High resolution mass spectral data from the analysis of copper chlorophylls and copper chlorophyll degradation products in bright green table olives.

This publication reports high resolution mass spectral data for copper chlorophyll and copper chlorophyll degradation products extracted from bright green table olives. These data support analyte identifications made in "Quantitation of copper chlorophylls in green table olives by ultra-high-performance liquid chromatography with inductively coupled plasma isotope dilution mass spectrometry" in the Journal of Chromatography A (Petigara Harp et al., 2020 [1]). Table olive pigments, divided into lipophilic and hydrophilic fractions by liquid-liquid repartition, were separated by ultra-high-performance liquid chromatography and detected by visible wavelength absorbance and high resolution mass spectrometry, using an Orbitrap HF with positive electrospray ionization. Full-scan mass spectra were acquired to assign pigment chemical formulae. Fragment-rich higher-energy collisional dissociation tandem mass spectra were acquired to facilitate structural assignments. Extracted ion chromatograms, full-scan, and tandem mass spectra obtained from representative lipophilic and hydrophilic green table olive extracts are presented in Figures 1-6. Annotated mass spectra comparing experimental and calculated isotope distributions, .raw mass spectral data files, and experimental details linking .raw data files to annotated spectra are provided as Supplementary Material. Spectra extracted from these native data files can be added to mass spectral libraries for use in other studies. Access to native data files uniquely enables rigorous data examination (e.g., molecular ion isotopic distribution, effective mass resolution, presence of overlapping ion series) and use in ways that are not possible when spectra are otherwise reported in simple tables listing mono-isotopic peaks and mass errors. Mass spectra reported here can be used to design multiple-reaction monitoring methods to detect these bright green pigments in agricultural food commodities and finished products.

Quantitation of copper chlorophylls in green table olives by ultra-high-performance liquid chromatography with inductively coupled plasma isotope dilution mass spectrometry.

Table olives, a widely consumed delicacy, are often selected by consumers based on the shade of their green color. The appealing coloration of fresh olives fades to brown or pale yellow during the industrial processing necessary for commercialization and storage, as a result of the degradation of chlorophyll a and b to their corresponding pheophytins and other chlorophyll degradation products (CDP). The re-greening of table olives may be achieved by complexation of CDP with Cu2+, to form stable bright green copper CDP (Cu-CDP) complexes. To study this phenomenon, we developed a novel method to separately extract lipophilic and hydrophilic Cu-CDP and quantify Cu-CDP by UHPLC combined with inductively coupled plasma isotope dilution mass spectrometry (UHPLC-ICP-ID-MS) using post-column isotopic dilution with 65Cu. This technique does not require species-specific calibration standards and was applied to survey the Cu-CDP composition of the various types of table olives sold in the US market. The CDP and Cu-CDP extracted from table olives were identified by high resolution full-scan mass spectrometry. Total elemental Cu in table olives was measured by microwave digestion followed by ICP-MS detection and correlated with the content of Cu-CDP. Pale yellow olives contained <1 mg/kg lipophilic Cu-CDP and <3.5 mg/kg total elemental Cu. Bright green table olives contained 4-22 mg/kg lipophilic Cu-CDP and 14.4-161 mg/kg total elemental Cu in contrast to <6 mg/kg reported for natural abundance, indicating the formation of Cu-CDP was achieved by addition of copper salts. A dark green sample with 2.5 mg/kg of total copper and 0.267 mg/kg lipophilic Cu-CDP may have been processed by addition of sodium copper chlorophyllin (SCC); the higher content of Cu isochlorin e4 compared to Cu 152-Me-chlorin e6 supports this conclusion.

Effects of the Adulteration Technique on the Near-Infrared Detection of Melamine in Milk Powder.

The United States Pharmacopeial Convention has led an international collaborative project to develop a toolbox of screening methods and reference standards for the detection of milk powder adulteration. During the development of adulterated milk powder reference standards, blending methods used to combine melamine and milk had unanticipated strong effects on the near-infrared (NIR) spectrum of melamine. The prominent absorbance band at 1468 nm of melamine was retained when it was dry-blended with skim milk powder but disappeared in wet-blended mixtures, where spray-dried milk powder samples were prepared from solution. Analyses using polarized light microscopy, Raman spectroscopy, dielectric relaxation spectroscopy, X-ray diffraction, and mass spectrometry indicated that wet blending promoted reversible and early Maillard reactions with lactose that are responsible for differences in melamine NIR spectra between wet- and dry-blended samples. Targeted detection estimates based solely on dry-blended reference standards are likely to overestimate NIR detection capabilities in wet-blended samples as a result of previously overlooked matrix effects arising from changes in melamine hydrogen-bonding status, covalent complexation with lactose, and the lower but more homogeneous melamine local concentration distribution produced in wet-blended samples. Techniques used to incorporate potential adulterants can determine the suitability of milk reference standards for use with rapid detection methods.

