Quality designations

When ordering chemicals, it is necessary to specify the quality accurately, since the purity of a chemical is critical to the success of an experiment. The following additional indications of the quality of a chemical are arranged in order of increasing purity:

1. crude
2. technical
3. synthesis
4. pure
5. ultrapure
6. for analysis
7. ultra pure

However, the required purity is not standardized and is determined by the respective manufacturer. The exact specification of a chemical of apparently the same purity is therefore dependent on the manufacturer.

In the case of fine chemicals that bear at least the designation "pure," the type and amount of impurity can be determined from certificates of analysis. The minimum substance content and the number of impurity parameters tested are usually supplier-dependent. If you need a high degree of purity, you must check on a case-by-case basis which parameters are important to you and which supplier has the product in its range that is most suitable for your purposes.

Instructions for use

In some catalogs you will find additional instructions for the use of the substance. This should not be interpreted as a restriction of use. Application notes "for microscopy" or "for biochemical purposes" merely state that certain specifications are specially adapted to these applications.

Pheur at mychem.ch means that this substance is suitable for pharmaceutical purposes.

Components

Read all information about the desired chemical in the sales catalog carefully. The quality may also differ due to accompanying substances such as water content or residues from purification processes. Abbreviations are often used to describe chemicals more accurately. In addition, some chemicals have adjuvants added to them specifically to stabilize them for storage and transport (antioxidants, radical inhibitors, etc.).

Chemical purity grades

German and Latin designations from pharmacology are commonly used to describe chemical purity grades:

1. crd.
    crudum (= crude), i.e. unpurified grade

2. technical
    Technical quality. Products with the purity designation "technical" have a different content.
    They are usually produced on a large scale and may have some foreign odor and and color. They are used for general technical purposes.

3. for synthesis
    Usually contain small amounts of impurities, but these do not usually interfere with syntheses,
    since the product of the synthesis is finally purified and the impurities of the starting material are separated.
    Purified and the impurities of the reactant are separated.

4. pur.
    purum (= pure), i.e. chemically pure quality.
    - minimum content 97 %, unless another content is specified in %.
    - correspond to the literature in color and characteristic data except for minor deviations.
    - suitable for synthesis and laboratory purposes (also z. Synth.)
    - Sensitive products are filled under protective gases.

5. puriss.
    purissimum (= pure; of highest purity).
    These are substances of particularly pure quality, such that with normal chem. Methods of analysis no foreign substances can be detected with normal
    chemical analysis methods:
    - Content of at least 99 % or higher (specification).
    - correspond in appearance and characteristic
      and characteristic data of the relevant literature or deviate from them only to a very small extent.
    - are suitable for work with high purity requirements.
    - Certificates of analysis are usually supplied with the product or attached to the containers.
    - sensitive products are filled under protective gas.

6. p.a.
    per analysi (= for analytical purposes)
    z. A.
    = for analysis
    The chemical is so pure that it can be used for analytical analytical methods. In the case of p.a. chemicals,
    foreign substances contained therein as well as their content are indicated so that these can be taken into account in analyses and no incorrect analytical
    results are obtained due to the chemicals used.

7. Ultrapure
    High purity products for specific applications which bear special designations of the respective manufacturers.
    All are accompanied by detailed guarantee certificates, which specify maximum contents of many relevant impurities.

Examples
Chemicals for specific applications

- Uvasol®
  Solvent for optical spectroscopy

- LiChrosolv®
  Solvent for analytical chromatography

- PrepSolv®
  Solvent for preparative chromatography

- Pestilyse®
  Solvent for residue analysis in environmental, water and food testing

- Suprapur®
  Reagent for trace analysis (ppb range)

- SupraSolv ® solvent for residue and environmental analysis in gas chromatography

- Ultrapur ®
  Reagent for ultratrace analysis (ppq - ppt- range)

- SeccoSolv® solvents
  Dried solvents with extremely low water content

Abbreviations commonly used to describe chemicals

abs.                        absolute (= purified).
anhydr.                   anhydricus (= anhydrous)
bidest.                    double distilled
conc.                      concentratus (= concentrated)
cryst.                      or crist. cystallisatum = crystallized
dep.                        or depur. depuratum (= purified)
dest.                       destillatum (= distilled)
dil.                          dilutus (= diluted)
(GC)                       Content determined by gas chromatography
wt.%                       glass distilled High purity solvent, which during the distillation process
                               and until bottling only come into contact with glassware.
cryst.                      crystallized
praec.                     Abbreviation for praecipitatum = precipitated
redest.                    double distilled
resubl.                    twice sublimed
sicc.                        siccatum (= dried, anhydrous)
sine H2O                without water
sol.                         or solut. solutus (= dissolved)
stab.                       stabilized
subl.                       sublimatum (= sublimed)
subt.                       subtilis (= fine)
tot.                         abbreviation for totus = whole, undivided
pharm.                   pharmaceutical grade, suitable for pharmaceutical purposes
ACS                       American Chemical Society
DAB                       German Pharmacopoeia
DAC                       German Drug Codex
ISO                        International Organization for Standardization
Ph. Eur.                 European Pharmacopoeia

Pharmacopoeia quality

In the range of pharmacopoeia-compliant products, two groups can be distinguished, each of which is fully tested and documented according to the required standards:

- Reag. PhEur Analytical Reagents
  These are products that are chemically specified according to the methods of pharmacopoeial analysis, i.e. they meet the requirements of the European
  Pharmacopoeia. They are therefore suitable for standard pharmacopoeial analysis methods.

- ACC Analytical Reagents
  Analytical reagents may also be specified according to the American ACS standard only; they fulfill the requirements of the American Pharmacopoeia.