing calibration standards of caffeine over a range from 200 to 1000 ng. Laser desorption ambient sampling of complex mixtures was accomplished using SPME GC/MS.

Optimized method for black carbon analysis in ice and snow using the Single Particle Soot Photometer

Abstract. In this study we attempt to optimize the method for measuring black carbon (BC) in snow and ice using a Single Particle Soot Photometer (SP2). Beside the previously applied ultrasonic (CETAC) and Collison-type nebulizers we introduce a jet (Apex Q) nebulizer to aerosolize the aqueous sample for SP2 analysis. Both CETAC and Apex Q require small sample volumes (a few milliliters) which makes them suitable for ice core analysis. The Apex Q shows the least size-dependent nebulizing efficiency in the BC particle diameter range of 100–1000 nm. The CETAC has the advantage that air and liquid flows can be monitored continuously. All nebulizer-types require a calibration with BC standards for the determination of the BC mass concentration in unknown aqueous samples. We found Aquadag to be a suitable material for preparing calibration standards. Further, we studied the influence of different treatments for fresh discrete snow and ice samples as well as the effect of storage. The results show that samples are best kept frozen until analysis. Once melted, they should be sonicated for 25 min, immediately analyzed while being stirred and not be refrozen.