Effects of Wet-Blending on Detection of Melamine in Spray-Dried Lactose.

During the development of rapid screening methods to detect economic adulteration, spray-dried milk powders prepared by dissolving melamine in liquid milk exhibited an unexpected loss of characteristic melamine features in the near-infrared (NIR) and Raman spectra. To further characterize this "wet-blending" phenomenon, spray-dried melamine and lactose samples were produced as a simplified model and investigated by NIR spectroscopy, Raman spectroscopy, proton nuclear magnetic resonance (1H NMR), and direct analysis in real time Fourier transform mass spectrometry (DART-FTMS). In contrast to dry-blended samples, characteristic melamine bands in NIR and Raman spectra disappeared or shifted in wet-blended lactose-melamine samples. Subtle shifts in melamine 1H NMR spectra between wet- and dry-blended samples indicated differences in melamine hydrogen-bonding status. Qualitative DART-FTMS analysis of powders detected a greater relative abundance of lactose-melamine condensation product ions in the wet-blended samples, which supported a hypothesis that wet-blending facilitates early Maillard reactions in spray-dried samples. Collectively, these data indicated that the formation of weak, H bonded complexes and labile, early Maillard reaction products between lactose and melamine contribute to spectral differences observed between wet- and dry-blended milk powder samples. These results have implications for future evaluations of adulterated powders and emphasize the important role of sample preparation methods on adulterant detection.

Quantitative characterization of hemozoin in Plasmodium berghei and vivax.

The incidence and global distribution of chloroquine resistant (CR) Plasmodium vivax infection has increased since emerging in 1989. The mechanism of resistance in CR P. vivax has not been defined. The resistance likely relates to the formation and disposition of hemozoin as chloroquine's primary mechanism of action involves disruption of hemozoin formation. CR P. berghei strains, like CR P. vivax strains, are confined to reticulocyte host cells and reportedly they do not accumulate appreciable intraerythrocytic hemozoin. Reports comparing hemozoin production between P. vivax strains and CR to chloroquine sensitive (CS) P. berghei are absent. Here we compare in vivo patterns of hemozoin formation and distribution in blood, spleen and liver tissue of male Swiss mice infected with CS or CR P. berghei not treated with chloroquine and CR P. berghei also treated with chloroquine. Light microscopy, laser desorption mass spectrometry and a colorimetric hemozoin assay detect trace hemozoin in the blood of CR P. berghei infected mice but significant hemozoin accumulation in liver and spleen tissue. Field emission in lens scanning electron microscopy reveals CR P. berghei hemozoin crystals are morphologically smaller but similar to those formed by CS parasites. CR P. berghei produces approximately five-fold less total hemozoin than CS strain. Lipid analysis of CS and CR P. berghei sucrose gradient purified bloodstage hemozoin indicates a similar lipid environment around the isolated hemozoin, predominately monopalmitic glycerol and monostearic glycerol. In contrast to CR and CS P. berghei, colorimetric hemozoin analysis of P. vivax strains indicates similar amounts of hemozoin are produced despite differing chloroquine sensitivities. These results suggest CR P. berghei forms significant hemozoin which accumulates in liver and spleen tissues and that the P. vivax chloroquine resistance mechanism differs from P. berghei.

US Food and Drug Administration Perspectives on Clinical Mass Spectrometry.

Mass spectrometry-based in vitro diagnostic devices that measure proteins and peptides are underutilized in clinical practice, and none has been cleared or approved by the Food and Drug Administration (FDA) for marketing or for use in clinical trials. One way to increase their utilization is through enhanced interactions between the FDA and the clinical mass spectrometry community to improve the validation and regulatory review of these devices. As a reference point from which to develop these interactions, this article surveys the FDA's regulation of mass spectrometry-based devices, explains how the FDA uses guidance documents and standards in the review process, and describes the FDA's previous outreach to stakeholders. Here we also discuss how further communication and collaboration with the clinical mass spectrometry communities can identify opportunities for the FDA to provide help in the development of mass spectrometry-based devices and enhance their entry into the clinic.

Rapid turbidimetric detection of milk powder adulteration with plant proteins.

Development of assays to screen milk for economically motivated adulteration with foreign proteins has been stalled since 2008 due to strong international reactions to the melamine poisoning incident in China and the surveillance emphasis placed on low molecular weight nitrogen-rich adulterants. New screening assays are still needed to detect high molecular weight foreign protein adulterants and characterize this understudied potential risk. A rapid turbidimetric method was developed to screen milk powder for adulteration with insoluble plant proteins. Milk powder samples spiked with 0.03-3% by weight of soy, pea, rice, and wheat protein isolates were extracted in 96-well plates, and resuspended pellet solution absorbance was measured. Limits of detection ranged from 100 to 200 µg, or 0.1-0.2% of the sample weight, and adulterant pellets were visually apparent even at ∼0.1%. Extraction recoveries ranged from 25 to 100%. Assay sensitivity and simplicity indicate that it would be ideally suitable to rapidly screen milk samples in resource poor environments where adulteration with plant protein is suspected.

Quantification of allergenic bovine milk α(S1)-casein in baked goods using an intact ¹5N-labeled protein internal standard.

Intact bovine ¹5N-α(S1)-casein was used as an internal standard in a selected reaction monitoring (SRM) assay for milk protein in baked food samples containing fats, sugar, and gums. Effects on SRM results of sample matrix composition in two biscuit recipes containing nonfat dry milk (NFDM) were studied, including samples from a milk allergen ELISA proficiency trial. Following extraction of defatted samples with carbohydrate-degrading enzymes and acid precipitation of casein, the SRM assay exhibited an LOQ of <3 ppm NFDM with 60-80% recovery. NFDM levels measured by the SRM assay were 1.7-2.5 times greater than median levels determined by ELISA. Differences were observed in the α(S1)-casein interpeptide SRM ion abundance profile between recipes and after baking. ¹5N-α(S1)-Casein increases SRM analysis accuracy by correcting for extraction recovery but does not eliminate underestimation of allergen concentrations due to baking-related milk protein transformation (modifications).

Trapping a labile adduct formed between an ortho-quinone methide and 2'-deoxycytidine.

Selective oxidation by bis[(trifluoroacetoxy)iodo]benzene (BTI) provides an effective trap for quenching adducts formed reversibly between dC and an ortho-quinone methide (QM) under physiological conditions. A model adduct generated by 4-methyl-o-QM and 2'-deoxycytidine is rapidly converted by intramolecular cyclization and loss of aromaticity to a characteristic product for quantifying QM alkylation. However, BTI induces a surprising rearrangement driven by overoxidation of a derivative lacking an alkyl substituent at the 4-position of the QM.

Transgenic expression of aflatoxin aldehyde reductase (AKR7A1) modulates aflatoxin B1 metabolism but not hepatic carcinogenesis in the rat.

In both experimental animals and humans, aflatoxin B(1) (AFB(1)) is a potent hepatic toxin and carcinogen against which a variety of antioxidants and experimental or therapeutic drugs (e.g., oltipraz, related dithiolethiones, and various triterpenoids) protect from both acute toxicity and carcinogenesis. These agents induce several hepatic glutathione S-transferases (GST) as well as aldo-keto reductases (AKR) which are thought to contribute to protection. Studies were undertaken in transgenic rats to examine the role of one inducible enzyme, AKR7A1, for protection against acute and chronic actions of AFB(1) by enhancing detoxication of a reactive metabolite, AFB(1) dialdehyde, by reduction to alcohols. The AFB(1) dialdehyde forms adducts with protein amino groups by a Schiff base mechanism and these adducts have been theorized to be at least one cause of the acute toxicity of AFB(1) and to enhance carcinogenesis. A liver-specific AKR7A1 transgenic rat was constructed in the Sprague-Dawley strain and two lines, AKR7A1(Tg2) and AKR7A1(Tg5), were found to overexpress AKR7A1 by 18- and 8-fold, respectively. Rates of formation of AFB(1) alcohols, both in hepatic cytosols and as urinary excretion products, increased in the transgenic lines with AKR7A1(Tg2) being the highest. Neither line offered protection against acute AFB(1)-induced bile duct proliferation, a functional assessment of acute hepatotoxicity by AFB(1), nor did they protect against the formation of GST-P positive putative preneoplastic foci as a result of chronic exposure to AFB(1). These results imply that the prevention of protein adducts mediated by AKR are not critical to protection against AFB(1) tumorigenicity.

Human aflatoxin albumin adducts quantitatively compared by ELISA, HPLC with fluorescence detection, and HPLC with isotope dilution mass spectrometry.

Essential to the conduct of epidemiologic studies examining aflatoxin exposure and the risk of heptocellular carcinoma, impaired growth, and acute toxicity has been the development of quantitative biomarkers of exposure to aflatoxins, particularly aflatoxin B(1). In this study, identical serum sample sets were analyzed for aflatoxin-albumin adducts by ELISA, high-performance liquid chromatography (HPLC) with fluorescence detection (HPLC-f), and HPLC with isotope dilution mass spectrometry (IDMS). The human samples analyzed were from an acute aflatoxicosis outbreak in Kenya in 2004 (n = 102) and the measured values ranged from 0.018 to 67.0, nondetectable to 13.6, and 0.002 to 17.7 ng/mg albumin for the respective methods. The Deming regression slopes for the HPLC-f and ELISA concentrations as a function of the IDMS concentrations were 0.71 (r(2) = 0.95) and 3.3 (r(2) = 0.96), respectively. When the samples were classified as cases or controls, based on clinical diagnosis, all methods were predictive of outcome (P < 0.01). Further, to evaluate assay precision, duplicate samples were prepared at three levels by dilution of an exposed human sample and were analyzed on three separate days. Excluding one assay value by ELISA and one assay by HPLC-f, the overall relative SD were 8.7%, 10.5%, and 9.4% for IDMS, HPLC-f, and ELISA, respectively. IDMS was the most sensitive technique and HPLC-f was the least sensitive method. Overall, this study shows an excellent correlation between three independent methodologies conducted in different laboratories and supports the validation of these technologies for assessment of human exposure to this environmental toxin and carcinogen.

Long-term stability of human aflatoxin B1 albumin adducts assessed by isotope dilution mass spectrometry and high-performance liquid chromatography-fluorescence.

The measurement of the aflatoxin B(1)-lysine serum albumin adduct in human blood samples is the most facile biomarker for the assessment of chronic exposure to aflatoxin B(1). Many technologies have been developed for the measurement of this protein adduct including immunoassays, high-performance liquid chromatography (HPLC) with fluorescence detection, and a newly developed isotope-dilution mass spectrometry method. Irrespective of the technology used to determine this adduct level, an important question remains about the long-term stability of this damage product in stored samples. To address this issue, 19 human serum samples that had been previously analyzed for the aflatoxin B(1)-lysine adduct by high-performance liquid chromatography-fluorescence in 1989 were re-analyzed by isotope dilution mass spectrometry after storage at -80 degrees C. The adduct concentrations measured by these two techniques were identical within 4% over the range 5 to 100 pg of aflatoxin B(1)-lysine/mg albumin. In addition, the specific chemical structure of the aflatoxin B(1)-lysine adduct in human samples was confirmed for the first time by collision-induced dissociation full scan mass spectrometry analysis of the protonated adduct molecular ion. These results illustrate that the aflatoxin B(1)-lysine serum albumin adduct can be stable in human serum stored at -80 degrees C since 1989, and this provides confidence for the measurement of this biomarker in repository samples from epidemiologic investigations.

Measurement of aflatoxin and aflatoxin metabolites in urine by liquid chromatography-tandem mass spectrometry.

Automated immunoaffinity solid-phase extraction followed by liquid chromatography-tandem mass spectrometry and chemical analogue internal standardization is employed to detect and quantify the aflatoxins AFB(1), AFB(2), AFG(1), AFG(2), and the metabolites AFM(1) and AFP(1) in urine. The dynamic range of the method is nearly three orders of magnitude with limits of detection in the low femtogram on column range. The method was validated over a 12-day period by eight analysts. This method is suitable for agricultural, forensic, and public health laboratories during an accidental outbreak or a chemical terrorism event where a rapid and accurate diagnosis of aflatoxicosis is needed.

The role of neutral lipid nanospheres in Plasmodium falciparum haem crystallization.

The intraerythrocytic malaria parasite constructs an intracellular haem crystal, called haemozoin, within an acidic digestive vacuole where haemoglobin is degraded. Haem crystallization is the target of the widely used antimalarial quinoline drugs. The intracellular mechanism of molecular initiation of haem crystallization, whether by proteins, polar membrane lipids or by neutral lipids, has not been fully substantiated. In the present study, we show neutral lipid predominant nanospheres, which envelop haemozoin inside Plasmodium falciparum digestive vacuoles. Subcellular fractionation of parasite-derived haemozoin through a dense 1.7 M sucrose cushion identifies monoacylglycerol and diacylglycerol neutral lipids as well as some polar lipids in close association with the purified haemozoin. Global MS lipidomics detects monopalmitic glycerol and monostearic glycerol, but not mono-oleic glycerol, closely associated with haemozoin. The complex neutral lipid mixture rapidly initiates haem crystallization, with reversible pH-dependent quinoline inhibition associated with quinoline entry into the neutral lipid microenvironment. Neutral lipid nanospheres both enable haem crystallization in the presence of high globin concentrations and protect haem from H2O2 degradation. Conceptually, the present study shifts the intracellular microenvironment of haem crystallization and quinoline inhibition from a polar aqueous location to a non-polar neutral lipid nanosphere able to exclude water for efficient haem crystallization.

Quantitative comparison of aflatoxin B1 serum albumin adducts in humans by isotope dilution mass spectrometry and ELISA.

Metabolic activation of the hepatocarcinogenic mycotoxin aflatoxin B(1) (AFB(1)) results in the covalent attachment of AFB(1) to serum albumin. Digestion of adducted albumin releases AFB(1)-lysine, a biomarker of exposure status. AF-albumin adducts have been most frequently measured in precipitated serum albumin using an immunoassay (ELISA); however, a sensitive and specific isotope dilution mass spectrometric (IDMS) assay for measurement of AFB(1)-lysine in serum has recently been developed. The ELISA and IDMS methods were compared using 20 human sera collected in Guinea, West Africa, where AF exposure is endemic. Measurement of AFB(1)-lysine adduct concentrations by IDMS in serum and albumin precipitated from the same sample revealed that precipitation has no effect on the measured adduct levels. The concentration of AF-albumin adducts measured by ELISA and AFB(1)-lysine measured by IDMS in 2 mg of albumin were well correlated (R = 0.88, P < 0.0001); however, AF-albumin adduct concentrations measured by ELISA were on average 2.6-fold greater than those of the AFB(1)-lysine adduct. Although these data suggest that the ELISA is measuring other AF adducts in addition to AFB(1)-lysine, these biomarkers are comparable in their ability to assess AF exposure at AF-albumin concentrations > or =3 pg AFB(1)-lysine equivalents/mg albumin. Identification of other adducts may clarify the mechanistic basis for using AF-protein biomarkers to assess exposure status in future epidemiologic studies of liver cancer.

Quantitative analysis and chronic dosimetry of the aflatoxin B1 plasma albumin adduct Lys-AFB1 in rats by isotope dilution mass spectrometry.

Aflatoxin B1 (AFB1) is a major risk factor in the pathogenesis of liver cancer in Asia and sub-Saharan Africa. Biomarkers reflecting exposure will facilitate disease risk assessment and the efficacy of protective interventions in these populations. The Lys-AFB1 adduct in plasma albumin is a candidate biomarker for this role. Although aflatoxin albumin adducts are most frequently measured in epidemiological studies using an enzyme-linked immunosorbent assay, a more specific and 10-fold more sensitive isotopic dilution mass spectrometric assay for Lys-AFB1 has recently become available. Here, the dosimetry of chronically administered AFB1 at lower doses than have been previously studied was explored using this assay. AFB1 was administered to rats for nine consecutive days at eight dose levels ranging from 50 pg to 55 microg/kg body wt. Plasma samples were enzymatically digested and processed by solid phase extraction. Lys-AFB1 was isolated by HPLC and detected via selected reaction monitoring. The dose-response relationship was linear-quadratic exhibiting upward curvature at higher doses. The adduct yield [(pg Lys-AFB1/mg albumin)/(microg AFB1/kg body wt)] increased nonlinearly with the dose by 6-fold between the 0.05 and 55 microg AFB1/kg body wt groups and exhibited the onset of saturation in the highest dose group where the adduct yield was approximately 2%. Incomplete knowledge of the timing of exposure and the complexity of the underlying biology confound the precise determination of prior AFB1 exposures in humans; however, the dosimetry of AFB1 observed in chronically dosed rats conceptually suggests that measurements in humans may underestimate exposure if a constant fraction of the AFB1 dose, approximately 2%, is assumed to be converted to Lys-AFB1 without regard to the dose.

Detection of Plasmodium falciparum in pregnancy by laser desorption mass spectrometry.

Detection of Plasmodium falciparum malaria during pregnancy is complicated by sequestration of parasites in the placenta, which reduces peripheral blood microscopic detection. Laser desorption mass spectrometry (LDMS) has previously demonstrated sensitive detection of hemozoin from P. falciparum blood cultures and the ability to track parasitemia in a Plasmodium yoelii malaria mouse model. Here we use a simple, dilution in water, blood sample preparation protocol for LDMS detection of malaria in 45 asymptomatic, pregnant Zambian women. We compare LDMS to microscopy and polymerase chain reaction (PCR) analysis. All women were microscopy negative. LDMS detected P. falciparum hemozoin in 15 out of 45 women, while PCR results were positive in 25 women. Compared with PCR, which analyzed 20-30 microL of blood, the sensitivity of LDMS, which analyzed < 1 microL of blood, was 52%, with a specificity of 92%. LDMS is a potentially rapid and more sensitive alternate diagnostic method than microscopy.

Analysis of aflatoxin B1-lysine adduct in serum using isotope-dilution liquid chromatography/tandem mass spectrometry.

A method for quantitative analysis of aflatoxin B1-lysine adduct (B1-Lys) in serum by liquid chromatography using tandem mass spectrometry (LC/MS/MS) is presented. The protein in a 250-microL sample was digested in the presence of a stable-isotope internal standard during a 4-h incubation at 37 degrees C with Pronasetrade mark. B1-Lys and the internal standard were extracted using mixed-mode solid-phase extraction cartridges and eluted with 2% formic acid in methanol. Following evaporation and reconstitution, extracts were injected onto a Luna C-18(2) column and eluted with a step gradient of acetonitrile and 0.06% formic acid. The B1-Lys and the internal standard were detected in a positive ionization selective reaction monitoring mode with a ThermoFinnigan TSQ Quantum triple quadrupole mass spectrometer. Calibration curves were linear for concentrations from 0.05-8.0 ng/mL. The method was validated with aflatoxin B1 dosed rat serum diluted to anticipated high and low concentrations. Total imprecision determined from 30 measurements over 15 days was 5.6% and 9.1%, respectively. Recoveries of 78.8 +/- 6.4% for B1-Lys and 85.4 +/- 12.4% for the internal standard were based on the full extraction and reconstitution processes. The method can be used to quantitate B1-Lys at the 0.5 pg/mg albumin level and is suitable for routine analysis.

Nosocomial malaria and saline flush.

An investigation of malaria in a US patient without recent travel established Plasmodium falciparum molecular genotype identity in 2 patients who shared a hospital room. P. falciparum can be transmitted in a hospital environment from patient to patient by blood inoculum if standard precautions are breached.

Rapid detection of malaria infection in vivo by laser desorption mass spectrometry.

Rapid diagnosis leading to effective treatment is essential to control escalating infectious diseases such as malaria. Malaria pigment (hemozoin) detection by laser desorption mass spectometry (LDMS) was recently shown to be a sensitive (<10 parasites/muL) technique for detecting Plasmodium falciparum parasites cultured in human blood. To examine the use of LDMS in a rapid new malaria screening assay, we followed the time course of P. yoelii infections in mice in parallel with light microscopy and a colorimetric hemozoin assay. Hemozoin was detected by LDMS in 0.3 muL of blood within two days of infection independently of the inoculating dose of 10(6), 10(4), or 10(2) parasite-infected erythrocytes. Microscopy and colorimetric hemozoin determinations lagged the LDMS detection of infections by 2-4 and 3-5 days, respectively, except at the highest inoculation dose. The LDMS detection of hemozoin is a potentially more rapid screen than light microscopy for detecting malaria infection in this mouse model at parasitemias <0.1%.